JAN 1 2 2004 ‘r -J c ABSTRACT THE INTERRELATIONSHIPS 0F HONEY BEE ACTIVITY, FORAGING BEHAVIOR, CLIMATIC CONDITIONS, AND FLOWERING IN THE POLLINATION 0F PICKLING CUCUMBERS, CUCUMIS SATIVUS L. By Clarence H. Collison Prior to successful pollination of pickling cucumbers, anthe- sis, anther dehiscence, nectar secretion, and initiation of foraging by the honey bee, Apis mellifera L., must occur, and all were pri- marily dependent on temperature. Anthesis began at 15° C; nectaries became moist and anthers dehisced at l6° C; and foraging activity was first observed at 16.5° C under normal conditions. Completion of anther dehiscence occurred at l9° C and maximum foraging between 2l.5 and 30.0° C. Cucumber pollen was viable and stigmas receptive at the time of anther dehiscence. Pollination must take place on the day of anthesis, since pollen viability, stigmatic receptivity, and attractiveness to the bee last only one day. Daily foraging activity and nectar secretion fluctuated in relation to environmental conditions. Multiple regression analysis indicated that bee flight was a function of temperature, solar radia- tion, relative humidity, and wind speed. Nectar volume and sugar production in pistillate flowers were functions of temperature, solar radiation of the three previous days, relative humidity, and the Clarence H. Collison total precipitation of the four previous days. In staminate flowers nectar secretion was positively affected by wind speed and negatively by precipitation. The sugar concentration of nectar was dependent on relative humidity, wind speed, and temperature. The pattern of bee visits throughout the day produced a normal distribution centered at 11 - 12 a.m. EST. From 9 a.m. to 2 p.m. 82.3% of all visits occurred. From 7 - 9 a.m. pistillate flowers were more attractive than staminate. After 9 a.m. staminate flowers were preferred and preference increased throughout the day. Bees spent almost twice as long per visit on pistillate flowers as on staminate. Except for early morning and late afternoon, the average time bees spent on the flowers decreased throughout the day. Honey bees averaged 11.4 sec per flower visit for an overall foraging rate of 5.3 flowers per min. Sugar concentration was 40% higher in bee- excluded than bee visited flowers or nectar removed from the honey stomachs of bees. Cucumber pollen was found primarily on mouthparts, ventral surface of the thorax, prolegs, mesolegs, and metalegs. The bees first visit to a flower placed significantly more pollen on the stigma than succeeding visits. Honey bees are capable of distributing cucumber pollen 60 — 70 feet from the pollen source, although the efficiency of the movement decreased after 10 feet. Flowers should receive 15 - 20 visits on the day of anthesis for maximum fruit set. Multiple bee visits increased fruit set and the average number of seeds per fruit but the number of perfectly shaped fruit did not increase accordingly. Clarence H. Collison Availability of pollen along with decreased light intensity and increased plant vigor seemed to trigger parthenocarpic fruit production. Fruit inhibition limited fruit production and excessive production of staminate flowers limited fruit uniformity for mechani- cal harvesting. The transition from monoecious to gynoecious cultivars and high plant densities have changed the energetics of the flower- visitor relationship in the field. There was an inverse relationship between potential fruit production and total caloric reward available to the bee. Under optimum conditions, cucumbers produced an esti- mated 2.82 l of nectar/acre of 198,313 plants/day which would yield 2.13 pounds of honey. As the number of bee visits increased, the average area of individual visits increased. Perfectly shaped fruit contained from 0 - 546 seeds. No sig- nificant correlations were obtained between production of perfectly shaped fruit and daily staminatezpistillate flower ratio, average seed count, or total bee visits per flower. Maximum yield for machine harvest was achieved in less than a week when pickles had otimum pollen, uniform flowering, plenty of bees six days after the start of flowering, and good flying weather (temperatures above 21° C, relative humidity below 70%, winds less than 15 mph, plants dry, and bright sunshine). A technique is pre- sented for the grower or researcher to assess pollinator activity in pickle fields in relation to needs for optimum pollination. A simu- lated mathematical model was developed to interpret the complex interrelationships between bees, flowers, and pollination of the crop. Clarence H. Collison It applied to daily ratio of staminate and pistillate flowers, nectar yield, number of foraging trips to collect available nectar, and potential fruit yield for various plant populations, cultivars, and seed blends. THE INTERRELATIONSHIPS OF HONEY BEE ACTIVITY, FORAGING BEHAVIOR, CLIMATIC CONDITIONS, AND FLOWERING IN THE POLLINATION OF PICKLING CUCUMBERS, CUCUMIS SATIVUS L. By Clarence H. Collison A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Entomology 1976 ACKNOWLEDGMENTS I am indeed very grateful to Dr. E. C. Martin for his guid- ance, encouragement, patience, and support during the past three years which were needed to complete this work. Even while he was on his.new job and on other assignments he always found time to supply needed direction on the project. I am grateful to the USDA Agricultural Research Service, Entomology Research Division, Apicultural Research Branch for finan- cial and advisory support under a Cooperative Agreement arrangement during part of the work and to the MSU Ad Hoc Pickle Research Commit- tee forits support. Special thanks to Mr. S. E. McGregor and Dr. M. D. Levin of the Apiculture Research Branch, USDA for suggestions and ideas. I wish to thank those individuals who have served on my guidance committee, Dr. Roger Hoopingarner, Dr. Roland Fischer, Dr. Larry Baker, and Dr. Stanley Wellso. Dr. Baker is thanked for supplying seeds and Dr. James Motes for access to their plots. Thanks are extended to Dr. James Bath, chairman of the Ento- mology Department for providing an office, field plots, and green- house space. I would also like to thank Dr. R. L. Tummala and Ken- neth Dimoff for their help in developing the model and computer program. ii Special thanks to Dr. Lawrence Connor, Ohio State University for his assistance and advice during the project. Appreciation is extended to all summer help, especially to Larry Olsen, Torre Meeder, and Mike Corneil. I am most deeply grateful to my wife, Sally, sons Craig and Keith for the sacrifices they had to make during this project. Thanks to my wife for all of her moral support and proof reading. Finally, I thank our families and friends who have offered their support. TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES INTRODUCTION . . . . LITERATURE . Climatic Conditions Affecting Anthesis and Anther Dehiscence . Duration of Pollen Viability and Stigmatic Recep- tivity . Climatic Conditions Affecting Foraging Activity in the Field . . . Climatic Conditions Affecting Nectar Secretion . Sugar Concentration of Cucumber Nectar Throughout the. Day with Bee Visitation . . . Distribution of Cucumber Pollen on the Honey Bee' 5 Body The Number of Bee Visits Needed for Adequate Pollina-. tion . . The Timing of Honey Bees as They Foraged on Cucum- bers . . . . . . . . The Size of the Foraging Area . The Movement of Cucumber Pollen by Honey Bees . . The Relationship of Foraging Activity to Fruit Set Fruit Inhibition . . . MATERIALS AND METHODS Climatic Conditions Affecting Anthesis and Anther Dehiscence . Duration of Pollen Viability and Stigmatic Recep- ‘tivity . Length of Time Flowers are Open in the Field . Climatic Conditions Affecting Foraging Activity in the Field . . . Climatic Conditions Affecting Nectar Secretion . Foraging Activity in Relation to Flower Age . iv Page vii xiv 23 23 25 26 27 Page Sugar Concentration of Cucumber Nectar Throughout the Day with Bee Visitation . . . . . . . 28 Foraging Activity in Relation to Flower Sex . . . . 28 Distribution of Cucumber Pollen on the Honey Bee's Body . . 29 The Number of Bee Visits Needed for Adequate Pollina- tion . . 30 The Timing of Honey Bees as They Foraged on Staminate and Pistillate Cucumber Flowers . . . . . . . 30 The Size of the Foraging Area . . . . . 31 The Movement of Cucumber Pollen by Honey Bees . . . 31 The Movement of Fluorescent Powder . . . 34 The Relationship of Foraging Activity to Fruit Set . 35 Changes in the Foraging Population with Additional Colonies in the Field . . . 36 Fruit Inhibition . . . . . . . . . . . . . 36 RESULTS . . . . . . . . . . . . . . . . . . 38 Climatic Conditions Affecting Anthesis and Anther Dehiscence . . 38 Duration of Pollen Viability and Stigmatic Recep-. tivity . . . 41 Length of Time Flowers are Open in the Field . . . 44 Climatic Conditions Affecting Foraging Activity in the Field . . . . . 46 Climatic Conditions Affecting Nectar Secretion . . . 73 Foraging Activity in Relation to Flower Age . . . . 122 Sugar Concentration of Cucumber Nectar with Bee Visitation throughout the Day. . . . . . 122 Foraging Activity in Relation to Flower Sex . . . . 124 Distribution of Cucumber Pollen on the Honey Bee's Body . . 129 The Number of Bee Visits Needed for Adequate Pollina- tion . . 131 The Timing of Honey Bees as They Foraged on Staminate and Pistillate Cucumber FLowers . . . . . . . 141 The Size of the Foraging Area . . . . 151 The Movement of Cucumber Pollen by Honey Bees . . . 157 The Movement of Fluorescent Powder . . . 175 The Relationship of Foraging Activity to Fruit Set . 183 Changes in the Foraging Population with Additional Colonies in the Field . . . . 192 Fruit Inhibition . . . . . . . . . . . . . 193 Page DISCUSSION . . . . . . . . . . . . . . . . . 197 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . 245 APPENDICES . . . . . . . . . . . . . . . . . 252 A. Cucumber Grading Standards . . . . . . . . 253 B. Ecological Model of the Pickling Cucumber Field . 255 LITERATURE CITED . . . . . . . . . . . . . . . 260 vi Table 10. 11. 12. LIST OF TABLES The corolla expansion rate of staminate and pistil- late cucumber flowers on the morning of anthesis, 1969. . . . . . . Fruit development following hand pollinations made at the time of anther dehiscence in cucumbers . . Percentage of day-old staminate and pistillate cucum- ber flowers open in the pollen movement strips, 1969 . . . . . . . . . Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, 1974 Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, East Lansing, 1974 . . . . . . . . . . . Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, Eaton Rapids, 1974 . . Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, Mulliken, 1974 . . . . . Honey bee foraging activity in cucumbers as affected by solar radiation, East Lansing, 1974 Honey bee foraging activity in cucumbers as affected by relative humidity, East Lansing, 1974 Honey bee foraging activity in cucumbers as affected by wind speed, East Lansing, 1974 . . . Honey bee foraging activity in cucumbers throughout the day, Eaton Rapids, 1974 . . . . . . Honey bee foraging activity in cucumbers throughout the day, Mulliken, 1974 . . . . . vii Page 41 42 45 47 50 51 52 54 55 57 65 66 Table Page 13. Foraging activity of honey bees in cucumbers in rela- tion to climatic conditions, East Lansing, 1974 . . 67 14. Average daily foraging activity in cucumbers in rela- tion to temperature, Eaton Rapids, 1974 . . . . . 71 15. Average daily foraging activity in cucumbers in rela- tion to temperature, Mulliken, 1974 . . . . . . 72 16. The average volume of nectar, sugar concentration, and total weight of sugar secreted daily by pistil— late cucumber flowers, 1968. . . 88 17. The average volume of nectar, sugar concentration, and total weight of sugar secreted daily by stamin- ate cucumber flowers, 1969 . . . . . . . . . 89 18. Climatic conditions affecting nectar production in pistillate cucumber flowers during 1968 . . . . . 108 19. Climatic conditions affecting nectar production in staminate cucumber flowers during 1969 . . . . . 109 20. The affect of temperature on the volume of nectar produced in cucumber flowers . . . . . . . . 110 21. The affect of temperature on the sugar concentration of nectar from cucumber flowers . . . . . . . 111 22. The affect of temperature on the actual weight of sugar in the nectar of cucumber flowers . . . . . 112 23. The affect of humidity on the volume of nectar in cucumber flowers . . . . . . . . . . . . 113 24. The affect of humidity on the sugar concentration of nectar in cucumber flowers . . . . . . . . 114 25. The affect of humidity on the actual weight of sugar in the nectar of cucumber flowers . . . 115 26. The affect of solar radiation on nectar secretion of cucumber flowers as determined by correlation coef- ficients . . . . . . . . . . . . . . . 116 27. The affect of precipitation on daily nectar secre- tion in cucumbers as determined by correlation coefficients . . . . . . . . . . . . . . 119 viii Table Page 28. Concentration of cucumber nectar in the honey stom- achs of honey bees throughout the day . . . . . 123 29. Concentration of cucumber nectar in the honey stom- achs of honey bees after removal of low values . . 123 30. Daily variation in the concentration of cucumber nectar found in the honey stomachs of honey bees . . 124 31. Foraging behavior in relation to staminate and pistillate cucumber flowers in the field . . . . 125 32. Comparison of morning and afternoon foraging behav- ior in relation to staminate and pistillate cucumber flowers in the field . . . . . . . . . . . 127 33. Hourly foraging activity in relation to staminate and pistillate cucumber flowers . . . . . . . 128 34. The location of cucumber pollen on the honey bee's body . . . . . . . . . . . . . . . . 130 35. Cucumber pollen distribution on the bodies of honey bees taken from staminate and pistillate cucumber flowers . . . . . . . . . . . . . . . 132 36. Percentage fruit set, average seed counts, and fruit shape as affected by number of bee visits in cucum- bers . . . . . . . . . . . . . . . . 133 37. Amounts of pollen placed on the stigma of a pistil- late cucumber flower during varying numbers of bee visits as indicated by number of seeds produced . . 134 38. The flowering pattern of the cucumber cultivar Piccadilly prior to allowing a specified number of bee visits . . . . . . . . . . . . . 135 39. Flowering pattern of the June 30 planting of Picca- dilly prior to the start of bee observations . . . 136 40. Average number of seeds obtained from the three shapes of cucumbers . . . . . . . . . . . 137 41. The effect of time of day of pollination on percent fruit set, fruit shape, and seed countsiilcucumbers . 139 ix Table Page 42. Daily variation in fruit set, shape, and amount of pollen being distributed with each bee visit in cucumbers . . . . . . . . . . . . . . . 140 43. The effect of node position on fruit set and shape with competitive fruit removed in cucumbers . . . 142 44. The average visit time of a honey bee on cucumber flowers, throughout the day, including time in flight between flower visits . . . . . . . . 148 45. The average time spent per flower visit throughout the day including flight time between flower visits at Eaton Rapids and East Lansing in cucumbers . . . 150 46. Minimum and maximum distances and areas covered by the honey bee during foraging in cucumbers . . . . 152 47. Average area covered by a foraging honey bee in cucumbers . . . . . . . . . . . . . . 153 48. Average length, width, and feet per flower visit covered by a foraging honey bee in cucumbers . . . 153 49. The average foraging area per bee with a specific number of visits to cucumber flowers . . . . . . 155 50. Foraging profile of the honey bee in cucumbers throughout the day . . . . . . . . . . . . 156 51. Daily foraging profile of the honey bee in cucum- bers . . . . . . . . . . . . . 158 52. Average number of pickles per plant, pollen move- ment strips, 1969 . . . . . . . . . . . . 160 53. Average number of pickles per plant in the first harvest, pollen movement strips, 1969 . . . . . 162 54. Average number of pickles per plant in the second harvest, pollen movement strips, 1969 . . . . . 163 55. The affect of various levels of available cucumber pollen on fruit production and seed counts at differ- ent distances from the pollen source, 1969 . . . . 164 56. Average number of seeds per fruit in pollen movement strips, 1969 . . . . . . . . . . . . . . 166 Table Page 57. Average number of seeds per fruit, first harvest, pollen movement strips, 1969 . . . . . . . . 168 58. Average number of seeds per fruit, second harvest, pollen movement strips, 1969 . . . . . . . . 169 59. Cucumber fruit production at different distances from a source of pollen, 1972 . . . . . . . . 172 60. Number of seeds in cucumbers at different distances from a source of pollen, 1972 . . . . . . . . 173 61. Movement of bees in cucumbers as indicated by trans- port of fluorescent powder, 1971 . . . . . . . 175 62. Movement of fluorescent powder by honey bees in cucumbers using a circular sampling pattern . . . 176 63. Movement of fluorescent powder among cucumber flowers by honey bees at East Lansing, 1971 . . . . . . 177 64. Movement by honey bees of fluorescent powder in com- mercial cucumber fields . . . . . . . . . . 179 65. Movement of fluorescent powder from flower to flower in cucumbers by honey bees using a locus of 50 dusted flowers . . . . . . . . . . . . . 180 66. The number of staminate flowers in the gynoecious strips and the monoecious pollen source, 1972 . . . 181 67. Movement by honey bees of fluorescent powder in cucumbers at East Lansing, 1973 . . . . . . . 182 68. Comparison of movement by honey bees of two concen- trations of fluorescent powder in a field of cucum- bers, 1973 . . . . . . . . . . . . . . 184 69. Flowering pattern of cucumber cultivar Piccadilly, 1974 . . . . . . . . . . . . . . . . 185 70. Flowering pattern of cucumber cultivar MSU 9805, 1974 . . . . . . . . . . . . . . . . 186 71. Average daily foraging activity in cucumbers, East Lansing, 1974 . . . . . . . . . . . . . 187 xi Table Page 72. Fruit set in the Piccadilly cucumber plot, East Lansing, 1974 . . . . . .. . . . . . . . 189 73. Average number of seeds per fruit, Piccadilly plot, East Lansing, 1974 . . . . . . . . . . . . 190 74. Fruit shape analysis of the Piccadilly cucumber plot . . . . . . . . . . . . . . . . 190 75. Results of the Piccadilly simulated cucumber harvest . . . . . . . . . . . . . . . 191 76. The dollar value per acre of the cucumber cultivar MSU 9805-~estimate based upon 50,000 plants per acre . . . . 192 77. The inhibition of fruit development as affected by previous fruit set on the cucumber vine . . . . 194 78. Influence of position on the cucumber vine, on fruit set and shape, MSU 9805 . . . . . . . . . . 195 79. Projected number of bee visits for the day based on the number of bees visiting 10 cucumber flowers in ten minutes with three samples per hour . . . . . 227 80. The amount of nectar the honey bee removes from the pistillate cucumber flower throughout the day . . . 230 81. The predicted amount of nectar removed from pistil- late and staminate cucumber flowers throughout the day by the honey bee . . . . . . . . . . . 230 82. Flowering patterns of various cucumber cultivars . . 234 83. Projected production of staminate and pistillate cucumber flowers for different cultivars and seed mixtures (20,000 plants/acre, 10 acres) . . . . . 236 84. Projected potential nectar production in a 10 acre cucumber field of various cultivars and seed blends for 20,000 and 198,313 plants/acre . . . . . . 238 85. Projected number of foraging trips required to col- lect the nectar produced in a 10 acre cucumber field of various plant populations, cultivars, and seed blends . . . . . . . . . . . . . . . 240 xii Table Page 86. Projected potential fruit production of 10 acre cucumber fields- of various plant populations, 'cultivars, and seed blends for 20, 000 and 198, 313 plants/acre . . . . . 241 xiii 10. 11. 12. 13. LIST OF FIGURES Cucumber pollen movement strips, 1969 Cucumber pollen movement strip, 1972 . Piccadilly plot in 1974 used to determine the rela- tionship of foraging activity to fruit set in cucumbers . . . . . . . Staminate cucumber flowers opening at a faster rate than pistillate on August 5,1969, at 7 a.m. EST, 8° C O O O O O O I O O O O 0 Honey bee foraging activity in cucumbers in relation to temperature, 1974 . . . . . . . . . Honey bee flight activity hicucumbers throughout the day and average hourly temperature, 1974 . . . . Honey bee flight activity in cucumbers throughout the day and average hourly temperature in East Lansing Honey bee flight activity in cucumbers throughout the day and average hourly solar radiation in East Lansing . . . . . . . . . . Honey bee flight activity in cucumbers throughout the day and average hourly relative humidity in East Lans ng . . . . . Honey bee flight activity in cucumbers throughout the day and average hourly wind speed in East Lansing Above average foraging activity in cucumbers due to favorable climatic conditions, August 13, 1974 Below average foraging activity in cucumbers due to unfavorable climatic conditions, August 14, 1974 . The effect of threatening storms and rain on forag- ing activity in cucumbers, August 2, 1974 xiv Page 39 39 39 39 48 58 61 61 63 69 69 74 Figure ' Page 14. The effect of threatening storms and rain on forag- ing activity in cucumbers, August 16, 1974 . . . . 74 15. The effect of threatening storms and rain on forag- ing activity in cucumbers, August 23, 1974 . . . . 76 16. The percent of staminate and pistillate cucumber flowers producing nectar throughout the day . . . 78 17. The average volume of nectar produced by staminate and pistillate cucumber flowers throughout the day . 81 18. The average sugar concentration of cucumber nectar produced by staminate and pistillate flowers and as it is collected by the honey bee throughout the day . 83 19. The average weight of sugar in cucumber nectar pro- duced by staminate and pistillate flowers throughout the day . . . . . . . . . . . . . . . 85 20. The daily average volume of nectar produced by pistillate cucumber flowers in relation to tempera- ture . . . . . . . . . . . . . . . . 93 21. The daily average sugar concentration of nectar pro- duced by pistillate cucumber flowers in relation to temperature . . . . . . . . . . . . . . 95 22. The daily average weight of sugar in cucumber nectar produced by pistillate flowers in relation to tem- perature . . . . . . . . . . . . . . . 97 23. The daily average volume of nectar produced by stam- inate cucumber flowers in relation to temperature . 99 24. The daily average sugar concentration of nectar pro- duced by staminate cucumber flowers in relation to temperature . . . . . . . . . . . . . . 101 25. The daily average weight of sugar in cucumber nectar produced by staminate flowers in relation to tempera- 103 ture . . . . . . . . . . . . . . . . 26. Comparison of the time spent on pistillate and stam- inate cucumber flowers by honey bees throughout the day . . . . . . . . . . . . . . . . . 143 27. Average daily foraging time spent on staminate and pistillate cucumber flowers . . . . . . . . . 146 Xv Figure Page 28. A functional representation of the pollination ecol— ogy model used to interpret the complex interrela- tionships between honey bees, flowers, and pollina- tion in the production of pickling cucumbers . . . 256 xvi INTRODUCTION Flowers provide two types of attractants for the honey bee, Apjs mellifera L.; primary which satisfy demands for food (nectar and pollen), and secondary that serve as labels which start a direct or indirect reaction of the sensory system in the visitor and would include texture, form, color, and odor. Primary attractants serve as a reward for the visitor; however, they would be useless by themselves, unless accompanied by the secondary labels, Faegri and van der Pijl (1966). The efficiency of pollination of any bee-pollinated crop must depend upon its profitability as a source of food for the visi- tor. Hithout this reward and sensory stimulation, the stimulus for the next response in the foraging sequence would be absent and the behavior pattern broken, Doull (1971). Pollination of pickling cucumbers results from the establish- ment of a flower-visitor relationship. In plants where nectar appears to be more attractive than pollen, as in cucumbers, pollen presenta- tion must be synchronized with nectar presentation to accomplish pollination, Faegri and van der Pijl (1966). It is believed that long range attraction of the bee to the flower is based on vision, while close orientation depends on odor and surface texture. Surface texture is important in providing a foothold for the visitor and for light reflection. The original visual response depends on flower size, segmentation, depth, and 1 color, Faegri and van der Pijl (1966). Brett and Sullivan (1972) found that the corollas of cucumber flowers provide the bee with marked contrast in color. Photographs through an ultraviolet filter showed that the central part of the corolla reflected only yellow light compared to a mixture of yellow and ultraviolet in the outer portion of the corolla. The nectar supply present may also provide the bees with a visual clue. Thorp, Briggs, Estes and Erickson (1975) found that nectar of cucumber fluoresced in the visible and absorbed in the ultraviolet spectrum. They suggested this may serve as a visual cue that foraging bees could use to determine the quantity of nectar available. The honey bee exhibits a constancy for one flower species during foraging for long periods of time. Flower constancy is actu- ally a preference, since the bee has identified the location, learned the secondary flower labels, discovered how to manipulate the blossom, and experienced the reward of acceptable nectar and pollen, Faegri and van der Pijl (1966). Heinrich and Raven (1972) pointed out that little attention has been paid to the caloric reward provided by the flowers of a particular plant species to the pollinator. They hypothesized that the amount of nectar per flower, in terms of calor- ies of food energy needed to bring about maximum cross-pollination, would be related to the characteristic rate of energy expenditure of the pollinators. Other factors affecting the energetics of the interrelationship between plant and pollinator would be plant density, distance the bee has to travel between flowers, and ambient tempera- ture. The pollination mechanism of pickling cucumbers involves three phases; (1) release of pollen in the staminate flowers, (2) transfer of pollen from the staminate to the pistillate flower by a biotic agent, and (3) successful placement of pollen on the stigmatic surface followed by pollen grain germination. Honey bees have been recognized as necessary for economical cucumber production by Seaton, Hutson and Muncie (1936), Kremer (1943), Tuljyenkova (1955), Alex (1957), Glushkov (1958), Markov and Romanchuk (1959), Warren (1961), Shahin (1967), Williams and Kauffeld (1967), Connor (1969), Seyman et a1. (1969), and Brett and Sullivan (1972). Current recommendations vary from one colony per four acres, Ward (1973), 0.6-1 colony per 2.5 acres, Glushkov (1958), 1 colony per acre, Rahmlow (1970), Sims and Zahara (1968), Brett and Sullivan (1972), Steinhauer (1970), one colony for every 50,000 plants in the field, Connor (1969), Cantliffe (1974), 1-2 colonies per acre, Stanger and Thorp (1972), Stephen (1970a), Seyman et a1. (1969), 3 colonies per acre, Lawin (1974) and up to four hives per acre, Jaycox (1969). Michigan has led the nation in pickle production every year but two since 1918, Michigan Science in Action (1974). However, pickle production in Michigan has undergone recent changes which have greatly increased the need for bees and for a better understand- ing of the complex interrelationships involved in the pollination of the crop. The ratio of staminate and pistillate flowers has been altered in the field through the development and use of gynoecious (predominantly pistillate) hybrids and mechanical harvesting. Over 90% of the 1973 crop in Michigan was harvested mechanically, Michigan Science in Action, (1974). Because uniform, small cucumbers bring top prices, adequate pollination within a restricted time span is essential for an optimum machine-harvest yield. With the change to mechanical harvesting, plant populations in the field have increased rapidly from less than 20 thousand plants per acre to populations up to and exceeding 200,000 plants per acre. With more flowers per acre, the nectar and pollen productivity of the field is greatly increased and the honey bee has to expend less energy to get from flower to flower. This should make the crop more attractive to bees. On the other hand, the need for maximum pollina- tion in as short a time as possible for an economical and uniform fruit set, may influence the grower to flood the field with bees, which would cause the energy budget to flow in the opposite direction because of increased competition. In determining the number of honey bee colonies needed to pollinate a given area of a crop, various ecological factors must be considered. Any estimate of pollinator needs should take into account the attractiveness of the cr0p; weather conditions during the blooming period; density of flowering; the amount of neCtar and pollen produced; the number of pollinating insects present; the behavior of bees on the crop; competitive plants in the area; and the morphologi- cal, physiological, and behavioral characteristics of the flowers. The following study was undertaken to gain a better under- standing of the complex interrelationships between the honey bee, flowers, and the weather, all of which are involved in crop pollina- tion. This information should give apiculturists and pickle growers a better idea of the level of bee activity needed for maximum pollina- tion and economic return. It is hoped that this work will provide a useable procedure for rapid and accurate assesSment of the pollin- ating force required for cucumber production and that this knowledge may simplify development of similar formulae for other crops. -LITERATURE Climatic Conditions Affecting Anthesis and Anther Dehiscence Seaton, Hutson, and Muncie (1936) reported that both staminate and pistillate cucumber flowers usually open about two hours after sunrise, but the opening was markedly influenced by temperature and humidity. Seaton and Kremer (1938a) found that in Michigan the flowers reached anthesis at a temperature of 15 to 16° C. Peto (1951) observed that on average days, cucumber flowers were open at 6:45 a.m., Standard Time. In Russia, Nemirovich-Danchenko (1964) found the flowers to open between 7 and 11 a.m., 1.5-2 h later in colder weather. Seaton and Kremer (1938a) observed that the flowers borne above the leaves and exposed to the sun would open earlier than those in the shade under the leaves. However, they found the deter- mining.factor to be temperature, as all flowers opened at the same time when cloudy weather prevailed. Banadyga (1949) reported that temperature was the most impor- tant climatological factor influencing dehiscence of the pollen sacs in cucurbits. Dehiscence may occur at any time of day with the proper temperature. Seaton and Kremer (1938a) and Cantliffe (1974) found that anther dehiscence did not occur until 17° C and was opti- mum at 18-21° C. Brett and Sullivan (1972) observed that optimum dehiscence occurred at 19° C. Seaton and Kremer (1938a) found that anthesis and dehiscence during August and September usually occurred 6 between 6 and 9 a.m., with a mean time of 8 a.m. However, on warm days fully opened flowers with dehisced anthers were observed as early as 4 a.m. while on cool days (13° C or below) the flowers and the theceae of the anthers remained closed throughout the day. A highly significant positive correlation was found between the time of day and stage of anther dehiscence. However, they concluded that even though the time of day was a controlling factor for both anthesis and anther dehiscence, it undoubtedly was modified by temperature, since a highly significant positive correlation was found between temperature and anther dehiscence. Humidity apparently was not opera- tive in influencing the time of anthesis or dehiscence. Seaton, Hut- son, and Muncie (1936) reported that pollen was released soon after the petals were fully expanded. Duration of Pollen Viability and Stigmatic Receptivity Barnes (1947), working under greenhouse conditions, found that anthers dehisced between 9 and 9:30 a.m., and pollen remained viable until 1 or 2 p.m. The optimum time for effective pollination was noon. Hayase (1955) found that the pollen actually became viable before the anthers dehisced, with maximum viability being at 20-25° C. Viability changed little when the staminate flowers were stored at 15-30° C for 21h prior to anther dehiscence but with storage for 39 h, viability was prolonged by the lower temperatures and curtailed by the higher. Banadyga (1949) reported that the germination of pollen did not occur below 21° C, with the optimum being between 27-29° C. Therefore, he concluded in order to get pollination and fruit, the temperature must be above 21° C. Seaton and Kremer (1938b) found that little or no germination or pollen tube growth was observed at temperatures below 18° C. Knysh (1958) removed cucumber pollen from marked bees trapped at the hive entrance returning from plots 250, 500, 750, and 1000 m from the hive. This procedure was completed between 7-11 a.m. at temperatures of 19-20° C and a rela- tive humidity of 60-70%. Pollen viability rapidly diminished with distance, with no germination at 750 m or more. It was believed that the loss of viability was because of the drying of grains, as the bees flew in a current of dry air. Banadyga (1949) also reported that laboratory tests have shown cucumber pollen to be quite sensi- tive to water absorption. This would help explain poor pollination during long periods of rainy weather. Rain may also wash pollen off the anthers before fertilization takes place. Choudhury and Phatak '(1961) found that temperature influenced anther dehiscence and pollen fertility of cucumbers in India. However, under the high temperatures of Indian growing conditions, light intensity, and the time of day _ influenced anthesis far more than temperature. Under high tempera- ture conditions, the period of receptivity of the cucumber stigma was short. Connor (1969) found no evidence that the stigma of the pistil- late flower was receptive for only a Short period of time in Michi- gan, as was observed in India. Successful pollinations were obtained at separate intervals throughout the day, implying that whenever bees were present in the field, fruit could be set. Cantliffe (1974) reported that pistillate flowers were receptive to pollen for 24 h or less depending on environmental conditions. High temperature, high humidity, wind, or drought shortened the time for pollination to fertilization. Seaton, Hutson, and Muncie (1936) reported that the stigma was receptive on the day the flower opened until the afternoon of the same day. They found the stigma most receptive early in the morning, but greatly influenced by climatic conditions. Climatic Conditions Affecting Foraging Activity in the Field Kremer (1943) observed that bees did not appear in cucumber fields until after the pollen had begun to dehisce and nectar was being secreted. Banadyga (1949) reported that bees did not travel very far from the hive during cool, cloudy, or showery weather; thus, the proximity of hives to cucumber fields may decidedly influence the yield of fruit. Peto (1951) reported that weather conditions were the greatest cause of variability of visits to cucumber flowers. On cool, windy, and foggy days, the foraging population was definitely less. Kauffeld and Williams (1972) found that favorable conditions for cucumber pollination by honey bees were: temperature above 21° C, relative humidity below 70%, winds less than 15 mph, plants dry, and bright sunshine. When weather conditions were other- wise, the number of bees working cucumbers decreased. Connor (1969) observed bees working under the canopy of leaves during light show- ers, without any major change in their behavior. Lundie (1925) found that on heavily overcast days, with or without occasional precipitation, the low intensity of light seemed 10 to be the major factor inducing bees to stay in the hive. He found that in June and July the temperature at which flight commenced was very inconsistent, varying between 13 and 27° C, being most active from 19 to 25° C. He concluded that at this time of year, tempera- ture was not often a factor in retarding the beginning of flight. On one day, a wind velocity of 16-21 mph during the hours of 9-6 reduced the possible maximum flight by 28-53%. Bodenheimer and Ben-Nerya (1937) concluded that l6-32° C was the optimal range for flight activity, with reduced flight between 9-16° C and none below 8° C. Wratt (1968) found that wind speed was related to temperature and obtained a significant positive correlation between temperature and number of bees foraging. Nelson and Jay (1968) found that flight activity increased with environmental temperature and closely followed changes in it. Park (1923) discovered that bees did not continue to work in a wind blowing 15 mph or more. Butler and Finney (1942) found within any one day, the number of bees leaving the hive increased by 15% for each increase in solar radiation rate of 0.1 cal/cmz/min. Approxi- nately 30% of the variability in bee activity was ascribed to irregu- larities in light intensity. Bodenheimer and Ben-Nerya (1937) observed that foraging activity rose with low, and fell with high humidity. They found that 66% of the total bee flights were recorded at humidities ranging between lO-40%, compared to 26% at humidities ranging between 40-70% and 8% for humidities between 70 and 100%. Von Frisch (1967) found that during flight, bees could detect rela- tive humidity differences of 5-10%. 11 Brett and Sullivan (1972) reported that honey bees in cucum- bers began foraging in the morning and reached peak activity about three to four h after cucumber flowers opened. After 4 p.m. the bees were almost inactive. Connor (1969) found that the average number of bee visits in cucumbers throughout the day produced a normal distribution pattern centered around 11 a.m. EST. Of all the bee visits, 78% occurred from 9 a.m. to 2 p.m. Only 7.5% occur- red before 9 a.m. and 14.5% after 2 p.m. Seyman, Barnett, Thorp, Stanger, and Payne (1969) found that maximum bee pollination activity in cucumbers took place during mid-day. Bee counts taken at 8, 10, 12, 2, and 4 o'clock indicated that 91% of all bee activity occurred between 10 a.m. and 2 p.m. At 10 a.m. 26% of the bees were recorded, 46% at noon, and 19% at 2 p.m. However, Kauffeld and Williams (1972) fbund that the average daily activity of honey bees in cucumber fields had a bimodal effect; activity peaked near 11 a.m., decreased and a second, but lower, peak occurred between 2 and 3 p.m. Connor (1969) found that very warm mornings produced peak activity for the day between 8 and 9 a.m., while some cold days delayed the peak until 12 to l p.m., with no flight until 10 a.m. Climatic Conditions Affecting Nectar Secretion Flowering is one of the later events in the life history of an annual plant and any factor to which the plant has been exposed at any time prior to flowering will, to some degree, influence flower- ing and with it nectar production, Shuel (1967a). External factors influencing secretion are those of weather and soil. Weather is a 12 complex of interrelated factors, and it is often difficult to sepa- rate the individual components in field observations, Shuel (1975). In general, conditions which impose no appreciable limitations on growth and which promote a reasonable balance between vegetative and reproductive develOpment seem to support good nectar production, Shuel (1967a). Temperature has received more attention than any other factor and there is a difference of opinion regarding its importance. Rec- ords of daytime temperatures may reflect conditions of sunlight which in themselves cause wide variation in the nectar flow, Shuel (1967a). Temperature affects many plant processes which are proceeding at the same time. A certain threshold temperature is necessary if secretion is to occur. Within normal daily limits, temperature variation proba- bly has little influence on the amount of sugar which the plant syn- thesizes, but it has a very marked affect on the rate at which the sugar is consumed in growth, respiration, and other processes. Flower development is accelerated at high temperatures and the dura- tion of secretory activity is probably shortened, Shuel (1955a). Excessively high temperatures in combination with meager rainfall can lower nectar production by causing a moisture stress in the plant, Shuel (1975). Throughout the growing season, water is an important factor in the regulation of plant growth. Either a shortage or an over- abundance of water may stunt plant growth and lead to poor nectar yields.- During the secretory period, a lack of water may reduce the amount of sugar synthesized, Shuel (1955a). 13 There can be little doubt of the primary importance to nectar secretion of sufficient sunlight to support a high level of photo- synthesis. Most of the sugar in nectar probably comes from leaves fairly close to the flower. In herbaceous plants the nectar sugar is likely to be of recent origin, whereas in trees and shrubs, it may also be derived from stored carbohydrates, Shuel (1975). It is highly probable that any factor which alters the rate of buildup or breakdown of the carbohydrate supply will influence nectar secretion, Shuel (1955a). Several authors have found that humidity has a pronounced inverse effect on nectar sugar concentration. It is likely that this effect is chiefly physical, operating in the following manner. As nectar is secreted, it begins to undergo a regulation of concentra- tion until its vapor pressure comes to equilibrium with that of the atmosphere. Unless the humidity of the atmosphere is very high, the change will be a loss of water molecules to the air and an increase in sugar concentration. Rates of increase in nectar sugar concentra- tion can be extremely rapid in flowers in which the nectar is exposed, Shuel (1975). A direct effect of atmospheric humidity on secretion has not been established. Evaporation is hastened by high tempera- ture and rapid air movement across the nectaries. Also evaporation is more rapid from a thin film of nectar than from a large globule, Shuel (1955a). Individual projects involving climatic conditions and several crops have been extensively reviewed by Beutler (1953), Savos (1955a and b), Shuel (1954), Percival (1965), Shuel and Peder- sen (1953), and Kenoyer (1916). 14 Banadyga (1949) and Kremer (1943) reported that nectar secre- tion commenced in cucumbers at temperatures of l7-l8° C. Nemirovich- Danchenko (1964) found nectar secretion to be greatest in both stami- nate and pistillate flowers 3-4 h after opening. The daily average nectar yield was dependent on temperature. Kenoyer (1916) found that cucumber nectar contained less sugar and was of less volume when plants were kept in the dark. Sugar Concentration of Cucumber Nectar Throughout the Day with Bee Visitation Wilson, Moffett, and Harrington (1958) in analyzing the honey stomach contents of 18 bees, found cucumber nectar to average 42.2% sugar with a minimum of 37.8% and maximum of 49.2% in Colorado. Kauffeld and Williams (1972) made lO-20 hand refractometer readings of nectar from the honey stomachs of bees working cucumbers and found the range to be 36-41% sugar, depending on weather conditions in Wisconsin. Distribution of Cucumber Pollen on the Honey Bee's Body Free (1970) observed that the bees body may be covered with pollen, whether it was packing pollen or not. He found that usually there was about twice as much pollen on a bee's thorax, than on its abdomen. Connor (1969) observed that when a honey bee visits a staminate cucumber flower, pollen comes in contact with both sides of the proboscis, mouthparts, and head. He also found that the polé len grains readily adhere to the body hairs. Stephen (1970) observed 15 that the bees' access to the nectar of the staminate flower was gained through three narrow lateral passages between the stamens. When the bee inserted her proboscis into one of the passages, both sides of her head were dusted with pollen as well as the thoracic hairs. The Number of Bee Visits Needed for Adequate Pollination Shemetkov (1957) found that a Russian hothouse cucumber flower needed to be visited 8-10 times on the first day of flowering, if it were to be satisfactorily pollinated. The weight of the fruit and the number of seeds it contained increased with the number of bee visits, up to 40-50. When individual flowers were visited 2-8 times, 9 fruit were produced per plant with an average weight of 221 grams and 60 seeds. When each flower was visited 50 times, the number of fruits produced was also 9, but the average weight was 500 grams and the number of seeds 140. Connor (1969) found that single bee visits produced fruit 53.1% of the time. He found little differ- ence in the percentage of fruit set between single bee visits and multiple bee visits until nine or more visits, where fruit developed 79% of the time. A comparison of flowers receiving single visits and those receiving 9 or 10 visits were significantly different at the 5% probability level. Flowers receiving from 2 to 8 visits set fruit from 51.0% to 66.7% of the time, mean 57.8%. For 10-12 visits, fruit were set 80.0% of the time. In a greenhouse study, flowers received 2. 10, or 20 visits. Flowers receiving two visits developed 40.0% of 16 the time, averaging 48.3 seeds per fruit; with 10 visits fruit devel- oped 31% of the time, averaging 44.3 seeds per fruit. There was no significant difference. With 20 visits, fruit developed 55% of the time and produced an average of 64 seeds. The controls, which were flowers open to pollination the entire day, developed 93% of the time but did not contain any more seeds per fruit. Data indicated that at least 10 bee visits were needed to insure pollination under a variety of variable conditions. The Timing of Honey Bees as They Foraged on Cucumbers Connor (1969) found that the length of a bee visit to a _pistillate cucumber flower decreased as the number of visits increased. First visits to a cucumber flower in 1967 lasted an average of 36.2 sec, 39.2 sec in 1968, while the average length of subsequent visits dropped sharply. The average length of the fourth through twelfth visits to a flower was 10.6 sec in 1967 and 7.9 sec in 1968. Obser- vations in the field indicated that bees settling on a flower worked around the stigma and style for 5 to 10 sec, even if unsuccessful in finding nectar, before moving on to another flower. The length of the first visit to a flower varied with the time of day of the visit. Early morning visits were shorter than those occurring after 11 a.m., indicating that a greater supply of nectar had accumulated. The average hourly visit length throughout the day ranged between 8.8 and 45.0 sec. Visits from 8—10 a.m. lasted 9—11 sec, 10 to 11 a.m. lasted 30 sec, and 11 a.m. to 6 p.m. lasted 38-45 sec. 17 The Size of the Foraging Area Levin (1966) found a close relationship between landmarks and the size of the working area of an individual bee. On the average, each bee worked an area of 210 m2. In small plots with good land- marks, the bees confined their activities to a smaller area. Singh (1950) found that foraging areas were particularly restricted in size during calm, sunny weather when abundant nectar and pollen were pres- ent, but when forage was sparse, either because few flowers were present or the flowers were yielding little nectar or pollen, forag- ing areas were larger and the bees spent less time per flower and were more easily disturbed. He observed that individual bees returned to the same small area of the crop, trip after trip, day 2 in various after day. This area varied from about 10 to 30-40 ft flowers. Weaver (1957) found that competition from other foragers was important in determining the size of the foraging area. Compe- tition operated by decreasing the amount of nectar available from the blossoms or by the reaction of a bee to the physical presence of competing fOragers. The Movement of Cucumber Pollen by Honey Bees The use of genetically marked cultivars of Cucumis sativus and Cucumis melo has provided several investigators with an indica- tion of the distance that bees move pollen. Jenkins (1942) used such a genetic marker to separate two inbred lines of cucumbers. He found that in adjacent rows spaced six ft apart, the amount of natural crossing between rows was 32.9%. Knysh (1958) used two varieties of 18 cucumbers and planted them at distances ranging from 250-2,000 m apart as well as adjacent to each other. Adjacent plots produced hybrids 23-25% of the time. Hybrids were also produced from seeds grown 250 m from the pollinating variety. Hybrids did not occur beyond 250 m nor in the control. Foster and Levin (1967) concluded that hybrid seed counts in muskmelon did not reveal individual bee movements, but the amount of cross pollination was dependent upon total bee activity. They found that the greater the distance from the pollen source, the less hybrid seed produced. Generally working bees traveled short distances, but their studies indicated that pollen was retransferred from flower to flower at least 35 ft beyond the point of initial transfer. Connor (1969) used strips of gynoecious hybrids with a pollen source at one end to determine the distance honey bees moved cucumber pollen. In 1967 he found the weight of fruit per plant increased as the distance increased from 0 to 37.5 ft from the pollen source, while from 37.5 to 96 ft the weight of fruit per plant decreased. The percentage of perfectly shaped fruit increased from 23.8% at O-7.5 ft, to 44.4% at 39-45 ft. Again, the values decreased beyond this point. In 1968 the strips were divided into 25 ft sections. The highest yield based on dollar value per acre (60,000 plants) was found in the.section adjacent to the pollen source at $281 per acre, then decreased to a low of $126 at 225-250 ft. Connor concluded that some of the fruit development at the greater distances was due 19 to a few staminate flowers in the gynoecious strips rather than move- ment of pollen from the pollinator plot. There was a definite reduc- tion in the number of fruit produced per plant and in seed counts as distance from the pollen source increased. No definite correlation was found.between fruit shape and distance from pollinator. Yield of the gynoecious line decreased 35% twenty-five ft from the pollen source, although yields indicated some pollen movement took place up to 125 ft. The Relationship of Foraging Activity to Fruit Set Kauffeld and Williams (1972) found that the use of five colonies per acre in Wisconsin produced a cash return only 10.9% higher and a total average weight of fruit only 16% higher than was obtained with one strong colony per acre. Connor (1969) in Michigan with a bee population estimated to be three colonies per acre found the average number of visits per flower for ten 30 min observation periods was 45.1 visits. Values were doubled to reflect 10 h of pollination. On this basis, the average flower received 90.2 visits from 7 a.m. to 5 p.m. On an average, each flower was visited once every 6.65 min at a rate of 9.02 visits per flower per hour (V/F/H). He found by taking counts at identical times in the plots of East Lansing, Michigan, and in a 20-acre field at Springport, Michigan, that the Springport field received 2.78 V/F/H, while the East Lansing plots received 8.28 V/F/H. Therefore, the Springport field, with one colony per acre, had one third the pollination activity of the East Lansing plots where three colonies per acre were present. When plants 20 were harvested in both fields, the number of cucumbers produced per plant under these different bee populations did not differ statisti- cally at the .05 probability level. East Lansing averaged 1.46 fruits per plant compared to 1.54 fruits per plant at Springport. At another time, similar counts were taken in a 16 acre field at Cedar Springs, Michigan, (1 colony per acre) and compared to East Lansing. At Cedar Springs 2.95 V/F/H were recorded compared to 8.68 V/F/H at East Lansing. Thus, the bee visit activity in the Cedar Springs field was 34.2% of that in East Lansing. Upon harvesting, the East Lansing plots averaged 1.47 fruit per plant and Cedar Springs 1.38, a non- significant difference. In two days time, the plants at Cedar Springs increased from 0.56 pistillate flowers per plant to 0.92 flowers per plant which represents an increase from 28,000 to 46,000 pistillate flowers per acre. No correlation between bee visits and yield should be inferred from these data, due to the variability in maturity of plants at the time counts were made. Fruit Inhibition McCollum (1934) found that the growth of fertilized fruits had a strikingly depressive affect on plant development. Elongation of the central axis of the plant ceased when the developing fruit was about four inches in length. The growing region of the plant became a cluster of pistillate flower buds, which were yellow and abortive. The leaves lost their dark green color and showed a lack of vegeta- tive vigor. Fruit from pollinated flowers remained on the plant in a dormant state, apparently without deterioration. The first sign of 21 plant rejuvenation coincided with maturity or picking of the inhibit- ing fruit. At maturity fruit began to turn yellow and the seed coats harden. When fruits were produced on early nodes near the base of the plant, they did not have as great of an inhibiting effect on growth of the plant as did fruits produced further along the stem. By tagging fruits and recording the dates of pollination, fruit from the first pollinated flower developed 92% of the time and suppressed the growth of other fruits. In a number of cases, a second fruit started development, but only one fruit at a time continued to matur- ity. Foliage near the fertilized flower seemed to be essential for fruit development. Accumulation of accessible synthesized materials is apparently necessary for fruit development, but fruit development was not associated with an accumulation of carbohydrates in the plant. His explanation was that fertilized ovaries produced a growth- regulating substance. He found that fruit produced at the outermost node on the vine had a physiological advantage because of its physical nearness to photosynthetically active leaves. Connor (1969) found that in competition for growth, fruit closest to the root developed 39.5% of the time; fruit in second position developed 29.1%, third position 18.5%, fourth position 15.8%, and fifth position 0.0% of the time. Never more than four fruits per plant developed at one time. The frequency of necks (fully formed only at the flower end) and nubs (fully formed only at the stem end) decreased very slightly as the number of other fruit increased, whereas the frequency of crooked fruit increased slightly, Fruit 22 closest to the crown had the greatest probability of developing and the greatest probability of being well shaped. Perfect-shaped fruit decreased as the position increased, 29.4%, 17.5%, 16.5%, 10.5%, and 0.0% respectively. Young (1943) also found that developing fruits inhibited early growth of other fruits on the same vine. Stout, Ries, and Putnam (1963) reported that usually only one to three fruits developed to a marketable size at one time. Zobel and Davis (1949) found that the total yield of cucumber seed was not increased by regulating the number of fruits per plant. Maximum seed yields were obtained in treatments where all fruits were left on the vine to mature. MATERIALS AND METHODS Climatic Conditions Affecting Anthesis and Anther Dehiscence In 1969 flowers were observed at 6 a.m. EST for 13 mornings at East Lansing, Michigan, to determine the factors that regulate flower anthesis and anther dehiscence. A centigrade thermometer was placed among the vines so that accurate prevailing temperature read- ings could be recorded. Ten pistillate flowers (MSU 356) and ten staminate flowers (SMR 58) were picked daily each time the tempera- ture increased one degree. Anther dehiscence was verified under a dissecting microscope. Duration of Pollen Viability and Stigmatic Receptivity, To check the viability of pollen and stigmatic receptivity at the actual time of anther dehiscence, hand pollinations were made in the field with a camel hair brush on three different days. The pol-' linated flowers were immediately closed with paper clips to prevent further pollination. The fruit were allowed to develop to maturity fOr seed counts. At the time the pollinations were made, bees were not flying in the field. The vines were not checked for previously developing fruit. The duration of pollen viability and stigmatic receptivity was determined by the following studies. In order to determine if pollen from day-old staminate flowers still remained viable, 23 24 20 pistillate flowers (MSU 356) were hand pollinated in cages on August 23, 1968, at 10 a.m. EST. Ten of the flowers were pollinated with pollen from day-old staminate flowers and ten with fresh pollen from the cultivar, Piccadilly. The flowers were evaluated on Sep- tember 4. Similar studies were continued during 1969 in both the greenhouse and field. From June 24 to July 2, 33 pistillate flowers (7006) were pollinated with pollen from day-old flowers (Chipper) at 10 a.m. and clipped shut. The fruit were harvested before they were fully developed, since the vines were mature and ready to be destroyed. A second greenhouse study was conducted, starting on July 25 and ending on August 7. Forty-six pistillate flowers of the cultivar MSU 350 were pollinated with day-old pollen from Piccadilly flowers and clipped shut. Pollinations were done at 10:30 a.m. under very warm conditions. A similar group of controls were pol- linated with pollen from fresh flowers. In the field, pollinations were done at 10 a.m. and 4 p.m. In both cases SMR 58 served as the pollen source and the caged pistil- late flowers were from MSU 356. The afternoon pollinations were done from August 5 to August 19 and the morning from August 27 to Septem- ber 2. Sixty-two flowers were hand pollinated in the afternoon and 51 in the morning. To determine if the stigmas of one-day-old pistillate flowers were capable of setting fruit with fresh pollen, six day-old flowers (Piccadilly) were hand pollinated on August 23, 1968, with fresh pollen (Piccadilly) at 9 a.m. EST. The caged pistillate flowers 25 were tagged during the previous day and evaluated on September 10. Similar work was continued in the field and greenhouse in 1969. From July 25 to August 7 in the greenhouse, 37 day-old pistillate flowers of the cultivar MSU 356 were pollinated with fresh pollen from Picca- dilly. The flowers were pollinated at 10:30 a.m. under very warm conditions and were clipped shut. Fresh pistillate flowers of the same cultivar were pollinated with fresh pollen to serve as controls. In the field, pollinations were done at 10 a.m. and at 4 p.m. In both cases SMR 58 served as the pollen source and the caged day-old pistillate flowers were from MSU 356. Afternoon pollinations were done from August 5 to August 19 and morning from August 27 to Sep— tember 2. Thirty-three flowers were hand pollinated in the afternoon and 49 in the morning. Length of Time Flowers are Open in the Field Since previous studies had shown that day-old pistillate flowers were capable of setting fruit with fresh pollen, and pollen from day-old staminate flowers still has some viability, a survey was taken to see how long day-old staminate and pistillate flowers were open in the field in 1969. Counts of 100 flowers were taken with hand counters at different times of day from 9 a.m. to 3 p.m. The flower was considered closed if a honey bee could not work it and open if it could be worked. Counts of pistillate flowers were taken in the pollen movement strips (MSU 356) and for staminate flowers in the monoecious plants (SMR 58) serving as the pollen source at the end of the strips. 26 Climatic Conditions Affecting,Foraging_Activity in the Field Honey bee flight activity in relation to the environment was recorded during 1974 in plots at East Lansing and in commercial fields at Eaton Rapids and Mulliken, Michigan. Each day 10 fresh flowers, five staminate and five pistillate within visual sighting range were tagged. Bees were counted on these flowers for alternat- ing lO-min periods from 7 a.m. to 4 p.m. EST. This method was described by Levin, Kuehl and Carr (1968). After each lO-min samp- ling period of bee activity, the temperature was recorded within the plant canopy. Counts were made on 12 consecutive days during the period of August 13 to 24 at East Lansing, on seven days between July 25 through August 6 at Eaton Rapids, and on August 26, 29, and 30 at Mulliken. Additional data on relative humidity, solar radiation, and precipitation for the East Lansing location were obtained from the department of agricultural engineering, MSU. Wind speed data were supplied by the Michigan Weather Service, Lansing, Michigan. Bees in East Lansing consisted of a private apiary of 13 colonies 0.4 miles from the cucumber plots. All of the colonies included two deep hive bodies and a sin- gle shallow super. The university apiary was 1.2 miles away and contained 26 colonies of assorted sizes. On August 16 two colonies were moved from the university apiary to the plot perimeter at 6:15 a.m. The previous day the number of square inches of sealed brood in each of the colonies was measured to provide an index of 27 colony strength. Colony #26 contained 484 sq inches of sealed brood and Colony #28, 430. Both of the colonies consisted of a deep hive body and a shallow super and were established on June 17, 1974, from two pound packages. Climatic Conditions AffectingiNectar Secretion Analysis of nectar secretion within the staminate and pistil- late flowers in relation to climatic conditions Was carried out in 1968 and 1969. The nectar was removed with Drummond microcaps, meas- ured, and analyzed with a Bausch and Lomb Abbe 3L refractometer as described by Collison (1973). Plants of the cultivar MSU 356 were planted on June 7, 1968. Each day from 7 a.m. to 4 p.m. a minimum of two pistillate flowers were picked each hour on the hour from July 26 to August 26. The flowers were either bagged prior to anthesis or caged. Staminate flowers of the cultivar SMR 58 were picked daily from August 14 to August 29, 1969. Each day from 7 a.m. to 4 p.m. six caged flowers were picked on the hour and nectar removed. Tem- perature and humidity data were recorded on campus and furnished by the agricultural engineering department. Solar radiation data was also recorded on campus and obtained from the Michigan Weather Serv- ice. Additional temperature data, wind speed, and precipitation were recorded at the NOAA station, Capital City Airport, Lansing, Michigan. Foraging Activity in Relation to Flower Age, Since it was shown that day-old pistillate flowers were cap- able of setting some fruit, the following studies were undertaken to determine if honey bees work day-old pistillate flowers in the field. 28 On August 19, 1968, 35 pistillate flowers (MSU 356) one day prior to anthesis were bagged in 2.5 inch2 organdy bags. The flowers remained bagged until 8:30 a.m. on August 21. At that time the bags were removed from the 35 one-day-old flowers, an additional 35 fresh pis- tillate flowers were tagged. All 70 flowers were exposed to foraging bees until 4:30 p.m., then clipped shut. All of the flowers were evaluated on September 10. The experiment was repeated on August 9, 1969. In addition, on August 27, 1969, one-day-old pistillate flow- ers were unbagged in the field for 10 min intervals during the after— noon to determine bee visitation. Sugar Concentration of Cucumber Nectar Throughout the Day with Bee Visitation In order to see how nectar sugar concentration changes in the field throughout the day with bee visitation, honey bees were col- lected from cucumber flowers during the first two weeks of August, 1970. When a bee was observed working a cucumber flower, it was killed in a cyanide killing jar. Within five minutes after collec- tion, the head of the bee was removed and its honey stomach contents squeezed onto the prism of the refractometer for analysis. Foraging Activity in Relation to Flower Sex During 1969 in plots at East Lansing, in commercial fields at Mulliken in 1971, and at Eaton Rapids in 1974, foraging honey bees were followed as they visited staminate and pistillate flowers. The bees foraging pattern in relation to flower sex was recorded and compared to the staminate:pistillate flower ratio in the field. 29 Honey bee flight activity throughout the day in relation to flower sex was recorded in 1974 in plots at East Lansing and in commercial fields at Eaton Rapids and Mulliken. Each day 10 fresh flowers within visual sighting range were tagged, five staminate and five pistillate. Bees were counted on these flowers for alternating 10- min periods from 7 a.m. to 4 p.m. EST. Counts were made on 12 con- secutive days during the period of August 13 to 24 at East Lansing, on seven days between July 25 through August 6 at Eaton Rapids, and on August 26, 29, and 30 at Mulliken. Distribution of Cucumber Pollen on the Honey Bee's Body To determine the location of cucumber pollen on honey bees, pinned specimens from the summers of 1968 to 1970 were observed through a binocular microscope. The pollen was identified by making pollen slides and comparing them to reference slides previously made. A total of 236 honey bees were examined, 78 from the 1968 collection, 136 from the 1969 collection, and 22 from 1970. Eight body regions were checked for pollen grains: (1) face, (2) mouthparts, (3) neck, (4) thorax-underside, (5) prolegs, (6) mesolegs (7) metalegs. and (8) abdomen.. If a large amount of pollen was found, it was noted. Since the 236 bees were collected from staminate flowers only, 100 bees were collected from staminate and pistillage flowers in 1971 to see if differences existed. 30 The Number of Bee Visits Needed for Adequate Pollination The number of honey bee visits to pistillate flowers were con- trolled to determine the effect of varying numbers of bee visits on fruit set, from July 28 through August 14, 1970, at the MSU research plots. Three plantings of the culitvar Piccadilly were made on May 23, June 6, and June 30 in rows three ft apart. Flower counts prior to the start of observations were taken daily to monitor the availability of pollen. No fruit set was allowed until flowering had reached at least the seventh node. Pistillate flowers were 2 organdy bags. The bagged one day prior to anthesis in 2.5 inch flowers were unbagged and one, five, ten, fifteen, or twenty separ- ate bee visits were allowed on each flower between 10 a.m. and noon (EST). After the specific number of visits were completed, the flowers were clipped shut with paper clips, dated, and tagged. Fruit and flowers other than those observed were removed from the cucumber vines to prevent competition. On August 12, plants of the last planting were used and previous conditions were maintained. The Timing of Honey Bees as They Foraged on Staminate and Pistillate Cucumber Flowers In 1968 honey bees working the cultivar Piccadilly were fol- lowed and timed with a stopwatch on staminate and pistillate flowers. Since this cultivar produced more staminate than pistillate flowers, more timings were taken from staminate than pistillate flowers. 31 The honey bees were timed at different periods during the day from July 22 to August 23, 1968. Time started when they began working the center of the flower for nectar and ended when they finished removing nectar from the flower. Often a honey bee will stop and groom itself after removing nectar from a flower before moving on to another. The time spent in grooming was not included in our timings. Also during 1974 as time allowed, bees were followed and timed with a stopwatch as they foraged on cucumbers to obtain a foraging rate. The number of staminate and pistillate flowers each bee visited was recorded as well as the total foraging time. The Size of the Foraging Area To better understand the way bees moved cucumber pollen, indi- vidual honey bees were followed from flower to flower in 1969. The number of flower visits along with the length and width of the forag- ing area were recorded for each foraging trip. Observations started on July 31 and ended on August 19. The Movement of Cucumber Pollen by_HoneygBees To investigate the distance honey bees move cucumber pollen and the effect of different amounts of available pollen, six 240 ft long strips of gynoecious MSU 356 were planted on June 16, 1969. Each strip was 10 ft apart and contained two rows which were planted two ft apart. At the east end of each of these strips, a ten ft ' strip of monoecious SMR 58 was planted on June 12 to provide the pol- len at various concentrations. The monoecious blocks were replicated 32 twice in order of O, 200, and 20 plants per block. The 240 ft long strips of MSU 356 were planted with a v-belt planter and the monoe- cious plants by hand. Because of poor germinating conditions, the plot layout was replanted on June 25 between the previous rows. The original plants were left for other experiments and destroyed as we finished with them (Figure l). The first planting of monoecious plants was caged so as not to interfere with the pollen movement study. The first flowers appeared in the gynoecious strips on August 8 and the 12 strips were checked each morning for staminate flowers and any plants producing them were removed. The cucumbers were harvested twice from the strips, when a majority of the cucumbers had started to yellow. Harvest dates were August 25 to 26 and September 15 to 18. The strips were divided into 10 ft sections and all cucumbers larger than two inches were har- vested. Two adjacent colonies of honey bees provided pollination activity. For each 10 ft section, the number of plants and cucumbers were recorded. A minimum of 10 pickles of the first harvest and five the second were selected from each 10 ft section of each strip for ”seed counts. The seeds from 2,188 fruit were counted, 1025 from the first harvest and 1163 from the second. There was one monoecious plant for every 19.5 gynoecious plants. To determine if the higher percentage of open, day-old pistil- late flowers found at the end of the pollen movement strips farthest from the pollen source in 1969 was because of a lack of pollination, a total of 150 flowers were tagged on August 14, 15, and September 5. 33 Each day 25 red tags were numbered and placed on day-old pistillate flowers that were open and 25 white tags on day-old pistillate flowers that were closed. To further assess if pollinated flowers close up faster than nonpollinated, a total of 72 flowers were observed from July 16 to August 11, 1970. Each day one half of the caged flowers were hand pollinated and the other half were not. They were then compared throughout the day and again the next morning. Because data from the 1969 pollen movement strips indicate (a) an inadequate pollen supply, and (b) the possibility that some staminate flowers in the gynoecious strips released pollen before they were found and removed; another approach was taken in 1972 to remove these sources of error. An area 24 ft x 250 ft was planted on June 10. The first 30 ft at the east end contained 20 rows of the monoecious cultivar SMR 15 to serve as the pollen source. Perpendicu- lar to these rows were 16 rows of 713-5 x 71521 (100% gynoecious) each 220 ft long. The first staminate flowers appeared in the gynoecious block on July 24 and were destroyed as they appeared (Table 66). On August 15 all fruit and pistillate flowers were stripped from the vines and three colonies of bees were moved to the plots (Figure 2). Two of the colonies were placed adjacent to the gynoecious block between 111-130 ft from the pollen source. The gynoecious block was divided into 10 ft sections and harvested on September 11 and 12. Seed counts were taken on 736 nature fruit, 32 from each section. There was one monoecious plant for every 9.7 gynoecious plants. 34 The Movement of Fluorescent Powder To further verify the results of 1969, the movement of fluor- escent powder by the honey bee under various experimental designs was used in 1971. Fluorescein (Sodium Salt) was dusted on the petals of staminate flowers in the morning; later in the day flowers were sampled at 10 ft intervals from the dusted flowers. FLowers were then examined in a dark room with an ultraviolet light to check for traces of the bright yellow fluorescing powder. In the first set of trials, in a 25 x 50 ft plot at East Lansing, six SMR 58 flowers at the edge of the plot were dusted on three different days (August 9, 11, and 18). In the afternoon a total of 21 flowers were sampled at 10 ft intervals each day. Each 10 ft section contained three rows, therefore seven flowers were randomly picked from each row. Four strong nuclei of honey bees provided a high pollinator density. In a second set of trials, two commercial pickle fields at Mulliken were used with both a circular and a rectangular sampling pattern. In each case flowers were sampled at 10 ft intervals from the dusted flowers. Depending upon the study, either 1, 6, 12, 18, or 50 flowers were dusted with the powder. On two days (August 21 and 24), multiple 30 x 70 ft strips, 200 yards apart were used, while on August 25 a 30 x 100 ft strip was used. Circular designs were used on July 29 and August 5. The dusted flowers were observed for two hours on both days to see that they were being visited. Two native bees and five honey bees visited the dusted flowers on July 29 and 77 honey bees visited the six 35 dusted flowers on August 5. Sample size was determined by size com- parison of sampling areas. Commercially rented colonies of honey bees provided pollinator activity; eight colonies on July 29 and 40 the other days. Additional studies in 1973 involved the movement of fluor- escent powder by the bees at East Lansing. On June 19 a block of 12 rows, 30 inches apart and 110 ft long of the cultivar MSU 356 x 3816 was planted. The dusting of flowers and sampling began on August 14. The Relationship of Foraging Activitygto Fruit Set The relationship of foraging activity to fruit set was moni- tored in an East Lansing plot during the summer of 1974, from the start of flowering until optimum mechanical harvesting conditions were reached (Figure 3). The plot consisted of seven rows, three ft apart and 72 ft long, of the culitvar Piccadilly (Med 1, Ferry Morse Co.) which were planted on June 27. Flowering began on Aug-~ ust 6 and each days flowers were picked from the vines through August 12 to prevent fruit development. Daily observations of flower- ing, bee activity, and climatic conditions were recorded from Aug- ust 13 to 24. The number of bees working five pistillate and five staminate flowers were counted as described previously. The five pistillate flowers being observed were tagged and the number of visits each received during the day recorded. All staminate and pistillate flowers in the plot were counted daily and the pistillate flowers tagged. 36 On August 27, three days after bee observations had ceased, yield counts were taken at destructive harvest time, but the fruit were left on the vines until maturity, for subsequent seed counts. The final destructive harvest was completed on September 22, 29 days after the bee observations had ceased. Adjacent to this plot was a similar sized block; cultivar MSU 9805 with 10% SMR 58. The two plots were separated by an 8 ft strip of bare soil. The second plot began flowering on August 8 and flowers were picked from the vines until August 13. The staminate and pistillate flowers were counted daily through August 24. The plot was destructively harvested on August 27 and the fruit were graded by size and shape. Changes in the Foraging Population with Additional Colonies in the Field The effect of moving in colonies of bees on the activities of an existing foraging population was determined in the East Lansing plots during 1974. Four days after observations began on August 16, colonies #26 and #28 were moved from the university apiary to the plot perimeter at 6:15 a.m. The strength of the two colonies plus the size of the foraging population in the area were indicated earl- ier. Fruit Inhibition A developing fruit on a cucumber vine inhibits the develop- ment of other fruit along the vine. In 1974 an attempt to assess the extent of inhibition and its implications in providing effective pollination was carried out. Fruit inhibition was assessed by 37 determining the percentage of flowers that died and fruit that remained alive but stunted because of inhibition. Observations were made of the occurrence of individual flowers relative to other flow- ers on the same vine. RESULTS Climatic Conditions Affecting_Anthesis and’Anther_Dehiscence Observations showed that antheSis was not entirely dependent on time of day and temperature. On August 19 at 6 a.m., at 22° C in a field, with a heavy haze, flowers were closed and bees were trying to work them. When opened, 90% of the pistillate flowers contained many large beads of nectar and the staminate flower anthers had com- pletely dehisced. By 6:30 the sun was beginning to break through the haze. At this time the flowers started to open slowly. On days when light conditions were normal, anthesis began at 15° C. Over the course of the sampling period, flowers were always tightly closed at temperatures from 9.5 - 15° C. Microscopic examination of the anthers showed that 60% of staminate flowers started to dehisce at 16° C. At 17° C, 80% of the flowers were dehiscing, 92% at 18°, and 100% at 19°. Seventy flowers examined at temperatures between 12° and 15° C showed no signs of anther dehiscence. Periodic measurements of the expanding flower corollas as they opened on six mornings indicated that staminate flowers often opened at a faster rate than pistillate flowers (Fig- ure 4). The faster opening rate was observed on August 5, l3, and 20 but not on August 12 (Table 1). Measurements excluding those of August 12 showed the average opening staminate flower to be 1.1 times larger than the pistillate flower. The staminate flower averaged 38 39 Figure l.--Cucumber pollen movement strips, 1969. Figure 2.--Cucumber pollen movement strip, 1972. Figure 3.--Piccadi11y plot in 1974 used to determine the relation- ship of foraging activity to fruit set in cucumbers. Figure 4.--Staminate cucumber flowers Opening at a faster rate than pistillate on August 5, 1969, at 7 a.m. EST, 18° C. 40 41 TABLE 1.--The corolla expansion rate of staminate and pistillate cucumber flowers on the morning of anthesis, 1969. Average corolla size Date Time N Staminate N Pistillate flowers flowers July 30 7:00 30 27.7mm 30 24.1mm July 31 6:00 20 24.7mm 20 23.1mm August 12 6:00 20 14.9nm 20 15.0mn August 12 6:30 20 18.4mm 20 20.4mm August 14 6:00 20 27.9mm 20 23.4mm 26.8 mm compared to 23.5 for the pistillate. This difference does not seem great, but Collison (1973) found that pistillate flowers were 1.06 times larger when fully expanded. An attempt to correlate the factors inducing them to open faster on some mornings and not on others was made. These factors included the amount of sky cover, relative humidity, wind speed, temperature, low temperature during the night before anthesis, and percent of possible sunshine the pre- vious day but no correlation could be ascertained. Duration of Pollen Viability and Stigmatic Receptivity The early morning pollinations made at the time of anther dehiscence, prior to bee flight, showed that cucumber pollen was viable and stigmas receptive (Table 2). Mature fruit developed in 86.7% of the hand pollinations and the average seed count was 328 :_36 seeds per fruit. A11 fruit were perfectly shaped and seed 42 om umm 2m: x mmmzm a 0 amp so omum mom, .e. umamz< oop appwumuowa x mmmZm m 0 amp Em cons mmmp .m pmamz< cop appmcmoumm x mmmZm a 0 amp Em cons mom_ .Pm zpaa oo_ x—Fpumuuwm x wmmzm e u ONF Em cone momp ._m apzq pewsqopm>mn . umamcwppon upscm N mgm>wu_:u Longsz mcspmgmasmh wswh mama .mgmnssuzo cw mocmomwgwu cucucm we we?» mzu um mums mcowumchFOQ ace; mcwzoppow pcman~m>mu uwzgmnu.~ m4m<~ 43 counts ranged between 125 - 512 seeds. The seed counts indicated high pollen viability at the time of anther dehiscence. The hand pollinations in 1968 showed that day-old pollen was not viable in the field. All 10 of the fresh pistillate flowers that were pollinated with day-old pollen failed to set fruit. In the con- trols that were pollinated with fresh pollen, 80.0% of the flowers developed into mature fruit and 20.0% of the ovaries were still alive after three days but were inhibited from growing by the presence of other developing fruit on the vine. The first set of hand pollinations with day-old pollen, 30.3% set fruit in the greenhouse during 1969 (Chipper x 7006). However, most of the fruit were parthenocarpic and misshaped which indicated that in any assessment of effectiveness of pollination, fruit should be left on the vines to maturity and seed counts taken. In the sec- ond set of greenhouse pollinations (MSU 356 x Piccadilly) 10.9% of the pollinated flowers produced mature fruit with seeds from day-old pollen compared to 61.1% of the controls. The controls averaged 144 seeds per fruit and the experimental group 123. Seed counts ranged from 82-228 in fruit produced from day-old pollen. In the field, 2.0% of the morning pollinations with day-old pollen produced fruit com- pared to 85.7% for the controls. Only one fruit with 15 seeds devel- oped in the day-old pollen group. The controls contained from 150 - 216 seeds with a mean of 183. In afternoon pollinations, 4.8% of the flowers pollinated with day-old pollen produced fruit. Seed counts ranged from 23 - 82 with a mean of 48 seeds per fruit. All were 44 perfect in shape. The controls contained from 82 - 307 seeds with a mean of 151. Fruit developed on 73.3% of the controls and all were perfectly shaped. Hand pollinations in 1968 showed that day-old pistillate flowers were capable of setting fruit with fresh pollen. Fruit developed on 83.3% of the pollinated flowers. Similar results were obtained in the greenhouse in 1969. Fruit developed on 43.2% of the day-old flowers pollinated with fresh pollen. Seed counts ranged from 26 - 237 seeds with a mean of 137. In the field 57.1% of the morning pollinations of day-old flowers produced fruit. Only two of the 28 fruit produced in the experimental group were misshapen. The fruit contained from 0 - 412 seeds with a mean of 141 seeds per fruit. Only one of the fruit contained no seeds. In the afternoon pollina- tions, 48.5% of the day-old pistillate flowers produced fruit contain- ing 19 - 487 seeds with a mean of 190. Length of Time Flowers are Open in the Field The counts of day-old flowers in the field indicated that fewer staminate flowers were open than pistillate (Table 3). From 30-76% (mean 47.8) of the pistillate flowers the day after anthesis were open compared to 2-26% (mean 13.3) of the staminate flowers. The east end of the pollen movement strips which were near the pollen source had a smaller percentage of flowers open than the west end, 38.3% compared to 56.6%. The number of open day-old flowers decreased slightly during the day. Day-old staminate flowers averaged 14.4% open in the morning and 11.6% in the afternoon. Pistillate flowers averaged 50.4% open in the morning and 44.5% in the afternoon. TABLE 3.--Percentage of day-old staminate and pistillate cucumber flowers open in the pollen movement strips, 1969. % flowers Open location Time Date Staminate Pistillate % east % west 9:00 am 8/ 8 8 44 8/13 26 52 8/19 10 -- 33 54 8/21 20 -- 60 76 10:00 am 8/18 2 -- 30 51 8/20 9 -- 40 62 10:30 am 8/15 8 63 11:00 am 8/10 23 51 8/ 8 -- 40 8/13 24 49 Noon 8/17 21 59 12:30 pm 8/ 9 13 46 1:00 pm 8/19 6 -- 33 52 8/ 8 -- 37 3:00 pm 8/15 8 57 8/23 13 -- 33 49 8/24 9 -- 39 52 Overall 48.3 38.3 56.6 13.3 47.8 N = 100 46 Climatic Conditions Affecting Foraging ActivityAin the Field The tagged flower technique of sampling bee populations within the field showed that in 1974 foraging began at 17.5° C; subsequent field observations supported this. A highly significant positive correlation was found between flight activity and tempera- ture (Table 4). Of 6281 bees counted on tagged flowers, 85.6% of them were foraging at temperatures between 21.5 and 30° C. Only 3.8% of the bees were counted at temperatures below 21.50 C and 10.6% between 30.5 - 34.5° C. The average number of honey bee visits per sampling period was 1.9 at temperatures between 17 - 21° C, 10.0 at 21.5 - 25.5° C, 15.1 at 26 - 30° C and 8.9 for 30.5 - 34.5° C. Fig- ure 5 indicates that foraging increased with temperature until 29° C, decreased between 29 - 32° C, and increased again from 32° - 34° C. Conditions other than temperature must also have had some effect on the commencement of foraging, since observations varied from day to day and with location. Foraging was first observed on tagged flowers at 17.5° C in East Lansing (Table 5), at 19° C in Eaton Rapids (Table 6) and at 20.5° C in Mulliken (Table 7). Like- wise, activity peaked at different temperatures, 29° C at East Lans- ing, 26° at Mulliken, and at 30.5° and 32.5° at Eaton Rapids. On August 2, bee activity was first observed at 19.0° C (9:37°’C, Eaton Rapids); August 1 (9:02, Eaton Rapdis), August 22 (8:07, East Lansing), and August 29 (10:00, Mulliken), at 19.5° C, August 21 (8:12, East Lansing), August 23 (8:22, East Lansing), and August 26 (8:59, Mulliken) at 20.5° C. At the other extreme on 47 TABLE 4.--Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, 1974. Number of Total number*of visits/ Average number Temperature °C Sampling 10 flowers/ of visits per periods 10 min periods sampling period 10.0 2 0 0.00 13.0 3 0 0.00 14.0 1 0 0.00 15.0 4 0 0.00 15.5 5 0 0.00 16.0 8 O 0.00 16.5 5 0 0.00 17.0 7 0 0.00 17.5 17 4 0.24 18.0 7 2 0.29 18.5 14 0 0.00 19.0 13 5 0.38 19.5 23 51 2.22 20.0 13 34 2.62 20.5 26 117 4.50 21.0 6 24 4.00 21.5 27 153 5.67 22.0 22 127 5.77 22.5 45 314 6.98 23.0 12 154 12.83 23.5 35 397 11.34 24.0 17 191 11.24 24.5 42 437 10.40 25.0 16 302 18.88 25.5 53 628 11.85 26.0 23 290 12.61 26.5 42 478 11.38 27.0 20 268 13.40 27.5 30 484 16.13 28.0 13 253 19.46 28.5 22 416 18.90 29.0 5 103 20.60 29.5 12 273 22.75 30.0 10 109 10.90 30.5 15 246 16.40 31.0 5 35 7.00 31.5 24 169 7.04 32.0 6 20 3.33 32.5 10 65 6.50 33.0 3 9 3.00 33.5 9 94 10.44 34.0 1 9 9.00 34.5 2 20 10.00 TOTAL 675 6281 r --0.3847*** t = 10.8 df = 673 *** = significant at the .001 probability level. 48 Figure 5.--Honey bee foraging activity in cucumbers in relation to temperature, 1974. 49 an on 8 to. «N cu m. o. c. a. o. a . .J1I11Ududl9IOIOIOIOI9IOxJ 0 . O\ . . ox . \.v o\ 0\0 \ cl \4 IO 220895... a... 5:23. 5 $384 .0533... 'NIIN OI ISHBMOWJ OI / SLISM 338 'ON 'BAV 50 TABLE 5.--Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy. East Lansing, 1974. Number of Total number of visits/ Average number Temperature °C sampling 10 flowers/ of visits per periods 10 min periods sampling period 15.5 3 0 0.00 16.0 3 0 0.00 16.5 2 0 0.00 17.0 3 0 0.00 17.5 7 4 0.57 18.0 5 2 0.40 18.5 5 0 0.00 19.0 4 1 0.25 19.5 12 41 3.42 20.0 6 25 4.17 20.5 15 108 7.20 21.0 2 9 4.50 21.5 15 98 6.53 22.0 7 61 8.71 22.5 23 210 9.13 23.0 6 89 14.83 23.5 18 218 12.11 24.0 10 138 13.80 24.5 12 177 14.75 25.0 9 199 22.11 25.5 23 328 14.26 26.0 8 155 19.38 26.5 23 282 12.26 27.0 6 96 16.00 27.5 19 324 17.05 28.0 8 191 23.88 28.5 13 304 23.38 29.0 3 99 33.00 29.5 9 192 21.33 30.0 4 72 18.00 30.5 10 211 21.10 31.0 1 13 13.00 31.5 18 142 7.89 32.0 4 19 4.75 32.5 5 34 6.80 33.0 1 8 8.00 33.5 1 6 6.00 34.0 1 9 9.00 TOTAL 324 3865 r = O.4077*** t = 7.99 . df = 322 ***Significant at the .001 probability level. 51 TABLE 6.--Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, Eaton Rapids, 1974. Number of Total number of visits/ Average number Temperature °C sampling 10 flowers/ of visits per periods 10 min periods Sampling period 13.0 1 0 0.00 14.0 1 0 0.00 15.0 2 O 0.00 16.0 1 0 0.00 16.5 3 0 0.00 17.5 4 0 0.00 18.5 5 0 0.00 19.0 7 4 0.57 19.5 7 10 1.43 20.0 7 9 1.29 20.5 3 8 2.67 21.0 2 15 7.50 21.5 6 55 9.17 22.0 7 57 8.14 22.5 8 77 9.62 23.0 4 61 ' 15.25 23.5 13 175 13.46 24.0 5 50 10.00 24.5 18 245 13.60 25.0 5 96 19.20 25.5 16 258 16.12 26.0 5 90 18.00 26.5 13 179 13.77 27.0 8 153 19.12 27.5 11 160 14.55 28.0 3 58 19.33 28.5 5 101 20.20 29.5 3 81 27.00 30.0 2 36 18.00 30.5 1 28 28.00 31.0 2 20 10.00 31.5 2 22 11.00 32.5 1 28 28.00 33.5 6 85 14.17 34.5 2 20 10.00 TOTAL 189 2181 r = O.5232*** t = 8.44 df = 187 ***Significant at the .001 probability level. 52 TABLE 7.--Honey bee foraging activity in cucumbers as affected by temperature within the plant canopy, Mulliken, 1974. Number of Total number of visits/ Average number Temperature °C sampling lO flowers/ of visits per periods 10 min periods sampling period 10.0 2 O 0.00 13.0 2 0 0.00 15.0 2 0 0.00 15.5 2 0 0.00 16.0 4 0 0.00 17.0 4 0 0.00 17.5 6 O 0.00 18.0 2 0 0.00 18.5 4 0 0.00 19.0 2 O 0.00 19.5 4 0 0.00 20.5 8 1 0.12 21.0 2 O 0.00 21.5 6 0 0.00 22.0 8 9 1.12 22.5 14 27 1.93 23.0 2 4 2.00 23.5 4 4 1.00 24.0 2 3 1.50 24.5 12 15 1.25 25.0 2 7 3.50 25.5 14 42 3.00 26.0 10 45 4.50 26.5 6 17 2.83 27.0 6 19 3.17 28.0 2 4 2.00 28.5 4 11 2.75 29.0 2 4 2.00 30.0 4 l 0.25 30.5 4 7 1.75 31.0 2 2 1.00 31.5 4 5 1.25 32.0 2 1 0.50 32.5 4 3 0.75 33.0 2 l 0.50 33.5 2 3 1.50 TOTAL 162 235 r = 0.2633*** t = 3.46 df = 160 *** = Significant at the .001 probability level. 53 August 6 at Eaton Rapids the first bee observed in the field was at 16.5° C at 8:35 a.m. On August 5, a few bees were observed flying in the field between 14° and 15° C. At this time the flowers for the day had not undergone anthesis, so the bees were working the flowers of the previous day. Possibly this unusual behavior could be explained by the fact that bad weather kept the bees in the hive the two previous days. Highly significant positive correlations between temperature and foraging activity were found at all three locations sampled, East Lansing, Mulliken, and Eaton Rapids. Between 21.5 - 30.0° C, 83.7% of the flight activity occurred in East Lansing, 88.6% in Eaton Rapids, and 90.2% at Mulliken. In East Lansing 4.9% of the field population was foraging at 21° C and below, compared to 2.1% at Eaton Rapids, and 0.4% at Mulliken. At temperatures over 30° C, 11.4% of the field population was foraging at East Lansing, 9.3% at Eaton Rapids, and 9.4% at Mulliken. Overall, at the three loca- tions, there was 14.8% association between foraging activity and temperature within the plant canopy as indicated by the correlation coefficient. Comparison of locations showed from 6.9% - 27.4% asso- ciation between the two variables, Mulliken and Eaton Rapids respec- tively. East Lansing was close to the overall average at 16.6%. During the 12 day sampling period at East Lansing, hourly average temperatures ranged between 15.7 - 33.3° C, with a mean of 24.8° C. Bee visits/10 flowers/hour during the same time ranged from O - 115 with a mean of 35.8. 54 A highly significant positive correlation was also found between solar radiation and foraging activity in East Lansing (Table 8). TABLE 8.--Honey bee foraging activity in cucumbers as affected by solar radiation, East Lansing, 1974. Number of Total number Average number 8012;]:adiafiion sampling of visits/ of visits per periods 10 flowers/30 min sampling period 0 - 5 2 0 0.00 6 — 10 5 8 1.60 11 - 15 4 44 11.00 16 - 20 6 96 16.00 21 - 25 6 93 15.50 26 — 30 5 108 21.60 31 - 35. 7 203 29 00 36 - 40 10 259 25 90 41 - 45 16 721 45 06 46 - 50 9 308 34 22 51 - 55 10 523 52 30 56 - 60 9 424 47 11 61 - 65 10 577 57 70 66 - 70 8 448 56.00 71 - 75 1 53 53.00 Overall 108 3865 35.79 . r = 0.5425*** t = 6.68 df = 106 *** = Significant at .001 probability level. From 2.4 - 71.4 cal/cmZ/h were recorded with a mean of 42.1 cal/cm2/h. Foraging activity was first observed in an hourly period when 10.8 cal/cm2 were recorded. There were six hourly periods receiving from 2 2.4 - 9.6 cal/cm in which no activity was observed. However, 10.8 2 cal/cm cannot be considered a minimum threshold since no activity was recorded at values of 19.2, 20.4, 21.6, 33.6, and 36.0 cal/cm2 on 55 six different occasions. Overall, there was 29.4% association between solar radiation and foraging activity. Analysis indicated that there was a highly significant positive correlation between temperature and solar radiation, r = .6644 (significant at the .001 probability level) which indicates 44.1% association between the two variables. A highly significant negative correlation was found between foraging activity and relative humidity in East Lansing (Table 9). TABLE 9.--Honey bee foraging activity in cucumbers as affected by relative humidity, East Lansing, 1974. Number of Total number Average number % Humidity sampling of visits/ of visits per periods 10 flowers/3O min sampling period 90 - 100 7 48 . 6.86 80 - 89 10 205 20.50 70 - 79 12 324 27.00 60 - 69 16 603 37.69 50 - 59 20 960 48.00 40 - 49 29 1372 47.31 30 - 39 14 353 25.21 Overall 108 3865 35.79 gr = -.2630** t = 2.82 df = 106 ** = Significant at .01 probability level. Relative humidity during the study ranged from 33 to 96%, with a mean of 58.4. Of 108 sampling periods, 12 had no foraging activity. Dur- ing these periods the relative humidity ranged from 65 - 96%. Over- all, there was 6.9% association between relative humidity and forag- ing activity. Highly significant negative correlations were also found between temperature and humidity, solar radiation and humidity; 56 r = -.7841 (significant at the .001 probability level), r = -.7400 ‘(significant at the .001 probability level) respectively. Therefore, there was 61.5% association between temperature and humidity and 54.8% association between solar radiation and humidity. Wind speed during observation periods varied from 0.0 to 14.9 mph in East Lansing withamean of 8.1 mph. A significant posi- tive correlation was found between foraging activity and wind speed (Table 10). No activity was observed at wind speeds ranging from O to 9.2 mph during some of the sampling periods. Overall, there was 4.2% association between foraging activity and wind speed. A highly significant positive correlation was found between temperature and wind speed, r = .4341 (significant at the .001 probability level), which indicated 18.8% association between the two variables. No correlation was found between solar radiation and wind speed, r = .1050"°5'. A highly significant negative correlation was found between humidity and wind speed, r = -.3726 (significant at the .001 probability level) which indicated 13.9% association. Overall, the pattern of bee visits throughout the day in 1974 produced a normal distribution pattern centered around 11 - 12 a.m. EST (Figure 6), with 82.3% of all bee visits occuring between 9 a.m. and 2 p.m. Only 4.3% of the visits occurred before 9 a.m. and 13.4% after 2 p.m. At East Lansing 82.4% of all bee visits occurred from 9 a.m. to 2 p.m., compared to 83.4% at Eaton Rapids and 73.6% at Mulliken for the same time period. Prior to 9 a.m., only 4.9% of the visits occurred at East Lansing, 3.4% at Eaton Rapids, and 0.0% at 57 TABLE lO.--Honey bee foraging activity in cucumbers as affected by wind speed, East Lansing, 1974. Wingpipeed 22$311n3f Tgtaligumger . Svecagetgugger periods 10 flowers/3O min sampling period M 5 31 5.20 3'5 2 50 25.00 4.6 14 359 25.64 5-8 9 298 33.11 6.9 12 484 41.33 8.1 14 508 36.29 9.2 18 794 44.11 10.4 12 609 50.75 11.5 17 644 37.88 12.7 2 24 12.00 13.8 2 37 18.50 14.9 1 27 27.00 TOTAL 108 3865 r = .2039* t = 2.15 df = 106 * = Significant at the .05 probability level. 58 Figure 6.--Honey bee flight activity in cucumbers throughout the day and average hourly temperature, 1974. NO. BEE VISITS/1O FLOWERS/HOUR ' — AVE. 125 1.0 75 59 0 0‘“ ‘\ 4‘“ ‘0 0 ‘\ ‘0 ‘0 0 ‘0 .0 ‘0 ‘0 ‘0 ‘0 ‘\ .\ .0 “ ‘Q ~ 0‘ § 4? Q ‘ ~ ~ 0' 4' ~ Q «3 ~ TIME OF DAY “““..00000 12 000000,," 0 0 27 21 19 'C 00000000000 'EM PER A'URE 60 Mulliken. After 2 p.m., 12.7% of the total visits occurred at East Lansing compared to 13.2% at Eaton Rapids, and 26.4% at Mulliken. Overall, as bee activity increased until noon, the average hourly temperature also increased until 2 p.m., rising from 18.0 - 27.5° C, then decreasing slightly to 27.4° and 26.6° C (Figure 6). At East Lansing the average foraging pattern throughout the day also produced a normal distribution pattern centered around 11 - 12 a.m. EST (Figure 7). During the day, the average temperature increased from 18.7 — 27.8° C by 2 p.m., then decreased to 27.7° C and finally to 27.1° (Figure 7). The average solar radiation increased throughout the day until 1 p.m., going from a low of 13.8 cai/cm2 to a high of 55.7, then decreased during the rest of the afternoon down to 38.1 (Figure 8). The average relative humidity decreased during the day starting at a high of 85.1% and reaching a low of 43.0% at 3 p.m. (Figure 9). The average wind speed increased during the day until 5 p.m., going from 5.3 - 9.9 mph (Figure 10). Foraging activity and temperature changes throughout the day were similar at Eaton Rapids (Table 11) and at Mulliken (Table 12). Average daily foraging activity at East Lansing fluctuated significantly in relation to environmental conditions. The flowers received from 10,739 to 94,478 bee visits per day (Table 13). How- ever, values for August 13 - 16 should be considered separately since additional bees were moved in on August 16. Total visits between August 13 - 16 varied between 10,739 and 24,604. After the colonies were moved in, the visits ranged between 35,828 and 94,478. Compari- son of flight activity on August 13 (Figure 11) and August 14 61 Figure 7.--Honey bee flight activity in cucumbers throughout the day and average hourly temperature in East Lansing. Figure 8.--Honey bee flight activity in cucumbers throughout the day and average hourly solar radiation in East Lansing. 62 u. man—<32: o>< .il. 0 5 O 5 O 3 .2 2 1 1 5 ““““ O O 0 O O O 6 5 4 3 2 1 .1. I Oaxm¢m30au 0:92»; maul 12 11 10' 7 1'! I! 82\«IU\J:a_l== o>< I... o O 7 6 5 4 3 80 0 O 0 o o 0 0 0 0 B 5 4 3 2 1 .38 ou\n¢u39._u 0:92»; umul 12 11 1O 7 TIME 0 1 auutm na-i 0>¢ 7’! o 1 9 8 7 6 5 fl 4,, \ / 0 0 0 o O 0 6 5 4 3 2 1 4:! On\m¢uio.: Op\m.—.m; mun .l 65 TABLE 11.--Honey bee foraging activity in cucumbers throughout the day, Eaton Rapids, 1974. Time Avg. number of visits/ Mean R3098 0f 10 flowers/day temperature temperature 7:00 - 7:10 0.3 17.4 :_1.1 13.0 - 21.5 7:20 - 7:30 1.0 17.8 :_ .9 14.0 - 21.5 7:40 - 7:50 0.6 18.7 :_ .8 15.0 - 22.0 8:00 - 8:10 2.0 19.7 :_ .7 16.5 - 22.5 8:20 - 8:30 3.1 20.4 :_1.0 17.5 - 24.5 8:40 - 8:50 3.7 21.1 :_1.0 18.5 - 25.5 9:00 - 9:10 8.4 22.0 :_ .9 19.5 - 26.5 9:20 - 9:30 9.6 22.6 :_l.0 19.5 - 27.5 9:40 - 9:50 15.6 23.3 :_1.1 19.5 - 28.5 10:00 - 10:10 18.1 23.9 :_1.2 19.0 - 29.5 10:20 - 10:30 19.4 24.5 :_1.3 19.0 - 29.5 10:40 - 10:50 17.6 24.9 :_1.3 20.0 - 30.5 11:00 - 11:10 20.4 25.7 :_l.5 20.5 - 32.5 11:20 - 11:30 18.9 27.2 :_1.3 24.0 - 33.5 11:40 - 11:50 23.9 26.1 :_0.8 23.5 - 29.5 12:00 - 12:10 17.1 26.7 :_1.0 23.5 - 31.5 12:20 - 12:30 23.1 27.0 :_0.7 24.5 — 30.0 12:40 - 12:50 21.1 27.1 :_0.8 24.5 - 31.0 1:00 - 1:10 20.3 27.0 :_1.2 23.5 - 33.5 1:20 - 1:30 15.6 26.6 1 0.9 23.5 - 31.0 1:40 - 1:50 10.7 27.1 1 1.3 23.5 - 34.5 2:00 - 2:10 10.1 27.1 :_1.4 23.0 - 34.5 2:20 - 2:30 6.0 26.6 :_1.3 22.5 - 33.5 2:40 - 2:50 9.3 25.9 :_1.4 22.0 - 33.5 3:00 - 3:10 6.4 26.3 :_1.4 22.0 - 33.5 3:20 - 3:30 4.4 25.8 :_l.4 22.5 - 33.5 3:40 - 3:50 4.7 25.4 :_1.1 22.5 - 31.5 2181 bee visits/10 flowers/7 days July 25, 26, 29 Aug 1, 2, 5, 6 66 TABLE 12.--Honey bee foraging activity in cucumbers throughout the day, Mulliken, 1974. Time Avg. number of visits/ Mean Range of 10 flowers/day temperature temperature 7:00 - 7:10 0.0 14.2 _+_ 2.2 10.0 - 17.5 7:20 - 7:30 0.0 15.7 i 1.4 13.0 -18.0 7:40 - 7:50 0.0 17.0,:_0.9 15.5 - 18.5 8:00 - 8:10 0.0 18.0 :_1.3 16.0 - 20.5 8:20 - 8:30 0.0 18.7 :_1.0 17.0 - 20.5 8:40 - 8:50 0.0 19.3 :_l.2 17.5 - 21.5 9:00 - 9:10 0.3 21.2 :_1.7 19.5 - 24.5 9:20 - 9:30 1.7 21.8 :_1.3 20.5 - 24.5 9:40 - 9:50 0.0 22.8 :_l.4 21.0 - 25.5 10:00 - 10:10 0.3 23.2 :_1.4 21.5 - 26.0 10:20 - 10:30 0.7 23.5 :_1.8 21.5 - 27.0 10:40 - 10:50 5.3 24.2 :_1.9 22.0 - 28.0 11:00 - 11:10 4.3 24.5 :_2.0 22.5 - 28.5 11:20 - 11:30 3.3 25.2 :_1.8 22.5 - 28.5 11:40 - 11:50 9.7 26.2 :_1.9 22.5 - 30.5 12:00 - 12:10 6.7 26.7 :_2.0 23.5 - 30.5 12:20 - 12:30 5.3 26.2 i 1.9 22.5 - 29.0 12:40 - 12:50 4.7 26.8 :_2.4 22.5 - 31.0 1:00 - 1:10 6.7 26.8 :_2.5 23.0 - 31.5 1:20 - 1:30 2.0 28.0 :_2.0 25.5 - 32.0 1:40 - 1:50 6.7 28.3 :_2.6 25.5 - 33.5 2:00 - 2:10 5.3 28.5 :_2.0 26.5 - 32.5 2:20 - 2:30 6.0 28.2 :_2.4 25.5 - 33.0 2:40 - 2:50 3.0 27.8 :_2.3 25.5 - 32.5 3:00 — 3:10 2.3 26.7 :_2.4 23.5 - 31.5 3:20 - 3:30 1.0 26.3 :_1.8 24.5 - 30.0 3:40 - 3:50 3.0 26.2 :_1.9 24.0 - 30.0 235 bee visits/10 flowers/3 days August 26, 29, and 30. 67 moo.aom o moms asp: com: m>wuopme coo: empom cow: meagmgmaEmh cam: gmzope _apoh .aum. .mcwmcao ummm .mcowuwvcou uwumewFu ca cowpm—mg cw mgmnezusu cm moon zocoz mo xuw>wauo m:_mugouui.m_ m4m

an. 71 responsible. Temperature was the major factor that appeared to be involved when comparing August 23 with 24. Triple combinations of temperature, wind, and humidity for August 14 and 15 and temperature, solar radiation, and humidity for August 17 and 18 seemed to be involved. Differences between August 18 and 19 were due to humidity and solar radiation compared to August 20 and 21, where wind speed and humidity were involved. All four factors were probably important when comparing August 22 and 23. During the seven days of observation at Eaton Rapids, the total number of visits per flower fluctuated between 45.8 and 95.2 (Table 14). Average daily temperature ranged between 21.7 and TABLE l4.--Average daily foraging activity in cucumbers in relation to temperature, Eaton Rapids, 1974. Average number of Date visitsgpgrhflower Temgggzture Tempggggure July 25 53.4 24.7 :_.5 19.0 - 28.5 July 26 81.4 29.5 :,.8 21.5 - 34.5 July 29 95.2 24.0 :_.4 20.0 - 27.5 August 1 52.0 21.7 :,.4 15.0 - 24.5 August 2 46.8 22.2 :_.6 17.5 - 26.5 August 5 51.6 23.0 :_.9 13.0 - 27.5 August 6 55.8 24.5 :_.7 16.0 - 30.0 29.5° C. Positive correlations between temperature and foraging activity were found for all chronological pair comparisons except July 26 and 29 and August 1 and 2. Other climatological factors must 72 have been involved but the data did not indicate what they were. A positive correlation between average daily temperature and total num- ber of visits per flower at Mulliken was not found (Table 15). Total TABLE 15.--Average daily foraging activity in cucumbers in relation to temperature, Mulliken, 1974. Average number of . . Temperature Temperature Date Visitsgpgrhflower mean range August 26 4.9 27.3 :_1.0 17.5 - 33.5 August 29 8.3 21.4 :_ .8 10.0 - 26.5 August 30 10.3 22.6 :_ .7 15.0 - 27.0 .1.— number of visits per flower ranged from 4.9 - 10.3 for the three days while temperature fluctuated between 27.3 and 21.4° C. The effect of threatened storms and rain on foraging activity throughout the day was observed on August 2, 1974, at Eaton Rapids and on August 16 and 23 at East Lansing. On August 2 (Figure 13) at 7 a.m. flowers were open and the temperature was 17.5° C. It had rained during the night and was still sprinkling. From 7:35 to 8 a.m. there was no rain, then it rained again from 8 to 8:15. The sun came out at 8:15 and the first bee in the field was observed at 8:37. At 8:47 it started to rain, but two bees continued to work and rain stopped at 8:55. It rained again from 9:47 to 10:15. Again three bees were observed working during the rain. As a result, bee activity was delayed until 11 a.m. and peaked between 1 and 2. On August 16 73 (Figure 14) at 7 a.m., temperature was 19.5° C, sunny with a slight haze, and flowers were completely open. At 10:30 it clouded upland a strong wind came up. As a result flight activity leveled off. At 12:35 it started to thunder, but the storm blew over and the sun came back out at 12:48. Bee activity peaked between 1 and 2 p.m. At 2:05 it clouded up and light rain started at 2:22. It became dark, started to thunder, and the wind came up. As a result bee activity decreased rapidly. By 5 p.m. 0.06" of rain had fallen. On August 23 (Figure 15) bee activity was interrupted in late morning and did not recover during the afternoon. At 7 a.m. temperature was 20° C and the flowers were fully open even though it was foggy. The sun broke through the haze at 7:15. With the temperature above average at 7 a.m., bee activity increased more rapidly than normal in the early morning. However, at 10:50 black clouds appeared and rain started at 11:08. A light rain continued until 11:45. As a result bee activity rapidly declined. At 12:47 the sun reappeared for the afternoon, but foraging activity remained depressed. Climatic Conditions AffeCting,Nectar Secretion Because temperature and other weather factors vary daily, cucumber floWers begin to secrete nectar at different times of the day.- The number of staminate and pistillate flowers producing nectar increased throughout the day at recorded hourly intervals until noon (Figure 16). The remainder of the afternoon values remained high and were not significantly different. On August 12, 1968, measurable amounts of nectar in the pistillate flowers did not appear until 74 Figure 13.--The effect of threatening storms and rain on foraging activity in cucumbers, August 2, 1974. Figure 14.--The effect of threatening storms and rain on foraging activity in cucumbers, August 16, 1974. 75 ‘ 7 9 ‘ . 2 OI 0' t "0 s 000 u 000 " G o: .0 U :2...- A 33:... 5 OCOOOCO I O... I 0:. 5 CO. 5 CC. on 5 CC! 2 ‘0'. 5 ‘C I QQQQQ QQQQ 9.. \Q‘ QQQ \QQ 00 00 Q QQQQ §§§ [ n w u. m .2. on\m.u30.: 0: m2!) 15 13 3:00 2:00 12:00 1:00 10:00 11:00 8:00 9300 7300 TIME unmmuAUGUSt 10. 1070 75 —AVEIAGE FORAGING ACTIVITY. .8.‘ ooxu¢u30au opxaha.) 5 1 14 76 Figure 15.--The effect of threatening storms and rain on foraging activity in cucumbers, August 23, 1974. 77 cos oo& co; co"! co": oouow 'haw .nN hmn—Gafl :22...- >._._>:.U< 02.9126... ua<¢u>< I I I O If) n F 'III 08 ISIJM011 Ol/SLISIA 338 I m C I o 0 lab 78 Figure 16.--The percent of staminate and pistillate cucumber flowers producing nectar throughout the day. 79 .3.me 92:. 090 con 8...». 8“ 80 co": «wagon—h. m... u0< (88311710801111) HVLOBN :IO BWG'TOA 83 Figure 18.--The average sugar concentration of cucumber nectar produced by staminate and pistillate flowers and as it is collected by the honey bee throughout the day. 84 . 2.2. m2... 3.... oofi 88 con. 30 09.. 86. 85 86 m:0<20hm >550... ........ mmw304m m...< 008 0. ON on 0.? 00 HVGI‘IS 111130836 85 Figure l9.--The average weight of sugar in cucumber nectar produced by staminate and pistillate flowers throughout the day. 86 $.va ma; 00"? 00"” 00% 00". 00$. 00".. 000. 00% 000 00a. 0¢u3040 ugh-5.34...» -1101 c 0,330...“— u._.<...=._.0_n_ II \ ><0 wt... h:0:0:0¢:.—. £4030 “.0 5.20.29 u0<¢m>< (0W) evens :10 10101301 87 with a mean of 2.23 mg/day. All mean values were based only on those flowers which produced nectar. . Throughout the morning as the average volume of nectar and actual weight of sugar increased, along with the number of flowers producing nectar, the average temperature also increased. In 1968 the average temperature when flowers were producing nectar by 7 a.m. was 23.4° 0 increasing to a high of 28.2° C by 4 p.m. Similarly, in 1969 temperatures went from 19.4° C at 8 a.m. to a high of 28.0° C at 3 p.m. As the temperature increased, sugar concentration of nec- tar decreased. However, the two may not be related. Daily nectar production fluctuated in response to changing climatic conditions. The average daily volume of nectar produced by pistillate flowers excluding flowers which produced no nectar ranged between 1.99 and 10.80 ul (Table 16). When all flowers were included, the range was 0.00-10.48 ul per day. In staminate flowers, daily nectar volumes excluding flowers which produced no nectar averaged 3.17 to 7.25 ul with a mean of 4.68 ul (Table 17). For all flowers, values ranged between 1.74 and 7.25 ul per day. Daily average sugar concentrations for the nectar of pistillate flowers fluctuated between 29.8% and 42.7% compared to 40.4% to 48.0% in the staminate flowers. Similar daily fluctuations were observed in the actual weight of sugar present in the nectar. When all flowrs were included, pistillate flowers averaged from 0.00 to 4.02 mg per day compared to 0.89 to 4.07 mg for staminate flowers. Basing the results only on flowers that were producing nectar gave a range of 88 .1 oo.o 1. o.c —m oo..H oo.o oo. .H.o .o oo.c.H.oo.o Fm mmiw s¢..H um.m mm._.H m~.o~ o0 me..H.mp.e No.P.H ~.~m mm._.w_om.op mm «mum m¢..H.~o.e um.P.H um.o_ om me..H Np.e o~._.w m.mm em.P.H mm.o_ om mmim me..H mm.m «m.p.w_me.op KN me..H um.m hm.F.H.m.¢m pm.p.H.we.o_ “Ni, Pwiw om..H me.m ~¢.P.H em.w om om..H.mo.m .mo._.w.m.~m Fe.F.H me.m em ouim mm..H mm.F oh. .H mm.m mm em..H m¢.~ mo.p.w m.mm N“. .H -.c Ne mpnm mm..H_~m.p mm. .H._m.m em om..H mm.p mN.P.H a.mm mm. .H_~—.¢ Fm mpim em..H mm. mm. .H no.~ em mm..H mm. FN.N.H_o.~m mm. .H.mo.m ap mpiw ap..w.mo.F ow. .H o~.~ ow om..H —m.P PN.P.H ~.~¢ cc. .H.mp.m mm epim ~o..H me. mp. .H_mp.p Pm oo..H.m~.o po.F.H_m.em up. .H mm.~ Ne myum mo..w up. up. .H.m¢.o we op..H mu.o mm.m.H.o.mm cm. .H mp.~ m Npim mm..H mm.p mm. .H om.m mm m~..H em.~ mm.p.H_P.mm mm. .H_~s.m mm a 1m mm..H.mm.~ m_.p.H om.~ mm w~..H o~.m mm.p.H m.~m mP.P unmm.m om m .m ee..H up. mm.P.H om.m mm me._w.mm.m mp.~ www.cm em.p.H_¢_.m o_ u .m mu..H.m~.~ mm. .H me.m mm om..H_em.~ me.p.w_m._m mm. .H.m—.n mu m 1m m~..w.m¢._ en. .H_um.m mm mm..H mo.~ um. .H.o.¢m om. .H.m~.m m_ m .m up..H mm. me. .H mo.p mm mm..H pa._ o~.P.H_~.Fm ma. .H.Pm.m wF N 1m m...H mm. mm. .H pm.— oe up..H Pm.F mN.P.H.N.wm ma. .H so.m up P .m PF..H mm. mm. .H om._ om up..H no._ am.p.H e.Pm No. .H.m~.m PF Fm-“ mp..H no. me. .H.mo.~ mm up..w Np.~ mm.p.w_m.m~ mm. .H s¢.m pm onus mp..w mm. mm. .H N~.~ mm 0F..H mu.p wo.~.H a.mm so. .H.-.e mp mmin mm. + pm.p mo.~ + om.¢ cm mm. + mm.~ mm.~ + a.mm -.p + F5.“ ep owns mcmzoFm Fp< . - gmpum: cmosvoca page mcmzopw.co comcm Away ccmsm mo Apzv oE=Po> mNPm Amsv cmmzm mo cowumcucmucoo A~=V.mE=Po> «Npm mama unmwmz mmmcw>< mmcca>< . mpqsmm pzmwmz mmmcm>< cmmam mmmgm>< . mmcgm>< mpasmm .mmmp .mgmzopm conszuau mumppwum_g an hpwmu cmumcumm comam 0o agape: nope» use .coppccucmucou cmmam .ccpom: 0o mE=Fo> mmccw>m mzhui.m— m4m<~ 89 8. H3; 8. H85 am 2. H24“ 3. H93 5. H88 8 mg 8. H a: S. H SH 8 t. H .8; 3. H 9% on. H 86. mm 88 NoHam. am. Hm: o... 2. H8; 8. He: 8H 55 mm 8-x 3. H 3; R. H 25 em a. H SH 3. H 93 em. H 3.0 an 8-x 3. H 8; mm. H 35 3 4.8.. H o: E. H 92 mm. H 85 8 m3 .8. H 8; mm. H 2H 8 8. H N: 8. H 4.8 S. H :3 mm .3 8. H 8.. mm. H e: on a. H 8.. mm. H :0 mm. H :8 mm 8.8 3. H 80 Ne. H 88 o... 3. H m2 3. H 0.: S. H 33 Nm 2-» 3. H SH 3. H m: we 8. H 3:8. 3. H 0.8 3. H m: 8 24 B. H 3.0 mm. H m: we 3. H 3.0 a. H 93 mm. H m: we 2% 3. H 8H s. H 83 em a. H SH 3. H 3; om. H 58 Na :8 mcmzopw —F< genome mcpuzuoga mcmzopw apco High“ 22%.. Ha”. ‘._A_W.._.t...wmm...d ”fix? 0%.. a”. .momp .mgozop0 consausu mumcmscum Ha apwou umpmgumm cmmzm mo agape; pcuou use .covumcucmucou Luann .cmuum: mo mE:~o> mmmgm>m ushui.- m4m u>¢ 8 6 4 2 ‘ n V 4 .l 10 o In ’ I. s l U ss 3» IJ .c \a 99” N zv t! 332:: ’1, ---~5 ’1' m \ u L‘ «$990 “\ ‘ 30??? U“ ooooo “ tooaov ‘ u “1 u .. 2 5 1 6 5 m m w m 4 w. 4 m . 9. 2323.53 19 20 21 25 2o 27 23 29 AUG 14 15 18 101 Figure 24.--The daily average sugar concentration of nectar pro-v duced by staminate cucumber flowers in relation to temperature. 102 32. 8.0200 «(Gan 6>< 0 5 I x. ‘ . \\ .... h a... \ \ §§§~§§~ pA” :8. 1’ QQQP 11V m ‘ OOOOO \ IO'OO “ I’ll ‘. IO ‘. 1‘ q‘ .. 2 w m 4 00 m¢=h¢¢u51mh 40 “-100 ‘ 25 26 27 28 29 19 2O 21 AUG 14 15 18 103 Figure 25.--The daily average weight of sugar in cucumber nectar produced by staminate flowers in relation to tempera- ture. 104 m 26.7 15.6 10.1 o: 3:50. .3 h! o>< 4 3 2 MG 4 ”100 6.5 mag—ht.— ugly.— -12.0 19 2O 21 25 26 27 28 29 18 15 AUG 14 105 August 12 when the threshold temperature was not reached until l p.m., only 0.14 mg. In 1969 the staminate flowers showed a similar trend (Tables 17 and 19). If the threshold temperature was reached ‘ by 8 a.m., the flowers averaged 4.24 u1 compared to 2.84 u1 if the temperature was reached by 9 a.m., 2.45 ul by 10 a.m., and 1.78 ul by 11 a.m. In the actual weight of sugar, values decreased from 2.34 mg for an 8 a.m. threshold to 1.57 mg for 9 a.m., 1.44 mg for 10 a.m., and 0.89 mg for 11 a.m. The average volume of nectar and actual weight of sugar increased along with the number of flowers producing nectar until noon, while the average humidity decreased during the same time interval. At the same time the average sugar concentration of the nectar in both staminate and pistillate flowers was also decreasing. In 1968 the humidity decreased from a high of 97.4% at 7 a.m. to a low of 60.6% at 3 p.m. compared to 1969 when it went from 78.7% at 8 a.m. down to 46.7% at 4 p.m. Average daily humidity values fluc- uated between 49.1% and 92.0% with a mean of 71.6% in 1968 (Table 18). During 1969 values were found between 44.6% and 64.7% humidity, with a mean of 54.3% (Table 19). Comparison of the daily humidity means with the average volume of nectar produced gave a correlation coeffi- N'S° for the cient of .4946N‘S' for the staminate flowers and .2029 pistillate which indicated 24.5 and 4.1% association. respectively. Overall, highly significant negative correlations were found between relative humidity and volume of nectar (Table 23). Correla- tion coefficients of -0.1763 and -0.2817 were found for the pistillate . 106 and staminate flowers which indicated 3.1% and 7.9% association, respectively. Analysis of the nectar volume data by various levels of relative humidity indicated that average volumes ranged between 1.61 and 10.44 ul'hipistillate flowers and 0.00 - 5.38 ul in stamin- ate. These volumes occurred at 95 - 100% and at 60 - 64% humidity in pistillate flowers and at 90 - 94% and 40 - 44% humidity in stam- inate respectively. Overall, pistillate flowers at a mean relative humidity of 72.6%. averaged 6.7 ul of nectar compared to 4.68 ul at a mean of 54.0% relative humidity in staminate flowers. As was found with temperature, humidity only affected the sugar concentration of the nectar in the pistillate flowers (Table 24). A highly significant positive correlation was found with a correlation coefficient of 0.3350 which indicated 11.2% associa-~ tion. Mean sugar concentrations ranged between 40.8 and 30.9% at humidities of 95 - 100% and 551- 59%. respectively. In staminate flowers sugar concentrations ranged between 48.8 and 40.9%, which occurred at 85 - 89% and 30 - 34% relative humidity, respectively. A correlation coefficient of 0.0119 was obtained which was not sig- nificant. Overall, pistillate flowers averaged 35.1% sugar at a mean relative humidity of 72.6% compared to 45.2% sugar at a mean relative humidity of 53.7% in staminate flowers. Negative correlation coefficients found between relative humidity and actual weight of sugar in the nectar were highly signifi- Cant in both staminate and pistillate flowers (Table 25). The average weight of sugar found in the nectar fluctuated between 0.66 and 107 3.59 mg in pistillate flowers and between 0.00 and 3.10 mg in stamin- ate. The lowest values occurred at 95 - 100% and at 90 - 94% rela- tive humidity compared to 60 - 64% and 40 - 44% for the highest values in pistillate and staminate flowers, respectively. A correla- tion coefficient of -0.l322 (significant at the .01 probability level), which indicated a 1.7% association, was found for pistillate flowers compared to -0.3532 (significant at the .001 probability level) and 12.5% association for staminate. Overall, pistillate flowers produced an average of 2.51 mg of sugar at an average rela- tive humidity of 72.6% compared to 2.64 mg at 53.7% for the staminate. Total solar radiation produced during the day of sampling fluctuated between 366 and 652 langleys (calories/cmZ/day) in 1969 (Tables 18 and 19). At the same time, the percent possible sunshine for the day ranged between 7 and 96% in 1968 and 22 and 100% in 1969. However, when the total solar radiation on the day of anthesis was compared to the volume of nectar, % sugar, and actual weight of sugar for both staminate and pistillate flowers, significant corre- lations were not found (Table 26). Therefore, to focus on the amount of solar radiation prior to anthesis needed to affect nectar secretion, correlations were run between the daily average nectar volume, sugar concentration, and actual weight of sugar with various combinations of solar radiation. In pistillate flowers, a signifi- cant negative correlation was first obtained between total solar radiation for the day of anthesis plus the too previous days and both volume of nectar and actual weight of sugar. Correlation 108 TABLE 18.--Climatic conditions affecting nectar production in pistil- late cucumber flowers during 1968. Date l;::.::.l:‘ %sgg;;}:;e raii§i¥on gggggggy C¥Ea ggggggi- nectar (langleys) speed 7-26 9:00 96 710 49.1 4.9 .00 7-29 10:00 88 612 -- 4.9 .00 7-30 11:00 89 640 52.8 9.4 .00 7-31 9:00 24 252 86.8 11.4 .29 8- 1 10:00 70 565 71.5 5.6 .00 8- 2 9:00 92 639 53.6 5.2 .00 8- 5 9:00 7 175 92.0 6.3 .91 8- 6 8:00 25 309 88.8 9.9 .01 8- 7 -- 70 551 73.3 7.1 .08 8- 8 8:00 53 337 83.3 3.9 .30 8- 9 8:00 56 454 82.0 6.2 .09 _ 8-12 1:00 81 644 -- 3.6 .00 8-13 8:00 76 543 -- 11.8 .00 8-14 9:00 94 -- 54.6 6.0 .00 8-15 10:00 79 575 -- 8.8 .04 8-16 7:00* 40 -- -- 9.6 .78 8-19 8:00 81 573 -- 10.9 .75 8-20 7:00* 66 -- -- 12.5 .00 8-21 7:00* 65 376 -- 6.0 .00 8-22 7:00* 94 -- -- 9.9 .00 8-23 7:00* 92 548 -- 9.1 .00 8-26 no secretion 41 386 -- 7.9 .00 *First sampling period, nectar was present. 109 TABLE 19.—-Climatic conditions affecting nectar production in stami- nate cucumber flowers during 1969. Date $§2§uggbizt %SE:::§:;e ra§?;::on fizggggiy 3138 Egiggfii' nectar (langleys) speed 8-14 -- 22 366 61.3 10.8 T 8-15 8:00 24 491 59.5 9.5 0 8-18 -- 84 544 59.3 10.8 0 8-19 8:00 96 628 50.7 7.5 0 8-20 10:00 100 652 47.5 6.6 0 8-21 8:00 100 642 44.6 3.0 0 8-25 9 : oo 92 570 54.3 9. 5 0 8-26 10:00 100 604 51.0 6.8 0 8-27 11:00 89 551 47.0 7.5 0 8-28 9:00 82 482 57.9 7.9 0 8-29 8:00 45 383 64.7 7.2 0 110 TABLE 20.--The affect 0f temperature on the volume of nectar pro- duced in cucumber flowers. Pistillate Flowers 1968 Staminate Flowers 1969 Temperature Mean Mean N volume Range N volume Range 10.0 0 -- 6 0.0 0.0 11.7 9 0.0 0.0 6 0.0 0.0 12.2 16 0.0 0.0 0 -- -- 12.8 3 0.0 0.0 12 0.0 0.0 13.3 23 0.0 0.0 0 -- - 13.8 3 0.0 0.0 0 -- - 14.4 7 0.0 0.0 0 —- -- 15.0 23 0.0 0.0 6 0.00 0.00 15.6 11 0.0 0.0 6 0.00 0.00 16.1 .17 0.0 0.0 12 0.00 0.00 16.7 14 0.0 0.0 0 -- -- 17.2 3 0.0 0.0 6 0.00 0.00 17.8 11 0.0 0.0 16 0.00 0.00 18.3 9 0.27 0.00- .22 0 -- -- 18.9 30 0.07 0.00- .25 12 0.02 0.00- 0.24 19.4 6 0.00 0.00 0 -- -- 20.0 38 0.37 0.00- 3.28 23 0.06 0.00- 0.73 20.6 32 1.09 0.00- 5.31 12 0.00 0.00 21.1 21 1.48 0.00- 7.19 30 0.78 0.00- 4.15 21.7 15 2.57 0.00- 8.91 12 2.48 0.00- 6.10 22.2 43 1.41 0.00- 6.83 18 0.85 0.00- 4.88 22.8 25 1.97 0.00- 6.83 17 1.58 0.00- 4.39 23.3 23 2.64 0.00-10 00 43 2.89 0.00- 9.51 23.9 66 3.25 0.00-13 90 6 1.50 0.24- 3.41 24.4 49 3.83 0.00-12 44 42 2.93 0.00- 9.02 25.0 18 5.58 0.00-17.32 12 3.40 0.00- 7.56 25.6 53 2.74 0.00-15.63 24 3.42 0.00- 9.76 26.1 32 4.96 0.00-17.07 19 4.58 0.00- 9.27 26.7 32 6.27 0.00-17.32 36 3.48 0.73-10.98 27.2 13 7.75 0.24-14.23 18 5.99 l.95-ll.7l 27.8 24 8.18 0.00-18.29 30 4.07 0.00-10.24 28.3 19 9.78 l.22-3l.95 42 ~4.73 0.00-12.69 28.9 13 9.98 0.00-31.71 48 5.68 0.00-13.18 29.4 26 9.81 0.00-23.90 36 5.44 1.71-12.44 30.0 33 10.73 0.00-23.66 36 6.74 l.7l-l3.66 30.6 13 6.44 0.49-13.66 12 9.43 2.68-14.88 31.1 14 11.81 3.17-33.66 6 7.85 3.90-10.00 31.7 15 13.45 0.00-30.49 0 -- - -- 32.2 19 19.49 8.05-34.15 0 -- - -- 32.8 0 -- -- -- 0' —- - -- 33.3 6 13.94 2.20-25.12 0 -- - -- Overall 827 604 with zero values r = .6550 r = .6575 t = 24.81*** df = 825 t = 21.92*** df = 602 without zero values r = 0.6392 r = 0.4881 t = 19.31*** df = 496 t = 11.85*** df = 430 ***Significant at the .001 probability level. 111 TABLE 21.--The affect of temperature on the sugar concentration of nectar from cucumber flowers. Temperature Pistillate flowers 1968 Staminate flowers 1969 C N Mean Range N ' Mean Range 18.3 3 35 8 28.3 47 8 0 -- -- -- 18.9 2 42 2 38 6 - 45 7 1 34.2 34.2 19.4 0 -- -- -- 0 -- -- -- 20.0 5 40.9 36.1 - 47.3 3 36.1 33.4 - 40.4 20.6 14 41.5 37.1 - 54.5 0 -- -- -- 21.1 8 44.0 40.7 - 57.1 12 47.9 38.2 — 60.2 21.7 7 36.1 27.2 - 43.6 8 44.0 29.0 - 51.0 22.2 21 40.4 30.8 - 49.2 9 44.9 32.8 - 55.3 22.8 21 37.6 26.4 - 48.8 9 46.0 42.2 — 49.0 23.3 16 38.3 23.6 - 47.7 33 45.9 34.7 - 55.2 23.9 56 35.5 19.4 - 55.0 5 41.5 37.7 - 46.5 24.4 38 35.6 24.3 - 47.9 32 43.8 29.0 - 54.7 25.0 17 37.8 29.1 - 47.8 11 46.0 31.6 - 52.3 25.6 45 38.2 21.9 - 48.7 23 45.9 34.9 - 51.8 26.1 30 37.1 21.6 - 49.5 18 48.0 38.8 - 50.9 26.7 27 33.4 22.2 - 42.0 36 44.4 27.8 - 53.1 27.2 12 34.2 13.6 - 46.5 18 47.7 45.4 - 55.9 27.8 21 35.3 28.4 - 43.6 29 45.1 31.0 - 54.4 2813 16 32.6 21.7 - 41.2 39 45.0 30.1 - 50.0 28.9 12 28.6 20.3 - 40.8 46 44.8 37.2 - 51.2 29.4 22 31.1 21.1 - 45.8 36 43.4 31.0 - 50.4 30.0 32 30.7 21.3 - 46.8 36 46.5 39.7 - 54.8 30.6 13 34.8 27.7 - 46.7 12 43.2 35.0 - 45.5 31.1 14 35.8 30.1 - 49.2 6 45.9 44 0 - 47.4 31.7 14 29.0 24.2 - 34.3 0 -- -- -- 32.2 19 29.6 25 8 - 35.2 0 -- -- -- 32.8 0 -- -- -- 0 -- -- -- 33.3 6 22.9 20.0 - 25.4 0 -- -- -- Overall 491 35.2 13.6 — 57.1 422 45.1 27.8 - 60.2 r = -0.4150 r = 0.0013 489 t = .026NS df = 420 t = 10.37*** df *** = Significant at the .001 probability level. NS = Not significant. 112 TABLE 22.--The affect of temperature on the actual weight of sugar in the nectar of cucumber flowers. Pistillate flowers 1968 Staminate flowers 1969 Temperature C N x33" Range N 3:3" Range 10.0 0 -- -- 6 0.00 0.00 11.7 9 0.00 0.00 6 0.00 0.00 12.2 16 0.00 0.00 O -- -- 12.8 3 0.00 0.00 12 0.00 0.00 13.3 23 0.00 0.00 O -- -- 13.9 3 0.00 0.00 O -- -- 14.4 7 0.00 0.00 O -- -- 15.0 23 0.00 0.00 6 0.14 0.00 - 0.87 15.6 11 0.00 0.00 6 0.00 0.00 16.1 17 0.00 0.00 12 0.00 0.00 16.7 14 0.00 0.00 0 -- -- 17.2 3 0.00 0.00 6 0.00 0.00 17.8 11 0.00 0.00 16 0.00 0.00 18.3 9 0.11 0.00 - 43 O -- -- 18.9 30 0.04 0.00 - 69 12 0 01 0.00 - 0 16 19.4 6 0.00 0.00 O -- -- 20.0 35 0.12 0.00 - 1.48 23 0.03 0.00 - 0.29 20.6 22 0.47 0.00 - 1.72 12 0.00 0.00 21.1 14 0.24 0.00 — 0.71 28 0.44 0.00 - 1.85 21.7 13 0.85 0.00 - 2.67 12 1.34 0.00 - 3.56 22.2 43 0.65 0.00 - 3.01 15 0.46 0.00 - 1.83 22.8 25 0.85 0.00 - 2.57 17 0.88 0.00 - 2.42 23.3 23 1.15 0.00 - 4.99 42 1.64 0.00 - 4.94 23.9 64 1.25 0.00 - 5.07 5 0.89 0.43 - 1.87 24.4 46 1.45 0.00 - 4.87 41 1.54 0.00 - 4.09 25.0 18 2.33 0.00 - 6.92 12 1.91 0.00 - 4.16 25.6 53 1.16 0.00 - 4.61 24 1.95 0.00 - 5.51 26.1 31 1.92 0.00 - 5.18 19 2.68 0.00 - 5.79 26.7 29 2.58 0.00 - 7.06 36 1.90 0.35 - 6.30 27.2 12 3.18 0.86 - 5.40 18 3.57 1.09 - 8.28 27.8 24 3.30 0.00 - 7.68 30 2.25 0.00 - 5.46 28.3 16 3.78 0.79 - 11.93 42 2.57 0.00 - 7.29 28.9 13 2.81 0.00 — 8.03 47 3.02 0.00 - 8.36 29.4 26 3.33 0.00 - 7.49 36 2.86 0.85 - 6.85 30.0 33 3.68 0.00 - 8.01 36 3.84 0.94 - 7.97 30.6 13 2.49 0.28 - 5.24 12 5.10 1 38 - 7.64 31.1 14 4.72 1.33 - 8.90 6 4.37 2.06 - 5.63 31.7 15 4.42 0.00 - 10.84 0 -- -- -- 32.2 19 6.56 2.82 - 12.33 0 -- -- -- 32.8 0 -- -- -- O -- -- -- 33.3 6 3 55 0.58 - 7.07 O -- -- -- Overall 792 295 With zero values r = 0.6607 r = 0.5492 t = 25.03*** df = 790 t = 16.59*** df = 593 Without zero values r = 0.6050 r = 0.1731 t = 17.49*** df = 489 t = 3.61*** df = 416 *** = Significant at the .001 probability level. 113 TABLE 23.--The affect of humidity on the volume of nectar in cucumber flowers. Humidity Pistillate flowers 1968 Staminate flowers 1969 Mean ean N volume Range N volume Range 95 - 100 93 1.51 0.00 17.07 0 -- '90 - 94 90 2.47 0.00 17.32 18 0.00 0.00 85 - 89 84 2.79 0.00 31.71 30 0.09 0.00 - 1.22 80 - 84 74 3.25 0.00 18.29 '58 0.53 0.00 - 4.39 75 - 79 53 5.14 0.00 31.95 12 1.08 0.00 - 4.15 70 - 74 79 5.95 0.00 23.90 35 1.74 0.00 - 7.07 55 - 59 87 4.53 0.00 23.55 24 2.20 0.00 - 7.07 50 - 54 55 10.44 0.00 32.44 50 2.81 0.00 - 12.59 55 - 59 35 5.79 0.00 34.15 72 4.32 0.00 - 10.98 50 - 54 72 3.33 0.00 13.90 95 5.11 0.00 - 14.88 45 - 49 18 3.19 0.00 8.91 84 3.85 0.00 - 11.71 40 — 44 15 8.20 2.20 15.53 50 5.38 0.00 - 11 71 35 - 39 0 - -- -- 5 4.31 2.44 - 5.10 30 - 34 0 -- -- -- 12 4.35 0.00 - 9.02 r = -O.1763 r = -O.2817 t = 4.05*** df = 503 t = 5.88*** df = 395 *** = Significant at the .001 probability level. 114 TABLE 24.--The affect of humidity on the sugar concentration of nectar in cucumber flowers. Pistillate flowers 1968 Staminate flowers l969 Humidity Mean sugar Mean sugar N concentra- Range N concentra- Range tion tion 95 - 100 51 40.8 21.6 - 55.0 0 -- -- -- 90 - 94 47 39.2 30.3 - 48.7 18 -- -- -- 85 - 89 43 36.6 21.3 - 47.8 3 48.8 44.6 - 57.0 80 - 84 34 34.9 15.6 - 45.6 13 45.5 41.1 - 55.3 75 - 79 36 32.7 21.1 - 47.3 5 44.7 38.2 - 49.8 70 - 74' 50 35.8 24.5 - 49.2 25 45.1 39.3 - 50.9 65 - 69 66 33.6 21.7 - 57.1 18 42.8 27.8 - 47.2 60 - 64 60 31.5 21.9 - 48.8 40 46.1 40.5 - 50.6 55 - 59 18 30.9 20.0 - 42.0 54 45.1 37.0 - 54.2 50 - 54 56 33.3 19.4 - 52.5 78 44.3 29.0 - 60.2 45 - 49 12 34.2 21.7 - 48.1 76 45.5 27.8 - 54.8 40 - 44 15 32.0 22.5 — 47.8 59 47.2 34.7 - 55.9 35 - 39 O -- -- -- 6 42.3 31.1 - 46.5 30 - 34 O -- -- -- 11 40.9 30.5 — 46.3 r = 0.3350 r = 0.0119 t = 8.13*** df = 495 = .2380NS df = 404 *** = Significant at the .001 probability level. NS = Not significant. 115 TABLE 25.--The affect of humidity on the actual weight of sugar in the nectar of cucumber flowers. Pistillate flowers 1968 Staminate flowers l969 ~ 2:22.12. ~ 12:62.1; 95 100 92 0.66 0.00 - 5.18 O 90 94 90 1.09 0.00 - 6.92 18 0.00 0.00 85 89 84 1.07 0.00 - 6.98 30 0.05 0.00 - 0.66 80 84 73 1.31 0.00 - 7.68 54 0.29 0.00 - 2.48 75 79 53 2.19 0.00 - 11.93 12 0.56 '0.00 - 1.85 70 74 79 2.27 0.00 - 7.49 35 1.00 0.00 - 4.09 65 69 85 1.71 0.00 - 8.01 24 1.13 0.00 - 3.77 60 64 66 3.59 0.00 - 12.33 60 1.58 0.00 - 7.29 55 59 35 2.20 0.00 - 11.40 72 2.36 ' 0.00 - 2.66 50 54 71 1.21 0.00 - 5.07 93 2.79 0.00 - 8.36 45 49 18 1.18 0.00 - 2.89 84 2.16 0.00 - 7.55 40 44 15 2.78 1.04 - 4.61 60 3.10 0.00 - 8.28 35 39 O -- -- -- 6 2.15 1.17 - 3.41 30 34 0 -- -- -- 12 2.13 0.00 - 4.09 r = —O.1322 r = -0.3532 t = 3.04** df = 495 t = 7.53*** df = 387 ** *** Significant at the .01 probability level. Significant at the .001 probability level. 116 ._m>a_ »p__wamnoea _oo. 5;“ pm acmu_c_=mwm ..m>a_ auw_wnanoea ._m>mp xup_wnmnoeg mo. 5:3 pm pcmuwe_=m_m «*2 2* Po. 8:3 an ucmu_ew=mwm ¥ acmuwemcmmm uoz mz mzmemm.o- mzm_op.o- mzoFNm.o- m=o_>aca xwm mzemom.o- mzmmoF.o- mzamm¢.o- m=o_>mea o + mpmagacm co xeo «cmam.o- mzom~e.o- «Neeo.o- m=Ow>mea a>wu mzmmnm.o- mzomFm.o- mzm_em.o- mzow>aea m + mpmmggcm 45 ago .mem.o- mzo¢~_.o- .4moo~.o- mzow>aea 2:82 emppm.o- mzmmoo.o- 4mm~o.o- mzow>aea e + mwmaguca co Ana mz-_~.o- 4eom~m.o- mzm~m_.o- mzem-.o mzom2_.o- 44mmmm.o- mzow>aen «weep mzeomm.o- 44~Fm~.o- mzmmmo.o- mzmeoo.o mz.o_m.o- 4484-.o- maov>aea m + memagpem 48 ago mzem~m.o- 44omm~.o- mzumqo.o- mzmpmo.o mzmmmm.o- 44¢em~.o- 8288 maom>aca ozh mzemm¢.o- «mmm~.o- mzoo_o.o mzomwp.o- mzomom.o- «4mmm.o- msow>meq N + m_ma;p=8 co Ame mzomem.o- mz_¢mm.o- mammoo.o- mzeFo_.o- «cmmm.o- mzmoem.o- ua=_nEoo spam 4~4mm.o- mzm_mm.o- mz_mmp.o- mzmoe_.o- 4wm_~.o- mzmmmm.o- amt m=o_>aea mzmmm~.o- mzmeep.o- mzemm_.o mzemm_.o mzmwom.o- mzmmm..o- mmmmgpcm 40 Ana mpmcw58um mumFPPHmwa mumcwsmum mumppwumPa mumcwsmam mumppwummn cowgmwumg ngom 4o mew» gmmam mo a: Pozuu< gmmsm a waspo> .mucmpuwwmmou cowumpmcsou a8 umcwELmamu mm mgmzopm goaszuzu 4o zowumeumm smuumc co copumwume empom mo uomymm mzhii.mm m4mi“'both staminate and pistillate flowers did not produce significant 121 correlations. The pistillate flowers averaged 5.89 ul of nectar (r - 0.0144) containing 33.4% sugar (r = 0.0096) with an actual weight of 2.18 mg (r = 0.0671). The mean wind speed during sampling was 7.8 mph. The staminate flowers averaged 4.47 ul of nectar (r = 0.5013) containing 45.1% sugar (r = 0.3033) with an actual aver- age weight of 2.48 mg (r = 0.5565). The mean wind speed during samp- ling was 7.9 mph. To further evaluate the effect of wind speed on nectar secre- tion, data from individual flowers were compared to the average wind speed at 7 a.m., 10 a.m., 1 p.m., and 4 p.m. In staminate flowers highly significant positive correlations were found between wind speed and both nectar volume and sugar concentration. A correlation coefficient of 0.1999 (N = 162) was found for nectar volume and 0.2050 (N = 150) for sugar concentration. These indicated 4.0 and 4.2% association, respectively. A significant positive correlation was also found for actual weight of sugar (r = 0.1661, N = 160) which indicated 2.8% association between the two variables. Staminate ‘flowers averaged 5.08 ul of nectar containing 44.9% sugar with an actual weight of 2.84 mg while mean wind speed was 11.0 mph. In pis- trillate flowers, a significant negative correlation was found between wind speed and sugar concentration, (r = 0.1777, N = 196). "On-significant correlation coefficients of 0.0662 (N = 200) were 1:'0 und for nectar volume and 0.0613 (N = 196) for actual weight of sugar. Pistillate flowers averaged 6.6 ul of nectar containing 234.8% sugar with an actual weight of 2.38 mg when exposed to a mean “"1 rid speed of 10.6 mph. 122 ForaginggActivity in Relation to Flower Age Comparison of fruit set between newly Opened pistillate flow- ers and day-old flowers in the field during 1968 showed that bees generally do not work day-old flowers, even though they were not visited on the day of anthesis. Only 2.9% Of the day-old pistillate flowers developed into fruit compared to 74.3% of the flowers exposed on the day of anthesis. The newly opened flowers and the day-old flowers were randomly mixed within the same group of plants. Fruit production indicated that honey bees were successfully pollinating fresh flowers, so they were carrying pollen to all flowers visited. The one fruit that did develop from a day-old flower may have resulted from parthenocarpic prodUction. Seed counts were not taken. In 1969 40.0% of the fresh flowers set fruit compared to 7.0% for the day-old flowers. Examination of the two fruits that developed from day-old flowers showed that both had developed parthenocarpically. Day-old pistillate flowers in the field that were unbagged for 10 min inter- ‘vals received no bee visits while the fresh flowers surrounding them \vere visited often. SugarConcentrationof:Cucumber Nectar with Bee ' Visitation throughout the Day The analysis of nectar from 495 honey bees foraging on cucum— be rs showed that the sugar concentration of the honey stomach con- 't£301ts did not significantly vary during the day. Average values "Eltaged from 17.1% to 28.3% sugar (Table 28). The overall average ”Vales 24.5%. Morning values were highest, averaging 26.0% and the a"“‘l:ernoons averaged 23.0%. Values peaked at 9-10 a.m. and 12-1 p.m. 123 TABLE 28.--Concentration of cucumber nectar in the honey stomachs of honey bees throughout the day. . . Sample Avg. sugar T1me size concentration Range Of values 8. 00 - 9:00 58 22.7 :_l.43 6.3 - 38.6 9:00 - 10:00 94 28.3 :_0.98 6.9 - 46.5 10: 00 - 11: 00 70 27.0 :_1.19 6.5 - 38.7 11:00 - 12: 00 76 26.2 :_1.30 6.8 - 40.0 12:00 - 1:00 ' 97 27.5 i 0.97 7.7 - 39.9 1:00 - 2:00 41 23.9 :_1.77 7.1 - 38.3 2:00 - 3:00 27 23.3 :_1.41 10.0 - 32.0 3. 00 - 4. 00 32 17.1 :_1.55 2.6 - 33.7 Overall 24.5 i_l.28 with a decrease throughout the rest of the afternoon. The range of values shows that the lowest sugar concentration of nectar carried by a bee was 2.6% and the highest 46.5%. Since some authors discard small samples with low sugar concentrations when analyzing honey stomach contents, the data used in Table 28 was reanalyzed, excluding iany value less than 10% (Table 29). No new trends were found. Daily 'TABLE 29.--Concentrati0n of cucumber nectar in the honey stomachs of honey bees after removal of low values. . . . ' Avg. sugar T1me Sample S129 concentration 8:00 - 9. 00 45 25.9 i 1.28 9:00 - 10:00 84 30.7 i 0.74 0:00 -11:00 54 28.8 i 1.05 1 :00 - 12: 00 55 28.8 11.18 2 : 00 - 1:00 88 29.4 i 0.83 1 : 00 - 2:00 34 27.0 i 1.57 2 : 00 - 3:00 27 23.3 _+_1.41 3:00- 4:00 22 21.211.50 / 124 variation in sugar concentration was not significantly different from the overall mean (Table 30). Daily averages varied between 22.9 and 27.8% sugar. TABLE 30.--Daily variation in the concentration of cucumber nectar found in the honey stomachs of honey bees. . Avg. sugar Date Sample S1ze concentration 8-5-70 10 24.9 :_2.18 8-6-70 109 25.3 :_0.91 8-7-70 15 27.5 :_2.41 8-10-70 99 27.8 :_1.04 8-11-70 128 27.1 :_0.90 8-12-70 56 22.9 :_1.51 8-13-70 62 24.1 :_1.43 ForaginggActivity in Relation to Flower Sex Following bees in the field as they foraged on staminate and pistillate flowers indicated that they had a slight preference for staminate flowers (Table 31). At the time the bees were followed, the staminate:pistillate flower ratio was determined and compared to the taee's foraging ratio. Overall, flowering in the fields gave a mean sstaminatezpistillate flower ratio of 1.46. A total of 290 bees were 'fiallowed, as they visited 2441 flowers giving a mean staminate:pistil- Tate flower foraging ratio of 3.03. Comparison of the two mean ra tios indicated that the bees visited 2.08 times more staminate than F’1'15tillate flowers. During the 10 days of sampling, a floral prefer- er1<:e for staminate flowers was exhibited on seven days. Preferences 125 mo.m we.F coo: 94.0 . cop 04 Dee op mm.o mm _m ee-em-e me.o we, em New ON mm.o mm em _e-m~-m om.~ co. om. 9mm em m_.F mm Fe _e-m~-e ~m.o am mm Ne PF Pm.F em cm _~-N~-~ ma.» om m_m can om No.m om cap _~-_~-~ om.e mo_ mme «an we mm.P me mo. Fe-8_-~ No.4 22 mmN com mm ~_._ on no _e-ep-e mm._ 85 mo_ Fm, mm e~.o mmm Nap .N-mp-h um.m e_ me_ mop m om.~ mm ON mm---m oo.e 2 mm mm 4 oo.~ 8. mm mm-ep-~ omwmg mswzopm mcmzoFm umawmw> vmmmwmcm owwmg msmzope mgmzopw mums mewmaeoa ogappwemea oeeeVEaem meozope ea .52 epome oee_pepmwe oeeePEeem b .vpmww 8;» cm memzopm consauau mumppwpmwa new mumcmsmum ou.=owumpme cw Lom>mcmn a=~mmgok.-.Nm NSQRN 126 on those days for the staminate flower ranged from 1.29 - 3.63 times that of the staminate:pistillate flower ratio available in the field. For days in which sampling occurred in both mornings and afternoons, the data were analyzed to see if honey bees preferred staminate flowers during the entire day (Table 32). In the morning, the mean staminate:pistillate flower foraging ratio was 2.30 com- pared to 3.06 for the afternoon. Five out of six days of sampling showed increased preference for staminate flowers in the afternoon. Using daily comparisons, increased preferences ranged from 1.09 to 1.59 times greater. During the morning, the maximum number of observed flower visits by one bee on one trip was 38 compared to 37 for the afternoon. In 1974 the number of flowers of each sex was maintained at a 50:50 ratio so if bees indicated a floral preference, it could be monitored. Results indicated that bees exhibit floral preferences 1Nh1Ch change during the day (Table 33). Overall, results indicated ‘that from 7 - 9 a.m., the pistillate flower was more attractive than ‘the staminate with s/p ratios of .63 and .60. Evidence for this was (abserved at the East Lansing plots, but not at Eaton Rapids. N0 bee activity was noted at Mulliken while sampling in 1974. In addition 'tI) counting the number of visits to 10 marked flowers, other observa- tions yielded similar results. On August 23, 1974, (8:45 a.m.) a hOney bee was followed as it foraged at East Lansing. In 11 min and 46 sec 38 flowers were visited. She visited one out of every f‘i ve staminate flowers that she approached. During the same morning 127 mo.m om.~ com: —¢.o mm Fm mm.o mm m mm.o enuemin om.o «mp ow o~.o om mm 11 Pmuemim mw.— pm pm? mm.— mm me mp.~ Fuummun nv.¢ . mp mm mw.m mo mew uo.m Pmipmin mm.o mm m¢~ mm.m vm NmN mm.p Fnumpim Fw.¢ mm why m~.m em —PF Np.p puiepim emeee e\m uoawmw> eoepmc> aoewmw> eoewme> ovum; mu. _.m _.> mLmZO me30 0 Sb.» n—\m mLmzo €030 Q\m mgmo ooecoee< ogepp_emwe oeeePEeem oeappwem_e oeeeVEeem e_owe .upmwe as» cw memzopm smassuau mpmppwpmwa new mumcwEmum op cowucpwc cw cow>mgmn mcwmmcoe cooccmpmm new mcwccoa yo comwccasouii.~m m4m mumppwpmwa cum mpm mwop oemp weep ¢¢Fp cow mop mm muwmm> mumcwsmpm _pmcm>o n_.m mm.F so.m mP.N om.m mm.m o.N o.o o.o o_uwe a\m NF mm on mm mp m e o o mummm> mumppwamwm mm «m we mm mm mm m o o muwmp> mumcwemum :mxwppsz ~¢.P N¢.F ¢M.F mp.— mo.F mo.p o~.p we. mm. ovum; a\m cmp mmm mmw mam Nan mew mom NPN mm mpwmw> mumppwpmwa mpm mmm mom ewe omm «on cam mm om mu_m_> mpmchmum mawmcmg “mam m¢.P mm.p mm._ Pm.p mm.p m—.F mm. no._ m~.~ ovum; n\m mm omp Nam mum mom mom mmw on m mawmm> mump_wumwm omp com com mme wme op¢ «mm we mp mummw> macawEmum muwaom cone“ 8 i m m i N N 1 F F 1 NF Np 1 _p PF . op o— i m m 1 m w u n ezog\memzope op\mpwmw> own co cmnszz savanna; .memzope consaosu mum—qumwn can mumcmEmpm on cowumpmc cw xgw>wuua mcwmmeow xpgaozii.mm m4mo_ NHFFFeeaoca mo. one pa eeeoFeFemFa pee - Feeee cm» “Feet eoaeem pooceoe .Eovwmem 4o momemmu e x .Fm>mF quFFncaoca mo. 8:» pm pcmuFFchFm yo: 1 uummcmaEF em» “Face uwamsm uummcma .soummcm co moocmou e 56F; No.m n Nx .Fe>o_ NNFFFaeeoea mo. 8:» on eeeoFcFemFm pee - Feeoo cm» “Face eoeo_o>oa .Eonmmgm mo mmmcmmu ¢ x .Fm>mF quFanaoea moo.o on“ no pcmuFFchFm 1 voaoFm>wuicoc am» mFagm umaoFm>mo .cmxmu mew: mpcaou comm mcommn uFmFF :F weapon was .umaoFm>mu gFacF Fix .Fpmwp comFemaeoo quFpFas szmx . cmszmz . “covaumv .Fm>mF quFannoea am as» an ucmLmFFFu ancmuFFchFm yo: mew meFmF FFmsm msmm esp an umzoFFoF casFou some :F mucsou ummm coo: .Fo>oF NHFFFnaaoca Foo. 8:3 ea peeoFeFemFme44 FFeN u Ft .422mmm~.o u 2v muczou comm mzmgo> mmeF> own Fo consaz ssz mm.m u N :62: em.ee n N 1.oo~ mum F o.mF m.~ F.Fw a.mm ¢¢~ mmm FmFoF Fqu.H oeN mme Ne m.m o.o m.Fm m.om mm mm xacmZF meF.H FNN me mF F.mF F.m m.mF w.Fm em on :mmuFFm muomFF.H mmF mFm FF F.mN m.m F.mF m.mF mm mm cmF unom.H mmF mFm m a.mF ~.e «.mn m.Fm xme FF m>Fm amcm + mNF new F F.mF N.m o.om F.mv Fm FF mco cum: 1 . .Esanez;.e=chFz,.m wanna. was: a uuomema N pom qucm pom “Face mNFm memwaMwa mucsou umom macgm pFacm mmmucmuemm co consaz mFQEmm mo Lucas: .mcmnsaosu cF mmeF> won F0 2835:: an vapommFm mm mecca qucF.ucm .mucaoo comm mmmeo>m .umm “F324 mmcpcmoeomii.mm m4mFm mNF Fm mem Fm mco “FmF> can mcFmem :mFFoa mFFmF> mo mummm we now uFacF emzoFF can m>FaumFFm Fe 2885:: m>< Lassa: quoF Logan: FepoF Fo consaz muFmF> mo 289232 .vmusuogg mummm Fe 2835:: an umpmuFucF mm mmeF> own Fo mcoae:: mchgm> mchzu LozoFm consausu mmmFFFFmFa 8 Fe mEmem on» :o umomFa :mFFoq mo mucaos new: Eseerz Estch mxom: a man: N puchmg N awn mchLm pom uFacm z FoxwmpF chFoa m>< mgcaou nmmm maczm “F323 & . .mcmaEzuao :F pesou umwm can .onmsm “Facm .pmm szeF ucmucma co :oFgmcFFFoa mo zen Fo 85F» 40 pumFFm 85F--.F¢ m4m< mamsm «F323 .meoasaoao :F uFmF> won comm guF: vmuaanumFu mcan :oFFoa Fo «cacao vcm .mgmzm .umm qucF :F :oFucho> AFFmaii.Ne u4m muomm mvmmm szcF umamgm pom \mcFmem :oFFoa quoF .0: cow: was: a mxomz a Noumea; x uFacu a z mooz .mcmnE=u=u cF um>osoe “Facm m>FpFuuanu gqu mamgm vco pom quem co :oFuFmoa one: we uuommm szii.me m4mo u.o.H m.FF m.oF meF eoF n¢.N ¢n on m cone 1 ooum m.o.H o.oF N.oF Fame owe Nm.N mmm ONF mN ooum 1 oouN ¢.o.H m.m o.m momv me¢ mm.m mcm mm Nm oouN 1 oouF n.o.H N.FF ~.oF some Fme mm.m mmm Nm om oouF 1 ooNNF ~.F.H m.FF m.oF emmF emF mn.F mFF no NF oouNF 1 oonFF m.e.H ¢.ON m.mF meF moF wo.N mu mN m oouFF 1 ooqu 8.8.“ N.NF N.mF NNON Nm. Ne.m aOF pm F_ cone. - cone o.N.H m.mF . m.¢F FmFN N¢F nn.N woF mm NF oonm 1 oouw w.F.H N.NF m.mF emFF Nu mo.F ov mm c ooum 1 cons own szoFF umm uanmF> opumc umuFmF> mcozoFm vouFmF> memzoFF cmzoFFoF qu \cozoFF \uwm. mcmzoFF . wumchmum mamFFFumFa moon \OOm com: mo Longs: quoF FmaoF n\m oEFF ca .82 ea .82 to .ez. . .muFmF> gmzoFF comzpmn psmFFF :F 85F“ mcFusFocF .xmu we“ uaocmaogcu .memzoFF cmoszusu co won Nose; a we 05F» aFmF> mamcm>m ozFii.ee u4m moFez m. .H _.N_ e._F NmNmF NQNF NN.N mem NNe 8N A.S.NV meape memo nee NF_.eeooFa o._.H o.o_ N.N wNoe Nee o._m mme m cm A.S.NV mSOFN m.__oz ee< o. .H m... m.o_ ommmF mmw_ mN.m eoeF Nme NN_ Faooe mcchNA “mom c._.H m.m_ _.m_ emNm NmN Fm._ meF mop NN me_aam eopem eoHFmF> eoSFmes eozoFFoc mmn\cozoFF ewzoFF umm mcwzoFF \umm new: \umm quoF FmpoF a\m memzoFF mgmzoFF mama Fo coFamqu oeeeFEeom oeeFPFOWFN consez .memnszozu cF mcchmN “mom can vagmm coumm um muFmF> cozoFm cmmzpmn mEFp uanFF mcFuaFocF New 85F usogmaocgu FFmF>;Nmzochma pcmam 85F“ mmmcm>m mcFii.m¢ m4mo om emON m me NN ow oe - em ooF ooe m NF . NF om mm - Fm em amNF N Nm NF Ne om - 8N oe cmN m «N m Nm mN - FN NN NNNF m NN o 44 ON - 8F N ewe F MN e mm mF - FF F mNa F mN F on oF - m ease Fee adv eoca Feevteuer F642 eequ FFFV nemeoF FFFV semeoF mFFmF> eozoFF ummFFmsm pmmmgmg EschFz EaeFxmz EachFz Estxmz mo 282532 .mgmaE:u:u 5 9.328 9.2% mon .38; m5 .3 3.3.60 women 25 86:33.3 Esstws use 5:552:68 39:. 153 TABLE 47.--Average area covered by a foraging honey bee in cucumbers. ‘ No.-of . 5:?gle Avg. area Avg. sq ft/ flower v1s1ts (No. bees) (sq ft) flower v1s1t 5 - 10 223 59.9 i 5.3 8.2 _+_ .8 11 - 15 73 147.8 1 13.5 11.9 11.1 15 - 20 55 253.0 2‘. 32.3 13.8 11.7 21 - 25 22 259.8 5: 43.5 11.4 11.9 26 - 30 16 458.8 :_122.4 16.1 :_4.2 31 - 35 7 261.0 :_ 44.0 7.8 :_1.3 36 - 40 6 764.8 :_284.1 19.6 :_7.0 Over 40 10 591.5 1 203.9 13.1 i 3.5 TABLE 48.--Average length, width, and feet per flower visit covered, by‘a foraging honey bee in cucumbers. No of Sample Avg. ft/ Avg. ft/ visits size length visit width visit 5 - 10 223 8.9 i. .4 1.19 5.2 :_ .2 0.69 11 - 15 73 15.2 1; .7 1.17 8.9 i .6 0.68 16 - 20 56 19.6 :_l.2 1.09 11.4 :_ .8 0.63 21 - 25 22 18.9 :_1.4 0.82 12.3 1_1.3 0.56 26 - 3O 16 22.2 :_2.7 0.79 17.3 :_2.1 0.62 31 - 35 7 22.9 i_4.7 0.69 13.6 :_l.9 0.40 36 - 4O 6 37.5 :_6.0 0.99 19.0 :_5.4 0.50 Over 40 10 27.9 i 3.9 0.54 21.2 :_3.0 0.41 154 length and the average width increased with the number of flower visits. The average length fluctuated between 8.9 to 37.5 ft com- pared to 5.2 to 21.2 ft for the average width. Between 5 and 25 visits, the mean average length was 15.7 ft and the mean average width was 9.5 ft. For over 26 visits, the corresponding values were 27.6 and 17.8 ft respectively. During the same time interval the average distance covered between flower visits for both length and width decreased as the number of flower visits increased. For length, the average distance between flowers visited decreased from 1.19 to 0.54 ft. For width, the average distance between flowers visited decreased from 0.69 to 0.40 ft. Regression analysis comparing the number of visits (5 - 24) to the average length, width, area, and square feet per flower visit gave highly significant positive correlations (Table 49). There was 84.2% association found between the number of bee visits and average length [r - .9176 (significant at the .001 probability 1evel)], df = 18) compared to 80.0% between bee visits and average width (r = .8944, df = 18). A correlation coefficient of 0.8851 was found between number of flower visits and area compared to 0.6690 for the average square feet per visit indicating 78.3 and 44.8% association respectively. Analysis of the hourly data indicated that the average length, width, area, and square feet per flower visit increased throughout the day (Table 50). The average length increased from 7.4 to 16.6 ft, average width from 5.1 to 10.9 ft, average area from 52.1 to 155 TABLE 49.--The average foraging area per bee with a specific number of visits to cucumber flowers. No. of N Avg. Avg. Avg. area Avg. sq v1s1ts length Wldth sq ft ft/V151t 5 56 6.2 :_ .40 3.7 :_ .30 25.9 :_ 3.25 5.2 i_0.64 6 46 10.2 :_l.70 5.1 :_0.42 56.1 :_ 10.37 9.1 :_l.71 7 37 10.1 :_l.40 5.1 :_0.66 62.5 :_ 16.35 8.9 :_2.33 8 34 8.7 :_0.67 5.2 :_0.37 49.1 :_ 6.96 6.1 :_0.86 9 33 12.1 :_l.31 7.4 :_0.91 118.9 :_ 31.33 10.0 :_l.90 10 17 12.3 :_1.33 6.8 :_0.63 83.5 :_ 11.64 8.3 :_1.16 11 25 14.4 i_l.39 8.4 :_1.04 142.8 :_ 28.20 13.0 :_2.56 12 14 16.1 :_l.66 10.2 :_l.55 152.6 :_ 27.44 12.7 :_2.29 13 11 15.4 :_l.47 8.9 :_l.61 155.6 :_ 33.03 12.0 :_2.54 14 12 16.0 :_l.25 10.2 1 1.38 163.8 :_ 26.38 11.7 :_l.88 15 11 15.0 :_l.76 7.6 :_1.25 127.4 :_ 34.57 8.5 :_2.30 16 13 16.3 :_1.37 11.4 :_1.31 197.7 :_ 32.35 12.4 :_2.02 17 6 19.7 :_1.94 10.8 :_1.82 223.5 :_ 51.10 13.1 :_3.01 18 11 18.7 :_2.39 11.3 :_l.87 242.7 :_ 63.73 13.5 :_3.54 19 12 21.8 :_3.11 10.8 :_2.09 279.3 :_ 93.67 14.6 :_4.94 20 14 21.4 :_3.24 11.9 :_l.62 296.0 :_ 81.71 15.2 :_4.18 21 3 18.0 :_5.69 15.7 :_4.63 333.7 :_185.94 15.9 :_8.86 . 22 7 17.1 :_1.68 9.6 :_1.36 165.6 :_ 28.38 7.5 :_1.29 23 4 20.0 __1.23 13.0 :_0.91 257.8 :_ 14.47 11.2 j_0.63 24 5 25.0 i_2.61 17.6 :_2.77 464.2 :_108.88 19.3 :_4.54 Greater than ., 24 42 25.1 :_2.00 17.0 :_1.45 497.1 :_ 81.13 13.5 :_2.11 r = .9176 r = .8944 r = .8851 r = .6690 t = 9.79*** t = 8.49*** t = 8.07*** t = 3.82** 5 .Significant at the .01 probability level. Significant at the .001 probability level. 9 *** 156 .. 1 N. cmozuma mums mcomun>smmao snow mmc:.o:.« 5.8. 5.8m. «.8 a.m. ..m. 5m.¢ ..8L5>o ..m. «.mm. m.m m.m. a.m. 8.. cooccm..< ..w ..m~. 8.. ~.~. ¢.m. amm m=.=to= .3 H .3. 3.8 H 8.8. 8.. H 8.... N... H a.m. .m.. H .3. o. 82.. - 83 a; H 8.... 8.... H was 8.. H «.8. 8.. H a.m. 8. H m... .m 8:. - 88 8.. H o... 8.8 H .8. 8. H 5.. 8.. H 8.... 2... H 8.... 8 85 - 8& 8.. H 8.2 ....5 H :8 8. H .8. 8.. H 8.8. 8.. H .3. 8 8& - 8". 8.. H «z... 8.8 H 8.2. 8. H .8 8. H a.m. 3.. H 8.: 8 88. - 8... .... H o... 3.8 H 8.8. .8. H m... 8. H 2. 8.. H 8.... 8 8... - 85. 8.. H E 8.8 H 8.2.. 8. H 8.. 8.. H .3. 8. H 3. K 85. - 88 8. H N... 8.: H .8 2. H ..m 8. H 8.. 8.. H .8 .m 85 - 88 p.mm>\uw amen spam: guano. mummw> mupm hmu .am .m>< .m>< .m>< .m>< .o: .m>< opqsmm adv mo meme .xuv on» uaogmaosza mgonssozu :. own xuco: as» mo o.pwosa acmmmsom--.om mam\88 8888. 8.8.3 888:8. 88.8.> cm .m>< .m>< .m>< .m>< .m>< z mama .888858030 :8 888 88cc: 8:8 mo 8.8.088 8:888808 8.888--..8 848 a H m a o cmwz wocmnmma 8.888 pamEm>oe cm..o8 .888. .mqwgpm acmEm>oE :8..oa .pmm>88; 888.8 .88388 888 mummm mo 88852:.mmmgm><11.nm mgm<8 TABLE 58.-Average number of seeds per fruit, second harvest, pollen movement strips, l969. Mean Pollen movement strip Distance OQN ONF QNNOMQNmmmmome'F-NNMQ'QVN('05 NMr-F- MI—l—F-m +I+l+l+|+l+l+|+|+I+I+I+I+HI+I+I+l+l+l+|+l+l+l+l+l NN¢¢GNMN2QNOMGJ¢NNOSM¢LONFQP (DP-LOU) !- LOQNI—Q' MM KOQNmmSVQ‘mN:O\NwmI—meNPwI—MN MMNQ'F I—‘Nf— IOU" +I+I+I+l+l+l+|+l+l+|+Hl+l+l+l+I+I+I+I+I+I+I+I+I+I NONNNLO‘DQ'OONQ'I—Ofitou—meNNNv—d'm NNO‘Nmm F-NNNMNN Q'F— NLD I— CON F" r—r— PNOIQ'NNIDQ'MIOOMOIOMMMMKOr-PIDI—N QM N r- m:—- '— MF- MID +I+I+I+I+I+I+I+l+l+l+l+I+I+I+I+I+l+l+|+I+I+I+HI oxoxoxomooauotomoq-md-mmnmoooopmd-d- [\Nmoo F- N 03¢F- I— QF 01-- NF FF ooocnd-Q-ONNtomtomeovxopmmmNooNNd- MOP-NFr- ON I—" or—I\N o P +I+|+l+l+l+l+l+l+l+|+I+l+l+l+l+l+l+HHHHHHHI Lad-oou—Nmoosoecrmeoovxmaspcsmmwmm gamF—MNNOQ'l-l—l— l—t—Q'Nl— NMQ‘ 0N!— l— r- '— OMNNKO‘OS-‘NQ'QSOImtOMF-MI—NLDQ'I I I I NNF' NNNN OFOI I I I +l+l+l+l+l+l+l+l+I+I+I+l+l+l+l+l+l+l+l+l+l+l mOWNNOStOI—I—OINGDQIONI—N Nde’m I I I mmco I—Nd'd’ Md'N Q00“) oI\mp 888pwnmaoga xm asp pm pcmcm888u >8pcmo888cm8m no: mew: mucmspmmch _N. u ANP.NV8 mucm8cm> 8o m8mxpmcm he: mco mz «.8 m.¢ m.e m.¢ _N 88 cm - _e F.FF m.m~ m.¢ w.e _N 88 as - _m P.wm m.~e m.¢_ _.~m _N 88 on 1 _N m._o m._m _.~m 8.08 _N 88 cm - FF m.mm ~.mm “.mm o.oop _N 58 op - o peasmwa :88: N “augmwa :88: & “caemwg :58; 8 “swamwa :88: R m~_m magnumpo F_acm>o mp-m P_-m m-m mFasam . .Psmp .mc8mcmg ummm pm mmmn zone; ma mcozop8 Luggauau macaw quzoa acmummco=_8 8o acmem>oz11.mo m4mO m8OOmm mocmpm8O ON1O 8N1O 8583 5.5 R .mupm88 conssuau pm8ucmsaou :8 gmuzoa pcmummcosp8 8o mama xmco; NO acmEm>oz11.¢O OOO<8 180 TABLE 65.--Movement of fluorescent powder from flower to flower in cucumbers by honey bees using a locus of 50 dusted flowers. fggmtggfiice Sample size % Flowers with powder 0 - 10 ft 20 95.0 11 - 20 ft 20 45.0 21 - 30 ft 20 35.0 31 - 40 ft 20 40.0 41 - 50 ft 20 10.0 51 - 60 ft 20 0.0 61 - 70 ft 20 25.0 71 - 80 ft 20 0.0 81 - 90 ft 20 0.0 91 - 100 ft 20 0.0 The movement of fluorescent powder, within a plot 32 x 110 ft2 in 1973 indicated that within an isolated area, bees could move pollen at least 110 ft (Table 67). A highly significant nega- tive correlation was obtained when the distance was compared to the percent of the flowers receiving fluorescent powder (r = -0.9904, df = 9), which indicates 98.1% association. Over the 110 foot dis- tance, the percentage of flowers containing powder decreased from 91.1% to 42.1%, mean of 70.0%. A one-way analysis of variance showed that there were highly significant differences when the data from the nine days were analyzed. Comparison of powder movement with two concentrations of powder in the field, showed that there were sig- nificant differences at the .05 probability level (Paired t-test, t = -2.07, df = 86). When 10 flowers were dusted, 50.9 to 89.1% of 181 TABLE 66.--The number of staminate flowers in the gynoecious strips and the monoecious pollen source, 1972. Gynoecious block Monoecious block Nodes where Date gggg$gagg staminate flowers Egggggagg flowers appeared flowers 7-24 10 3,4 23 7-25 45 2,3,4,5,6 56 7-26 14 3,4,5 202 7-27 , 5 3,4,5 368 7-28 10 3,4,5,6,7 519 7-31 11 3,4,5,6,7 416 8-1 0 --- 302 8-2 0 --- 450 8-3 1 5 593 8-4 1 6 599 8-7 Rained all day 8-8 0 699 8-9 1 6 742 8-10 0 --- 672 8-11 0 --- 617 182 .s.a N 1 _ =8mc 858841 m O8 mN O8 mN O8 mN O— mN Omumau mcmzo—8 8o cmassz m 8 O8 O8 O8 O8 O8 O8 O8 umm8 cap \umxu8a mguzo88 8o LmOEOZ 8.Nv 0.0N 0.0N 0.0m 0.0¢ 0.0m 0.00 0.00 0.0N 0.0e O8 O88 1 _OP m.Om 0.0e m.¢8 0.0¢ 0.0m 0.0m 0.0N 0.00 0.0m 0.00 88 OOP 1 PO «.mm 0.0¢ 0.0N 0.0m 0.0m 0.0¢ 0.08 0.008 0.00 0.00 88 OO 1 8w P.¢O 0.0¢ 8.8m 0.0m 0.0m 0.0m 0.00 0.00_ 0.08 0.00 88 OO 1 88 N.mO 0.0 8.8m 0.0m 0.0e 0.0N 0.00 0.008 0.00 0.008 O8 O8 1 Fe 0.00 0.0 8.8m 0.0N 0.0¢ 0.08 0.00 0.008 0.00 0.00P O8 OO 1 8m 8.m8 0.00 c.88 0.0N 0.0¢ 0.00 0.00P 0.00_ 0.00 0.008 88 Om 1 PO «.m8 0.0N N.mm 0.00 0.0m 0.00F 0.00 0.008 0.0w 0.00— H8 OO 1 8m n.8m 0.00 N.mm 0.0m 0.00 0.00_ 0.008 0.008 0.008 0.00P H8 on 1 _N p.8O 0.0N 0.008 0.008 0.008 0.00_ 0.008 0.00_ 0.008 0.00P #8 ON 1 88 8.8m 0.0N 0.00F 0.008 0.008 0.008 0.008 0.008 0.008 0.008 88 O8 1 O O1O m1m _m1m *Om1m ON1O ON1O NN1O O—1O «_1O mQLOOm Eoc8 Ppmcm>o maze; 8 8888M gmuzoa :88: mngo88 8o & mucmpm8O .mnmp .Oc8mcm4 pmmm um mswaszuzu :8 gonzon ucmumwcozp8 8o mama Nacoz On pcmsw>oz11.NO mgm<8 183 the flowers received some powder with a mean of 69.4% compared to 65.4 to 97.3%, and mean of 80.7% when 25 flowers were dusted (Table 68). Since all daily means of the two treatments were not signifi- cantly different from each other, differences were probably due to climatic conditions and differences in bee populations. Comparison of the overall means for the two treatments at the various distances indicated the first significant difference at 21 - 30 ft. Beyond 21 ft treatments of 25 dusted flowers showed greater distribtuion of the powder to flowers than treatments of 10 flowers. The Relationship of Foraging_Activity to Fruit Set The Piccadilly plot used to determine the relationship of foraging activity to fruit set in 1974 produced an excessive number of staminate flowers over the 12-day monitoring period (Table 69). The staminate:pistillate flower ratio fluctuated between 1.30 and 3.93 with a mean of 2.24. A total of 2638 pistillate flowers and 5899 staminate flowers were produced. The number of flowers per vine each day ranged from 0.38 to 1.68, with a mean of 1.02. In comparison the adjacent plot of MSU 9805 over the same time period had a staminate:pistillate flower ratio between .84 and 4.47, with a mean of 2.25 (Table 70). A total of 1696 pistillate flowers and 3823 staminate were produced in the 12 days while the number of flowers per plant ranged between .14 and 1.53, with a mean of .80. Foraging activity in the plot based on number of flowers and bee visits varied from 10,739 to 94,478 visits per day, with a mean of 47,055 (Table 71). Individual flowers received from 34.2 to 102.0 184 .AHmmH mace; mHO8HH:=_mpzw¥1cmszm21HcmO=Hmv Hm mzH Hm chgm888u AHHcmu888cm8m Ho: mew LmHHmH HHosm msmm mOH Ha um3o8808 OEOHOU comm 8o mcmm: ._e>m_ HHHHHQeeoee s8¢¢.OH u AOO.OOO mo=m8gm> 8o mHmzpmce an: mOO eee.me eeo.o~ em.Hm o.om em.~e ea.om eeH.mw eeee.mH ewe: m.8¢ 0.0m 0.0m 0.00 0.0e N.Ne 0.0N 0.0¢ 0.0w 0.0N H8 OFF 1 —O_ m.NO 0.0¢ 0.0m 0.00 0.00 F.—¢ m.¢F 0.0m 0.0N 0.0m H8 OO— 1 pm m.8O 0.0m _0.0¢ 0.00H 0.00 N.Ne 0.0N 0.0m 0.0n 0.00 H8 OO 1 pm m.Nm 0.0m 0.0m 0.00_ 0.0m O.pO F.8m 0.0m 0.00 0.08 H8 OO 1 —8 0.00 0.0m 0.08 0.00~ 0.00~ m.mO F.8m 0.0¢ 0.00 0.00 H8 O8 1 8O O.mw 0.08 0.0N 0.00F 0.00P m.OO p.mm 0.0e 0.0m 0.00 H8 OO 1 Pm m.Nm 0.0m 0.00 0.00P 0.008 O.N8 c.88 0.0e 0.00P 0.00 H8 om 1 Fw O.mm 0.0m 0.00~ 0.00F 0.00F ¢.O8 m.mm 0.0m 0.00 0.00 H8 Oe 1 pm O.mm 0.00 0.00~ 0.00_ 0.00P ¢.Ow 8.mw 0.00 0.00— 0.00P H8 on 1 FN 0.00P 0.00~ 0.00F. 0.00F 0.00P 0.00P 0.00~ 0.00P 0.00~ 0.00F H8 ON 1 Pp 0.00P 0.00P 0.00— 0.00F 0.00P 0.00F 0.00P 0.00~ 0.00F 0.00~ H8 Op 1 O 8m1m ON1O 8N1O ¢p1O m1m Om1w ON1O O81w prgm>O Hpmgm>O mucmHm8O OmHmzu mgmzop8 m>881chm38 OmHmau mgmxop8 cmH .MNOH .msmn53usu 8o OHmH8 a :8 gmczoa Hcmummgoap8 8o m=o8Hmchmucou 03H 8o mean Haze; HO Hamew>os 8o comHLmOsou11.OO OHO<8 185 TABLE 69.--Flowering pattern of cucumber cultivar Piccadilly, 1974. Date . PE§§;:£:te Sggfi;fi€:e r2110 f13§21s F61::ES/ August 6 5 0 0 5 .01 7 5 1 .20 6 .01 8 5 2 .40 7 .01 9 14 20 1.42 34 .05 10,11 148 42 .28 190 .28 12 100 97 .97 197 .29 13 108 154 1.42 262 .38 14 137 179 1.30 316 .46 15 118 321 2.72 439 .63 16 175 435 2.49 610 .88 17 170 361 2.12 531 .77 18 283 505 1.78 788 1.14 19 319 461 1.45 780 1.13 20 246 376 1.53 622 .90 21 304 632 2.08 936 1.35 22 271 699 2.58 970 1.40 23 280 884 3.16 1164 1.68 24 227 892 3.93 1119 1.62 9*.79—15 186 TABLE 70.4-Flowering pattern of cucumber cultivar MSU 9805, 1974. ... £§fi§m stag? .3; fat; ‘33?/ August 8 0 2 0 2 .00 9 2 1 .5 3 .01 10,11 33 13 .39 46 .08 12 51 21 .41 72 .12 13 45 38 .84 83 .14 14 63 55 .87 118 .21 15 79 157 1.99 236 .41 16 133 257 1.93 390 .68 17 109 212 1.95 321 .56 18 205 282 1.38 487 .84 -19 206 301 1.46 507 .90 20 181 293 1.62 474 .82 21 176 430 2.44 606 1.05 22 176 473 2.69 649 1.13 23 183 699 3.82 882 1.53 24 140 626 4.47 766 1.33 187 _H.H NNNH ONON mom.eem NNmN a.mNN mean _eHeH NN.H mm 8N. ONN.om eHHH a.me mNN eN Hm=o=< mm.8 OOH mm. eem.mm eeHH c.8m mmN NN Hm=m=< Nm.o NeN CNN NNe.em OHN e.Nm Nme NN Hm=m=< mm.o mNH _NH Neo.we mmm N.NN eem _N Hm=m=< mm.o eON oHH eee.~e HNc 8.8N Nam 0N Hm=m=< no.8 NNH NNH _N_.Nm eNN N.NN mam mH Hm=m=< MN._ NNN _NN eNm.om NNN o.No_ OHm N. Hm=m=< mm.H meH NNH NNN.mm omm m.Ne wmm NH Hm=m=< ee.H NN ON. eoe.eN moo e.oe NON eH Hm=m=< me._ _N o__ HmN.NH ame a.mm NNH m_ Hm=m=< mm.o mm mm mmN.oH HHN N.em _NH e. Hm=m=< m_.H NeH mop eNH.m_ NeN a.mN mom NH Hm=m=< memmmeee eHe_H_Hm_e eHeeHENHm. Nee\m88m8> NHMWWMWNWN A; av emze_8 Aeomyww8mflmzNW8 euea 1 O8m88 HmHOH PHHOH \mH8m8> HmHOH guess: _mHOH memon8 O8\mH8m8> Lungs: HeHoH .eNOH .OOHmcmO Hmmm .mcmnszuzu :8 >H8>8Hum OOHOmLO8 xp8mu mmmgm><11.88 NHOeO OOOOHWWMMWOOOO wwnnwe meeze_8 eHeHHHOmHO OOOO OH Oc888m8 H OO8OOOOOO H OOHOOOOLO a HOHOH .ONOH .OOOOOOO Omem .OOHO OOOOOOOO OHHHOee68O OOH O8 Hem OwOeO--.NN OOOOH 190 TABLE 73.--Average number of seeds per fruit, Piccadilly plot, East Lansing, 1974. 5:152: 2:2..“.“.1bi:.1: August 13 98 232 :_ 8 21 - 426 August 14 _ 117 226 i 3 17 - 475 August 15 93 253 i 11 5 - 540 August 15 119 245 i 11 o - 465 August 17 95 230 i. 11 23 - 450 August 18‘ 127 222 i 10 o - 420 August 19 101 203 :_10 4 - 417 August 20 54 218 i 14 2 - 411 August 21 50 205 1 15 o - 417 August 22 55 225 .t 14 o - 403 August 23 45 234 _+_ 18 7 - 459 August 24 47 233 i 19 15 - 492 TABLE 74.--Fruit shape analysis of the Piccadilly cucumber plot. Date lgtglugg. pggfeggs % Ngubgf % Ngecgz % August 13 98 87 88.8 6 6.1 5 5.1 August 14 117 106 90.6 7 6.0 4 3.4 August 15 93 86 92.5 4 4.3 3 3.2 August 16 119 101 84.9 16 13.4 2 1.7 August 17 95 75 78.9 15 15.8 5 5.3 August 18 127 100 78.7 22 17.4 5 3.9 August 19 101 66 65.3 24 23.8 11 10.9 August 20 54 48 88.9 5 9.3 1 1.8 August 21 60 47 78.3 6 10.0 7 11.7 August 22 55 45 81.9 8 14.5 2 3.6 August 23 45 38 84.4 3 6.7 4 8.9 August 24 47 30 63.8 4 8.5 13 . 27.7 Overall 1011 829 82.0 120 11.9 62 6.1 191 not give significant correlation coefficients; r = -0.3195, r = 0.4274, and -0.4600 (df - 10), respectively. 0f 54 tagged pistillate flowers with known number of bee visits, 51.8% set fruit. The fruit contained from 4 to 411 seeds, with a mean of 233. The flowers that set fruit received from 18 to 184 bee visits with a mean of 58. The flowers that died received from 16 to 134 visits, with a mean of 64. There was 75% of the fruit perfectly shaped and 25% nubs. The perfectly shaped fruit averaged 264 seeds compared to 140 for the nubs. Comparison of the number of flower visits with the number of seeds in each fruit did not give a significant correlation coefficient (r = 0.1181, df = 26). Each bee visit placed a minimum average of 5.7 effective pollen grains on the flower's stigma. The Piccadilly plot produced a total of 849 fruit or 1.23 fruit per plant (Table 75). In the simulated harvest, TABLE 75.--Results of the Piccadilly simulated cucumber harvest. Grades Total 1 2 3 4 5 5 m” t Total fruit 229 102 234 148 . 117 19 849 % of harvest 27.0 12.0 27.6 17.4 13.8 2.2 27.0% of the fruit were grade 1, 12.0% grade 2, 27.6% grade 3, 17.4% grade 4, 13.8% grade 5, and 2.2% grade 6 (Appendix A). With a similar overall flowering pattern and foraging popula- tion, the adjacent plot of MSU 9805 averaged 1.15 fruit Per plant. 192 Fruit shape analysis indicated that 92.0% were perfectly shaped, 4.5% nubs, and 3.5% necks. In regard to the curvature of fruit, 82.5% were straight, 13.1% slightly curved, and 4.4% severely curved. At the time of the destructive harvest, the fruit graded from 1 - 6 respectively were 28.4%, 20.7%, 33.8%, 14.0% 3.0%, and 0.1% (Table 76). An estimate based on a plant population of 50,000 plants per TABLE 76.--The dollar value per acre of the cucumber cultivar MSU 9805--estimate based upon 50,000 plants per acre. Grade Total % of Weight of No. pickles/ Wt./ $/ pickles harvest sample (lbs) acre acre acre 1 188 28.4 3.25 16,330 282.3 16.94 2 137 20.7 11.00 11,902 955.6 28.94 3 224 33.8 46.50 19,435 4034.5 80.69 4 93 14.0 32.25 8,050 2791.5 27.92 5 20 3.0 9.5 1,725 819.4 4.10 6 1 0.1 0.75 57 42.8 0.11 Total 158.43 Number of plants = 557 Total pickles = 663 Number of fruit per plant = 1.15 Number of fruit per acre = 57,500 acre, indicated that the dollar return per acre would be $158.43 (Appendix A). Changes in the Foragjng_ngulation with Additional Colonies in the Field For four days prior to moving two colonies of honey bees into the plots at East Lansing, the flowers averaged 23.4 bee visits per 4.5 h. For eight days after the colonies were moved in, the flowers 193 averaged 36.6 visits per 4.5,h. Therefore, the two colonies with a total of 914 sq inches of sealed brood increased the field population 1.57 times- Comparison of the two sample means with the Student's T- test indicated that they were significantly different [t = 3.99 (sig- nificant at the .001 probability level, df = 322]. Fruit Inhibition Fruit inhibition was rapidly expressed in the field of Picca- dilly (Table 77). Flowers pollinated on the first day that pistil- late flowers appeared on the vine developed into mature fruit 91.7% of the time. The second day‘s flowers developed into mature fruit 49.6% of the time and with each succeeding set of flowers, fruit production decreased rapidly from 19.9% for the third set to 0.0% for the seventh set. Only 39.9% of the pistillate flowers produced mature fruit. In addition, 6.6% of the flowers set fruit, but devel- opment ceased before reaching maturity. These growth—inhibited ovaries either withered and died or remained green and unchanging for several weeks. This would indicate that there is an inhibition threshold present that probably varies from plant to plant and possi- bly with cultivar. Such under-developed fruit appeared on the second day of flowering and peaked at 12.6% on the seventh day (Table 72). Fruit inhibition appeared from the time the first flower on a vine was fertilized. A mean of 9.1% (6.1 to 10.5) of flowers on nodes 2 to 5 produced growth-inhibited fruit and those on nodes 6 to 9 produced 3.2% (2.1 to 4.0) growth-inhibited fruit with the remaining flowers aborting. 194 0.00F 0.0 0.0 m muo: :HOF 0.00 O.v 0.0 mN muo: :HO 0.00 ¢.m 0.0 Om one: :HO 0.00 N.m 0.0 mm muo: :HN 8.mm P.N N.¢ Nep Ono: :HO m.8w P.O 0.0 NON mac: :Hm m.OO 0.0 F.OF mvm mvo: OHO 0.00 m.O_ a.mp NMO Ono: Ogm ¢.O¢ 0.0_ 0.0¢ Omm wuoc OON _.n N.— N.FO NOO mgmzop8 mHmFPHHmHO muo: Hmp OH Oc888O8 H 80 cgmHHmO mc8tmzopm OO8EOOO H OOHELOO H HOHOH .m=8> gmasauau OOH co Hmm H8388 mOOH>mOO An OmHum88O mm HOOEOo—m>mu H8388 8o co8H8O8;:8 OOH11.NN OOO<8 195 The five pistillate flowers that were observed daily in the East Lansing Piccadilly plots during 1974 provided further opportu- nity to analyze fruit inhibition. 0f the flowers that set fruit and developed to maturity, 51.9% were found on node one, 33.3% on node two, 11.1% on node three, and 3.7% on node four. Of the flow- ers that died, 7.7% were found on node one, 11.5% on node two, 15.4% on node three, 19.2% on node four, 23.1% on node five, and the remaining 23.1% were scattered on nodes 6 - 18. In the cultivar MSU 9805 during 1974, 62.0% of the fruit were found in position one, 28.3% in position two, 7.3% in position three, 2.0% in position four, and 0.4% in position five (Table 78). The TABLE 78.--Inf1uence of position on the cucumber vine, on fruit set and shape, MSU 9805. Position 52mpée % Perfect % Nubs % Necks %fo:i§he l 410 94.2 2.9 2.9 62.0 2 187 72.7 18.2 9.1 28.3 3 48 83.3 12.5 4.2 7.3 4 13 84.6 15.4 0.0 2.0 5 3 66.7 33.3 0.0 0.4 highest percent of perfectly shaped fruit was found in position one, 94.2% and the lowest in position five at 66.7%, with an overall mean of 80.3%. Nub-shaped fruits were found in position one (2.9%) and in position five (33.3%). Neck shaped fruits were found only in the 196 first three positions, 2.9%, 9.1%, and 4.2% in order. Overall, 87.0% of the fruit were perfectly shaped, 8.3% nubs, and 4.7% necks. DISCUSSION This study has indicated that a series of events, linked to climatic conditions having minimum thresholds, must occur before bee foraging will be initiated, successful pollinations'toccur, and fertili- zation takes place in pickling cucumbers. Under normal light condi- tions, the sequence of events was initiated at 15° C conditions of reduced light, the process may be delayed. However, under As the corolla expanded and the temperature rose, anthers of staminate flowers began to dehisce and the nectaries of pistillate flowers gained a moist appearance under the microscope at 16° C, Collison (1973). At 16° C 60% of the anthers started to dehisce and 100% of the flowers were dehiscing at 19° C Anthers observed at tempera- tures between 12° C and 15° C showed no signs of dehiscence and below .16° C, all pistillate flower nectaries were dry, Collison Connor (1969) found that honey bees began foraging flights (1973). in cucumbers at the same general time that the flowers reached anthe- Therefore, it would appear that foraging commences in sis (16° C). response to the initiation of anther dehiscence in the staminate flowers, and to nectar secretion, in the pistillate flowers rather Additional support than anthesis, since anthesis comenced at 15° C comes from observations made on August 19, 1969, when the flowers were tightly closed at a temperature of 22° C, and bees were vigor- Both nectar and pollen were present, even us 1y trying to work them. 197 198 though the flowers were closed. Connor (1969) found that the aver- age time and temperture of the first bee visits to flowers were at 7:30 a.m. EST at 17° C, excluding those nights when the overnight temperature did not fall below 21° C. This study indicated that at 17° C, 80% of the staminate flowers in the field were undergoing anther dehiscence and small beads of nectar were forming on the inner surface of the pistillate flower's cup-shaped nectary, Collison Activityin the field was first observed visually, at 16.5° C (1973). However, when bee flight while flowers were undergoing anthesis. had been restricted, foraging began at lower temperatures to the pre- vious day's flowers. Collison (1973) showed that almost 1/3 of the day-old flowers contained some nectar under normal weather condi- tions. Connor (1969) observed that bee flight rarely became abundant until the temperature reached 21° C. Collison (1973) found that from 18 to 21° C, the percentage of nectaries containing beads of nectar increased as well as the number and size of the beads. He found that the first amounts of nectar measurable with microcaps were obtained at 21° C and the volume was equal to 0.24 ul. Connor (1969) observed that flight commenced earlier than 7:30 a.m. when the overnight tem- Seaton and Kremer (1938a) perature did not fall below 21° C. When temperatures dur- observed dehisced anthers as early as 4 a.m. ing the day remained below minimum thresholds, flowers remained closed, anthers intact, nectaries dry, and the bees in the hives. At the time of anther dehiscence, pollen was viable, and stigmas receptive. These results concur with the observations of 199 Hayase (1955) who found that pollen was viable before the anthers dehisced. Connor (1969) made similar observations when he exposed flowers to bees as soon as they started morning flights and found that 55.0% of the flowers set fruit and averaged 108 seeds per fruit. However, as the day progressed pollen viability and stigmatic recep- tivity decreased. Pollen viability was greatly reduced in day-old staminate flowers. Hand pollinations in both the field and green- house indicated that lower humidities and wind exposure may cause 1 pollen to lose its viability sooner. Hand pollinations also indi- .r cated that day-old pistillate flowers were capable of setting fruit However, honey bees generally did not work day- Connor (1969) with fresh pollen. 01d staminate and pistillate flowers in the field. found that hand pollination of second day flowers was occasionally successful. Day-old pistillate flowers bagged in the field and opened for 10 min intervals received no bee visits, while fresh flowers surrounding them were visited often. Cucumber flowers normally/ closed in the afternoon on the day of anthesis and by the following ( morning the petals were withered. Pollination of fresh pistillate flowers with day-old pollen,‘ indicated that stigmas remain receptive longer than pollen remains I viable. Undoubtedly, the rate at which pollen viability and stig- matic receptivity are reduced depends upon environmental conditions. Barnes (1947) found that pollen remained viable in the greenhouse lflTt11 1 or'2 p.m. on the day of anthesis. Connor (1969) found by exposing flowers to honey bees at different times of the day that the percentage of fruit development decreased after 2:30 p.m. Fruit 200 pollinated between 10:30 a.m. and 12:30 p.m. produced slightly more seeds, but the differences were not significant. Therefore, it I”, appeared that the amount of pollen or the loss of viability were not lhnfifing factors in late afternoon pollinations. Significant positive correlations were found between foraging activity and temperature, solar radiation, and wind speed. A sig- nificant negative correlation was found between foraging activity and relative humidity. .Therefore, it appears that the number of bee visits to the field are affected by temperature, solar radiation, wind speed, and relative humidity. A series of step-wise multiple regression analyses were run on the data, with the number of bee visits as the dependent variable and the various climatic conditions as the independent variables. Stepwise regression is a method of finding the combination of inde- pendent variables that most effectively predict the variation in the dependent variable. Using this technique, the independent variables are added successively to a regression equation according to their improvement of goodness of fit. Such information is needed to develop a predictive foraging model for the crop and a better under- standing of the affect of the complex of climatic factors on the number of bee visits occurring in the field. The data used for the analysis were collected from the East Lansing plots in 1974. During the 108 hourly sampling periods, from 0 -_F1_15_bee_visitsnwere recorded on 10 flowers, with an overall mean of 35.8 visits/10 flowers/30 min, which would be equivalent to“’7Hvisits/flower/hour __ _.—«w--..O———.M .- (V/F/H). Temperatures during sampling ranged from 15.7 'to 33.3° C 201 and the amount of solar radiation between 2.4 and 71.4 cal/cm2/h. The mean temperature was 24.8° C and the mean solar radiation was 42.1 cal/cmZ/h. Comparison of the individual correlation coeffi- cients between foraging activity and the various climatic conditions indicated that solar radiation was most important followed by tem- perature, relative humidity, and wind speed. Considering both tem- perature and solar radiation the following predictive linear regression equation was obtained. Yvisits = -19.17 + .95 (temperature) + .75 (solar radiation) An AOV for the above regression indicated that it was signifi- cant at the 0.0005 probability level (F = 22.97). The coefficient of multiple determination was equal to .3044 which indicated 30.4% association between the number of bee visits and the two climatic conditions. With the addition of relative humidity, the following linear regression equation was obtained. Yvisits = -l47.60 + 3.15 (temperature) + 1.13 (solar radiation) + .99 (relative humidity) The relative humidity ranged between 33 and 96%, with an overall mean of 58.4%. The level of significance did not change when relative humidity was added (F = 24.09). mination was equal to .4100 which indicated 41.0% association between The The coefficient of multiple deter- the number of bee visits and the three climatic conditions. average wind speed was 8.1 mph, ranging between 0.0 and 14.9 mph. 202 Theffinallinear regression equation, with wind speed added also remained at the same level of significance (F = 20.71). Yvisits = -l61.01 + 2.41 (temperature) + 1.30 (solar radiation) + 1.12 (relative humidity) + 2.11 (wind speed). However, the overall coefficient of multiple determination only equaled .4457, meaning 44.6% of the variation can be accounted for by the four independent climatic variables chosen. Probably the remainder of the variation was due to the level of nectar secretion and sugar concentration present in the flowers which was also depen- dent on the climatic conditions as well as flower density and size of the foraging population. Optimum foraging occurred between temperatures of 21.5 and Only 3.8% of the bees were counted at temperatures 30.0° C (85.6%). Foraging began at below 21.5° C and 10.6% between 30.5 - 34.5° C. lower temperatures in areas having the largest bee populations. Foraging was first observed on tagged flowers at 17.5° C in East Lansirm;(Table 5),at 19° C in Eaton Rapids (Table 6), and at 20.5° C in Philliken (Table 7). Also, in East Lansing, 4.9% of the population was foraging at 21° C and below, compared to 2.1% at Eaton Rapids, and 0.4% at Mulliken. East Lansing averaged 64.4 flower visits per day, Eaton Rapids 62.3, and Mulliken only 15.7. Lundie (1925) found that the internal condition of the colony was important in determining the temperature at which flight began. 203 Stronger colonies commenced flight at somewhat lower temperatures. Woodrow (1932) also found that in general, at any given temperature, the flight of a colony was roughly pr0portiona1 to its strength. Even though solar radiation appeared to be the most important climatic variable affecting foraging activity, no minimum threshold could'be established from the data. Peak activity was observed at 61 - 65 cal/cmZ/h, averaging.57.7 bee visits per sampling period. No activity was observed below 10.8 cal/cmzlh. During the entire samp- ling period, a mean of 42.1 cal/cmZ/h of solar radiation was recorded and the flowers received an average of 35.8 bee visits/10 flowers/ 30 min. Peak flight activity was observed at relative humidities between 50 and 59% averaging 48.0 visits per sampling period A highly significant negative correlation was found (Table 9). Similar observa- between foraging activity and relative humidity. tions were made by Bodenheimer and Ben-Nerya (1937). Foraging activity in relation to wind speed indicated a significant positive correlation. The wind speed fluctuated between 0.0 and 14.9 mph with a mean of 8.1 mph. Peak flight was recorded at a wind speed of 10.4 mph, and flight decreased at higher speeds. Park (1923) found that flight was reduced at wind speeds above 15 mph. Connor (1969) reported that high wind velocity was often associated with poor bee activity. However, he observed that bees were able to work cucumbers at relatively high wind speeds due to the dense protec- tive cover provided by the plants. 204 Observations at all locations indicated that foraging activ- ity fluctuated significantly in response to environmental conditions Comparison of daily flight activity at times seemed to indicate that temperature, solar radiation, relative humidity, and wind speed collectively affected flights while at other times only one variable seemed to dominate. Temperature, solar radiation, and wind speed usually increased during the day while relative humidity decreased. Even thoUgh significant positive correlations were found between foraging activity and temperature, solar radiation, and wind speed, and a negative correlation between foraging activity and relative humidity, clear distinct explanations for the large variations in foraging activity as expressed in Table 13 are not evident. Multiple regression analysis indicated that climatic conditions were not At times the affect of threatening storms and entirely responsible. However, a few bees rain were observed to reduce foraging activity. continued to work while it was raining, under the canopy of the leaves. Collison and Martin (1973) found that overhead irrigation during the day reduced honey bee activity in the cucumber fields by 80%, and flights were never fully resumed during the same day. Nectar secretion data indicated that pistillate and staminate flowers of pickling cucumbers differ in nectar secretion, though their In both types of flowers, nectar secretory rhythms were similar. Some flowers secretion varied with prevailing climatic conditions. did not secrete any nectar, and the percentage of both staminate and pistillate flowers secreting nectar increased until noon. No significant change was observed in the afternoon. Without bee 205 visitation, the average volume of nectar and total weight of sugar increased until late afternoon for both types of flowers. The aver- age sugar concentration for both staminate and pistillate flowers did not significantly change throughout the day. On the day of anthe- sis, comparison of mean values indicated that pistillate flowers produced approximately 1.5 times more nectar than staminate flowers. Maximum production in both showed an even greater difference, 34.15 ul for pistillate flowers compared to 14.88 ul for staminate. Stam- inate flower nectar had a higher average sugar concentration, but in total weight of sugar produced, the two types of flowers were similar. As the average temperature increasedduring the day, the volume of nectar, actual weight of sugar, and number of flowers pro- ducing nectar increased, the average temperature also increased. At the times the flowers were producing measurable amounts of nectar, average temperatures ranged between 23.4 - 28.2° C in 1968 and from 19.4 - 28.0° C in 1969. As temperature increased sugar concentration decreased. Daily nectar production fluctuated in response to changing «climatic conditions. Significant positive correlations were obtained between daily average temperature and daily average volume and when temperature was compared to volume of nectar and actual weight of sugar for. individual staminate and pistillate flowers. A significant negative correlation was found between temperature and sugar concen- tration for pistillate flowers only. The data strongly indicated that the amount of nectar and sugar potentially available to bees depended upon the time of day that the threshold temperature was reached. 206 Average daily relative humidity was not significantly corre- lated with the average volume of nectar produced each day by stamin- ate or pistillate flowers. However, highly significant negative correlations were found between relative humidity and volume of nec- tar as it was sampled hourly throughout the day in both staminate and pistillate flowers. As was found with temperature, a significant positive correlation was found only in the pistillate flowers between relative humidity and sugar concentration. Significant negative correlations were found between relative humidity and actual weight of sugar in the nectar of both types of flowers. Highly significant negative correlations were obtained between solar radiation of the three previous days and daily nectar volume and actual weight of sugar in pistillate flowers only. In staminate flowers significant correlations were obtained between daily nectar volume, actual weight of sugar and solar radiation of the previous day. When the volume of nectar and actual weight of sugar obtained at each hourly sampling throughout the day was compared with the solar radiation of the three previous days, highly significant nega- tive correlations were obtained for pistillate flowers. When comparing the average daily nectar volume, sugar con- centration, and actual weight of sugar in pistillate flowers with precipitation on the day of anthesis, no significant correlations were found. Continued analysis showed however, that for both daily average volume and actual sugar weight, correlations were highest 1when compared to the precipitation of the four previous days. During 'the sampling of staminate flowers in 1969, no precipitation was 207 observed. When the hourly volume of nectar and actual weight of sugar for individual pistillate flowers was compared to the total precipitation of the four previous days, highly significant positive correlations were obtained. Daily average wind speed was not correlated with average daily volume of nectar, percent sugar, or actual weight of sugar in staminate or pistillate flowers. However, significant correlations were obtained between wind speed and hourly nectar volume, sugar con- centration, and actual weight of sugar in individual staminate flow- ers. In pistillate flowers a significant negative correlation was found between wind speed and sugar concentration only. From the individual correlations presented it would appear that the nectar volume in pistillate flowers was a function of tem- perature, solar radiation of the three previous days, relative humid- ity, and the total precipitation of the four previous days. In staminate flowers, wind speed would be added and total precipitation deleted, since no precipitation was recorded during sampling. Sugar concentration of nectar from pistillate flowers was dependent on relative humidity, wind speed, and temperature. The actual weight of sugar in the nectar of pistillate and staminate flowers was affected by the same variables. Since many authors have found that the quantity of nectar present in flowers influences their attractiveness to foraging bees, a series of step-wise multiple regression analyses were run on the data with volume of nectar as the dependent variable and the various 208 climatic conditions as the independent variables. For pistillate flowers, data was obtained for 11 days. The average daily volume 0f nectar ranged from 3.07 to 9.87 ul with a mean of 5.87 ul while the average temperature ranged from 20.7° C to 27.8° C with a mean of 24.5° C. The average humidity ranged from 49.1 to 92.0% with a mean of 71.6%. Total precipitation for the four days prior to anthesis averaged 0.66 inches, ranging between 0.00 and 1.31 inches, while total solar radiation during the three previous days averaged 1464 langleys, within a range of 1035 - 1892 langleys. When considering the four independent variables, the following predictive linear regression equation was obtained. Yvolume = -9.93 + .30 (temperature) - .01 (relative humidity) + .18 (precipitation) - .004 (solar radiation). An AOV for the above regression indicated that it was significant at the 0.009 probability level (F = 9.44). The coefficient of multiple determination was equal to .8628 which indicated 86.3% of the varia— tion can be accounted for by the four independent climatic variables chosen. For the improvement of goodness of fit, the analysis indi- cated that precipitation and relative humidity should be deleted from the regression equation. If relative humidity was included, its significance would be .584 and precipitation .798. With the deletion of precipitation, the overall regression was significant at the .002 probability level and when relative humidity was deleted, the regres- sion was significant at the 0.0005 probability level (F = 23.73). 111.1123. 209 The final predictive linear regression equation obtained for pistil- late flowers was: Yvolume = -8.51 + .28 (temperature) - .005 (solar radiation) The coefficient of multiple determination was equal to .8558 which indicates 85.6% association between volume of nectar and the two climatic conditions. A similar type of analysis was performed on the data for staminate flowers. During the 11 sampling days when a complete set of weather data was available, the flowers averaged from 3.17 to 7.25 ul of nectar, with a mean of 4.68 ul. The average temperature was 26.4° C, fluctuating between 22.0° C and 29.4° C and the average relative humidity was 54.3%, fluctuating between 44.6 and 64.7%. Total precipitation four days prior to anthesis averaged .008 inches, ranging between 0.00 and 0.03 inches while total solar radiation dur- ing the three previous days averaged 1621 langleys, within a range of 1074 - 1865. When considering the four independent variables, the following predictive linear regression equation was obtained. Yvolume = -2.65 + .12 (temperature) + .02 (relative humidity) - 21.8 (precipitation) - .002 (solar radiation). An AOV for the above regression indicated that it was signifi- cant at the .432 probability level. The coefficient of multiple determination was equal to .4253 which indicated 42.5% of the varia- tion can be accounted for by the four independent climatic variables chosen. For the improvement of goodness of fit, the analysis 210 indicated that precipitation, relative humidity, and solar radiation should be deleted from the regression equation. For each variable not included in the final regression, its significance if it were added next would be solar radiation .633, precipitation .782, and relative humidity .847. With the deletion of relative humidity, the overall regression was significant at the .252 probability level. With precipitation also deleted, significance improved to the .120 probability level and the removal of solar radiation gave a final significance of .039 (F = 5.83). The final regression equation was obtained for the staminate flowers. Y = -8.58 + .17 (temperature) volume The coefficient of multiple determination was equal to .3931, therefore, 39.3% of the variation can be accounted for by temperature. Since the test flowers were not accessible to bees, the rest of the variation was probably due to the general physiology of the plant. Sinceailack of precipitation was evident, most of the variation was probably due to water stress. A second possibility would be develop- ing fruit on the vine. As Shuel (1955b) indicated, the carbohydrates that are synthesized during photosynthesis, are utilized in growth, respiration, and other vital processes. Since plots were adjacent soil was probably not a factor. In general, nectar secretion in cucumbers responded to cli- matic conditions as described by the literature, except solar radia- tion. Some authors have found significant positive correlations between nectar yield and solar radiation in some plants, our data 211 indicated a significant negative correlation between solar radiation and nectar production in cucumbers. The individual flowers sampled were excluded from bees, however, fruit development continued on the vines and stress of fruit formation would appear to be the primary reason why a negative correlation was obtained. As Shuel (1975) indicated in his discussion on sugar translocation, the growth of a fruit creates a sink (region of utilization) to which sugar moves, and this would influence its availability to nectaries. When a vine has formed a fruit, its development becomes the primary function of the plant and this requires priority for use of the carbohydrate supply. Dearborn (1936) reported that the fertilization of the ovules of the cucumber flower results in a stimulation of growth which extends beyond the reproductive organs. He found that the fruit had a dominating influence upon the growth and chemical composi- tion of the plant. Banadyga (1949) reported that high temperatures with a maximum amount of sunshine produced a higher sugar content in the fruit than in cloudy weather. Nectar taken directly from pistillate flowers averaged 36.3% and from staminate flowers 45.3% sugar during the day when bees were excluded from the blossoms. The overall mean of the two values was 40.8% while the overall average sugar concentration of nectar from bee's honey stomachs was 24.5%, a 40% decline (Table 28). Collison (1973) also showed that nectar secreted in a flower after its removal was of lower sugar concentration than the original nectar. He found that the concentration of nectar removed from flowers at hourly 212 intervals dropped from 42.3% to 13.8%. This reduction in sugar con- centration must be considered in determining the caloric reward that the honey bee receives as it visits the flowers. Cucumber flowers are typically visited several times an hour by honey bees. There- fore, each load of nectar is an accumulation of small quantities from many individual flowers, both staminate and pistillate. Throughout the day, the sugar concentration of the honey stomach contents did not vary a great deal, with average values being 17.1 to 28.3% sugar. The morning values were highest averaging 26.0% and the afternoons 23.0% which also indicated a reduction in sugar concentration with visitation. Both Wilson, Moffett, and Harrington (1958) in Colorado and Kauffeld and Williams (1972) in Wisconsin obtained much higher sugar concentration values using a similar technique. However, their sample sizes were small and if taken with a hand refractometer may be subject to inaccuracies. Connor (1969) found that maximum bee flights in the field extended from 9 to 2 p.m. Similar observations were made in 1974 during this study. During this time interval, the sugar concentration of the honey stomach contents peaked at 9 - 10 a.m. and 12 - 1 p.m. with a decrease throughout the rest of the afternoon, which indicated a correlation between nectar concentra- tion and presence of bees on the crop. In both plot and commercial field studies, bees were shown to exhibit a preference for staminate flowers as they foraged. While pistillate flowers produced approximately 1.5 - 2.3 times more nectar than staminate flowers, staminate flower nectar had a higher sugar concentration. It would appear that bees prefer staminate flowers 213 because of the higher sugar concentration. However, both types of flowers were quite close in total weight of sugar (caloric reward), with pistillate flowers having a slight edge. The honey bee has to visit more staminate than pistillate flowers to get a load of nectar, and therefore expends more energy, but is about equally rewarded by the staminate flower, because of the higher concentration of sugar. Therefore, one might expect them to be visited equally. . Staminate flowers offer both nectar and pollen and this may make the flower more attractive to bees. However, very few bees have been observed collecting cucumber pollen, and pellets which were collected were quite small compared to other major pollen sources. Connor (1969), Olsen (1975), and Williams and Kauffeld (1967) made similar observations. It has also been shown that the collection of cucumber pollen decreases during the day which is probably due to the depletion of the field supply. Doull (1966) found that when bees were collecting less attractive pollens, they worked more slowly in collecting the load and generally collected smaller loads. There- fore, if the amount of pollen being collected is an indicator of its attractiveness, cucumber pollen would not rate as a reward attractant but it may possess volatile materials which may attract bees. When gynoecious hybrids are used, the number of staminate flowers and available pollen is further reduced. It is not known whether cucum- ber pollen contains attractants like those that have been isolated from other pollens, Hugel (1962), LePage and Boch (1968), Hopkins et a1. (1969), Starratt and Boch (1971). If attractants are present, cucumber pollen should be attractive from 7 — 9 a.m. after anthesis 214 has occurred. However, the effects of chemical attractants could be masked first thing in the morning since Seaton, Hutson, and Muncie (1936) reported that at the time cucumber pollen is released, it is covered with an oily film and remains in masses in the pollen sac. It is possible that exposure to the air dries the film releasing the volatile chemical attractants. Since the largest amounts of cucumber pollen were found on the mouthparts and metalegs, with most bees having some pollen on the ventral surface of the thorax, prolegs, and mesolegs, the honey bee should be very efficient in distributing pollen uniformly over the stigmatic surface as it collects the nectar which is located directly below the stigma. While removing nectar from a pistillate .flower, a honey bee usually inserts and withdraws her proboscis 2 - 3 times. She inserts her proboscis at the periphery of the stigma, between the lobes, to reach the cup-shaped nectary below, Collison (1973). Therefore, her pollen-laden mouthparts are in direct contact with the receptive stigma 2 - 3 times each visit. In order to reach the nectar of a staminate flower she has to insert her proboscis between the central mass of the five anther lobes and the corolla, which would replenish the pollen supply of the mouthparts, Collison (1973). In moving about the pistillate flower, no doubt the pollen on the prolegs and ventral surface of the thorax comes in direct con- tact with the stigma occasionally. The dependability of pollen transfer with a specific number of bee visits would vary with the availability of pollen in the field, the staminate:pistillate flower ratio, and density as 215 well as distribution of the two types of flowers in relation to each other. Therefore, the projected number of visits that each flower should receive during the day would vary from field to field and day to day. This study has indicated that under high pollen concentra- tions the first visit to a pistillate flower places significantly more pollen on the stigma, than subsequent visits.. A similar situation probably exists under lower pollen concentrations, but the decrease in pollen transfer with additional visits would not be as rapid. Apparently a large portion of the stigma is coated with pollen dur- ing the first visit and with each succeeding visit there is signifi- cantly less receptive surface available. Connor (1969) presented data which supports this observation. He found that flowers in the field receiving one or two bee visits produced fruit with an average of 258 seeds, which indicated that a large amount of pollen was placed on the stigma with one to two visits. With additional visits, there was an increase in fruit set and average number of seeds per fruit. However, as the number of visits increased, the number of perfect-shaped fruit did not increase proportionately. However, with 20 visits 90.8% of the fruit were perfectly shaped compared to 79.6% for 15 visits. Average seed counts from fruit set on flowers receiv- ing 15 and 20 visits, were not significantly different, 227 and 246 seeds respectively. In all cases only one fruit was allowed to develop per plant. During 1974 first node pistillate flowers in the plots set fruit 91.7% of the time and received an average of 34.2 to 102.0 visits, 66.3 mean visits per day (Table 77). Fruit produced each day averaged between 203 and 263 seeds, with an overall mean of 216 229 seeds per fruit (Table 73). Of the pistillate flowers in posi- tion one that were monitored daily in 1974, 88.9% set fruit. The 18 flowers involved received from 18 to 100 visits and the resulting I fruit contained from 74 to 411 seeds. Overall means were 46.2 visits per flower and 272 seeds per fruit. As an indication, rather than a direct comparison Connor (1969) found by taking counts at identiCal times in the plots at East Lansing and in a 20-acre field at Springport, Michigan, the Springport field received 2.78 V/F/H compared to 8.28 in East Lansing which would represent 28 and 83 flower visits per day, respectively. When plants were harvested in both fields, the number of cucumbers produced per plant did not differ statistically at the .05 probability level. Similar counts taken at Cedar Springs (2.95 V/F/H) and East Lansing (8.68 V/F/H) at another time, also gave a nonsignificant difference when harvested. 0n the basis of these results, it appears that flowers receiving more than 20 visits will not significantly produce more fruit, even though they may contain a few more seeds. The number of seeds would actually be an indicator of pollination efficiency. Conversely, flowers receiv- ing one visit set fruit only 43.7% of the time. Connor (1969) found that single bee visits were capable of producing fruit 53.1% of the time, but Stephen (1970) reported that only under rare circumstances does one visit result in fertilization. He indicated that four or fewer visits were not dependable, but eight or preferably twelve provided sufficient pollen for adequate seed set and well formed fruit. Shemetkov (1957) under greenhouse conditions found that 8 - 10 visits were required. Additional visits increased fruit weight and 217 number of seeds. Connor (1969) found little difference in the per- centage of fruit set between single and multiple bee visits until 9 - 10 visits. In the greenhouse, he found that flowers receiving two or ten visits did not differ significantly in fruit set. He suggested that at least 10 bee visits were needed to insure pollina- tion under a variety of variable conditions. In cantaloupes, McGregor et a1. (1965) found that fruit set and marketability improved with additional bee visits up to 13 to 14 visits per flower. Connor (1969) found that fruit receiving 11 or 12 visits averaged 320 seeds per fruit, significantly less than the 393 seeds found in fruits exposed to a full day of pollination. These results indicated that a flower on the day of anthesis should receive from 15 to 20 visits for maximum fruit set. Node position after the sixth node did not significantly affect daily percent fruit set or production of perfectly shaped fruit. Therefore, the large daily variation in fruit set and shape that was observed, was due to factors other than fruit inhibition and node position. Honey bees spent more time per visit on pistillate than on staminate flowers, with overall means of 12.6 and 6.3 sec, respec- tively. Collison (1973) found that nectaries of pistillate flowers had secreting surfaces approximately twice as large as nectaries of staminate flowers and they produced 1.5 - 2.3 times more nectar than staminate flowers, which correlated with the length of the visit. Honey bees, if not disturbed, stayed on a flower until they removed all the nectar. The pattern of bee visits throughout the day 218 produced a normal distribution centered around 11 - 12 a.m. EST with 82.3% of all visits occurring from 9 a.m. to 2 p.m. (Figure 6). Only 4.3% of the visits occurred before 9 a.m. and 13.4% after 2 p.m. Prior to 9 a.m. the average time spent on each flower was greater than for the rest of the day. Fewer bees were working the flowers and the flowers contained a larger supply of nectar. As bee density increased after 9 a.m., the average time per visit decreased because flowers being visited had only partially replenished their nectar supply following removal by earlier bee visits. Connor (1969) found that the length of a bee visit to a pistillate flower decreased as the number of visits increased. First visits to a cucumber flower lasted an average of 36.2 sec in 1967 and 39.2 sec in 1968, while the average length of subsequent visits dropped sharply. Collison (1973) showed that successive removal and replacement of nectar reduced sugar concentration and actual weight of sugar. Late day increases in the time spent on flowers increased from 2 - 4 p.m. for staminate flowers and l - 4 p.m. for pistillate flowers. Decrease in flight activity after 2 p.m. allowed greater accumulation of nectar per flower resulting in longer bee visits. Linsley and MacSwain (1947) observed a depression in the number of bees working alfalfa in the early afternoon, followed by an increase later. The depression corresponded with periods of high- est temperature and lowest relative humidities; such a decrease was observed in cucumbers at 32°C. Bodenheimer and Ben-Nerya (1937) found a reduction at 33° C and a rapid increase between 34 and 39° C, which they concluded was probably due to water transport. Flight 219 activity in cucumbers decreased during the entire afternoon (Fig- ure 6). Bees were followed for 53 flower visits in the morning and 63 in the afternoon. The number of visits required to obtain a load of nectar depended on the bee and flower density in the field as well as the staminate:pistillate flower foraging ratio. From 7 - ll a.m., bees averaged 15.2 sec per flower visit (3.95 flowers per minute) compared to 10.3 sec for the rest of the day (5.83 flowers per minute) and flight activity peaked from 11 - 12. Foster and Levin (1967) found that bees worked cantaloupes at a rate of 3 - 7 sec per flower with an average of seven bee visits per minute. Mann (1953) reported 5.39 - 7.27 flower visits per minute. Bees spent an aver- age of 5.28 sec at each flower and 5.85 sec between flowers. McGregor et a1. (1965) observed that the average visit time of a honey bee on a cantaloupe flower was 10 sec. Foraging mobility varied greatly from day to day due to dif- } ferences in flower density, staminate:pistillate flower ratio, size 1 I of the foraging population, nectar production, and climatic conditions. 1; Several authors have shown that flowering and sex expression are dependent on climatic conditions. McGregor and Todd (1952) observed that bees working_canteloupes visited plants along a row more fre- quently than shifting from row to row. With dense cucumber plant populations rows are no longer visible and foraging patterns become more random although oriented more strongly in one direction. Following individual bees as they foraged indicated that bees are capable of distributing cucumber pollen a distance of 60 ft. 220 Pollen movement and fluorescent powder studies indicated that honey bees carry cucumber pollen a considerable distance from the pollen source, although the efficiency of the movement decreased in as little as 10 ft as indicated by seed counts. Peak production of fruit occurred at 0 to 10 ft from the pollen source. Fruit production decreased as the distance from the pollen source increased, up to 90 ft in 1969 and 30 ft in 1972, then began to increase. Seed counts indicated pollen movement up to 60 ft in 1969 and 70 ft in 1972. A highly significant negative correlation was found between distance and average number of seeds. Besides the direct movement of cucumber pollen from the pollen source, the possibility of re-transfer of pollen from stigma to stigma exists. Seed counts indicated that retransfer of pollen was not of great significance to pollination. Foster and Levin (1967) observed the re-transfer of pollen from stigma to stigma in watermelon pollination. Connor (1969) found evidence for the movement of pollen for at least 50 ft. Beyond 25 ft from the pollen source, there was a reduction in the dollar value, the number of fruit per plant, and the number of seeds per fruit. Foster and Levin (1967) found evidence for movement of canteloupe pollen at least 35 ft and Knysh (1958) for movement of cucumber pollen a distance of 250 m. Fluorescent powder movement rapidly decreased as the distance from the source increased. In 1971, no powder was detected beyond 70 ft from dusted flowers. Most of the powder was distributed in the first 20 ft from the source. The use of the fluorescent powders 221 indicated that the size of the bee population, weather conditions, and concentration of powder affect its distribution. Comparison of pollen movement strip pairs for the various levels of pollen present seemed to indicate an inverse relationship between the number of fruit per plant and amount of pollen present, but the opposite was true for seed counts. There was a direct rela- tionship between the amount of pollen available and the distance it was moved by the bees. Evidence suggests that the level of pollen present and its distribution along with decreased light intensity in late summer, Tiedjens (1928), seem to trigger the mechanism for parthenocarpic fruit production. Plants located farthest from the pollen source were greener and healthier looking, had larger leaves, and more flowers. McCollum (1934) found that parthenocarpic fruit did not put as much stress on the plant as fruits containing seeds. Decreased light intensity in August and September, and less available pollen may partially explain the increase from 9.4% parthenocarpic fruitfor the first harvest, to 42.6% for the second harvest. Because of increased plant vigor indicated by a greater "vegetative response" plants farthest from the pollen source set more fruit parthenocar- pically than those close to pollen. Parthenocarpic fruit were first found at 50 ft from the pollen source in the first harvest and at 30 ft in the second harvest. In 1972 when pollen levels were higher, only 4.1% of the fruit developed parthenocarpically and was first observed at 90 ft during the same time of the year. The monitoring of two field plots in 1974 indicated that fruit inhibition limits fruit production and excessive production of 222 staminate flowers limits fruit uniformity for mechanical harvesting. Staminate flower production predominated throughout the flowering period, particularly as the plant matured and fruit formed. In the Piccadilly plot, the daily staminate:pistillate flower ratios fluc- tuated between 1.30 and 3.93 with a mean of 2.24. In comparison the adjacent plot of MSU 9805 over the same time period had a staminate: pistillate flower ratio between .84 and 4.47 with a mean of 2.25. Similar situations were observed several times in commercial fields and other plots. Fruit inhibition was rapidly expressed in the field. The first pistillate flowers that appeared on the vine developed into mature fruit 91.7% of the time; 49.6% of the second group developed into mature fruit. With each succeeding set of flowers, fruit pro- duction decreased rapidly from 19.9% for the third set to none for the seventh set. In the adjacent MSU 9805 plot, 62.0% were in posi- tion one, 28.3% in position two, 7.3% in position three, 2.0% in position four, and 0.4% in position five. Flower counts and seed counts indicated that there was no shortage of pollen. Foraging activity was not a limiting factor with projections of 10,739 - 94,478 bee visits per day. Climatic conditions were favorable for flight activity and fruit set during the entire monitoring period. Even under optimum pollination conditions, the Piccadilly plot averaged only 1.23 fruit per plant and the MSU 9805 plot 1.15 fruit per plant. Each succeeding flower has a decreasing chance to set fruit. Even if fruit development begins, it often reaches the inhi- bition threshold before attaining a size of economic value. Such 223 growth-inhibited ovaries either withered and died or remained green. and unchanging for several weeks, depending on the stage of develop- ment. The data indicated this threshold peaked within flowers 2 - 4 on the vine. If more than one flower on a plant is produced and pollinated on the first day of bloom further fruit set may be com- pletely inhibited. It is likely that each cultivar has a genetic limit to the number of fruit it can mature at one time. If fruit is hand-picked, growth inhibited fruit further along the Vine will than develop. Ability to develop many fruit at one time is an impor- tant economic factor in a cultivar for machine harvest. Sims and Gldehill (1969) reported that several commercial gynoecious hybrids produced up to 50% staminate flowers. The blends ing of monoecious seed with the gynoecious hybrids is done but unnec- essary. When staminate flowers are present in excessive numbers, they may be produced on some vines for several days in succession, resulting in a fruit set that is not uniform for mechanical harvest- ing. Connor (1969) found that best yields for a single harvest could be expected from the use of a highly gynoecious hybrid seed blended with a pollinator to produce a 1:2 staminate:pistillate flower ratio. Monoecious varieties produce an S:P ratio of approximately 20:1. The 1974 study indicated that if a pickle field has adequate but not excessive pollen, uniform flowering, plenty of bees brought in about six days after the start of flowering, and good flying weather (temperatures above 21° C, relative humidity below 70%, winds less than 15 mph, plants dry, and bright sunshine), maximum fruit set for machine harvest could be achieved in less than a week. 224 Connor and Martin (1970) found with delayed pollination, an exposure period of six days of active bee pollination was sufficient for optimum single harvest yields. Without considering fruit inhibition, any estimate of pollinator needs may be excessive. As the seeds begin to mature in the fruit, they slowed the development of new pistillate flowers and inhibited further fruit set, Cantliffe (1974). Some correlation was observed between the number of seeds and fruit shape. However, the extent of pollination only appears to be one factor involved. Other factors are probably physiological, climatic, and genetic in nature. Perfect-shaped fruit were found to contain from 0 to 546 seeds. No significant correlation was found between production of perfectly shaped fruit and daily staminate: pistillate flower ratio, average seed counts, or total bee visits per day. Connor (1969) found perfectly shaped fruit containing from one to 520 seeds. Connor (1969) was unable to find a correlation between the percentage of perfectly shaped cucumbers and the number of bee visits to the flowers. He found that the perfectly-shaped fruit had approximately twice as many seeds as the necks and three times as many as the nubs. Tiedjens (1928) found no correlation between the number of seeds and shape of the cucumbers. Seaton (1937) found that the number of developing seeds determined the amount of fruit tissue that developed, implying that more seeds resulted in better fruit shape. Wong (1938) found that a constriction of the stem end or blossom end of the fuit was due to seedlessness of that particular portion. Kremer (1943) hypothesized that anything interfering with the germination and growth of the pollen tubes through the ovary may 225 be responsible for the constrictions in the various regions of the fruit. Seaton, Hutson, and Muncie (1936) reported that fruit shape depended largelycwithe weather conditions prevailing at the time fruit set. Miller and Ries (1958) found that conditions leading to a faster rate of growth were more conducive to better shaped fruit. An attempt was made to determine the number of bees required for maximum pollination and crop yield. Most current pollinator recom- mendations call for a specific number of colonies per acre of crop. However, the colony is not a standard unit and in order to have real meaning, it needs to be defined. Strong colonies are usually recom- mended in pollination literature but attempts to define this term vary widely. Such terms as "thousands of bees," "frames of brood," "square inches of brood," "the number of frames the cluster covers," and combinations of these have commonly been used. However, to the grower such terms have little meaning, since they refer to bees in the colony rather than on the flowers. From a pollination standpoint, the usefulness of a colony of bees is indicated by the number of foraging trips to the crop per unit of time. Various types of count- ing techniques and devices for measuring bee flight from a colony have been developed by Lundie (1925), Farrar (1931), Woodrow (1932, 1934), Brittain (1933), Bodenheimer and Ben-Nerya (1937) and Gary (1967). However, in assessing cucumber pollination such techniques have limited value since there are usually several species of plants in the area of the pickle fields that are more attractive to honey bees than cucumbers, Collison and Martin (1970). The following sampling technique was developed for the grower or researcher to 226 assess pollinator activity in pickle fields and to determine if sufficient activity is present or more bees are needed. The incor- poration of weather data would make it too cumbersome for the grower to use. This research has indicated that flowers on the day of anthesis should receive from 15 - 20 visits for maximum fruit set. Between 9 a.m. and 2 p.m., 82.3% of all bee visits occurred. There- fore, on a sunny day when flower petals are dry, temperature above 24° C, between 10 a.m. and l p.m., wind less than 15 mph, at least six days after start of bloom, select 10 fresh flowers, five stamin- ate and five pistillate. Count the number of bee visits for 10 min. Rest 10 min, then repeat at two more locations. This will take one hour. Compare the one hour bee activity to Table 79 to obtain an indication of the adequacy of pollinations. Researchers requiring greater accuracy should extend sampling to three hours. The number of seeds per fruit provided the best indicator of the amount of pollination that has taken place. Fruit contained from O - 546 seeds under various field and plot conditions. In order to estimate the amount of pollen that a pistillate flower should receive, the average number of ovules per flower should be known. Seed counts of the fruit receiving a specified number of bee visits in 1970 indi- cated that honey bees placed a minimum of 18 effective pollen grains on the stigma with each visit. Prior to sampling, staminate:pistil- late flower ratios averaged 1.15 in the first plot and 2.28 in the second. Connor (1969) found a positive correlation between the length of the ovary and the number of ovules per longitudinal section. 227 OH8>8HOO OOO 8o .O>O. OOOOOEEOOOO ON ON O. O. O . 5235.8)5; OOO .3 59.5.. 38.3.8 O O O O . O O.O OOHO - OOHO .. O N Oe N O O.O OOHO - OONN O. O. .. N O . 0.0. OOHN - OO". NN O. O. O O . O... OO". - OOHN. ON .N O. O. O . N.ON OO N. - OO .. NN N. O. O O . N.N. OO .. - OO O. O. N. O O O . O.N. OO O. - OOHO O O O N . O -O.O OOHO - OOHO . . . O O O O. OOHO - OO". :85 OM\OOO3O.8.OM\OOOO 8o .0: .OHOH co OOOOO .O>O. O.OEOO OOHOE8HOO . OOO OOH O08 8mm OO.O.> .OOOO .5 O OO.. .OOOO LOO OOHOEOO OOOOH OH83 OOHOOHE OOH :8 OOOzo.8 OOOEOOOO O. OO8H8O8> OOOO 8o OOOEOO OOH co OOOOO Own OOH O08 mH8O8> OOO 8o OOOEO: OOHOOOOLO11.ON OOO< II II In the Piccadilly plot during the 1974 study, the field staminate: pistillate flower ratio was 2.24 and the foraging staminate:pistil- late flower ratio was l.12, exactly half the field ratio. Y O 1?:0391163P1FSP) FSP = Egrggigg sgsmgnatezpistillate The honey bee receives .29 mg of sugar with each staminate flower visit, and .54 mg with each pistillate flower visit when the overall sugar concentration of 24.5% sugar is used. An average load would contain 9.81 mg of sugar and a full load 17.14 mg. In order to attain a better understanding of the complex interrelationships between bees and flowers involved in the pollina- tion of pickling cucumbers, the following simulated foraging model of a field was developed (Figure 28 and Appendix B, Program Yield). Based upon data collected during this study, the model was used to project values for daily production of staminate and pistillate flow- ers, potential nectar yield, number of bee foraging trips required to collect the field's nectar supply (carrying capacity) and potential fruit production for various plant populations, cultivars, and seed blends. The effect of climatic conditions on nectar secretion and foraging activity have previously been equated. Prior to mechanical harvesting, plant populations ranged from 4,000 and 20,000 plants per acre. Oownes, Carpenter, and Reed'(l972) found the optimum plant population to be 198,313 plants per acre for 233 mechanical harvesting. For comparison, three cultivars, Spartan 27 (monoecious), Piccadilly (commercial hybrid, intermediate between gynoecious and monoecious), and Spartan Progress (gynoecious) with a 10% monoecious blend of SMR58 were used at plant densities of 20,000 and 198,313 plants per acre. Since Connor and Martin (1970) obtained higher yield and quality of fruit by delaying pollination f0r 5 to 11 days, flowering patterns of the various cultivars used in the predictive model started eight days after the first flower appeared in the 1968 test plots and were continued for 12 days ‘ (Table 82). Only flowers on the day of anthesis were included in the model. Collison (1973) found that to accurately compare nectar secreting characteristics of different culitvars, data for staminate and pistillate flowers had to be considered separately. No signifi- cant differences in nectar secretion were found in the cultivars compared. On a field basis, cultivars that produced predominantly pistillate flowers secreted larger volumes of nectar with more total sugar than staminate lines which produced nectar with higher average sugar concentrations. Since there was no significant difference between cultivars, values for the model were obtained from the samp- ling of MSU 356 in 1968 and SMR 58 in 1969. In both studies, the flowers were excluded from bee visitation and sampled throughout the day. The average pistillate flower produced 6.05 ul/day compared to 4.01 ul/day for the staminate flower. Each pistillate flower could potentially become a fruit of economic value, however, this study has indicated that fruit 234 .O. OH. me. me. OO. Ne. we. we. me. mm. 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S FCR ’RINY. 3131 LINES Cu 59957995990L000“ PAGES PRINT. LITERATURE CITED 260 LITERATURE CITED Adams, H.L., Peterson, C.E. 1972. Use of fruit counts for estimaté ing yields of once-over harvested pickling cucumbers. Hort. Sci. 7: 337. Alex, A.H. 1957. Honey bees aid pollination of cucumbers and canta- loupes. Glean. Bee Cult. 85: 398-400. Banadyga, A.A. 1949. Cucumbers For Pickles. Nat. Pickle Packers Assoc., Oak Park, I11., 276 pp. Barnes, W.C. 1947. Cucumber breeding methods. Proc. Am. Soc. Hort. Sci. 49: 227-30. Beutler, R. 1953. Nectar. Bee Nld. 34: 106-16, 128-36, 156-62. Bodenheimer, F.S., Ben-Nerya, A. 1937. One year studies on the biology of the honey bee in Palestine. Ann. Appl. Biol. 24: 385-403. Brett, C.H., Sullivan, M.J. 1972. Bee Attraction to Cucurbit Flowers and Pollination. N. Carolina State Agr. Exp. Sta. Bull. 443, 22 pp. Brittain, N.H. 1933. Apple pollination studies in the Annapolis Valley, N.S., Canada 1928-32. Can. Dep. Agr. Bull. 162: ! 119—25. 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