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'5 515155555551" 51 ' 15 1 JJJJJJJJ 1 l5 .5'.5 55.5 , 11.1 1 111 ~ 551 1511‘ ‘15' 111 '11 "1.1.15 . 1'1" 5 155' 551.111' ,' 1 JJJJJ 551555 515555 .55155‘5'55 , .5 15 155155 '5"5J5:'.51555J5J'J5 J'J'51'5J'5515 JJ.. .5 15 1 ...1'1E»'1'1,1'11"1-. . .,. . ,11'5 1'. 5115"“"~111J1 5' 1‘1 15'15551' H1551 1551152595111 ".21" {“0135 ,1 555551111.» 1111511111. 113.1151'1‘1" 11.'155 111511.11' 5.55111 " 5555555 |\\\l\\\\\\\\ \\\\\\\\ H \\ \\\\\\\‘\\\\\\\\\\\\\\l\\\\l 0366 w .3 N (0 w a o h 00 .a This is to certify that the thesis entitled THE BIONOMICS AND CONTROL OF CLIMBING CUTVORMS ATTACKING GRAPES IN MICHIGAN presented by FREDERICK WALTERS HARMOR has been accepted towards fulfillment of the requirements for Master' 9 degree in Entomology We“ “‘6‘ Major professor Date November 21, 1979 0-7 639 l Ammo anus “ESELPW AXVXEU'Z’ OVERDUE FINES: 25¢ per day per item RETURNING LIBRARY MATERIALS: Place in book return toremo charge from circulation records THE BIONOMICS AND CONTROL OF CLIMBING CUTWORMS ATTACKING GRAPES IN MICHIGAN BY Frederick Walters Marmor A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Entomology 1979 ABSTRACT THE BIONOMICS AND CONTROL OF CLIMBING CUTWORMS ATTACKING GRAPES IN MICHIGAN BY Frederick Walters Marmor A complex of six species of climbing cutworms was identified inhabiting vineyards in southwestern Michigan, damaging the developing buds in early spring. Amathes c-nigrum L., Agrotis badinodis Grote, Amathes smithii Snellen, Rynchagrotis cupida (Grote), Euxoa messoria Harris and Spaelotis clandestina (Harris) were identified. A laboratory rearing method was developed for Amathes c-nigrum L. and reared continuously through five consecutive generations. Detection of cutworm larvae was best accomplished by nightly inspection of vineyards in the spring and by using a sweep net on the ground cover in the vineyards after dark. Larvae of Euxoa messoria Harris were strongly attracted to a blacklight suspended above the ground. The efficacy of various insecticides was tested in vineyards and microplots. Synthetic pyrethroids, chlorpyrifos, monocrotophos and various baits were effective in cutworm control. ACKNOWLEDGMENTS To my major professor, Dr. Angus Howitt, I would like to extend my thanks for his friendship, guidance and support, and for the opportunity to work at the Trevor Nichols Complex. To my committee members, Dr. Stan Howell and Dr. Gary Simmons, I am grateful for their important inputs. The grape growers of Berrien and Van Buren counties have been very cooperative and provided me with an excellent background in viticultural practices, and it is greatly appreciated. The author is grateful to Robert Van Vleck, Gordon Brown, Robert Rogers, Ed Oxley, Dwight Brown, Cecil Bethe, William Streeter and William Cronenwett for the use of their vineyards and other facilities during the course of this study. A very special thanks is extended to Gordon Brown and Robert Rogers and their families for providing housing for me during the research project. I am indebted to the field staff of National Grape Cooperative for the initial introduction to the cutworm problem in grapes and for their help and guidance. The Van Buren and Berrien County Cooperative Extension Service provided help and guidance throughout the project. To Deb, my wife, I would like to thank for her patience, understanding and encouragement which made the completion of this endeavor a reality. ii LIST OF TABLES . . . . . . LIST OF FIGURES . . . . . . INTRODUCTION . . . . . . . LITERATURE REVIEW . . . . . BIOLOGY . . . . . . . . . . IDENTIFICATION OF CUTWORM Introduction . . . . . Methods and Materials . Results and Discussion TABLE OF CONTENTS Spotted Cutworm, Amathes c-nigrum L. . W-marked Cutworm, Spaelotis clandestina (Harris) Dark-sided Cutworm, Euxoa messoria Harris . . . . Spotted—sided Cutworm, Agrotis badinodis Grote . Brown Cutworm, Rhynchagrotis cupida Amathes smithii Snellen . . REARING TECHNIQUES . . . Introduction . . . . . Methods and Materials . Establishment of Colony . . Larvae Food Sources . Results and Discussion iii (Grote) . . . vi viii l2 16 18 20 25 26 26 26 26 3O 31 LARVAL FEEDING BEHAVIOR . Introduction . . . . . Methods and Materials . Bucket Experiments . Long Cane Experiments Results and Discussion Bucket Experiments . Long Cane Experiments SURVEY AND SAMPLING TECHNIQUES Grape Grower Questionnaire Survey Introduction . . . . Methods and Materials Results and Discussion Adult Sampling . . . . Introduction . . . . Methods and Materials Results and Discussion Larval Sampling . . . . Introduction . . . . Methods and Materials Results and Discussion CONTROL . . . . . . . . . . CHEMICAL CONTROL . . . . Introduction . . . . . Methods and Materials . Laboratory Studies . Field Evaluations in Established Vineyards iv 32 32 35 35 36 36 36 37 4O 4O 4O 4O 41 47 47 47 49 67 67 67 69 81 81 81 82 82 82 Field Evaluations in Non-producing Vineyards Residual Activity . . . . . . . . . . . . . . Results and Discussion . . . . . . . . . . . . Grape Grower Questionnaire Survey . . . . . . Laboratory Studies . . . . . . . . . . . . . Field Evaluations in Established Vineyards . Field Evaluations in Non-producing Vineyards Residual Activity . . . . . . . . . . . . . . BIOLOGICAL CONTROL . . . . . . . . . . . . . . . Methods and Materials . . . . . . . . . . . . . Parasites 0 O O D O O O O O O O O O O O O O 0 Disease 0 O O O O O O O O O O O O O O O O O 0 Results and Discussion . . . . . . . . . . . . Parasites 0 O O O I O O O O O O O O C O O O 0 Disease 0 O O O O O O O O O O O O O O O O O O CONCLUS ION O O O O O O O O O O O O O O O O O O O O APPENDICES A. HOST RANGE OF THE CUTWORM COMPLEX . . . . . . B. ARTIFICIAL DIET . . . . . . . . . . . . . . . C. GRAPE GROWER QUESTIONNAIRE SURVEY . . . . . . D. NATURAL ENEMIES OF CUTWORM COMPLEX . . . . . BIBLIOGRAPHY O O O O O O O O O O O O O O O O O O O 83 85 87 87 89 91 95 98 98 98 98 100 100 100 100 103 105 109 110 114 117 10. 11. 12. 13. 14. LIST OF TABLES Time Required for Development of Life Stages of the Spotted Cutworm, Amathes c-nigrum . . . . . . . . . Results of Bud Preference Feeding Tests for the Spotted Cutworm Using the Bucket Design . . . . . . Results of Bud Preference Feeding Tests for the Spotted Cutworm Using the Long Cane Design . . . . . Grape Acreage and Number of Fields by Township and Cutworm Damage as Reported from Questionnaires . . . Grape Vineyard Age Distribution in Relation to Cutworm Damage as Reported from Questionnaires . . . . . . . Cutworm Damage and Uncontrolled Weed Problems as Reported from Questionnaires . . . . . . . . . . . . Cutworm Damage and Adjacent Crops to the Vineyard as Reported from Questionnaires . . . . . . . . . . . . Summary of Total Spotted Cutworm Moths Caught Per Hour from the Brown, Rogers and Streeter Blacklight Traps for August 18, 25 and 31, 1978 . . . . . . . . . . . Summary of Total Dark—sided Cutworm Moths Caught Per Hour from the Brown, Rogers and Streeter Blacklight Traps for August 18, 25 and 31, 1978 . . . . . . . . Attraction of Dark-sided Cutworm Larvae to the BlaCklight O O O O O O O O O O O I O O O O O O O O 0 Number of Each Species Collected Per 122 Meters of Vineyard Row During Visual Inspections . . . . . . . Results of Baited and Unbaited Pitfall Traps as a Detection Tool for Climbing Cutworms . . . . . . . . Summary of Cutworm Species Located During 3x3 Meter Plot sampling 0 I O O O O O O O O O O O O O O O O O Cutworm Damage and Insecticide Usage as Reported from Questionnaires . . . . . . . . . . . . . . . . vi 32 38 39 42 44 45 46 65 66 71 73 74 80 88 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. Cutworm Damage and Time of Insecticide Applications as Reported from Questionnaires . . . . . . . . . . Direct Contact Toxicity of Fifteen Insecticides to Third Instar Fall Armyworm Larvae . . . . . . . . . Direct Contact Toxicity of Two Insecticides to Third Instar Dark-sided Cutworm Larvae . . . . . . . . . . Efficacy of Six Insecticides in Controlling Climbing Cutworms Attacking Grape Buds (1978) . . . . . . . . Efficacy of Five Insecticides in Controlling Climbing Cutworms Attacking Grape Buds (1978) . . . . . . . . Efficacy of Four Insecticides in Controlling Climbing Cutworms Attacking Grape Buds (1979) . . . . . . . . Efficacy of Eleven Insecticides in Controlling the Dark-sided Cutworm Attacking Young Grape Plants (1978) 0 O O C O O C O O O O O O O O O O O O O O O 0 Efficacy of Seven Insecticides in Controlling Dark— sided Cutworms Attacking Young Grape Plants (1979) . Mortality of the Spotted Cutworm Due to Residual Activity of Chemical Treatments in the Vineyard . . List of Parasites Reared from Climbing Cutworms Attacking Grapes from Field Collected Larvae in 1978 and 1979 . . . . . . . . . . . . . . . . . . . Mortality Counts of Dark-sided Cutworms Infected with En tomogrlo r a O O O I O O O O O O O O O O O O O O O O vii 89 90 91 92 93 94 96 97 99 101 101 10. 11. 12. 13. LIST OF FIGURES Distribution of Grape Acreage throughout Michigan with Acreage Reported for Each District . . . . . Insect Museum Records of Species Caught in Blacklight Traps in Michigan . . . . . . . . . . . . . . . . Climbing Cutworm Species Attacking Grapes . . . . . Climbing Cutworm Species Attacking Grapes . . . . . Equipment Used for Rearing Amathes c-nigrum in the Laboratory . . . . . . . . . . . . . . . . . . . . Cutworm Damage to Grapes . . . . . . . . . . . . . . Blacklight Trap Catches of Spotted Cutworms from the Brown, Fenn Valley and Van Vleck Blacklight Traps (1977) o o o o o o o o o o e o o o o o o o o o o o Blacklight Trap Catches of Spotted Cutworms from the Bethe, Brown, Rogers and Streeter Blacklight Traps (1978) o o o o o o o o o o o o o o o o o o o o o o Blacklight Trap Catches of Dark-sided Cutworms from the Bethe, Brown, Rogers and Streeter Blacklight Traps (1978) . . . . . . . . . . . . . . . . . . . Blacklight Trap Catches of Spotted Cutworms Per Degree-day from the Bethe, Brown, Rogers and Streeter Traps in 1978 . . . . . . . . . . . . . . Blacklight Trap Catch of Dark-sided Cutworms Per Degree-day from the Bethe, Brown, Rogers and Streeter Traps in 1978 . . . . . . . . . . . . . . Total Hourly Spotted Cutworm Moth Catch from the Brown, Rogers and Streeter Blacklight Traps for August 18, 25 and 31, 1978 . . . . . . . . . . . . Total Hourly Dark-sided Cutworm Moth Catch from the Brown, Rogers and Streeter Blacklight Traps for August 18, 25 and 31, 1978 . . . . . . . . . . . . viii 14 22 28 33 50 51 52 53 54 56 57 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. Hourly Spotted Cutworm Moth Catch from the Brown Blacklight Trap for August 18, 25 and 31, 1978 . Hourly Dark-sided Cutworm Moth Catch from the Brown Blacklight Trap for August 18, 25 and 31, 1978 . Hourly Spotted Cutworm Moth Catch from the Rogers Blacklight Trap for August 18, 25 and 31, 1978 . Hourly Dark-sided Cutworm Moth Catch from the Rogers Blacklight Trap for August 18, 25 and 31, 1978 . Hourly Spotted Cutworm Moth Catch from the Streeter Blacklight Trap for August 18, 25 and 31, 1978 . Hourly Dark-sided Cutworm Moth Catch from the Streeter Blacklight Trap for August 18, 25 and 31, 1978 . . . . . . . . . . . Dark-sided Cutworm Larvae under Blacklight in Vineyard, 1978 . . . . . . Distribution of Cutworm Larvae in Vineyard (Ryan #1) Distribution of Cutworm Larvae in Vineyard (Brown) Hooded Boom Sprayer Used for Chemical Application to Grapes . . . . . . . . Micro Plots in Young Vineyard ix 58 58 60 60 62 62 72 78 79 86 86 INTRODUCTION INTRODUCTION Production of grapes has been a major horticultural enterprise in Michigan for over 100 years. Grapes were first planted in Michigan's Van Buren county in 1867 by Charles Lawton. The first recorded commercial harvest was in 1878 with thirty tons of grapes harvested (Thomas, personal communication). Michigan currently ranks fourth in total grape production only to be exceeded by California, New York and Washington. In 1977, Michigan produced a total of 33,000 tons of grapes with a production value of 6.5 million dollars. The 1978 grape crop produced 67,500 tons, of which, 60,000 tons were Concord. Utilization of the 1978 crop was as follows: fresh--2,100, wine-- 4,200, juice--60,300 and other-—900 tons. Since 1973, Michigan has seen a decrease in grape acreage from 16,878 to 12,155 which is a 23 percent reduction. Nearly 99 percent of Michigan's grape acreage as reported in 1973 is located in Berrien, Kalamazoo and Van Buren counties in southwestern Michigan (Figure l). Grapes thrive in many soil types, and the Concord has a great adaptability to a wide range of soils. A good soil for grapes is a well-drained, deep, naturally fertile, gravelly or sandy loam with a subsoil that is not so heavy that it holds water (Shoemaker, 1978). Light soils are more easily worked, prepared for planting earlier in the spring, are tilled at less expense than clay soils and promote 2 earlier ripening and higher sugar content of the grapes than do heavy soils (Childers, 1973). Grapes are attacked by a variety of insect and disease pests. Common insect pests include rose chafers, flea beetles, leafhoppers and grape berry moth with black rot, Eutypa, downy mildew and powdery mildew being common grape diseases. One of the major and most destructive pests of grapes in Michigan are cutworms. Damage to grapes by various species of cutworms includes feeding on developing buds, cluster damage pre-bloom, foliage feeding on new shoots and destruction of the apical meristem of shoots at or below the ground level. Since the larvae are nocturnal feeders, feeding is not frequently observed. The investigations reported in this thesis were designed to understand certain aspects of the biology and control of climbing cutworms with respect to the production of grapes in Michigan. These investigations include studies to: (1) identify the cutworm complex attacking grapes, (2) understand the biology of the cutworms, (3) investigate the feeding behavior of the larvae, and (4) develop efficacy information for chemical control of cutworms. x’fisd .! D l \c‘némvcm‘i ”METI /. ’%3.\‘ . \ ‘ {may . . \ ._. madman i LEELANAU \\~ .4 .... ____ __ O o .1 . \. AHTRJM orsrco Inoumlm \0 ' uwww -—~—}——-4---—- NORTHWEST 13:»inr $312 WMECRAWFDRD: oscoDAl ALDDNA EASTERN ' - I ----- —-- who—l Es; 141 acres 22 acres MANIST wzxroao wswxczinoscomoalocmgw .1% __1_. I “L .8% -—1 -7I I “I ARENAC “A50” LAKE loscaou CLARE EGLADWIj- °- J, -J" (an HURON WEST CENTRAL 'MmmwA .._.__u_- occma Memo ISABELLAiMIDUNO' 1 1 22 acres 1 umnoum cm'nori SAGINAW I F’"L . 1% nusxtcou _| I— . ,4 ‘l __. .._.. _. ...._l"'""" - p... I KENT I. Icmsa: “"5“ I_s'cu\m 077”“ I tom cunronIsnumat l ' 1 I SOUTHWEST 16,693 acres 99% Figure 1. Distribution of Grape Acreage throughout Michigan with Acreage Reported for Each District LITERATURE REVIEW LITERATURE REVIEW European literature of the early 1800's contains several accounts of cutworms climbing grapevines and doing much damage to the buds and leaves (Slingerland, 1895). The earliest reference to climbing cutworms in America is found in the Massachusetts Ploughman for June 28, 1851. This article reported that naked caterpillars came out of the ground in the night, and crawling up the trunks of the fruit tree, devoured the leaves and returned to conceal themselves in the ground before morning. In 1866, Riley gave a detailed account of the operations of three different species on the buds of fruit trees and grapevines in Illinois. Cutworms may be grouped into categories based on the feeding habits of the larvae. The categories are: subterranean, tunnel makers, surface feeders, climbers and borers. Climbing cutworms are so termed due to the habit of the larvae to climb the host plant and feed on the stems, buds, foliage, flowers or seeds. Slingerland (1895) reports that probably no cutworms assume the climbing habit when there are plenty of low—growing grasses and weeds at hand. Trees in grass or clover are rarely attacked by cutworms, while those in fields kept free from other vegetation by cultivation always suffer the most, as the worms have to either climb or starve. He also states that all cutworms prefer light, loose soils. Light, 5 loose soils and a scarcity of low-growing succulent vegetation are conditions that may induce cutworms to assume the climbing habit. The moths, nocturnal in habit, rest during the day in sheltered locations on trees, fences and other suitable localities. The moths feed on the nectar of flowers and other plant exudates. As a general rule, the moths are of a dull gray or brown color with their wings obscurely marked. The moths' nocturnal habits and the fact that often when in obscurity their eyes shine very brightly, led to their common name, owlet moths. Life histories vary considerably and identification of the larvae is often very difficult. There are many keys available for cutworm identification (Crumb, 1929, 1932, 1956; Frost, 1955; Rings, 1976, 1977a, 1977b). Each contains a brief description of biology, damage and distribution. Cutworms are naturally controlled by parasites, disease, predators and environmental conditions. Crumb (1929) reported that the control of many multiple-brooded species is largely effected in the fall and winter by environmental conditions, and he observed that the rate of mortality from parasites and disease is not as high in multiple—brooded species as in the single-brooded. Insect parasites and disease are characterized by the fact that by initiating the destruction of the insect, a provision is made for the possible destruction of a larger number in the future. Therefore, a disease which kills a single larva may develop enough reproductive bodies sufficient to infest a very large number and a single host may produce enough parasites to destroy large numbers of larvae in the next generation. 6 Environmental conditions of cold, heat, rain and drought are selective in their effectiveness for cutworm control due to the varying resistance which the species are able to offer. Single-brooded species in general are resistant to cold in all of their life stages whereas most multiple-brooded species are only resistant to cold when they reach the pupal stage (Crumb, 1929). Cook (1934) suggests that the best way to prevent the ravages of cutworms is clean cultivation, thus eliminating sites for the larvae to overwinter. Ditching (Crumb, 1929) and fall plowing (Cook, 1934; Crumb, 1929) have also been recommended as possibilities for cutworm control. Chemicals have been widely used for cutworm control. Inorganic insecticides such as Paris green, lead arsenate and zinc ortho-arsenite were commonly recommended. Paris green and lead arsenate were mixed with bran and sweeteners to serve as poison baits (Cook, 1934; Crumb, 1929; Walkden, 1950). The choice of compounds for use in baits was limited to the insecticidal value of the compound, and some compounds had their value impaired by the repellent action they had on the cutworms. The introduction of the chlorinated hydrocarbon insecticides, e.g., DDT, dieldrin and endrin, resulted in more effective cutworm control. Recently developed pyrethroid insecticides show promise for control of some agricultural pests. Their activity in the soil is limited (Harris and Turnbull, 1978) but their high toxicity to lepidopterous larvae (Harris and Turnbull, 1975; Schuster and Clark, 1977) suggests that they might have potential for cutworm control. BIOLOGY BIOLOGY IDENTIFICATION OF CUTWORM COMPLEX Introduction Cutworms belong to a large group of insects in which the larvae have many characteristics in common. Species of different genera are sometimes so much alike that they can scarcely be identified in the larval stage. Positive identification of the species present is necessary so that an understanding of the biology of the species can be gained. Many different species may inhabit the same area so it is important to identify those species which attack the crop and those which cause no damage to the crop but occupy the same area. This study was initiated to determine what species of climbing cutworms cause damage to the grapes in the spring. Methods and Materials Inspections were made of vineyards in Berrien and Van Buren counties for the presence of cutworms. Vineyards selected were those which had a history of previous cutworm damage and also abandoned and neglected vineyards were monitored for cutworm activity. Vineyard inspection began in the spring as the grape buds first showed signs of development. Canes were visually checked for the presence of cutworms or cutworm damage. Sweep net samples were taken in the vineyards sweeping the cover crop and other vegetation. All 8 cutworm specimens collected were preserved in KAA and later transferred to 70% alcohol. Larvae specimens collected while they fed on grape buds were sent to the U.S.D.A. Insect Identification Laboratory in Beltsville, Maryland, for positive identification. Results and Discussion Vineyard inspections made during the spring of 1978 and 1979 identified the following complex of cutworms causing damage to the grapes: Amathes c-nigrum L. Spotted cutworm Spaelotis clandestina (Harris) W-marked cutworm Euxoa messoria Harris Dark-sided cutworm Agrotis badinodis Grote Spotted-sided cutworm Rhynchagrotis cupida (Grote) Brown cutworm Amathes smithii Snellen No common name The spotted cutworm and the spotted-sided cutworm are the most predominant species causing bud damage. The dark-sided cutworm, since it overwinters in the egg stage, attacks the grapes later in their development by feeding on the clusters pre-bloom. The insect museum at Michigan State University has specimens and Michigan records for those species caught in blacklight traps throughout the state (Figure 2). Spotted Cutworm, Amathes c-nigrum L. (Lepidoptera: Noctuidae) The spotted cutworm.was originally described by Linnaeus in 1758. Since its description, it has undergone several changes in its genus, Spotted-sided cutworm W—marked Cutworm Spotted Cutworm Brown Cutworm i ourouAcou F’ I . In . I_,_ W occur 7 I ._L__ . i MARQUETTE i Dark-sided Cutworm Amathes smithii 5.1 GOODDD \~ ' IRON ' \~ I .._.._. - “.an I—SC‘HKOLCMVT' . CHIPPEWA \. -'} L__I r"' _ ,oucxmsauF r'J DELTA , l MACKINAC ‘1“, U F‘A‘] J ' ' O cum PRLSOUE ISLE L_L-LL_ ID. ANTRJM OTSEGO MCRZNCY _I O ' A quu>vu lawrnvn OSCOOA ALCONA ‘ IOSCO A0- OSCEOLA CLARE ”m‘" V MEWS“ ISABELLA mourn ‘1 . .4 . M ——r‘ 1' Tuscou lswuc ONTCN'M 53,1307 SAG: NA‘N ’ r_. -3! I Auel .-._.,J -1 _ I KENT Q AAO , iumn [—— IONM CLINTON suuwuu “"25“ ...I_. I scum A A DI n A A CT I A AIADC muuo IMCM Aura/w um - mom mcnm'uvmcsrnu o I I 0.0 a- i TAUOI u IAU “m” M CALI-cw I JACKSON “WASHTE’M‘NI WWII: O. i- - Tau-IL— I — d a — 'KU" _. . MUSLIM aiwxcn lumpyu' LENAWEE [MONROE Figure 2. Insect Museum Records of Species Caught in Blacklight Traps in Michigan 10 from the original placement in Noctua, followed by Agrotis (Crumb, 1929) then to Graphiphora (Crumb, 1956) and finally to the genus presently used, Amathes. Distribution This species is found throughout the east and west width of the United States and across Ontario and Quebec as far north as James Bay. The southern border for this species is the southern boundaries of North Carolina, Tennessee, Missouri, Kansas, Colorado and Utah. Alaska, Europe and Asia are also included in the range of this insect (Crumb, 1929; Rockburne and Lafontaine, 1976). Food Plants The spotted cutworm is described as a very general feeder on most field, garden and orchard crops. walkden (1950) describes it as one of the most destructive cutworms in its range of abundance. A list of host plants is found in Appendix A1. Description of Stages Egg, The egg is white, spheroidal, slightly wider (0.65mm) than high (0.55mm) and is distinctly ribbed. There are 29-35 strong ribs with many conspicuous crossribs present (Salkeld, 1973). Soon after deposition the eggs become entirely pink, later turning nearly black before they hatch. Eggga, The larva is dull gray-brown, the summer brood sometimes dull olive, with faint pale dorsal and subdorsal lines and a broad subspiracle stripe. It has a series of black trapezoidal wedges on posterior segments, growing larger towards the rear, the last one on 11 the eighth abdominal segment. The head is reticulated with brown (Figure 3A). The mandible has four prominent outer teeth and one inner tooth. The skin is smooth. First instar larva have a head capsule .3Smm broad with a body 2-4mm long and .5mm wide while seventh instar larva head capsules measure 3mm broad and a body 30-36mm long and 6.5mm broad (Forbes, 1954; Crumb, 1929). £323, Pupae are about 18mm long and 6mm broad. The maxillary palpi are visible, labrum not emarginate, cremaster with four hooked spinules, and the spines are rather long (Crumb, 1929). EQElE: The head and thorax are dark gray, almost blackish with the basal half or more of collar and shoulders contrastingly pale. The forewing is dark brown with the antimedial and terminal areas contrastingly blackish. Subterminal costal spot is triangular and conspicuous (Figure 3B). The hind wing is gray, shading to darker grayish-brown in veins and at the margin. Wingspread is 30-40mm (Rings, 1977a). Life History The spotted cutworm passes the winter as larvae, usually nearly mature in size. Eggs laid by the last brood adults produce the over- wintering larvae. These larvae feed and develop in the fall with most of the larvae in the fourth instar by winter. These larvae overwinter in various locations providing protection from the winter. Crumb (1929) reported that there were three flights of adults in Clarksville, Tennessee; the first in late April and early May, the second in July and the third in early September. In Illinois, Forbes (1954) found but two flights of adults. Moths emerged the latter part 12 of May and early June. The second brood moths begin to appear in July and continued to emerge to the middle of August. In Michigan, the seasonal history is very much like that reported by Forbes except that the second brood moths emerge in early August and continue to mid- September. W-marked Cutworm, Spaelotis clandestina (Harris) (Lepidoptera: Noctuidae) The W-marked cutworm was described and named by Harris in 1841. The cutworm was not definitely described until 1869 when its climbing habits were first recorded by Fitch (Slingerland, 1895). Distribution This species is a northern cutworm occurring throughout the east and west width of the United States and in Canada as far north as James Bay. The southern limits of this species are approximately Kentucky, Missouri, Kansas, Colorado, Utah, Nevada and California (Crumb, 1929). Food Plants This species is described as a general feeder on trees, shrubs and a great variety of herbaceous plants. A list of known food hosts is given in Appendix A2. Description of Stages Earyg, Mature larvae have a head capsule measurement of 2.7mm broad with a body about 28mm long and 5mm broad. The skin is smooth with the color varying from pale gray to dark gray. The dorsal area is sharply defined. There is a slender, broken pale mid-dorsal line. A series of black subdorsal spots tend to be 13 present on all abdominal segments, becoming wedge-shaped on segments seven and eight. The two spots on each segment form a more or less definite W-shaped figure (Crumb, 1929). A distinct white or yellow subdorsal line broadened posteriorly is found on each segment. Spiracles are pale yellowish or white. The head is pale, brownish with black submedian arcs and reticulation (Figure 3C). Eupa, Pupae are about 16mm long and 5mm wide, maxillary palpi visible, labrum not emarginate, movably linked abdominal segments. Cremaster with hooked accessory spinules with the spines set close together. Adult, The deep brown collar is unicolorous with the thorax, outline of orbicular spot and inner margin of reniform spot is black, which color may also connect the two spots and extend somewhat past the orbicular towards the base of the wing. Hind wings are whitish (Figure 3D). Wingspread is 40-45mm. Life History The W—marked cutworm is a univoltine species having a period of retarded development following the emergence of the moths. This period is chiefly occupied by the egg stage, and possibly to some extent by an unusually long preoviposition period. The winter is passed as partially mature larvae. The moth when at rest folds its wings so closely and flatly over its back that it is enabled to get into very narrow crevices (Slingerland, 1895). 14 Figure 3. Climbing Cutworm Species Attacking Grapes. Spotted cutworm larva (A), spotted cutworm adult (B) , W—marked cutworm larva (C), W—marked cutworm adult (D), dark-sided cutworm larva (E), dark-sided cutworm adult (F) . 15 WELL-MARKED CUTWORM Spaelotis clande stina 16 Dark-sided Cutworm, Euxoa messoria Harris (Lepidoptera: Noctuidae) The dark-sided cutworm was originally described by Harris in 1841. Dyar (1902) placed this species in the Paragrotis genus and lists the following synonyms: spissa Guenee, cochrani Riley, repentis Grote and Robinson, displiciens Walker, reticens Walker, ordinata walker, inextricata Walker, indirecta Walker, septentrionalis Walker, and inducta Walker. Distribution The dark—sided cutworm has a North American distribution. It occurs throughout the width of the United States and as far south as Tennessee, California, Arizona and New Mexico (Cheng, 1973). This species is prevalent throughout Ontario and Quebec. Food Plants Walkden (1950) reports that the climbing habit has been well developed in this species so it has a wide range of host plants. This species has been reported causing damage to trees and shrubs, corn, onions, vineyards and sweet potatoes (Crumb, 1929; Walkden, 1950). A list of host plants is found in Appendix A3. Description of Stages Egg, The egg is circular in outline, .62mm wide and .43mm high with about forty-five slightly elevated ribs. The eggs are white after deposition and change to light brown and finally dark brown when the larva is fully developed. l7 Eggya, The general color is pale brown dorsally with the sub- ventral and ventral area whitish. A pale, narrow mesal stripe is bordered by an irregular, black stripe on each side. A broad, pale subdorsal stripe which includes two darkly pigmented tuberacles on each thoracic and abdominal segments is present. There is a dark brown supraspiracular stripe for which the species is named (Figure 3E). The head is pale brown with clusters of dark brown, round spots near the cervical shield and above and behind the ocelli. The skin is smooth and spiracles are dark brown (Rings, 1977b). First instars have a head capsule .28mm wide with a body 2.3mm long and .43mm wide, while sixth instars have a head capsule 3.2mm wide and a body about 30-37mm long and 5mm wide. Crumb (1929) reports only six instars for this species while Cheng (1973) reports seven. £223, Pupae are about 17mm long and 6mm wide, maxillary palpi visible and there is callus present on the prothorax before the mesothoracic spiracles. The creamaster has two pairs of straight accessory spinules, the spines are short, weak, convergent at the tips and set on the tip of the abdomen without a basal process (Crumb, 1929). Agglt, The wing patterns of this species are extremely variable. The fore wing is usually light, powdery, grayish-brown. The orbicular and reniform are filled with ground color and finely outlined in black. Antimedial and postmedial lines are double and wavy. Hind wings are grayish-white and darker on the outer margin and on the veins (Figure 3F). Wingspread is 30-35mm (Rings, 1977a). 18 Life History The dark-sided cutworm is univoltine. Moths emerge in late July. Moths may be found during the day resting under plants, leaves, boards or other objects which keep them protected from the sun. This species overwinters in the egg stage which is laid in the fall at a depth of l-2cm in the soil. Eggs complete their embryonic development before winter and hatch the next spring (Cheng, 1972). The distribution of the larvae in the field was found to be seldom uniform, mostly because moths lay their eggs in groups in the soil (Cheng, 1971; Jacobson and Peterson, 1965). Cheng (1973) showed that early instars fed near the leaf tips of food plants while later instars frequently cut the plants off at ground level or ate the growing points or leaves. The depth at which larvae rested during the day was regulated by soil moisture. Spotted-sided Cutworm, Agrotis badinodis Grote (Lepidoptera: Noctuidae) The spotted-sided cutworm was originally described by Grote in 1874. The literature is filled with various genus names beginning with Agrotis (Grote, 1874), Anicla (Walkden, 1950), Graphiphora (Crumb, 1956) and Agrotis where it presently stands. Distribution Crumb (1929) reports the range of this species includes the Atlantic coast from New York to North Carolina and extends westward to Iowa, Kansas and Texas. Specimens have also been collected from southern and eastern Ontario and western Quebec. 19 Food Plants The spotted-sided cutworm has been described to show a decided food preference for dock (BEEE§) and chickweed (Stellaria), (Crumb, 1929). Rings (1977) states that the species is generally of minor importance in the North Central states but occasionally attracts attention as a climbing cutworm in orchards. A list of host plants is found in Appendix A4. Description of Stages Egg, The egg is white, circular in outline, strongly, bluntly subconical in profile, .63mm broad and .54mm high. About twenty-five strongly elevated ribs are present with the micropyle set in a depression (Crumb, 1929). The second day after deposition a very distinct belt of pink appears on the micropyle. Eagza, This species is pale gray in color with a subdorsal series of triangular black spots at least posteriorly and oblique black spots just above the spiracles (Figure 4A). The mandible is provided with a characteristic large bidentate internal tooth. The skin is smooth. First instars have a head capsule measurement of .36mm broad with a body about 3mm long and .4lmm wide. Seventh instars have head capsules 2.5-2.7mm wide with larvae 25-32mm long and 5mm wide (Crumb, 1929). £223, The pupae are about 16mm long and 5.5mm wide. There is a row of large circular pits on the anterior margin of movably linked abdominal segments. The cremaster is without spinules, spines short, outcurved, set on a long subconical process (Crumb, 1929). 20 59253: The head and thorax are pale brown with the upper half of collar shading into black. The fore wing is light brown with a violaceous tinge. Antimedial and postmedial lines are prominent, pale brown and edged with black. The space between the orbicular and reniform is filled with dark brown scales (Grote, 1874). Wingspread is 28-35mm (Figure 48). Life History There is but one generation annually of this species. The adults are short—lived; only about two weeks of the life cycle are occupied by this stage. Moths emerge September to October. Eggs are deposited soon after the females emerge and hatch in about two weeks. The larvae feed to some extent in the fall and pass the winter as third or fourth instars (Walkden, 1937). The summer is passed in the pupal stage within an earthen cell. Brown Cutworm, Rhynchagrotis cupida (Grote) (Lepidoptera: Noctuidae) This species was originally described as Rhynchagrotis anchocelioides by Guenee with Dyar (1902) listing cupida as a synonym to this species. Distribution The brown cutworm is generally distributed in the eastern part of the United States, north of the southern boundaries of North Carolina, Tennessee, Missouri and Kansas (Crumb, 1929). This species also occurs across southern and eastern Ontario northward to Sudbury and in Quebec from Kazabazua to Forestville (Rockburne and Lafontaine, 1976). 21 Food Plants Crumb (1932) reported this species as feeding on the buds and newer growth of apple, grape and peach. A complete list of food hosts is listed in Appendix A5. Description of Stages Egg, The eggs are pale lemon-yellow, .50mm high and .60mm wide. There are 28-33 distinct ridges radiating from the micropylar area. Eggs become pink in color a few days after deposition. The underside of the egg is smooth and not adhaesive (Rings, 1972). Eggya, The general color is brown varying sometimes to gray. The middorsal pale line is broad, broken and diffuse. A segmental series of elongate black spots anterior to setigerous tubercle D2 are somewhat diffuse on their dorsal margins, more distinct and wedge-shaped on abdominal segments seven and eight (Crumb, 1929). The head is pale brown reticulated with black and black submedial arcs. The cervical shield is pale brown reticulated with black. Sixth instars have a length of 31-40mm and 5.4mm wide (Figure 4C). E223, Pupal length is l6-21mm with a width of 7mm. They are shining light brown, impunctate. A quadruple row of rounded pits on dorsum of fifth abdominal segment is present (Rings, 1972). The cremaster is distinct, blunt, rounded and heavily pigmented; laterally bearing three pairs of setae. Egglg, Ground color of fore wing is grayish or brownish. Anti- medial and postmedial lines are faint, dark and double, prominent at the costa. Subterminal lines are luteous, sometimes punctiform or obsolete, almost always preceded by a dark, triangular marking 22 Figure 4. Climbing Cutworm Species Attacking Grapes. Spotted—sided cutworm larva (A), spotted-sided cutworm adult (B), brown cutworm larva (C), brown cutworm adult (D), Amathes smithii larva (E), Amathes smithii adult (F). 24 extending to the costa. Orbicular is small and rounded, covered with scales, slightly darker than ground color (Rings, 1977). Hind wings are fuscous; fringes are tricolored (Figure 4D). Wingspread is 32-40mm. Life History Rings (1972) reported collecting wild, gravid females from June to October, but they did not oviposit until the end of September. Crumb (1929) explained this retardation as an evolutionary mechanism to keep single-brooded species on a univoltine schedule. Single-brooded species of cutworms tend to be of northern distribution in the United States. Eggs were laid singly and hatched about four weeks after deposition. Larvae feeding probably continued through October and November when air and soil temperatures were above 7°C (Rings, 1972). Larvae overwinter as third or fourth instars. In early spring, feeding is resumed after dark when temperatures are favorable. After the larvae enter the fifth and sixth instars, they develop a strong tendency to climb. At first, larvae eat the fruit and leaf buds and later the foliage. Prepupal chambers are formed about l-5cm below the surface. Marten (1880) offers the following description of this species and its feeding habits: "The larva of this species is of a greenish color, and may be found at night depredating upon grapevines. It crawls along the vines until it reaches a bud, when it stops and devours it; commencing its depredations as soon as the buds begin to start." 25 Amathes smithii Snellen (Lepidoptera: Noctuidae) This species was originally described by Snellen in 1896. It occurs generally in the United States north of the latitude of the Ohio River and in all adjacent provinces of Canada and in Alaska. Description of Stages E2333, General color is usually brown varying to gray, skin smooth. A segmental series of brown or blackish shield-shaped markings are present dorsally on abdominal segments, bordered laterally by a strong distinct subdorsal white line. Spiracles are pale yellowish to brown. The head is a bright brown with black submedial arcs (Figure 4E). EQEiE: The fore wings vary from gray-brown to red-brown. Trans- verse lines are a little darker than the ground color. The traverse posterior line is evenly bent, with a row of small black dots outside. Hind wings are fuscous (Figure 4F). Wingspread is 36-40mm (Beuten, 1901). Life History The larvae hatches in the fall, hibernates half-grown, feeds up rapidly in the spring and then aestivates for a month or more in the soil before pupating. During this period it can stand very wet conditions but it is more sensitive to drying of the soil. Forbes (1954) describes this species as sometimes injurious in vineyards in the spring, when the weeds which are its autumn food are cultivated out. 26 REARING TECHNIQUES Introduction Development of a rearing technique for the mass production of various life stages of an insect is important. Large numbers of insects are necessary for laboratory screening tests, biology studies and for use in artificially infesting plots for economic injury studies. The technique should be one that would provide the greatest number of insects for the amount of input with a minimum amount of mortality through time. Methods and Materials Establishment of Colony Larvae of the spotted cutworm were collected from the vineyards of Robert Rogers in Van Buren county in November 1978. One hundred and fifty larvae were collected as they remained protected and fed within the folds of fallen grape leaves. These larvae were taken back to the cereal leaf beetle greenhouse at Michigan State University for rearing. 24.2212 Emerging moths were removed from the pupal containers and transferred to mating and egg-laying cages. These cages (40x25x45cm) were constructed of plexiglass sides and top with 4cm holes covered with l6-mesh screen for ventilation. The front, back and bottom were made of plywood. A door (18x21cm) provided access to the cage. Twenty moths were placed in each cage. Cages were maintained at 25il°C and a 16-hour photophase. Food was provided daily by filling 9/16 ounce plastic cups with a 10% honey solution and inserting a cotton ball to 27 serve as a wick. Folded paper towelling and pots of clipped barley provided cover for the moths and sites for oviposition (Figures SA-B). Eggs Eggs were collected daily and placed in pint plastic containers with triangular sections of the plastic lid replaced with l6-mesh screen (Figure EC). No attempt was made to remove eggs from the paper towelling except to cut large egg masses from it. Eggs laid on the barley were clipped off at the soil surface and placed in the pint plastic containers. Egg containers were maintained at 25il°C, 50% RH with a 16-hour photophase. Eggs may be stored at 5°C and 70% RH for up to fourteen days until adequate numbers are available. Larvae Newly emerging larvae were fed clipped barley leaves which were placed in the egg containers. Larvae require little attention during the first week after emerging. Larvae were reared in the egg con— tainers until they reach the fourth instar when they were transferred into two-ounce plastic containers with slits made in the lids to prevent a build-up of moisture (Figure 5D). These small plastic con- tainers contained two larvae in each and were used to prevent cannibalism which takes place in the pint containers when the larvae reach fifth instar. Larvae were fed daily and the containers were changed every third day to prevent excessive build-up of feces and conditions favorable for the development of diseases. Larvae were allowed to pupate within the containers. 28 Figure 5. Equipment used for Rearing Amathes c-nigrum in the Laboratory. Mating and oviposition cages (A), barley and paper towelling oviposition sites (B), egg and young larvae containers (C), larvae containers for instars 4-6 (D), pupae container (E). 29 30 322$ Pupae were removed from the larvae containers daily and were placed in eight-ounce waxed paper ice cream cartons half filled with moist, sterilized soil. Five to ten pupae were placed in each container and covered with a plastic lid to prevent escape of the moth when it emerged (Figure 5F). These pupal containers were kept covered with cardboard sheets to eliminate light from the containers. Larvae Food Sources Barley Barley was grown in eight-ounce ice cream cartons three-fourths filled with sterilized soil, barley seed and enough soil to cover the seed. These containers were placed in a greenhouse maintained at 2112°C with an 18—hour photophase. The barley was watered and allowed to grow for seven to ten days before being used. The barley was clipped into 2-4cm sections and fed to the larvae. Artificial Diet The artificial diet used was obtained from Dr. Ring Cardé. The ingredients and preparation of the diet is described in Appendix B. After preparation, the diet was placed into the two-ounce larvae con- tainers so that each container was approximately half full (40-50 gm). A plastic lid was placed on the cup with no slits to avoid exposure of the diet to contaminants in the air. After the larvae were placed on the diet, the lid was removed only to clean the containers of excess feces (Figure 5E). 31 Results and Discussion Collection of a large number of larvae from the field provided a continuous supply of various life stages of the spotted cutworm through the winter and spring. Larvae collected from the field began to pupate fifteen days after being brought back to the rearing room and all of the larvae had pupated twenty-eight days after collection. The culture started in 1978 has been reared through five successive generations. Barley provided a constant food source for the larvae and a honey-water solution was supplied for the adults. Eggs and fourth and fifth instars have been kept for short periods of time in a 5°C refrigerator. Eggs have been stored for fourteen days and fourth and fifth instars for thirty days with low mortality rates. A complete generation took approximately seventy-five days at 25°C. Females would oviposit on paper towelling, barley leaves, soil, walls of the cage and on any other object which did not have a smooth surface. Egg production would increase as the humidity within the cage increased. Fertilized eggs could be distinguished from those unfertil- ized three days after oviposition by the change in color from pale yellow to pink. The first two instars could be found hanging from a silken thread from the top of the larvae containers. These young instars would feed on the upper surface of the leaves, never feeding through the lower epidermis. Later instars would consume the entire leaf. The duration of various life stages is summarized in Table 1. All of the observations were taken in the rearing room maintained at 2511°C, 50% RH and a l6-hour photophase. The somewhat shorter duration of the larva stage of those larvae reared on the artificial diet as 32 compared to those larvae reared on barley may be due to the food occasionally being limited in the barley-reared containers while those on the diet always had a constant supply. The additional handling which the barley-reared larvae were subjected to may have disrupted them slightly. Table 1. Time Required for Development of Life Stages of the Spotted Cutworm, Amathes c-nigrum Time in Days Life Stage . OEEEESZd Min. Max Mean Egg 5 11 6.5 901 Larva-barley 25 38 30.2 425 Larva-diet 25 34 27.8 309 Pupa ll 18 14.1 516 LARVAL FEEDING BEHAVIOR Introduction Damage to the developing grape buds in the spring by climbing cutworms can seriously affect the yield if the area is heavily damaged. Field observations show the cutworms exhibiting an observable prefer— ence of certain developmental stages, to others. Bud damage varies from the complete bud being eaten to those buds which the cutworm has fed on for only a short period of time (Figure 6). Damage done by the dark-sided cutworm includes feeding on developing clusters and damage to sucker growth both above and below ground level (Figure 6). 33 Figure 6. Cutworm Damage to Grapes. Bud damage (A-C) , cluster damage (D), damage to sucker growth (E-F) . 36 two-ounce plastic container filled with sand which was placed with its lip flush with the sand surface in the center of the bucket. This arena allowed the cutworms to emerge naturally during the night. The experiments were run at the Michigan State University Horticultural Farm in a cooler room maintained at 8°C; the light was adjusted to 100 lux to simulate full moonlight. Continuous observations were made on each bucket and the movements of each larva were traced on a sheet of paper corresponding to that bucket. Long Cane Experiments Single node canes and canes with three nodes were forced in the mist bed. Groups of canes were joined together with a piece of wire inserted into the cortex of each of the canes. The canes were arranged in a manner to simulate natural development of the buds in the field and also rearrangements of bud placement to measure its effect on bud preference. These canes were placed in a sand bed and a lO-ounce paper drink cup with its bottom removed was placed over the cane and pushed into the sand 3cm. This cup served as an arena for releasing the larvae. Each of the canes were checked at two—hour intervals, and room temperature was kept at 21°C. Results and Discussion Bucket Experiments A total of forty-five different trials were made utilizing this design. Of these trials, twelve never received any bud damage at all. In replicates where bud damage occurred, no significant differences 37 were observed between the developmental stage and bud damage (x2, P = .05). Table 2 summarizes the results of the bucket experi- ments. Various groupings of the developmental stages and bud damage never showed any significant differences. Long Cane Experiments Results from the long cane feeding tests for randomness of larvae feeding showed that they deviated significantly from random (x2, P = .05). Table 3 summarizes the results of the long cane experi- ments. Since the feeding behavior was not random, more damage can be expected in certain bud developmental stages. Various groupings of the damage data e.g. small buds, groups X, l and 2; and large buds, groups 3 and 4; removal of the X developmental stage still showed strong significant differences. Only when comparisons between stages 3 and 4 were made were there no significant differences in damage (x2, P = .05). The long cane experiments gave a more accurate representation of a grape cane in the field than did the bucket experiment. 38 m h v m v m h o N boo. bma.n N ma NH H H o m m o h v m m m N NmN. Nm.m o ma OH H H m m w w o m m o m N mna. mm.v 0 ma 0 o H m aw>mq x mmmama oz nuflz mamana owmmfimo uoz commama mmmum man mommONMNCmHm N mumxosm mo # mo ¢ mosm t mosm w .>wa H . a smflmwa umxosm on» msflmo Euozuso oouuomm map How momma mcflommm mosmnmmwum osm mo muHSmmm .N wands 39 v mH v H m m m H N mm H H NVHoo. vH.mo NH mN o o x U MH 5 w m 0H m m o N MN H H NVHoo. NN.N¢ m NN oo o x m 0N «H v m m m vH m N om N H AVHoo. nw.mH M NH HN o x N Hm>mH x wmmsmn oz nuHB mHMHHB commamo uoz ommmsma mmmum HMHHB mosmoHMHsmHm N mwsmo no t no t mosm # mosm # .>mo . :mHmmo mcmo mcoq mnu msHmD EHOSDDU oouuomm onu How mumoe OCHommm mosmnmmmum cam mo muHsmmm .m mHnma 4O SURVEY AND SAMPLING TECHNIQUES Grape Grower Questionnaire Survey Introduction Information and observations which growers have accumulated during their years of farming is often very keen and useful. Growers are willing to share their knowledge and to help researchers and extension personnel in any way that they can. The use of a survey form is a way to contact a large number of growers and to gain background information on the severity and distribution of the problem. Infor- mation on current practices used by growers and other factors which may add to or decrease the severity of the problem may also be gathered. Methods and Materials A questionnaire form was prepared and sent to grape growers which were on the county extension mailing lists of Berrien and Van Buren counties. Growers were sent a questionnaire packet which included the following items (Appendix C): 1. an introductory letter stating the purpose of the question- naire and the objectives of the ensuing research; 2. general farm information form; 3. two blank field questionnaire forms; 4. a completed field form example; and 5. a self-addressed stamped return envelope. This packet was then mailed to 917 grape growers on the county mailing lists. An appeal was made to growers attending the Michigan 41 Grape Day meetings in March of 1978, to return the questionnaire forms if they had not already done so. Results and Discussion 0f the 917 questionnaire forms mailed out in February, 132 were returned by those growers receiving them. The returned questionnaires accounted for 14.4 percent of the total mailed out. Of those returned, thirteen were not used for various reasons, e.g. no longer grow grapes, backyard gardener, etc. With these responses omitted, the returned questionnaires accounted for a total of 2,298.5 acres or 19 percent of Michigan's 12,155 acres of grapes. Results of the questionnaire per- taining to chemical control will be discussed in a later chapter on chemical control. Distribution of Grape Acreage and Cutworm Damage Counties represented from the questionnaires returned included Berrien and Van Buren reporting 96.3 percent of the acreage and Allegan, Cass and Kalamazoo counties reporting the remainder of the acreage. From the returned questionnaires, the top five grape-growing townships are Antwerp, Bainbridge, Keeler, Porter and Royalton report- ing 96.10 percent, 90.68 percent, 100 percent, 85.21 percent and 76.27 percent of their acreage damaged by cutworms respectively (Table 4). These five townships contain 64 percent of the grape acreage reported from the questionnaires. The soil type in Antwerp township reporting cutworm damage is predominately Chelsea sand. The largest percentage of this soil is used for fruits, mostly grapes. The main limitations of this soil for 42 farming are susceptibility to erosion, low soil moisture and low fertility. It is moderately suited to fruit from a soils standpoint but it is well suited because of topographic position (Austin and Lietzke, 1972). Table 4. Grape Acreage and Number of Fields by Township and Cutworm Damage as Reported from Questionnaires Cutworm Damage Township None Reported Reported Totals No. of No. of No. of No. of No. of No. of Acres Fields Acres Fields Acres Fields Almena 0 0 10 1 10 l Antwerp 16.6 3 409 19 425.63 22 Arlington 9 1 3 1 12 2 Bainbridge 11.4 3 111 18 122.4 21 Baroda 29.75 6 38.5 4 68.25 10 Benton 15 1 0 0 15 l Berrien 44.08 6 0 0 44.08 6 Chikaming 0 0 24 l 24 1 Coloma 0 0 12 2 12 2 Covert 7.7 2 0 0 7.7 2 Decatur 0 O 99.5 6 99.5 6 Ganges 18 l 0 0 18 1 Geneva 0 0 3 l 3 l Hager 2 1 6 2 8 3 Hartford 0 0 15 1 15 l Keeler 0 0 241 4 241 4 Lake 65.3 3 6 1 71.3 4 Lincoln 10 l 18 4 28 5 Oronoko 90 7 16.5 4 106.5 11 Oshtemo .l 1 0 0 .l l Paw Paw 52 3 124 6 176 9 Pipestone 2 l 26.25 3 28.25 4 Porter 76 2 438 10 514 12 Royalton 40.76 4 131 7 171.76 11 Silver Creek 0 0 12 l 12 1 Texas 0 0 10 1 10 1 Wayne 47 l 0 0 47 l Weesaw 8 2 0 0 8 2 1,753.75 97 544.69 49 2,298.44 H h 0‘ 43 Vineyard Age The age distribution of vineyards indicates that fewer new vine- yards are being established. Of the fields reported, 67.12 percent were greater than twenty years old with only 4.11 percent of the vine— yards being less than five years old (Table 5). Vineyards have the capability of continually being renewed by providing a layer from a plant which in turn will root and establish a vine in approximately three years, with the old, less productive vine being removed. New trunks may also be established by allowing a sucker to grow for several years and later removing the old trunk (Rogers, personal communication). Therefore, once established, a vineyard can be renewed as vines become less productive or after being damaged so the vines will be of various ages within the vineyard. Weed Problems The presence of uncontrolled weeds in the vineyards was reported in forty-one (36.28 percent) of the fields reporting no cutworm damage as opposed to twenty (17.70 percent) of the fields reporting heavy cutworm damage (Table 6). A significant difference was observed between cutworm damage and the presence of uncontrolled weeds in the vineyard (x§6 = 58.19, .01
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Table 6. Cutworm Damage and Uncontrolled Weed Problems as
Reported from Questionnaires
Cutworm Damage
Weed Total
None Light Moderate Heavy
Dock 2 0 3 0 5
Grasses 8 7 6 7 28
Asparagus 6 2 3 0 ll
Sumac 2 2 2 0 6
Milkweed 8 3 l 5 17
Morning glory 1 3 0 0 4
Woody plants 2 3 0 2 7
Wild onion 2 6 0 4 12
Horse nettle 0 0 2 0 2
Lambs quarter 0 0 1 1 2
Rag weed 0 2 0 0 2
Poison ivy 7 4 0 O 11
None 3 2 1 l 7
41 34 19 20 114
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omuuommm mm onmmwsH> may on mmouu uswommpé osm mmMEMQ Sho3u50 .h mHnms
47
A significant relationship was observed between the crop land adjacent
to the vineyard and the cutworm damage to the vineyard (X36 = 83.53,
P<.00001). These areas may contain necessary food plants for adult
survival and for those species with a long adult stage, may provide
shelter and protection for the moth during the extended preoviposition
period. For multiple-brooded species, these areas may serve as a
location for the summer generations to build their populations to a
sufficient number for overwintering purposes.
Adult Sampling
Introduction
Insect light traps have proven useful in entomological surveys
for determining the presence, abundance and time of occurrence of many
species of insects. This information can be used in determining an
estimate of time for egg hatch and occurrence of other life stages.
Additional work is needed for population estimation from the relative
trap catches.
Methods and Materials
Weekly Sampling
Adult cutworm flight activity was monitored with the use of
ElliscoR general purpose, 15-watt blacklight insect traps. Blacklight
traps in 1977 were located at Penn Valley Vineyards near Fennville in
Allegan county and at the farms of Gordon Brown and Robert Van Vleck
near Lawton in Van Buren county. The Brown blacklight trap was estab-
lished on June 13, 1977, with the Van Vleck and Penn Valley blacklight
traps being established on July 8, 1977. CyanogasR (American Cyanamid
48
Corporation) was used as a killing agent. This material was placed in
small paper bags in the bottom of the blacklight and was changed once
every week.
In 1978, blacklight traps were operated in Berrien and Van Buren
counties. The Cecil Bethe farm near Spinks Corners is where the
Berrien county trap was located, and the traps in Van Buren county were
all located near Lawton on the farms of Gordon Brown, Robert Rogers and
William Streeter. The blacklight traps were established on May 20,
1978, for the Brown and Rogers traps with the Bethe and Streeter traps
being established on June 14, 1978. Chloroform was used as a killing
agent in 1978. The chloroform was placed in an 8-ounce glass bottle
with a 7mm hole drilled in its plastic lid. Through the hole was
inserted a 15cm piece of cotton plug which extended to the bottom of
the bottle. This design allowed for the slow release of the chloroform
into the blacklight collecting basket. The bottle was filled with
chloroform as needed depending upon the previous weather conditions.
Pieces of crumpled paper towelling were added to the blacklight
collecting basket to provide a place for the moths to die and also to
help prevent damage to the moths by beetles entering the traps. The
samples were collected from the blacklight traps on two-day intervals.
The moth samples were dated, labeled and returned to the laboratory for
sorting and identification of the specimens at a later date.
HourlyiSampling
Information on the hourly moth flight activity was obtained by
removing the contents of the blacklight trap on hourly intervals from
10:00 P.M. to 6:00 A.M. This was done on three separate occasions
49
during 1978, August 18, 25 and 31, for each of the three traps located
in Van Buren county. The samples were collected and placed in labeled
paper bags until the following day when they were sorted, sexed and
counted.
Results and Discussion
Weekly Sampling
The blacklight trap catch for the spotted cutworm from Allegan
and Van Buren counties for 1977 is shown in Figure 7. Spotted cutworm
and dark-sided cutworm blacklight trap catches from Berrien and Van
Buren counties for 1978 are shown in Figures 8 and 9. Initial moth
catches for the spotted cutworm were taken on May 29 and 30, 1978, at
the Rogers and Brown blacklight traps respectively. Second generation
moths were taken on July 29, 1977, at the Van Vleck light trap and on
August 5, 1978, at the Rogers trap. Figure 8 shows a ten-fold increase
in blacklight trap catches between the first and second generations of
spotted cutworm. This large increase in the summer generation could
possibly provide a large number of larvae for overwintering purposes
due to the high mortality of the overwintering larvae.
Dark-sided cutworm moths were initially taken on July 14 and 21,
1978, at the Rogers and Brown traps and on August 6 and 16, 1978, at
the Bethe and Streeter traps respectively.
By changing the time axis from chronological time to degree-day-
accumulations (°D), moth catch can then be plotted against physiologi-
cal time (Figures 10 and 11). A base temperature of 10°C was used for
calculating °D since the actual threshold temperature for flight was
unknown. Degree-day accumulations were calculated from Michigan
50
0 BROWN
0 FENN VALLEY
1001 {If VAN VLECK
x
If, 50- .
3
c:
m
a.
l— . ,"0
(ID I :
s . \-
5
m 10- '
E
O
2
O' 5'1
2
° 0
I I I I I II I I I I I’ I If ‘r l
7142128512192629162330613
JUNE JULY AUG. SEPT.
Figure 7. Blacklight Trap Catches of Spotted Cutworms from
the Brown, Fenn Valley and Van Vleck Blacklight Traps (1977)
1000‘ . BETHE
a BROWN
*1} ROGERS
500- - STREETER
100‘
ES
Lu 50-
B :
0C
UJ
O.
p.
3C
(9
:3 ..
<(
O
a) 10"
E
O
2
o‘ 5"
2:
l I I I I I I‘ I I I I
22 5 19 3 17 31 14 28 11 25 9 23 6
JUNE JULY AUG. SEPT. OCT.
Figure 8. Blacklight Trap Catches of Spotted Cutworms from
51
the Bethe, Brown, Rogers and Streeter Blacklight Traps (1978)
52
OIBETIIE
CI BROWN
200.. . {IROGERS
1“ I STREETER
100-
E5
LIJ 50-l
3 .
0E
UU
O.
p.
3:
(D
:3
<2
0
a) “3d
3:
f— I
O
E
O' 5 "
I:
o " '
l I ‘r I l I T I l I
17 24 31 '7 14 21 28 4 11 18 25
JULY AUG. SEPT.
Figure 9. Blacklight Trap Catches of Dark-sided Cutworms from
the Bethe, Brown, Rogers and Streeter Blacklight Traps (1978)
53
10007
0 BETHE
500-I :1 BROWN
+1} ROGERS
I STREETER
100-
50-
O
o
0:
LL!
a
p.
I
(D
D
<
O
a) 10-
I
I—
O
2
0' 5‘
Z
l I I I I I l I I I I T I I l I
400 800 1200 1600 2000 2400 2800 3200
°D>50° F
Figure 10. Blacklight Trap Catches of Spotted Cutworms Per Degree-
day from the Bethe, Brown, Rogers and Streeter Traps in 1978
54
200--I
'\ o BETHE
\ a BROWN
100- .\ {1% ROGERS
I STREETER
50-1
o .
O
m
UJ
O.
F-
I
O
D
<
0 10-I -
a)
I
p.
O
2 5-1
0
Z
l l I I T T I I l
800 1200 1600 2000 2400
°D> 50° F
Figure 11. Blacklight Trap Catch of Dark-sided Cutworms Per Degree-
day from the Bethe, Brown, Rogers and Streeter Traps in 1978
55
weather stations which were in Fennville, Paw Paw and Sodus, Michigan.
This change in the axis removes much of the variations in the flight
curves between trapping locations.
Light traps are probably the most widely used insect traps, and
there are many references to them (Cook, 1928; Frost, 1953). The vari-
ation in the efficiency of the trap from insect to insect, from night
to night and from site to site is extremely great because light traps
are entirely artificial and rely upon the disturbance of normal flight
behavior to function. Light traps take fewer insects on nights of full
moon due to the fall in the efficiency of the trap (William, Singh and
El Ziady, 1956). Cook (1928) discussed the relative trap catch of
moths at light traps and those visiting flowers. He reported that the
dark—sided cutworm is not readily attracted to light traps with less
than 1 percent of the total moth catch being taken at the light trap.
These variations in trapping efficiency may explain the low
blacklight trap catches for Amathes smithii, the spotted-sided cutworm
and the brown cutworm.
Hourly Sampling
An estimate of the hourly flight activity of cutworm moths as
attracted by a blacklight trap is shown in Figures 12 through 19. Male
activity of the spotted cutworm indicates a flight which reaches its
first peak between 12:00 P.M. and 1:00 A.M., slowly decreasing in
activity and reaching a second peak between 5:00 A.M. and 6:00 A.M.
Female flight activity increased rapidly with its peak activity occur-
ring between 10:00 P.M. and 11:00 P.M. and declining rapidly by
12:00 P.M. and remained low the rest of the night. Females became
56
100-
--~a-- FEMALE
'--£1-- MALE
90J + TOTAL
80-
,3
I, \
g 70- /’ \\
I R ‘\
I: I' I
O. I, \
II
E / I I 1.---..
(D 507 / \ I I
2 I/ IV! 1‘
O {y A \\
.. II
(3’3 40 I§\ I I I R
'— \ I I ‘ l \
O \ I \ I. I
\ I \ \ \
:5 \ I \ \ I \
- 30 - {I \ ‘ I \
O \ ‘ I \
I! I \ / \
20- I‘x ‘ I \
\EL ‘ I ‘
‘\~ \‘I \x‘g'
it if, /
10! ‘\£P”’ ‘~15
0 I r I I I 1 l l I
22 23 24 1 2 3 4 5 6
TIME TRAP CHANGED
Figure 12.
Total Hourly Spotted Cutworm Moth Catch from the Brown,
Rogers and Streeter Blacklight Traps for August 18, 25 and 31, 1978
57
50' “writ-- FEMALE
74.1“- MALE
+ TOTAL
50H
I
:3
O
I 40d
95
a I
'- I I
\
330- I I
< I I
O I, \\
00 I \
I I \
’5 I ‘I
:E 20- / \ Igfii .z’3}
. ‘ \ /
o ’ I I?
2: €£‘""£§\ %{ ‘zk \ [I
\ ’ ‘\\ /
\\V/’ \ /
104 \fl—_"'¢'---# g
I»- x
\33uw—rir
O I I I I— I I I l I
22 23 24 1 2 3 4 5 6
TIME TRAP CHANGED
Figure 13. Total Hourly Dark-sided Cutworm Moth Catch from the Brown,
Rogers and Streeter Blacklight Traps for August 18, 25 and 31, 1978
58
Figure 14. Hourly Spotted Cutworm Moth Catch from the Brown
Blacklight Trap for August 18, 25 and 31, 1978
Figure 15. Hourly Dark-sided Cutworm Moth Catch from the
Brown Blacklight Trap for August 18, 25 and 31, 1978
59
50"-l
m A -_.¢_.. FEMALE
8 ,' ---r:1—- MALE
:1: 40.. I' ‘\ + TOTAL
c: I \
Lu ”III I \\
0.. ’, I
I— 12’ \\ I’ I‘
0 I \ . ’ I
2 I \\ I ‘I
‘0
o I, 'fi I\ /\\
(020- K: ’I \ I, \
I \ I I I \
'— ‘ ’ I I \
O \ I ‘ / \
2 fi\‘\\ I I, \\
C5 10- fi\‘ H
z tar-nag ,3
\ /
\\ ’l’ \\\ I,
RIF-"ii? 2g
0 r I I I T I r f I
23 24 1 2 3 5 6
TIME TRAP CHANGED
SO-II
I “'1'?!"- FEMALE
8 --~I::—- MALE
a:
LLI
Q.
E 30-I
0
D
<
0
(2? 201
I-
O
2
O‘ 1O-I
Z
O l I I r 1 I 1* r r
22 2 4 6
3 24 1 2 3
TIME TRAP CHANGED
60
Figure 16. Hourly Spotted Cutworm Moth Catch from the Rogers
Blacklight Trap for August 18, 25 and 31, 1978
Figure 17. Hourly Dark-sided Cutworm Moth Catch from the
Rogers Blacklight Trap for August 18, 25 and 31, 1978
NO. MOTHS CAUGHT PER HOUR
NO. MOTHS CAUGHT PER HOUR
61
40-
--{-I——- FEMALE
--'I¢i--o MALE
+- TOTAL
30"
20‘
10...
\ ”
0 E?!“
I I I I I I I I I
22 23 24 1 2 3 . 4 5 6
TIME TRAP CHANGED,
401
"'fi" FEMALE
""l‘k- MALE
-—+— TOTAL
30'-
I?
’ I
’ I
’ I
20" I \
I, \
I \
/ \ I}
I \
I ‘ ’fii //
fi\\ \ I/ \ “I
10- fi \Xk I?!’ R“ I,
\ / \\ /
\
\ l/ \\ [I
‘ ' m—»-§:~:§x .
V \ ’1 \Wafi‘a'
0 I I I I I l I I I
22 23 ' 6
24 1 2 3
TIME TRAP CHANGED
62
Figure 18. Hourly Spotted Cutworm Moth Catch from the Streeter
Blacklight Trap for August 18, 25 and 31, 1978
Figure 19. Hourly Dark-sided Cutworm Moth Catch from the
Streeter Blacklight Trap for August 18, 25 and 31, 1978
NO. MOTHS CAUGHT PER HOUR
as
63
--¢E- FEMALE
--£I>-- MALE
+ TOTAL
‘~~$~“ III:
“A?
0 I I I I 1 I T I I
23 24 1 2 3 4 5 6
TIME TRAP CHANGED
50-
a: -—¢I>-'- FEMALE
8 --r:—--' MALE
I 40.. + TOTAL
a:
LIJ
O.
I—
I 30- TI
0 I \
D I \
4; I
o [I \
g 20‘ II \Iv/{I‘A IR 7"“
I" I ," \ I \\ I/ \\
O I I} ‘ ‘ {5% I’ \ I fik Kin—:3
2 I ’I \\ \}/ \jx\ \\ I, [I \\ ,
I I \ , \ ,/
. _ / \ / /
9.10 [I]! \ I, I} fir~_.§ 1?
l/ ‘ I
g If
0 I I I I I I I I I
22 23 4 5 6
24 1 2 3
TIME TRAP CHANGED
64
active at the blacklight trap earlier in the evening than did males
with male activity reaching its peak shortly after midnight and another
peak prior to dawn.
Dark-sided cutworm activity indicates that male flight activity
reaches its peak between 5:00 A.M. and 6:00 A.M. with a consistent
catch prior to its peak. Female activity increased rapidly with its
first peak between 11:00 P.M., rapidly decreasing and reaching another
peak between 1:00 A.M. and 2:00 A.M. After the second peak, female
activity declined to a low level and remains there throughout the rest
of the night. Activity of females reached its peak near midnight with
a second peak shortly after midnight. Male activity remained level
throughout the night until early morning when their activity reached
its peak.
Tables 8 and 9 summarize the hourly trap catches for the spotted
cutworm and the dark-sided cutworm respectively.
65
Table 8. Summary of Total Spotted Cutworm Moths Caught Per Hour from
the Brown, Rogers and Streeter Blacklight Traps for August 18, 25 and
31, 1978
Percent of Percent of
Time Hourly Catch Hourly Catch Total Catch
Hours Female Male Both Female Male Female Male Both
22 38 42 80 47.50 52.50 6.48 7.17 13.65
23 56 29 85 65.88 34.12 9.56 4.95 14.51
24 21 66 87 24.14 75.86 3.58 11.26 14.84
1 19 77 96 19.79 80.21 3.24 13.14 16.38
2 15 53 68 22.06 77.94 2.56 9.04 11.60
3 8 56 64 12.50 87.50 1.36 9.56 10.92
4 11 13 24 45.83 54.17 1.88 2.22 4.10
5 9 41 50 18.00 82.00 1.53 7.00 8.53
6 18 14 32 56.25 43.75 3.07 2.39 5.46
195 391 586
Table 9.
25 and 31, 1978
66
Summary of Total Dark-sided Cutworm Moths Caught Per Hour
from the Brown, Rogers and Streeter Blacklight Traps for August 18,
Percent of
Percent of
Time Hourly Catch Hourly Catch Total Catch
Hours Female Male Both Female Male Female Male Both
22 l7 16 33 51.51 48.49 6.64 6.25 12.89
23 36 16 52 69.23 30.76 14.06 6.25 20.31
24 16 12 28 57.14 42.86 6.25 4.69 10.94
1 20 15 35 57.14 42.86 7.81 5.86 13.67
2 8 10 18 44.44 55.56 3.12 3.90 7.02
3 10 19 47.37 52.03 3.52 3.90 7.42
4 6 10 16 37.50 62.50 2.34 3.90 6.24
5 17 24 29.17 70.83 2.73 6.64 9.37
6 10 21 31 32.26 67.74 3.90 8.20 12.10
129 127 256
67
Larval Sampling
Introduction
The development of a sampling program suitable for certain life
stages of an insect must be based on the distribution and life cycle of
the insect involved. A sampling technique suitable for one insect may
not be suitable for another; there is no universal sampling method. A
study was undertaken to evaluate different larval sampling techniques
for their effectiveness in cutworm sampling.
Methods and Materials
Attraction to Blacklight
A general purpose ElliscoR, lS-watt blacklight trap was dis-
assembled using only the light and starting mechanism box. In 1978,
the light was suspended 45.7cm above ground level on the outside row of
a vineyard in Van Buren county. Five days after the establishment of
the light, it was noticed that large numbers of dark-sided cutworms had
congregated under the light. Counts of numbers of cutworms present
were made on the fifth night using a 45.7cm square frame. Counts were
made directly under the light and at a distance of 3 meters from the
light in north, south, east and west directions. In 1979, a similar
light was set up on the edge of a vineyard which had been removed one
week earlier. Samples were taken by using a .91 meter square frame and
digging to a depth of six inches directly below the light, 1.8, 2.74
and 7.6 meters from the light in north, south, east and west directions.
The samples were taken at establishment of the light, five and eight
68
days after establishment. At the end of each sampling period, the
larvae were removed from the area and the instars determined.
Visual Inspection
Vineyards were selected in 1978 and 1979 for visual sampling of
the vines at night for cutworm presence. In each vineyard selected,
four randomly selected areas were chosen and in each of these areas
30.5 meters of row was examined. The trunk, canes and wire in this
30.5 meters were closely examined for cutworms. Specimens found were
collected and labeled for identification the following morning.
Samples were sorted and counted and the number of each species
recorded.
Pitfall Traps
Pitfall traps were set out in thirteen vineyards in Berrien and
Van Buren counties during 1978. Pint containers constructed of wax-
coated cardboard were placed in holes made with a golf course hole
cutter. The traps were set with their lips flush with the soil
surface. Two types of traps were used: (1) baited with HopkinsR 5%
carbaryl apple-pomace bait, and (2) unbaited, containing two ounces of
ethylene glycol to serve as a preservation agent. A .63cm plywood
cover supported with nails 7.6 centimeters above the trap provided a
cover for each trap to prevent rain from entering the traps.
The pitfall traps were randomly placed throughout the vineyard in
locations in and between the rows. Vineyards used consisted of both
those with a cover crop planted and those which had a semi-permanent
cover of grasses.
69
Shingle Traps
Shingles were utilized as a trapping method in ten vineyards in
Berrien and Van Buren counties in 1978. The shingles (30.5x45.7 centi-
meters) were held in place on the ground with two pole barn spikes.
The traps were randomly placed in the vineyards and the vegetation
under the trap was thinned if the traps did not sit firmly on the soil.
Locations of the shingle traps were marked with colored plastic
flagging placed on the trellis system.
Spatial Distribution
The study of the distribution of the climbing cutworms was done
in five locations in Van Buren county in 1979. A site in the vineyard
was selected and a 3x3 meter square area was marked out. This area was
carefully checked for the presence of cutworms by removing the vege-
tation as needed. The soil was checked to a depth of 10 centimeters.
As the larvae were found, a stick with a corresponding piece of colored
ribbon indicating the species of the cutworm was used to mark its
location. After all of the larvae had been removed and their position
marked, measurements were taken so that their location could be mapped
out at a later date.
Results and Discussion
Attraction to Blacklight
The use of the blacklight has been shown to be a powerful
attractant for many different orders of insects. Olson and Rings
(1969) found that the spotted cutworm responded photopositively for
instars one through three while instars four through seven responded
70
photonegatively to various intensities and wavelengths of light. The
attraction of the dark-sided cutworm larvae to the blacklight is shown
in Table 10. After five days of operating the blacklight in 1978, an
area 45.7 centimeters square was sampled yielding 475 dark-sided cutworm
larvae (Figure 20). In 1979, the blacklight was placed in a recently
removed vineyard. After eight nights of operation, the trap attracted
167 dark—sided cutworm larvae within the .91 meter area sampled beneath
the light. This number of larvae is a 167 fold increase over the number
present when sampled prior to the operation of the light.
The blacklight could possibly be used to monitor population levels
of the dark-sided cutworm larvae in the spring and to concentrate larvae
in one area for purposes of collecting larvae to establish a colony, aid
in the release and establishment of parasites and possibly as a means of
aiding in control in some circumstances. This response of the
attraction of the dark-sided cutworm to the blacklight was not observed
with any of the other species of cutworms attacking grapes.
Visual Inspection
This type of sampling technique allowed for a large number of
vineyards to be inspected each night. A summary of the species of
cutworms collected and abundance of each species in the vineyards
sampled is found in Table 11. Sampling of this nature gives a quali-
tative determination of what species are present within an area.
Pitfall Traps
The results of the pitfall trapping study indicates that early in
the season the cutworms are attracted to the pitfall traps in a limited
degree (Table 12). The baited pitfall traps caught more cutworms than
71
Table 10. Attraction of Dark-sided Cutworm Larvae to the
Blacklight
Date Sampled
giggiign # Increase
6/1/79 6/5/79 6/8/79
At light 1 134 33 166
1.8 meters--N 3 62 2 61
1.8 meters--S l 50 7 56
1.8 meters--E 0 14 12 26
1.8 meters--W 0 29 5 34
2.74 meters--N 0 8 1 9
2.74 meters--S 6 43 3 40
2.74 meters--E 0 4 0 4
2.74 meters--W 4 37 3 36
7.6 meters--N 2 2 l l
7.6 meters--S 2 0 0 -2
7.6 meters--E l 2 0 l
7.6 meters—-W 5 l 0 —4
72
Figure 20. Dark-sided Cutworm Larvae under Blacklight in Vineyard,
1978
73
Table 11. Number of Each Species Collected Per 122 Meters of Vineyard
Row During Visual Inspections
No. of Each Species Found Per 122 Meters of Row
Brown Amathes Spotted Spotted-sided W—marked
Location Cutworm smithii Cutworm Cutworm Cutworm Total
1978
Abandoned 0 l 3 35 0 39
Oxley #l 19 l 6 0 0 26
Slevatz ll 0 0 2 0 13
Brown #1 0 0 2 0 0 2
Brown #2 0 1 0 0 0 l
Glavin 0 0 0 0 0 0
Cronenwett 0 0 4 l 0 5
Rogers #1 0 0 3 0 0 3
Ryan 0 2 5 ll 0 18
Wrona l 0 l 8 0 10
Total 31 5 24 57 0 117
1222_
Rogers #1 0 0 13 l 0 l4
Rogers #2 0 0 4 0 0 4
Oxley #2 0 0 5 l 0 6
Slevatz 0 0 0 0 2 2
Cronenwett 0 l 1 0 0 2
Brown, D. 0 0 0 0 0 0
Abandoned l 1 0 2 3 7
Brown #1 l 0 6 0 0 7
Brown #2 0 0 8 0 0 8
Ryan 3 0 10 22 0 35
5 2 47 26 5 85
74
Results of Baited and Unbaited Pitfall Traps as a
Detection Tool for Climbing Cutworms
Table 12.
Total
Number of Cutworms Caught Per Trap*
Location &
4/22 4/26 4/30 5/4 5/8
4/18
Trap No.**
bl-l
bl-2
u1-3
ul-4
b2-1
b2-2
u2-3
u2-4
b3-1
u3-2
u3-3
b4-l
u4-2
b5-l
b5-2
u5-3
u5-4
b6-1
b6-2
u6-3
u6-4
b7-l
b7-2
u7-3
u7-4
b8-1
b8-2
u8-3
u8-4
b9-1
b9-2
b9-3
u9-4
u9-5
u9-6
blO-l
blO-2
u10-3
u10-4
bll-l
bll-2
ull-3
ull-4
b12-l
75
Table 12. Continued.
Number of Cutworms Caught Per Trap*
Location &
Total
Trap No.**
4/18 4/22 4/26 4/30 5/4 5/8
b12-2 0 l 0 0 0 0 l
b12-3 0 0 0 0 0 0 0
u12-4 0 0 0 l 0 0 l
u12-5 0 0 0 0 0 0 0
u12-6 0 0 0 2 0 0 2
u12-7 0 0 0 0 0 0 0
u12-8 0 0 0 0 0 0 0
bl3-l 0 0 0 0 0 0 0
bl3-2 0 0 0 0 0 0 0
ul3-3 0 0 0 0 0 0 0
ul3-4 0 0 0 0 0 0 0
b13-5 0 0 0 0 0 l l
b13—6 0 0 0 0 0 0 0
ul3-7 0 0 0 0 0 0 0
ul3-8 0 0 0 0 0 0 0
b13-9 0 0 0 0 0 0 0
bl3-10 0 l 0 0 0 0 l
ul3-ll 0 0 0 0 0 0 0
ul3-12 0 0 0 0 0 0 0
b13-l3 0 0 0 0 0 0 0
b13-l4 0 0 0 0 0 0 0
ul3-15 0 0 0 0 0 0 0
u13-l6 0 0 0 0 0 0 0
b13-l7 0 0 0 0 0 0 0
bl3-18 0 0 0 0 0 0 0
u13-19 0 0 0 0 0 0 0
ul3-20 0 0 0 0 0 0 0
b13-21 0 0 0 4*** 0 0 4
b13-22 0 0 0 0 0 0 0
u13-23 0 0 0 0 0 0 0
ul3-24 0 0 0 l 0 0 l
b13-25 0 0 0 l 0 0 l
bl3-26 0 0 0 2 0 0 2
u13-27 0 0 0 0 0 0 0
u13-28 0 0 0 0 0 0 0
bl3-29 0 0 0 0 0 0 0
b13-30 0 0 0 0 0 0 0
0 6 0 ll 2 l 20
*All of the cutworms caught were the spotted cutworm unless
otherwise indicated.
**b = baited, u = unbaited.
***3 spotted-sided cutworms, 1 spotted cutworm.
76
did the unbaited traps. The apple-pomace bait used may have served as
a strong enough attractant to lure the cutworms to the trap.
Due to the presence of a cover crop in the vineyard, food is
generally readily available and movement of the cutworm is rather
limited. After the initiation of bud feeding, oftentimes cutworms
never return to the ground during the day but rather conceal themselves
under pieces of loose bark on the vine. Movement between vines is
often accomplished on the wire of the trellis system.
Shingle Traps
During the course of this study, the shingle traps were com-
pletely ineffective as a detection method for climbing cutworms as no
cutworms were captured in the traps. Walkden (1943) describes using
burlap sacks for sampling cutworms in the prairie with good success.
With the amount of ground cover present in many of the vineyards,
enough protection could be gained under the plant material without
seeking protection elsewhere.
Spatial Distribution
The distribution of cutworm larvae in the 3x3 meter square
sampled plots is shown in Figures 21 and 22 for two of the vineyards
sampled. These figures show that the distribution was aggregated. The
variance to mean ratio is a test based on the equality of the variance
and mean in a Poisson series and the inequality of both parameters in a
regular and contagious distribution. The variance to mean ratio is
calculated by the following formula,
:2. (x-X>2
X
I = = x (n - l)
77
where 52 = variance, x = arithmetic mean and n = number of sampling
units. The departures from unity can be assessed by using a X2 table
(Elliott, 1977).
2 2
2 _ _ _ s (n - l) _ (x - x)
X — I (n l) — x _.-——;?————
if I>l, contagious distribution is suspected, I = 1 a random distri-
bution and I