JIIWWHJHIWIHJWIHIIHHIWIHHIHWI'IIHHIHJI 4mg Iooo mum wag-$18 a L ‘ 1,1, lllllllllllllllllllllll\llllllllllllllllllll ‘ t 1 31293 0177 LIBRARY Michigan State University This is to certify that the thesis entitled Relationship of Aphodius granarius and Ataenius spretulus Activity to Air and Soil Based Degree-day Accumulations on Michigan Golf Courses presented by Julie Stachecki Johanningsmeier has been accepted towards fulfillment of the requirements for Master of Science degree in Crop & Soil Sciences i Major professor Date 31" 'Cll 0.7639 MS U is an Affirmative Action/Equal Opportunity Institution PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINE return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE 1M chIRC/DWpGS-p.“ RELATIONSHIP OF APHODIUS GRANARIUS AND A TAENIUS SPRETUL US ACTIVITY TO AIR AND SOIL BASED DEGREE-DAY ACCUMULATIONS ON MICHIGAN GOLF COURSES By Julie Stachecki Johanningsmeier A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop and Soil Sciences 1 999 ABSTRACT Relationship oprhodius granarius and Ataenius spretulus Activity to Air and Soil Based Degree-Day Accumulations on Michigan Golf Courses By Julie Stachecki Johanningsmeier In Michigan, Ataenius spretulus larval feeding has damaged golf course turfgrass and its presence has become more common and injury more prominent. Further, initial sampling revealed that Aphodius granarius, another Scarabaeidae beetle, was also present and causing injury on golf course turfgrass in Michigan. The biology of these pests in the State of Michigan has not been thoroughly understood. Therefore Six golf courses were sampled from April through September for A. spretulus and A. granarius life stages. Air and soil temperature data were sampled at three of the golf course sites, at 0.3 m above, and 2.0 cm and 5.0 cm below irrigated turfgrass, respectively and were converted to degree-days (DD) base 10°C beginning April 5 of the respective year. Life stages of the beetles were compared to the golf course air and soil DD accumulations and two sets of weather data from local National Weather Service stations. A. granarius and A. Spretulus life cycles were not well correlated with any of the DD indexes during these two years. Peak A. granarius larval activity occurred prior to that of A. Spretulus between calendar dates 174 and 181 in 1992, and between 165 and 172 in 1993. Calendar dates were a more accurate predictor of peak A. Spretulus grub activity than DD. In 1992 (leap year), peak A. Spretulus occurred between calendar days 202-209, and 200-207 in 1993. During these two years of observations, A. granart'us and A. spretulus were univoltine in Michigan. ACKNOWLEDGEMENTS My graduate committee involved three very supportive and encouraging individuals that brought distinct expertise to this project from each of their disciplines. I greatly appreciate the assistance I received from these mentors: major professor Dr. Paul Rieke, Dr. Dave Smitley and Dr. Jeff Andresen. I am thankful for the time I had interacting with them on an academic and personal level, for their guidance and their patience, especially in the end. Another important mentor of mine is Dr. Larry Olsen. Larry made it possible for me to pursue my goal of a graduate degree while working on his team. As with my major professor, Lany’s integrity, management of people, goal- setting and high standards are attributes that I have benefited from and hope to personify in my future endeavors. Certainly I thank the other graduate students who made learning bearable and fun and were available to help untangle software upgrades and upheavals. Lastly, I thank my family and Douglas for believing in me. Your support through this process was invaluable. iii TABLE OF CONTENTS LIST OF TABLES ....................................................................................................... v LIST OF FIGURES .................................................................................................... vii INTRODUCTION ........................................................................................................ 1 LITERATURE REVIEW ............................................................................................. 3 Aphodius granart'us ........................................................................................... 3 Ataem’us spretulus ............................................................................................. 6 Degree-Days ..................................................................................................... 9 MATERIALS AND METHODS ................................................................................ 15 On-Site and Regional Weather Observations and Degree-Day Calculations 15 Sampling for Ataem‘us spretulus and Aphodt‘us granan‘us ............................... l9 ADULT SAMPLING ................................................................................ l9 LARVAE SAMPLING .............................................................................. 20 RESULTS AND DISCUSSION ................................................................................. 23 1992 and 1993 Weather Data .......................................................................... 23 Movement of Adult Ataent'us Spretulus and Aphodt'us granarius on Golf Courses .............................................................................................. 39 Instars, Sizes and Occurrence of A taent'us Spretulus and Aphodius granarius Larvae ............................................................................. 47 Ataem'us spretulus and Aphodius granart'us Larvae and Degree-Day Indexes. 56 APl-IODI US GRANARI US ........................................................................... 5 7 A TAENI US SPRETULUS ............................................................................ 64 APPENDIX A - Regression values used for estimating missing temperature data. ...... 71 APPENDD( B - FORTRAN program for calculating degree—days base 10°C. ............. 73 APPENDIX C - Soil analyses from areas sampled for Ataem'us spretulus and Aphodius granan‘us larvae at three golf courses ................................ 7S LITERATURE CITED ............................................................................................... 77 iv TABLE 7 10 ll 12 13 14 15 LIST OF TABLES PAGE Degree-day data showing cooler conditions in 1992 than in 1993. ............... 23 Hourly temperature comparisons for air and soil at three golf courses. 1992 and 1993. ........................................................................................... 25 Total DD for air and soil at three golf courses. 1992 and 1993. .................. 29 Golf course air and soil hourly temperature comparisons. 1992 and 1993.... 30 Air and soil temperature data for three golf courses. 1992 and 1993. .......... 31 Golf course and regional airport hourly air temperature comparisons. 1992 and 1993. ........................................................................................... 34 Flight activity of adult Ataenius spretttlus and golf course air DD. 1992 and 1993. ........................................................................................... 42 Flight activity of adult Aphodius granan'us and golf course air DD 1993. 42 Ataent'us Spretulus adult trap data related with grub observations and golf course air DD. 1992. ........................................................................... 45 Ataenius .spretulus adult trap data related with grub observations and golf course air DD. 1993. ........................................................................... 45 Aphodt'us granarius adult trap data related with grub observations and golf course air DD. 1993. ........................................................................... 46 Dimensions of A taent'us spretulus and Aphodius granarius instars based on measurements (millimeters). .................................................................. 51 Percent ofAtaenius spretulus and Aphodt'us granarius in the populations sampled at six golf courses. 1992 and 1993. ............................................... 56 Peak Aphodius granarius grub collection dates and corresponding DD. 1992 and 1993. ........................................................................................... 63 Peak Ataenius spretulus grub collection dates and corresponding DD. 1992 and 1993. ........................................................................................... 66 List of tables cont’d 16 Mean monthly temperatures for Southeast Lower Michigan and monthly golf course air DD. 1992 and 1993. ............................................................ 67 Appendix A Regression values used for estimating missing temperature data. ........ 71 A.1 Values used to estimate missing data for Edgewood 1992. ................. 71 A2 Values used to estimate missing data for Tam O’Shanter 1992. .......... 71 A3 Values used to estimate missing data for Edgewood 1993. ................. 71 AA Values used to estimate missing data for Tam O’Shanter 1993. .......... 72 A5 Values used to estimate missing data for Forest Lake 1993. ............... 72 Appendix B FORTRAN program for calculating degree days base 10°C. ............... 73 B.1 FORTRAN program. .......................................................................... 73 Appendix C Soil analyses fi'om areas sampled for Ataem'us Spretulus and Aphodius granarius larvae at three golf courses. ................................. 75 C] Soil analyses from three golf courses. 1992. ...................................... 75 C2 Soil analyses from three golf courses. 1993. . ..................................... 75 vi FIGURE 10 11 12 13 14 15 16 I7 18 LIST OF FIGURES PAGE Air and soil DD for three golf courses. 1992. .............................................. 26 Air and soil DD for three golf courses. 1993 ............................................... 27 Golf course (mean) air and soil DD. 1992. .................................................. 32 Golf course (mean) air and soil DD. 1993. .................................................. 33 Regional and golf course air DD. 1992 ........................................................ 35 Regional and golf course air and soil DD. 1993 ........................................... 36 Total adult Ataenius Spretulus and golf course air DD. 1992 ....................... 40 Total adult Ataem'us spretulus and Aphodius granarius and golf course air and soil DD. 1993. ................................................................................. 4] Ataenius spretulus head capsule size frequency. ........................................... 49 Aphodius granan'us head capsule size frequency .......................................... 50 Ataenius spretulus instars. 1992. ................................................................. 52 Ataenius Spretulus instars. 1993. ................................................................. 5 3 Aphodius granart'us instars. 1992. ............................................................... 54 Aphodius granarius instars. 1993. ............................................................... 55 Ataem'us spretulus and Aphodius granarius grubs, golf course air and soil DD. 1992. ...................................................................................... 58 Ataent‘us spretulus and Aphodius granart’us grubs, regional and golf course air DD. 1992. ................................................................................... 59 Ataenius spretulus and Aphadius granarius grubs, golf course air and soil DD. 1993. ...................................................................................... 60 Ataenius .spretulus and Aphodt'us granan'us grubs, regional and golf course air DD. 1993. ................................................................................... 61 vii INTRODUCTION Ataenius spretulus (I-Ialdeman) has been found in 41 of the United States and is known to have caused damage to golf course turfgrass in at least 23 states (Tashiro, 1987). In Michigan, A. spretulus larval feeding has damaged golf course tees, greens and fairways and its presence is becoming more common and injury more prominent. While this Scarabaeidae beetle’s occurrence is familiar, limited information has been available on the biology of A. spretulus in Michigan. The root-feeding larvae of A. Spretulus have caused injury or death of many host turfgrasses including Poa annua L., Poa pratensis L., and Agrostis species (Tashiro, 1987). In West Virginia and Southern Ohio, A. Spretulus completes two generations per year (W egner and Niemczyk, 1981; Weaver and Hacker, 1978). In western New York, Ontario, Canada, and Minnesota, A. spretulus is believed to have one generation per year, although this is not confirmed (Tashiro, 1987). In addition to A. spretulus, Aphodt'us granarius (L.) have been found causing turfgrass injury on golf courses in Michigan. The first description of damage to turfgrass by A. granarius was from a golf course in Toronto, Ontario in 1976 and 1977 (Sears, 1978). Populations of A. granarius on golf courses have been observed in Michigan and elsewhere, as homogenous and more Often mixed with A. spretulus (Tashiro, 1987). The adults are shiny black beetles about 5 mm long and easily mistaken for A. spretulus (Tashiro, 1987). The white, c-shaped larvae cause injury by feeding on turf roots. Sampling for A. spretulus or A. granarius larvae in turfgrass is a precarious task for golf course superintendents. Often, by the time turf damage from larval feeding is apparent, the immatures have begun to pupate. Understanding the timing of their life stages will help determine when to sample for larvae of these two species and when the best opportunity for control exists. This study resulted from the need to learn the life cycles of A. granarius and A. spretulus on Michigan golf courses. A method used among scientists and agricultural producers interested in the biological development of many plants and cold-blooded animals is a temperature-derived index, growing degree-days, or simply degree-days (DD). Degree-days are based on the fact that grth and development of many plants and insects are dependent upon the amount of heat present in and or around the organism, and are normally used to estimate the amount of time spent above some organism-specific temperature threshold (Andresen, 1993). Part of this study was designed to relate A. spretulus and A. granarius life stages to DD. The hypothesis is that DD will be helpfirl in predicting their life stages, the larval stage in particular, in Michigan. Since A. Spretulus and A. granarius spend the winter in the soil and organic debris, and the egg, larval and pupae stages occur completely in the soil, it seemed logical to monitor accumulating thermal units in the soil. This study monitored DD for air temperatures and soil temperatures at 2.5 cm and 5.0 cm depths to determine which is a better indicator of the insects' development. In addition, two regional weather observation station DD indexes were compared to on-Site golf course temperature data and the A. spretulus and A. granarius biological activities Using air and soil temperature data should allow weather-related information to be a resource, enabling turf managers to interpret biological events so they may be more efficient at monitoring and managing turfgrass and its pests. LITERATURE REVIEW Aphodius granarius Aphodius granarius (L.) is in the order Coleoptera, family Scarabaeidae, and subfamily Aphodiinae. The Scarabaeidae family is one of the most diverse in the order based on biology, ecology and behavior (Woodruff, 1973). The family is divided into two groups based on morphology. The Laparosticti group has abdominal spiracles situated in a line on the membrane between the stemites and tergites. This group includes the dung- feeding and scavenger species of which Aphodiinae are a part (Woodruff, 1973). There is limited reference material on Aphodius granan‘us and much of what is available on the genus is in reference to dung habitat and dung-feeding behavior (Borror et al., 1989; Ritcher, 1966; Wilson, 1932; Woodrufl‘, 1973). A. granarius is an introduced species which is now widespread in the United States and Canada (Ritcher, 1966). Adults are oblong, shiny black beetles approximately 3-5 mm long with reddish-brown legs and paler antennae. The adults resemble Ataenius spretulus and are often mistaken as such (Tashiro, 1987). The adult A. granarius is distinguishable by the transverse carinae on the tibia of the meso- and metathoracic legs. Woodruff (1973) states that adults of many species oprhodius have been found on snow in the winter and that some species fly in swarms when emerging from overwintering sites during early spring in northern latitudes. A research team in Sapporo, Japan studied the oviposition habits of Aphodiinae with hopes of revealing information useful in studying the evolutionary origin of two major groups of dung beetles: Geotrupinae and Scarabaeinae (Yoshida and Katakura, 1992). From the nine species oprhodius that they studied, four types of oviposition habits were recognized. Type 1: Eggs Were laid singly in dung on the ground. Type 11: Eggs were laid singly in soil beneath the dung. Type 111: Each egg was laid in a small dung mass that had been stuffed in a shallow burrow excavated beneath the dung. Type IV: Each egg was laid in the soil near the terminal end of a sausage-shaped dung mass buried beneath the dung (Yoshida and Katakura, 1992). Adult A. granarius have been found abundantly in cow and sheep dung (Ritcher, 1966; Wilson, 1932; Woodruff, 1973). Wilson observed that the adult A. granarius preferred dung piles that had dried out and I formed a hard crust on the surface. It was under this hard crust that they laid their eggs. A. granarius adults and larvae are also found inhabiting soils under golf course turfgrass indicating that oviposition occurs in turfgrass soil as well as in dung. The oval-shaped A. granarius eggs are smooth, opaque and are approximately 0.80 mm long by 0.56 mm wide (Wilson, 1932). Wilson observed that eggs hatched in four to seven days and the first instar lasted three to four days (1 93 2). In a microcosm study, the development of A. fimetarius agreed with the general life cycle of aphodiinae beetles in the field (Stevenson and Dindal, 1985). In summer, Aphodius grubs hatch from eggs in three to five days, and the instars last two to four days (first instar), three to eight days (second), and three to five weeks (third) (Landin, 1961; Holter, 1975). In the Stevenson and Dindal microcosm study, they recognized that the diurnal temperature in the glass house was greater than the external environment and that grth rates of Aphodius larvae were proportional to temperature. The larvae of A. granarius are typical of Scarabaeidae larvae, c-shaped with the abdomen folded against the fore part of the body. The larvae have a white body, a light brown head and six legs. The maximum reported head capsule width of A. granarius is a range of 1.42-1.68 m (Tashiro, 1987). A. granart'us larvae can be distinguished from other Aphodius spp. and Ataenius spretulus by the presence of palidia on the raster (Tashiro, 1987). The palidia make a distinct v-shaped pattern in the middle of the last venter and have random spines outside of the pattern. Larvae of the dung beetle A. granan'us are found in pasture grasses in North America (Jerath and Ritcher, 1959). In Ontario, Canada A. gramm’us larvae were found in June, peaked in early July, and declined by the end of July (Sears, 1978). In Ohio, larvae peaked during the first . week of June and declined through the first week of July, indicating pupation (Niemczyk and Dunbar, 1976). In a laboratory setting, pupae from spring-collected adults that laid eggs, hatched and matured, averaged 9 days to complete the pupation process with the first adult of the new generation emerging on July 19 (W ilson, 1932). From the same New Jersey sheep pasture population the first pupae were Observed on July 23 and the new generation adults emerged in large numbers during the second week of August. Newly emerged A. granarius adults are lighter in color (callow) than the parent generation, but turn dark shortly after emergence. Wilson found one generation of A. granan’us per year in New Jersey with the adult overwintering (1932). In Ohio and Ontario, Canada, based on adult sightings in the spring and then again later in the year, it is suggested that A. granarius completes two generations per year but this is unconfirmed (Tashiro, 1987). Adults of most species of Aphodius are dung feeders, but some also feed in decaying fungi or in decaying organic matter in or on the soil. The larvae include feeders on dung, organic matter, and live roots (Ritcher, 1966). Lugger (1899) observed A. granarius larvae feeding on sprouting seeds of corn (Zea mays L.) in Minnesota. In turfgrass A. granarius and A. pardalis have been sited as pests because of their root- feeding activity (Ritcher, 1966; Woodruff, 1973; Sears, 1978). Turfgrass injury was caused on two mixed annual (Poa annua L.) and Kentucky bluegrass (Poa pratensis L.) fairways in Toronto, Canada during the 1976 and 1977 growing seasons (Sears, 1978). Damage to golf course turf in Michigan and Colorado was reported in 1978 and reports from Ohio indicate that A. granarius was present and causing injury in the early 1980’s (Tashiro, 1987; Sears, 1978). To learn more about the life cycle of A. granart'us in Michigan, this study initiated observations and sampling of adults and larvae at six golf courses from April through September during 1992 and 1993. Ataenius spretulus Ataenius spretulus (Haldeman) is in the order Coleoptera, family Scarabaeidae, subfamily Aphodiinae, and is commonly known as the black turfgrass Ataem‘us, or by turfgrass managers as simply Ataenius. Formerly, it was misidentified as Ataenius cognatus and described as such from specimens collected in Minnesota where A. spretulus is a common species (Woodruff, 1973). Although this beetle is classified as a dung beetle, turfgrass managers are familiar with it because of the injury it has caused on golf course turf (Borror, 1989; Sears, 1981; Kawanishi et al., 1974; Niemczyk and Dunbar, 1976; Weaver and Hacker, 1978). The first reported damage was to fairway turf in Minnesota in 1927 (Tashiro, 1987). It was not until afier 1970 that reports of golf course turfgrass damaged by A. spretulus became more prevalent (Weaver and Hacker, 1978). Found in 41 states and with reported turfgrass damage from at least 23, A. spretulus may be the most widespread white grub pest on golf courses in the United States (Niemczyk and Dunbar, 1976). The scope ofturfgrass injury caused by A. spretulus in Michigan continues to be revealed. A. spretulus is a shiny black beetle, approximately 5 mm long and 2.2 mm wide (Tashiro, 1987). A. .spretulus overwinters as an adult (Weaver and Hacker, 1978). Hibernating adults have been found beneath dry cow dung, in waste piles of milorganite mixed with grass clippings, in leaf debris, in the first two inches of soil along golf course fairways, in the upper two inches of loose, well-drained soil at the edges of wooded areas and river banks (Weaver and Hacker, 1978; Wegner and Niemczyk, 1981). In Ohio, the onset of migration fi'om overwintering sites occurs in early to late March with eggs first appearing in early to mid-May (Wegner and Niemczyk, 1981). They examined several specimens which revealed that 65% of all overwintering beetles were female, and 89.7% of those examined were inseminated. The females dissected in spring and summer had 12 ovarioles each containing three to four eggs in different stages of development. More than half of the females dissected in late May and June appeared to have oviposited already. The shiny, white, oval eggs are deposited in clusters of 11-12 in a cavity formed by the female in the lower 5 mm of thatch and upper 6 mm of soil among grass roots (Wegner and Niemczyk, 1981). The adult beetles are easy to see crawling in the short-mowed turf on golf greens. The abundance of adults has not been correlated with the subsequent levels of grub activity within a certain site or region (Weaver and Hacker, 1978). It is believed that egg-laying in West Virginia occurs primarily from mid-May through early June and in the same periods in Ohio (Weaver and Hacker, 1978; Niemczyk and Wegner, 1979). Eggs hatch soon after being deposited at the soil-thatch interface and larvae are present from late May to mid-July in Ohio, whereas, in West Virginia the researchers Observed pupae and callow adults by late June (1978). Grub population densities associated with turfgrass have been reported as 100-150 per 0.1 m2 in Connecticut, 200 — 300 per 0.1 m2 in Ohio, and 500 larvae per 0.1 m2 in Ohio (Niemczyk and Dunbar, 1976; Weaver and Hacker, 1978). A. spretulus have three larval instars, typical of scarabaeid beetles (Tashiro, 1987). Head capsule widths grow from a mean of 0.5 mm in firsts, to 0.83 mm in seconds, and to 1.3 mm in third instars (W egner and Niemczyk, 1981). Larvae are white, c-Shaped grubs. The larvae do not have a distinct raster pattern, but there are 40-45 randomly placed hamate setae. The grubs have two pad-like structures on the tip of the abdomen between the setae and the anal slit, which helps to distinguish them from other scarab larvae (Wegner and Niemczyk, 1981). According to Wegner and Niemczyk (1981), the period required for first generation A. spretulus to pass through one generation was 65 :1: 5 days at soil temperatures of 25 at 6°C. A. spretulus has one or two generations per year, depending on location and latitude (T ashiro, 1987). In Ohio and West Virginia, A. spretulus is bivoltine. In the latitude of western New York, Ontario, Canada, and Minnesota, A. spretulus are believed to be univoltine. Wegner and Niemczyk performed the most thorough study on the life history of A. spretulus in the turfgrass environment. In fact, Tashiro (1987) touts their work as the most comprehensive study of any turfgrass scarabaeid in turfgrass soil throughout the season. Part of their study involved establishing a degree-day index for predicting A. spretulus activity and development, and was based on a flight activity threshold of 13°C (1981). Insect models that use observations of one active grth stage to predict some future stage are usually successful (Pruess, 1983). The Ohio researchers used sampling techniques including light-traps, eight-vaned sticky cloth traps, soil samples pulled with a standard golf course cup-cutter, and flotation methods (1981). In Michigan, superintendents consistently list A. spretulus as a serious pest (Smitley, 1994). Cautious superintendents will make one or two prophylactic insecticide treatments to prevent turf injury fi'om the complex of scarab species when one-well-timed application could provide sufficient control (Nyrop et al., 1995). Michigan turfgrass managers suspected that there were two generations of A. spretulus per year based on many locations experiencing two separate periods of turf injury during the summer. The present study resulted from the need for additional information regarding the life cycle of A. spretulus in Michigan pertinent to its control. Degree Days Recognizing that A. spretulus and A. granarius are injurious pests of golf course turfgrass in Michigan, once their life cycles are better understood, a tool for predicting their occurrence and development would be beneficial for turfgrass managers. The complexity and variability in the biological world, the variability in potential strategies and the number of available tactics to reduce pest levels below economic levels requires an organized and structured approach (Gage, 1989). Part of a structured approach includes monitoring and sampling. Fine-tuning when these activities are best executed makes the tasks more efficient and saves resources. The concept that grth and development of many organisms is dependent upon the amount of heat present in or around the organism allows us to develop temperature- derived indexes to predict that development. In general, it holds that the cooler the temperatures are, the slower is the rate of growth and development of plants and invertebrate animals (Zalom et al., 1983). Knowing that some insects develop at rates determined by temperature, the thermal unit of measure is in degree-days (DD) (Shetlar, 1991). Useful DD indexes have been established for other turfgrass insects including annual bluegrass weevil, hairy chinch bug and larger sod webworm (Shetlar, 1991; Tashiro, 1987). Degree-days can be calculated in a multitude of ways. However, all methods of DD rely on the common principle that the biological process of interest will not begin until a certain temperature threshold is reached or exceeded. This threshold is known as the base temperature (Andresen, 1993). The selection of an appropriate base temperature is critical to the DD or any heat unit model (Yang et al., 1995). They feel that the methods commonly reported in literature for determining base temperatures are tedious and lack mathematical theory so they have proposed simple and mathematically-sound formulae to calculate the base temperatures for DD for organisms under study. Pruess (1983) may agree that the complexity of many DD models limits their application and validation. However, he recommends for practical application, that a standardized approach to establishing base temperature thresholds be instituted. To reduce the intimidation factor of sine wave approximations and different thresholds for every insect, Pruess proposes standardized thresholds of 5, 10 or 15°C for DD. Further, if standard thresholds are employed, the DD models are more likely to be employed where 10 comparable temperature data are available. The minimum threshold assumption is that the biological process of interest will cease below the base temperature. In addition, there may be an upper threshold which is less well-defined but is often observed as the temperature above which the rate of development, or the process of interest (e. g., respiration, maturation) begins to decrease or stops (Zalom et al., 1983). Degree-days are calculated using observed daily temperature data relative to the base temperature, and upper temperature threshold if available. The state of development of the organism in question is usually correlated with the accumulation of daily DD through the growing season. For overwintering insects in Michigan this accumulation ends sometime in the late fall and normally begins again in the month of March (Andresen, 1993). Several techniques are available for calculating degree-days through the use of daily maximum and minimum temperatures. From the simplest to the most complex, DD calculations include but are not limited to: averaging, single and double triangulation, sine wave, and modified sine wave (Allen, 1976; Zalom et al., 1983). These methods are considered linear models, because the rate of development is presumed to be a straight line directly related to temperature. The simplest of the DD calculations is the average method, also referred to as the historical, simple, or mean-minus-base method (Pruess, 1983). To use this equation, the maximum and minimum temperatures are required to find the mean temperature, from which the base temperature is subtracted, (Max - Min)/2 - Base. The average method can underestimate DD when the minimum temperature is below the threshold, as is common in the spring and fall seasons. Another version of the average method is to set any minimum temperatures below the base threshold up to the base temperature before 11 averaging. This would then be considered the modified average method (Andresen, 1993) The most referenced method of calculating DD was derived by Baskerville and Emin (1969). The Baskerville-Emin method (BE) also known as the sine, or sine wave method assumes that the diurnal temperature curve is similar to the trigonometric sine curve. This method uses a day’s low and high temperatures to create a sine wave over a 24-hour period, and then estimates DD for that day by calculating the area above the threshold and below the curve. This process weighs all temperatures during a day above the base in proportion to the amount of time the temperature actually exceeded the base temperature. This method is most important in the spring and fall when the minimum temperatures often fall below the base temperature. The BB method leads to more realistic DD totals than the average method. While this calculation requires a calculator with trigonometric functions and some Skill to perform the tabulations, the BE values associated with various base temperatures have been formatted in look-up tables. Further, in Michigan DD derived by the BE method are readily available. A popular resource used by Michigan turfgrass managers is a weekly newsletter, the Crop Advisory Team Alert (CAT Alert) Landscape edition (MSU Extension [PM Program, East Lansing, MI). This newsletter is available printed or electronically on the worldwide web (www.msue.msu.edu/ipm). The DD values provided in the newsletter represent 32 stations throughout Michigan, and include Toledo, Ohio. The use of automated on-site weather observation equipment by turfgrass managers is expanding. This equipment is typically capable of providing mean hourly temperatures and calculating DD based on direct integration of the hourly data. The 12 direct integration method is the most realistic approximation of the actual amount of heat accumulated during a day vs. approximations calculated with daily maximum and minimum temperatures alone (Zalom et al., 1983). To calculate DD using hourly mean temperatures for a 24-hour period, the base temperature is subtracted from each of the hourly mean temperatures, all negative values set to zero and all differences summed. The total for the day is then divided by 24, the total number of Observations. Pruess (1983) highly recommends that either the direct integration method, also referred to as actual DD method, or sine wave estimates of DD (BE) be used for the value of standardizing and making data more universally practical. The DD indexes most commonly used are based on air temperatures. To encourage broader application of DD models, it is recommended that when developing prediction models, researchers use air temperatures obtained with equipment in locations comparable to temperatures operationally reported by the National Weather Service (NW S) (Pruess, 1983). This is because the NWS data are currently the most widely available. Further, soil and other micro-environmental records are encouraged during development Of prediction models. When an organism being studied resides in the soil environment, it seems logical that temperatures used for DD estimation would be more representative of the organisms’ activity if they were measured in its immediate environment—the soil. However, this assumption did not hold for winter wheat (T riticum aestivum L.) phenology (McMaster and Wilhelm, 1998). Both air temperatures and near-surface sOil temperatures were collected across the US. Central Great Plains to determine if predictions of winter wheat phenology could be improved when based on measured near-surface soil temperatures, 13 closer to the shoot apex, rather than on air temperature. Afier evaluating multiple sites and thermal unit accumulation models, in no instance did soil temperatures significantly improve the prediction of winter wheat phenology. The Northern masked chafer is a scarab pest of turfgrass that causes damage by feeding on roots (Tashiro, 1987). Air and soil based DD base 10°C are well correlated with the Northern masked chafer’s first emergence from hibernation but are less useful for predicting the date of 50% and 90% flight (Potter, 1981). On a golf course, knowing when scarab larvae were present in the soil and actively feeding on turfgrass roots would allow for more accurate and efficient sampling. Sampling confirms the need for management intervention to prevent turf injury or provides confidence that no intervention is necessary. Calendar dates have long been used for initiating control measures for insect pests while degree days (DD) are used in integrated pest management programs primarily to time sampling activities (Peterson and Meyer, 1995). Since many golf courses are equipped with on-site weather monitoring systems that calculate DD based on hourly data, and BE derived DD are readily available, in this study these indexes were correlated with observed biological activity of A. granan’us and A. spretulus. Further, many of the life stages of A. granart'us and A. spretulus occur in the soil. So, DD based on heat units accumulated in the soil were also related to these scarab insect life Stages. The hypothesis is that DD indexes will be usefirl in predicting A. Spretulus and A. granarius life stages, make scouting more efficient, and improve pest management decisions. 14 MATERIALS AND METHODS On-Site and Regional Weather Observations and Degree-day Calculations Activity of Ataem‘us spretulus and Aphodius granarius species were monitored at six golf course sites in Oakland County, Michigan during 1992 and 1993: Edgewood Country Club in Union Lake; Forest Lake Country Club in Bloomfield Hills; Tam O’Shanter Country Club in Orchard Lake; Franklin Hills Country Club in Franklin; Oakland Hills Country Club in Bloomfield Hills; and Orchard Lake Country Club in Orchard Lake. All six courses are located in the northern greater Detroit area and have a history of Ataenius spretulus infestations. Weather data were collected at Edgewood Country Club, Forest Lake Country Club, and Tam O’Shanter Country Club in 1992 and 1993 from April 5 to September 30 using on-site EnviroCaster® equipment (Neogen, Inc., Lansing, MI). These three courses are located approximately 8 km from each other. The EnviroCaster is a solar-powered, battery back-up, field installed micro- processor that collects data fi'om a variety of sensors. The EnviroCaster processes weather data into models developed for predicting a variety of biological events. Air and soil temperature data were collected in. this study. Temperature data were recorded by resistance thennometric devices (RTDs) that are made with a single platinum plate upon which the change in resistance is measured in response to temperature changes. Data were sampled by sensors every 15 minutes, averaged hourly, and stored in a 21-day memory file. Air temperatures were measured at a height of 0.3 m. Soil temperatures were monitored at 2.5 cm and 5.0 cm depths below a mix of irrigated Kentucky bluegrass and perennial ryegrass turf mowed at 5.0 cm at Edgewood and Tam O’Shanter Country 15 Clubs, and under irrigated annual bluegrass mowed at 1.3 cm at Forest Lake Country Club. In 1992, a portable soil temperature probe was periodically used to validate the accuracy of the permanently installed temperature probes. Repeatedly during the two seasons one or more of the sensors malfunctioned leaving gaps in the data sets. To estimate the missing data, linear regression analyses were run with the other two sites’ data to approximate data at the missing station. The regression values that were used are listed in Tables A.1 - A.5 located in Appendix A. The best-fit regression values were used to interpret the missing data using the equation: (3') = "100 + b where y is the missing data point, In is the slope, x the known data point, and b the regression constant. Of the 77,328 temperature measurements recorded in both years, an average of 6.7% of these were estimated (3% in 1992, 10% in 1993). Hourly temperature data were downloaded from the EnviroCaster equipment at the three golf course sites weekly. Air temperature data were also obtained from the National Weather Service at two regional airports—Flint Bishop International Airport, Flint, Michigan and Detroit Metropolitan International Airport, Detroit, Michigan. The airport data are referred to as regional data in the following text. Flint Bishop airport is about 50 km north, while Detroit Metropolitan airport is about 40 km southeast of the golf courses sampled. In contrast to the golf course data, the National Weather Service observations are operationally taken in an open field in the middle of the airport runways at 1.5 m above the ground. Soil temperatures are not monitored at the regional airport locations. 16 For this study, it was deemed beneficial to pool the golf course temperature data for several reasons. The first was to compensate for estimated and missing temperature data due to season-long and intermittent probe failures among the sites. Further, the temperature data were ultimately compared to biological information. Scarab grubs are patchily distributed (Nyrop et al., 1995). Difiiculty in obtaining adequate sample sizes of the grub species made it necessary for grub data to be pooled over six sites. The pooled temperature data were therefore considered most representative of the sampling area. In a study using DD for predicting sod webworm emergence, Tolley et al., 1986, found it more reliable to pool data for identifying adult peak flights. Before pooling the temperature data from the three golf course sites, hourly temperature data for each variable at each of the golf courses were compared Statistically to test for significant differences. The classical application of the analysis of variance or other tests for comparing sample means could not be directly applied because temperature data do not satisfy the assumption of independence (Wilks, 1995). That is, with classical Statistics it is assumed that all the x, values are mutually independent and that the x; values are mutually independent. For the temperature data, the averages tested were time averages, and the residual violates the assumption of independence. Golf course temperature data, as paired l7 variable and location, were tested for differences using the following equation (Wilks, 1995) appropriate for data with serial correlation, or time dependence: [$1-2]- E51472] = [(8.2/nf + Sflné) - 2p r.2((s,2/n,' )y2 (Si/n; )y2)]% 2 where p12 is the Pearson correlation between x1 and x2; 71' is the efi‘ective sample size estimated using r1, lag-1 autocorrelation coefficient; and the expected differences, between sites E[ :5, _ 3:2] is assumed to be 0. The approach chosen to address the problem of serial dependence was to determine an efl‘ective sample size, or equivalent number of independent samples, n'. That assumes that the fictitious sample size n' < n of independent values, and that the sampling distribution of the average has the same variance as the sampling distribution of the average over the n autocorrelated values. It was assumed that the data for which n' was estimated followed a first-order autoregressive process, which are often reasonable approximations for representing the persistence of daily meteorological values (Wilks, 1995). Further, the persistence in a first-order autoregression is completely characterized by the single parameter p., the lag-1 autocorrelation coemcient, which was estimated fiom the data series using the sample estimate, r]. The correlation r1 was substituted for p: to estimate the efi‘ective sample Size using the following approximation: '1' E "[(l - p1)/(1 + 101)]- For each calendar date during the study, mean hourly temperatures for the variables air, soil at 2.5 cm, and soil at 5.0 cm were calculated fiom the three golf courses’ data. These golf course (mean) data were subjected to analysis of variance for serial correlated data using the Wilks methodology described above. The air and soil data were 18 compared to evaluate how differently they responded to weather-induced temperature fluctuations. Further, regional temperature data fiom DTW and Flint Bishop airports were compared to the golf course (mean) hourly air temperature using the same analysis appropriate for time dependent data described above. A FORTRAN program (Appendix B) was used to calculate degree-day accumulations for air temperature, and soil temperatures at soil depths of 2.5 cm and 5.0 cm for a minimum development threshold temperature of 10° C (Kawanishi et al., 1974). Daily degree-day (DD) totals were obtained by integration of the average hourly temperatures above the threshold with all negative hourly totals set to zero. Seasonal accumulations for 1992 and 1993 data sets began on April 5 of both years. This DD calculation method is the most representative of the actual temperatures and periods of time they occur in the study area. Degree-days at the airports were calculated and reported by the National Weather Service using the Baskerville-Emin (BE) method, which utilizes daily maximum and minimum temperatures. This method is the closest in accuracy to calculating degree-days with a 24-hour continuous sensor as was done at the golf course sites using the Envirocasters® (Andresen, unpublished data). Sampling for Amenius spretulus and Aphodius granart'us ADULT SAMPLING Traps were used to monitor adult A. spretulus and A. granarius activity. Eight 2.54 cm by 2.54 cm wooden stakes equipped with metal clips to hold two, 15 cm by 15 cm cards coated with Tanglefoot® (Grand Rapids, MI), were erected at each golf course 19 site. The sticky cards were attached to stakes 0.6 m above the ground (Wegner and Niemczyk, 1981). Traps were placed in the rough between fairways and in out-of-play, wooded areas where organic debris and duff had accumulated—typical of the beetles’ overwintering habitat (Weaver and Hacker, 1978). Of the 48 traps, 16 were in natural areas and 32 were located in golf course roughs with maintained turf. Traps (sticky cards) were observed and beetles counted and identified weekly from April through September at the sites with EnviroCaster equipment, and May through August at the three other golf courses sampled during this study. Sticky cards were treated with an aerosol formulation of Tanglefoot® to maintain adhesive, or were replaced if A. spretulus or A. granarius beetles were on the cards, if they were heavily covered with other insects, had been broken, or were covered with grass clippings, leaves or other debris. On occasion the cards were broken by wind or knocked down by maintenance equipment. The total number of beetles caught per week was plotted with calendar dates and correlated to the accumulated DD. LARVAE SAMPLING A. Spretulus and A. granarius larvae were sampled fi'om six golf courses. At three sites, Oakland Hills Country Club, Orchard Lake Country Club, and Franklin Hills Country Club, soil samples were examined once per week for A. spretulus and A. granarius larvae from May through August. Samples were taken with a standard golf course cup cutter, 10.8 cm in diameter and 10 cm deep. Five samples were pulled fiom each of five plots in the fairway, and fiom each of five plots in the rough for a total of 10 plots and 50 soil cores per golf course. Each plot was 10 m x 5 m with 5 m between 20 plots. Plots in the rough were directly across from plots in the fairway with a 3 m border on both sides of the fairway-rough interface before plots started. At three other golf course sites larvae were sampled from one or two designated areas. At Edgewood Country Club soil core samples ,were taken from a practice chipping area consisting of a bentgrass putting green surface in 1992, and from the Kentucky bluegrass collar area around the practice green, which was mowed at rough height (5.0 cm) in 1993. At Forest Lake Country Club samples were taken from a 585 m2 area across the 13th fairway in both years. Samples at Tam O’Shanter Country Club were taken from a 500 m2 section of the 13th fairway in 1992 and from a 500 m2 section of the 2nd fairway in 1993. Five samples were collected per week in 1992 and 10 cores per week in 1993 from each of the sample areas. Samples were examined for A. spretulus and A. granarius larvae by pulling them apart by hand. Soil cores were then reshaped and placed back into the ground. Plugs recovered and grew back within 2 weeks of sampling. Previously sampled turf plugs were avoided during subsequent sampling. Grubs collected from samples were counted, put into vials of KAA (kerosene, acetic acid, 95% ethanol, triton; Chu, 1973) and taken back to a laboratory for identification, measurement, and dissection under a microscope. In 1992, to confirm that the method used for observing the soil cores was not overlooking beetle eggs or early instars, an efi‘ort was made to separate eggs and small larvae of A. spretulus and A. granarius using a rapid centrifirgal flotation technique. This technique has been used for extracting nematodes from soil (Jenkins, 1964). No organisms of interest to this project were recovered so the method was not repeated. 21 The nature of Scarabaeidae infestations on golf courses poses many sampling problems (Wegner and Niemcyzk, 1981; Ives and Warren, 1965). Very low grub samples at the three courses equipped with Envirocasters® reflected this difficulty. Among the six courses studied, where grub populations were adequate, grub sampling revealed synchronized biological events. Therefore, to obtain adequate sampling sizes and because the sampling sites behaved alike, grub data from the six golf courses were pooled together. The grubs were identified by the pattern of the setae on their tasters. A. spretulus larvae have a random pattern of 40 to 45 hamate setae on their rasters, while A granarius larvae have a v-shaped pattern of setae (Tashiro, 1987; Wegner and Niemczyk, 1981). Using a calibrated eyepiece micrometer, the head capsule of the grubs were measured and recorded according to the date of collection and location. In 1992, only grubs from the EnviroCaster-equipped sites were measured while in 1993 grubs from all six sampling sites were measured. The incidence of A. granart'us and A. spretulus larvae during each year was coupled with degree-day data for air temperature, soil temperature at 2.5 cm, and soil temperatures at a depth of 5.0 cm in 1992 and 1993. The incidence of A. granarius and A. spretulus larvae during each year were also correlated to regional DD data. Soil samples were taken at the three EnviroCaster®-equipped golf courses from the areas sampled for grubs. Soil samples were analyzed for physical and chemical characteristics. Results of the soil analyses are presented in Tables Cl and C2 in Appendix C. 22 RESULTS AND DISCUSSION 1992 and 1993 Weather Data Climatological records from the National Climatic Data Center show consistently below normal temperatures (-1.6 °C) for the state of Michigan from April-October 1992. There were even greater departures from normal for July-August (-2.6 °C), the two climatologically warmest months of the year (NOAA, 1993). In the 1993 study year, Southeast Lower Michigan averaged only slightly below normal temperatures (-0.08°C) from April-October, with July and August (12°C) slightly above normal (NOAA, 1994). Golf course temperature observations for this study are expressed in degree-days (DD) base 10°C beginning April 5 of the respective year. Regional temperature data are expressed as DD or DD BE (Baskerville-Emin, 1969). Consistent with the National Climatic Data Center, the accumulated DD for 1992 and 1993 at the golf course locations and two regional airports included in this study also verify that 1992 was the cooler season (Table 1). The greatest departure fiom normal and between years, occurred in the mid to late season, while May and June were cooler than normal but not greatly different between years. Table 1. Degree-day data showing cooler conditions in 1992 than in 1993. Flint Bishop Detroit Metro Golf Course DD Airport DD BE Intern. Airport DD BE Date 1992 1993 1992 1993 1992 1993 May 1St 24 33 46 51 57 64 June 1St 164 176 227 215 238 254 July 1St 379 422 478 499 507 566 August 181 660 796 781 904 836 1016 Sept 1"1 910 1136 1052 1262 1131 1443 Sept. 30th 1090 1254 1256 1396 1344 1637 DD base 10°C beginning April 5 of the respective year. BE method of DD calculation, Baskerville and Emin, 1969. 23 During 1992, air data from Edgewood Country Club, soil 2.5 cm data from Tam O’Shanter Country Club, and soil 5.0 cm data from Forest Lake Country Club could not be reported due to temperature probe failures. The hourly temperature data for air, soil 2.5 cm, and soil 5.0 cm were compared among sites using paired variable and locations to test for significant differences. The statistics used were appropriate for serial correlated data which included the use of a lag- 1 autocorrelation coefficient n, and an effective sample size n’ (W ilks, 1995). The paired variable and location comparison results are located in Table 2. Hourly temperature data collected at three golf courses with EnviroCaster® equipment for air, soil at 2.5 cm and soil at 5.0 cm at three golf courses were converted into degree-day units. Figure 1 represents the degree-day (DD) units for the available air, 2.5 cm soil and 5.0 cm soil from the three golf courses in 1992, and Figure 2 represents similar data for 1993. The similarities among the variables between the sites are apparent in these charts. 24 Table 2. Hourly temperature comparisons for air and soil at three golf courses. 1992 and 1993. 1992 Variable Location Pair Z Statistic§ Air T° Forest Lake - Tam O’Shanter 1.232 Soil 2.5 cm T° Edgewood - Forest Lake -2.19* Soil 5.0 cm T° Edgewood - Tam O’Shanter 1.664 1993 Variable Location Pair Z Statistici Air T° Edgewood - Forest Lake 0427 Edgewood - Tam O’Shanter 4166* Forest Lake - Tam O’Shanter 3664* Soil 2.5 cm T° Edgewood - Forest Lake 0.624 Edgewood - Tam O’Shanter 0.795 Forest Lake - Tam O’Shanter 1.21 Soil 5.0 cm T° Edgewood -Forest Lake 3203* Edgewood - Tam O’Shanter 1.96 Forest Lake - Tam O’Shanter 0.682 *Significant at the or .05 level §Following Wilks' (1995) analysis for serial correlated data. 25 .33 dew—=3 2e» 09:: a8 Ga :8 was a? A 0.53m 38 39.0.00 umtmwmwasmmm mummmwmmwi mm .11 \II III". I \...\. \\ fin II. \\\\ no so on 4.8 $542.90 sill \ no .8 ca 3.8 000508 8...: \ no so 3 3.0.0. mxfi Emmo“. 1|: NM” on ,8 3 3.8 00033811. 23 on «.2 152‘.me .25] on mi 9.5 Emacs I coop comp 83 89 36/9/17 Buruurfioa 0.01 are do 26 £23 .858 2cm 8...: 5m an :8 25 .:< .N 0.53.,— 88 39.25 amnnuuuwmwmmummmmmmuume Ir Stables]. Ir 91.6Ivoo [halves \111 - o .\ H1. . .. 8N 84 8m 8m 89 no E on 3.8 mwpzsimb sill on so 3 .__Om 9.5 ammo". I , . 89 on .8 ca 3.8 000508 I on so 3 3.8 mmezsimo 25' on 58a .__Om 8.5 ammo“. ll 83 on .83 5.8 893.08 II no a? «923‘me 25' ,l- 89 no m_< m5: Emmoi I on m_< 000358 I com— 27 mn Buruurfioa 0.01 one do For effective use of on-site weather data, placement of weather observation equipment should be representative of the property at large or placed near a location that historically had the first outbreak of a disease or insect in which the turf manager is interested in monitoring. When placing the units there Should be no interference from buildings or other structures that may alter the wind, temperature, or moisture readings. The Envirocasters® at Forest Lake and Tam O’Shanter Country Clubs were free from obstruction. Forest Lake Country Club soil probes were placed at the edge of a fairway and the primary housing unit with the relative humidity/air sensor was in the rough 7.5 m east of the maintenance building. The one-story building did not cast shade on the unit. Tam O’Shanter Country Club’s Envirocaster® was centrally located on the golf course in a sod nursery. Security from vandals for the weather station at Edgewood Country Club took priority over placement in a representative or unobstructed site. The unit was situated close to maintenance buildings that could have influenced the readings compared to the golf course at large. The total DD from Edgewood County Club were slightly greater than the other sites as seen in Figures 1 and 2. Table 3 provides the total DD on the last calendar date of the project for each golf course and variable measured. 28 Table 3. Total DD for air and soil at three golf courses. 1992 and 1993. Location and Total DD September 30, 1992 and 1993 Variable Year Edgewood Forest Lake Tam O’Shanter Air 1992 NA 1099 1083 1993 1290 1295 1 176 Soil 2.5 cm 1992 1413 1267 NA 1993 1631 1471 1412 Soil 5.0 cm 1992 1396 NA 1323 1993 1618 1442 1401 NA — Data not available. *DD base 10°C beginning April 5 of the respective year. While some of the sites’ temperature data were significantly different at the or .05 level, the majority are not significantly different (Table 2). Due to missing and estimated data as a result of faulty probes, and the difficulty in obtaining effective sample sizes of the grubs under study, it was deemed beneficial to pool the sample data rather than to evaluate the variables and locations individually. Mean hourly temperatures were calculated for each variable using data from the three golf courses with Envirocasters® for both 1992 and 1993. These pooled data were used to statistically compare the air temperatures with the soil temperatures at 2.5 cm and 5.0 cm depths. The results are listed in Table 4 and are consistent with patterns normally observed between air and soil temperatures. Over the season, the air temperatures were significantly cooler than the soil temperatures at 2.5 cm and 5.0 cm depths. The soil temperatures at 2.5 cm and 5.0 cm depths were not significantly different. 29 Table 4. Golf course air and soil hourly temperature comparisons. 1992 and 1993. 1992 Variable Pair Z Statistic§ Air - Soil 2.5 cm -3.056* Air - Soil 5.0 cm -3.456* Soil 2.5 cm - Soil 5.0 cm 0.335 1993 Variable Pair Z Statistic§ Air - Soil 2.5 cm -2.211* Air - Soil 5.0 cm -2.043* Soil 2.5 cm — Soil 5.0 cm -1.012 * Significantly different at or .05. §Following Wilks’ (1995) analysis for serial correlated data. Table 5 summarizes the mean temperatures and standard deviations (SD) for air and soil depths of 2.5 cm and 5.0 cm at each of the golf course locations. The greatest variability occurs in the air temperature data for 1992 with SDS of i 6.58 to 6.75. In 1993, the soil at 2.5 cm shows the greatest variability with SDS of i 7.91 to 8.57. The 5.0 cm soil data exhibit the greatest consistency in both years with a maximum SD of i 5.23 in 1992, and 6.25 in 1993. As with the site-specific air and soil DD, the golf course (mean) DD for air and soil at 2.5 cm and 5.0 cm depths were plotted with calendar dates in Figures 3 and 4 for 1992 and 1993, respectively. In April and May during both years the DD accumulation for the soil is slower than for air. As the seasons progressed, the soil DD surpassed the accumulated air DD at the end of May (calendar dates 148 in 1992, and 150 in 1993). Once soil temperatures increased, the soils’ capacity to retain heat allowed more DD to accumulate over longer periods in contrast to air temperatures that fluctuated more rapidly (Hanks, 1992). 30 Table 5. Air and soil temperature data for three golf courses. 1992 and 1993. 1992 Location Variable Mean i SD Total DD Edgewood Air NA 2‘. Air DD = NA Soil 2.5 cm 17.57 i 5.28 2 Soil 2.5 cm DD = 1413 Soil 5.0 cm 17.46 i 5.23 2 Soil 5.0 cm DD = 1396 Forest Lake Air 15.3 i 6.58 2 Air DD = 1099 Soil 2.5 cm 16.69 i 5.29 2 Soil 2.5 cm DD = 1267 Soil 5.0 cm NA 2 Soil 2.5 cm DD = NA Tam O’Shanter Air 15.05 i 6.75 2 Air DD = 1083 Soil 2.5 cm NA 2 Soil 2.5 cm DD = NA Soil 5.0 cm 17.07 i 5.01 2 Soil 5.0 cm DD = 1323 1993 Location Variable Mean 3: SD Total DD Edgewood Air 16.43 i 7.1 2 Air DD = 1290 Soil 2.5 cm 18.17 i 8.45 2 Soil 2.5 cm DD =1631 Soil 5.0 cm 18.55 i625 2 Soil 5.0 cm DD= 1618 Forest Lake Air 16.5 i 6.99 2 Air DD = 1295 Soil 2.5 cm 17.28 i 8.57 2 Soil 2.5 cm DD = 1471 Soil 5.0 cm 17.73 i: 5.65 2‘. Soil 2.5 cm DD = 1442 Tam O’Shanter Air 15.68 i 7.02 2 Air DD = 1176 80112.5 cm 16.89 i 7.91 2 Soil 2.5 cm DD = 1412 Soil 5.0 cm 17.42 i 5.42 2 Soil 5.0 cm DD = 1401 NA — Data not available. DD base 10°C beginning April 5 of the respective year. 31 .83 .5 :8 23 .5 385 8.58 :5 .n 2:3... 800 5560.00 I'LL mmmmm 113 1793 £98 913 mmmmm ll." llLL uwmmwm 181 731 £11 011 801 owe—l ham—3| comp Do Eu o.m 4.0m mmEDOO “300' on E0 md 4.0m mmmzoo ”500' 00 £2 mmeOo “300' g s zeta/r Buruurfiea 0.01 «as do comp 83 009 32 vmmr mm: momp .naau .GQ :8 E5 be $525 09:59 :8 .v 0.5me 0505.50.00 mwmwafluwvmmmmuummmwmmwswwmw \ .......... rO cow \ 8* com com coop com. no So 9m 4.0m mmeOO “3001' no .53 .__Om mmmaoo Bowl , -83 OD m=< wmeOO “300' 009. 86/911? Buruurfies 0.01 331113 on 33 Golf course (mean) hourly air temperatures and regional (airport) hourly air temperatures from April through September were statistically analyzed using Wilks’ methodology for serial correlated data (Table 6). In both 1992 and 1993, the golf course temperatures were significantly cooler than temperatures observed at DTW airport. The golf course temperatures were cooler but not significantly different than those observed at Flint Bishop airport in either year. The two airport temperature data sets were Significantly different from each other both years with DTW consistently reporting warmer temperatures during the study period. Table 6. Golf course and regional airport hourly air temperature comparisons. 1992 and 1993. 1992 Paired Locations Z Statistic§ Golf Course - DTW -3.913* Golf Course - Flint -1.926 DTW - Flint 2459* 1993 Paired Locations Z Statistic§ Golf Course - DTW -8.321* Golf Course - Flint -0.376 DTW - Flint 5383* *Significant at or .05 level §Following Wilks' (1995) analysis for serial correlated data. After hourly temperature comparisons were made between the golf course and regional data, the regional DD BE base 10°C were plotted with golf course air DD for 1992 and 1993 in Figures 5 and 6, respectively. The DTW site had the highest DD accumulations, which would be expected. DTW is the farthest south location and is the 34 .82 .5 ca 8.58 .3» as. .825: .m 9:5... 3005.25.00 mamasmaamsommwmmumammwmmumv 801 301 omo F ommw com a e zeta/v Buruurfioa 0.01 «as do 8 S‘.‘ 35 \ 30w . l .l 11‘ . 1i: -L OD r=< mwm—DOU “300' an. ._.Z_.._n_ Ill 00 EDI .33 A5 =8 05 be 858 2% E5 .aaomwom .9 P53..— 300 5.50.00 alvlrlrlblr I’LL wwmmuwwmw 1L3 893 993 L173 683 183 833 9 13 981 £31 61 1 1 1 1 801 96 8m coop , oom— vmmw l, . 82 II no so on 3.8 $500 Bowl 8: $311. 8 so cm 3.8 $500 500' 891.. 8 m2 mmmaoo ”noel . 89 8911 on 5:”. 1| 8 3.8 II 009 36 2619/1» Buruurfioa 0.01 one do site with the greatest amount of urbanization—more paved vs. vegetated surfaces. In general, paved surfaces gain and lose heat more Slowly than vegetated surfaces (Hanks, 1992), possibly contributing to warmer temperatures overall. Although located farther north, accumulated DD from the Flint Bishop airport were also greater than the golf course DD. The same reasons that DTW was warmer may also hold true for the Flint site——an abundance of paved surfaces near the station vs. the turfgrass on and around the golf course Sites, which are affected by the cooling of evapotranspiration. (Beard, 1973) Figure 5 illustrates that the 1992 departure of DTW and Flint’s DD above golf course DD occurred at the end of April-early May, calendar dates 117-124. The DTW and Flint DD began departing from each other at about two months later, approximately calendar date 173. Season-long DD values were 1344 for DTW; 1256 for Flint, and 1090 for golf course air. Figure 6 shows all the 1993 variables—air and soil 2.5 cm and soil 5.0 cm—from the golf course DD data set plotted with the regional DD. As in 1992, the regional DD began departing from the golf course air DD in early May, around calendar date 125. The departures between the two regional data sets are less dramatic than in 1992 but are still significantly different (Table 6). The total DD accumulated by golf course soil at both 2.5 and 5.0 cm depths exceeded the Flint DD but were less than the DTW total DD in 1993. The soil 2.5 cm DD surpassed Flint DD in mid-July, calendar 201, whereas the soil at 5.0 cm DD took until August 4 (calendar 216) to exceed them. For turfgrass managers, site-specific data would be desirable for obtaining temperature data pertinent to pest management. If located properly, data generated from on-site sensors best represents local conditions allowing for more precise and informed 37 decision-making. Turf managers using airport based weather observations in their region should recognize that airport data will likely report higher temperatures than what occurs on the golf course. Adjustments should be made to compensate for differences in the environments where the temperature observations are taken, i.e., bare ground and paved surfaces at the airports vs. turfgrass covered areas. 38 Movement of Adult Ataenius spretulus and Aphodius granarius on Golf Courses In April 1992 and 1993, sticky card traps were erected to monitor the adult flight activity of Ataenius spretulus and Aphodius granart'us. Figures 7 (1992) and 8 (1993) show the periods when the adults of these two beetles were actively flying. No A. granarius beetles were trapped in 1992 and very few were trapped in 1993. There was not much flight activity by either species in 1993 between days 134 and 144 when it was cool. During this period only an average of three DD accumulated per day. Trap numbers indicate that there was an early and a late season flight of A. .spretulus. The first flight period reflects the time when the beetles moved between winter and summer habitats and were looking for oviposition sites. Based on work done by Wegner and Niemczyk, approximately 65% of all overwintering beetles are females and almost 90% of those examined in April were already inseminated. So, spring is apparently not when the beetles mate. The second period of flying activity was by the generation of insects hatched during the current season. Beetles flying in August or September may be heading for over-wintering habitat, or looking for oviposition sites. Table 7 provides information about the spring and fall flight periods for A. Spretulus and Table 8 presents similar data for A. granart'us. In 1992, the spring A. spretulus flight lasted 7 weeks while 290 air DD accumulated. The 1993 flight lasted almost twice as long as in 1992 and nearly twice as many DD accumulated during that period. Considering that in 1992 Michigan experienced below normal temperatures climatologically (NOAA, 1993), the beetles from the 1992 generation may have overwintered in a less mature State than in a normal year and required additional time and heat to complete development, or mating and ovipositing in 1993. The first adult A. 39 zeta/v Buruurfioa 0.01 «as do dag .0: =8 0.5 .5. 358 he» 05 53.2% 5.585.. :25 53,—. .h 9.5»?— 300 Lance—GO vhm wow wow vmw tum saw 05 NE mow 00? 5F #0.. st. 0:. 00.. 00F 03. N3. mar map 5.. 009 L 00¢... p % fl “ L4 # w E S .10 1 o O \ . . 8 8m 1.. ovm.\ . E - \. om - o . NR 3 2 68. \.\ . 8 ca 3.8 $58 38101 a . 05 . .89 News on m m 3.0m mwmnoo “soon-1 89 on m2 $500 "3061.1 5.232 539' on 000.. paddu; 8011008 40 eaten Buruurfios 0.010»: an 8.58 a...» 05 5.553% 353$? .5: 5.52% 5.5% :25 .33. .n 950...— .maa~ .A—Q :8 0.5 has 8.” 02.. \ \ E ‘ “.11 1 o \\ -QN mm 88 3228 2m 8m 8m 8m as man. mum 8358388. a: a: at 8. 8. mm. a: B. X: R. E a: o I x 8m -. 8.. if So - 8m L1 82 : 8m. - 8 on 3.8 $550 Boot-1 , saw. a...“ F\ . 8 3 3.8 $500 “300101 : \. 8: B: \. .5 on m_< mmmaoo boot? .\. 950:“? 5:9- We: 9.2%? 523' 82 41 spretulus beetles trapped in both 1992 and 1993 occurred the same calendar week (124- 131) although the 1992 air DD base l0°C were only 60% of those for the same week in 1993. This may suggest that something other than air temperature incites emergence from overwintering sites. Figures 7 (1992) and 8 (1993) plot adult A. spretulus and A. granarius flight activity with golf course air DD. Table 7. Flight activity of adult Ataenius spretulus and golf course air DD. 1992 and 1993. Spring [Beginning] r End 1 DD accumulated flight-Year Date DD Date DD Duration during flight 1992 128 41 177 331 49 days 290 1993 127 64 200 652 73 days 588 Fall [Beginning] F End 1 on accumulated fight-Year Date DD Date DD Duration during flight 1992 218 694 274 1090 56 days 396 1993 207 725 273 1254 66 days 529 Table 8. Flight activity of adult Aphodius mains and golf course air DD. 1993. Spring [Beginning] r End 1 DD accumulated _Fl_ight-Year Date DD Date DD Duration during flight 1992 No adults trapped. 1993 127 64 187 486 60 days 422 Fall [Beginning] 1 End 1 DD accumulated [light-Year Date DD Date DD Duration during flight 1993 250 1] 13 NA-The only beetle trapped was on date 250. The soil DD during the same calendar period (124-131) when the initial flight occurred were 27 at soil 2.5 cm in 1992, and 45 in 1993; 20 at soil 5.0 cm in 1992 and 41 in 1993. As with the air DD, the soil DD in 1993 were greater than those in 1992 the week that adult beetles were first trapped in this study. 42 Because DD indexes are usefiil indicators of biological development of some insects and plants (Richmond and Shetlar, 1996; Branham and Danneberger, 1989) the difference in the DD associated with flight activity between 1992 and 1993 was enigmatic. The thought occurred that the beetles may be developing and behaving in response to DD units not only from the current season but also from the thermal units to which they were exposed as adults the season prior to their overwintering. To investigate this theory, DD from summer and fall 1991 were counted with spring 1992 DD. Also, DD of summer and fall of 1992 were combined with spring 1993 DD. These DD combinations were then evaluated in relation to spring flight information. The Flint Bishop airport DD data were used for this comparison because it was available for reference from 1991 and through the study period. Further, the Flint temperature data were not statistically different from the golf course air DD (Table 6). In 1991, 1,004 DD BE base 10°C accumulated between calendar date 212 and 269 at the Flint airport. This would have been the approximate period when the 1991 A. spretulus adult generation were exposed to thermal units prior to seeking overwintering habitat in the fall. Based on Flint DD in 1992, 358 DD accumulated during the A. spretulus’ spring flight following the 199] late season accumulation of 1,004 DD for a combined total of 1,362 DD. In 1993, 659 DD accumulated during the spring flight following the 1992 late season DD accumulation of only 474 DD for a combined DD of 1,133. By considering the DD from the late summer and fall seasons prior to the 1992 and 1993 spring adult flight activity, there was a smaller difference in the total DD than when only the spring seasons’ DD were compared, i.e., 229 vs. 301. Although these DD totals did not include temperatures exceeding the 10°C threshold in October through 43 March, this may suggest that temperatures in the seasons preceding spring emergence might be a factor to consider in the developmental and mating stage of the beetles and thus their spring activity. Overall, this approach did not increase our confidence in the DD data and its correlation with the biological activity of A. spretulus and A. granarius. When comparing the 1992 and 1993 A. spretulus fall flight periods, the duration is nearly the same with 1992 lasting 8 weeks (56 days) and 1993 lasting just over 9 weeks (66 days). The 1993 DD are about 25% greater than in 1992 during the fall flight periods (Table 7). Tables 9 and 10 present the A. spretulus trap and flight period information in relation to the larval observations. In 1992, there were 46 days between the first adult A. spretulus trapped and the first grub collected. In 1993, there were only 17 days between these same events. Ifadult trap catches (averaged over all 6 sites) indicate oviposition activities, then the 1992 oviposition period was shorter (7 weeks) than the 1993 oviposition period (10.4 weeks). In 1992 there were 67 days between peak A. spretulus adult trap numbers and the peak grub numbers. During this 67-day period DD totals were 485 for air, 597 soil 2.5 cm; and 601 soil 5.0 cm. In 1993, 73 days passed between the peak A. spretulus adult trap numbers and peak grub sampling data. During this 73-day period DD totals were 615 for air; 747 for soil cm; and 731 for soil 5.0 cm. Wegner and Niemcyzk (1981) determined that in their Ohio golf course study the period required of A. spretulus to pass through one generation was 65 i 5 days at soil temperatures of 25 :t 6°C (range = 13 to 38°C), based on first generation periods estimated from life sampling data. Their first generation periods were determined as the number of days between appearances of first and second-generation eggs in samples. Table 9. Atacnius spretulus adult trap data related with grub observations and golf course air DD. 1992. 1992 Air DD DD Since 1“ DD Since Peak Calendar Date Adult Trapped Adult Trap 1't adult trapped 128 4 1 - - Peak adult trapped 135 81 40 - 1" grubs collected 1 74 3 19 278 23 8 Peak grub collection 202 566 525 485 Table 10. Ataenius spretulus adult trap data related with grub observations and golf course air DD. 1993. 1993 Air DD DD Since 1“ DD Since Peak Calendar Date Adult Trapped Adult Trap 1“ adult trapped 127 64 - - Peak adult trapped 134 1 10 46 - 1" grubs collected 144 123 59 13 Peak grub collection 207 725 661 61 5 45 In Michigan during this study, eggs were found only at Edgewood Country Club while sampling on calendar 165 and 172, 1993, and there were no indications of a second generation in either year. The first pupae found at this same site (Edgewood) was on calendar 200, 1993. Pupae were found up to day 228 and a callow adult was found on day 235, 1993—5 weeks after the first pupae sighting. Table 11 provides the 1993 adult A. granarius trap information for spring activity which lasted 60 days (8.6 weeks) during which time 422 air DD accumulated. There were 31 days between peak A. granarius adult trap numbers and peak grub sampling numbers. During this 31-day period the total DD were 150 for air; 199 for soil 2.5 cm; and 190 for soil 5.0 cm. Thirty-one days from peak A. granarius adult trap numbers to peak grub activity is less than half the number of days that the A. spretulus took between peak adult trap numbers and peak grub activity; 67 and 73 days in 1992 and 1993, respectively. Table 11. Aphodius granarius adult trap data related with grub observations and golf course air DD. 1993. 1993 Air DD DD Since 1" DD Since Peak Calendar Date Adult Trapped Adult Trap 1“ adult trapped 127 64 - - Peak adult trapped 134 110 46 - 1" grubs collected 144 123 59 13 Peak grub collection 165 260 196 1 50 Eighty days passed between the peak adult A. granarius trapping and the last A. granarius grub found in soil samples. A. granarius grubs were found for 10 weeks, yet the peak grub numbers occurred three weeks after the first grub sighting. Although the 46 time required for completion of one generation of A. granarius appears to be shorter than for A. spretulus, there was no evidence of a second generation by A. granarius. In 1998, when temperatures for the January-October period in the East North Central US. were 22°C above normal (NOAA, 1998), there was no evidence of a second generation of A. granarius observed at golf courses that had a first generation (Forest Lake CC). As was observed by Woodruff in New Jersey (1973), A. granarius appear to be univoltine in Michigan. The number of adult insects trapped in the late summer and early fall of 1992 compared to the number of grabs observed during June and July, reveals that there were 9% adult A. spretulus (58 adults, 613 grubs) and no adult A. granarius (0 adults, 283 grubs) trapped. In 1993, late season adult trap numbers compared to the summer grub counts revealed that 18% A. spremlus (42 adults, 228 grubs) and 0.4% A. granarius (1 adult, 256 grubs) were trapped while flying. From these observations A. granarius appear to be less active fliers than the A. spretulus beetle. There appears to be no relationship between the number of adult A. spretulus or A. granarius trapped at a given site with the number of grubs found at that same site. Instars, Sizes and Occurrence of Atacm'us sprerulus and Aphodius granarius Larvae Using an eyepiece micrometer, the head capsules of 61 A. spretulus grubs were measured in 1992 and the head capsules of 209 grubs were measured in 1993. The head size data from these two years were analyzed statistically. There were no significant differences in the head capsule sizes between years with F = 3.70, P-value = 0.056, and F critical = 3.88. Using the frequency of the head capsule sizes, a histogram (Figure 9) was 47 created and determination of size ranges per instar determined for A. spretulus collected in 1992 and 1993. Dimensions of the three instars for both A. spretulus and A. granarius are presented in Table 12. Only one specimen of a first instar A. spretulus was collected and it’s head capsule measured 0.58 mm. The mean size A. spretulus second instar was 0.85 mm :l: 0.07 and the mean size of the third instar was 1.32 mm i 0.062. Head capsule widths of A. spretulus larvae collected in Ohio (Wegner and Niemczyk, 1981) averaged 0.5, 0.83, and 1.3 mm, respectively for the three instars based on 20 specimens per life stage Although similar, apparently some variation in life stage sizes exists between populations. Figure 10 is a histogram representing the size (mm) frequency of all A. granarl'us measured. In 1992, 61 A. granarl'us head capsules were measured, while 266 were measured in 1993. Only one specimen of a first instar A. granarius was collected and it’s head capsule measured 0.7 mm. The mean size A. granarius second instar was 1.02 mm i 0.069, and the third instar was 1.53 m i 0.079. When comparing the two species of grubs, A. granarius is larger than A. spretulus during each of the three instars. Based on this project’s sampling and mean sizes, the A. granarius first instar head capsule was 0.12 mm larger than A. spretulus, 0.17 mm larger in the second instar, and 0.21 mm larger in the third instar. 48 335:3...— oumn 0.398 18.. uSSoamn 9.3.363; d 0.5!..— EE on.” 3.6a me... an... Nmé omé was 9.. mo... 1: 36 «ad 8.0 56 mud mod 3.0 $6 mw on mv on mu om _ 55:02.... _ m9. Aouenbug 49 N \\\\ .\\V B Frequency c‘ .\\\‘ \\\‘ \\\\ \\\' \\\‘ c\\\‘ \\\‘ A.“ .\\V \\\‘ u\\\ \\ ‘ u\\V \\\‘ \\\\ .\\\‘ \\\‘ u\\\ \\\ .\‘ \\\\ \\\‘ \\\F SE 1.08 1.15 1.02 0.70 0.76 0.83 0.89 0.” 110 50 Figure 10. Aphodius granarius head capsule size frequency. Table 12. Dimensions of Ataenius spretulus and Aphodius granarius instars based on measurements (millimeters). Ataenius seretulus Head Capsule Width Life Stage Range Mean :t SD Instar 1 0.58 Instar 2 0.63 —O.98 0.85 10.076 Instar 3 1.09 — 1.43 1.32 i 0.062 Aghodius ganarius Had Capsule Width Life Stgge Range Mean :1: SD Instar 1 0.7 Instar 2 0.89 — 1.21 1.02 i 0.069 Instar 3 1.3 - 1.78 1.53 i 0.079 Figures 11 and 12 represent the instar stages of A. spretulus plotted on the calendar date of the respective year that the specimens were collected. Figures 13 and 14 represent the instar stages of A. granarius plotted on the calendar date that the specimens were collected. There were no grubs found before calendar date 142 (May 21) in either year. With the exception of three of each specie found on calendar 261 in 1992, no other A. spretulus or A. granarius grubs were found after 235 (August 21) in either year. In 1992 and 1993, the presence of both grub species occurred predominantly between calendar dates 184 and 205, a three week period. The A. granarius were mostly in third instar stages and the A. spretulus were in second and third instar stages. If grub damage from both A. granarr‘us and A. spretulus is to be prevented using insecticides, timing of the application may be most beneficial during this period of species overlap. Table 13 provides a breakdown of A. spretulus and A. granarius grub populations at each golf course sampled in 1992 and 1993. Tam O’Shanter Country Club had limited A. spretulus grubs in both 1992 and 1993, and no A. granarius in either year. At three 51 .23 6.33.: 8.38%? Brice; .: unsur— ofio cue—.28 9N NPN mom 8.. 3w #3 NE. at a a - a r. in! o m op m. 93.5! ”2.52. omihl Ill]. cm «(.52. ozoomwfl m>...O IOI mD.Zm<._.