Foraging behavior and reproductive biology of the southern pine beetle, Dendroctonus frontalis Zimmermann, parasitoid complex

Areas of reproductive biology and ecology of adult Dendroctonus frontalis Zimmermann parasitoids are addressed within this dissertation. In Chapter 1, the baseline egg load of D. frontalis parasitoids is examined, while in Chapter 2, the effects of D. frontalis and Ips calligraphus (German) size on body size and baseline egg load of their parasitoid, Roptrocerus xylophagorum Ratzeburg, is examined. Adult D. frontalis parasitoids in the family Pteromalidae had the most mature eggs, followed by D. frontalis parasitoids in the Braconidae and Eurytomidae. Variation in number of eggs was noted among individual parasitoid taxa. Female R. xylophagorum females reared from the larger bark beetle, I. calligraphus , were larger and contained more eggs, than those reared from D. frontalis. Female body length of R. xylophagorum was positively correlated with number of mature eggs. In Chapter 3, the impact of rainfall on trap catch of D. frontalis parasitoids on infested pine boles is explored, while in Chapter 4, the height distribution of D. frontalis parasitoids trapped along pine boles is examined. Any rainfall over a single 2-day trapping period increased trap catch of D. frontalis parasitoids. Rain differentially affected catch of each species. A positive correlation existed between height on the bole and number of parasitoids, with the majority of parasitoids preferring the upper bole. Each parasitoid species had different height preferences. In Chapter 5, an initial foraging study is expanded to determine if adult D. frontalis parasitoids will forage for Eliminade™, an artificial food, on hardwood understory foliage and the degree of foraging for Eliminade™ on pine canopy, boles or hardwood understory foliage by parasitoid adults over time and with respect to individual parasitoid species. Percentage of parasitoids feeding was 62% ± 10%. Parasitoid feeding remained the same immediately after application, regardless of Eliminade™ location. Seven days after Eliminade™ application, parasitoid feeding on pine boles had not declined, while feeding in canopy and understory declined to be no different than control infestations without Eliminade™. Differences in degree of foraging existed between parasitoid species, but it was not based on location of food. In Chapter 6, the incidence of homopteran honeydew under pines and hardwoods within D. frontalis infestations is examined to determine if any is available to D. frontals parasitoids. There was more honeydew beneath hardwood trees compared to pines. Amount of honeydew changed between sampling dates, depending on site. Mean weekly temperature and rainfall were both negatively correlated with number of honeydew droplets.