EFFECT OF TEMPERATURE ON DEVELOPMENT OF HYMENOPTEROUS PARASITOIDS OF DENDROCTONUS-FRONTALIS (COLEOPTERA, SCOLYTIDAE)

Investigations were conducted on effect of temperature on development of parasitoids of the southern pine beetle, Dendroctonus frontalis Zimmermann. Coeloides pissodes (Ashmead), Dendrosoter sulcatus Muesebeck, Spathius pallidus Ashmead, Dinotiscus dendroctoni (Ashmead), and Heydenia unica Cook & Davis were studied in the field and at constant temperatures of 15, 20, 25, and 30-degrees-C in the laboratory. Development of parasitoids from egg to adult at field temperatures during August 1991 required almost-equal-to -2 wk for all species. The southern pine beetle requires almost-equal-to 1 mo to complete development at optimum temperatures. There was little difference in development times among these parasitoid species at 20-degrees-C. All parasitoid species required approximately twice as long to develop at 20-degrees-C than at the two higher temperatures. Males generally developed more rapidly than females at all temperatures. Survival of all species except D. dendroctoni decreased at 15-degrees-C. The greatest numbers of parasitoids were reared from study trees that contained an almost-equal-to -1:1 host-stage ratio of late instars to pupae.