Seasonally acclimatized diapausing larvae of Bathyplectes curculionis (Thomson) were exposed to extreme hxgh and low temperatu~es to determine lethal temperatures for this stage of the parasite. The possible effects of relative humidity on high temperature mortality, mortality induced by repetitive exposures to sublethal temperatures, and differential survival between sexes, were also measured. The upper lethal temperature for summer larvae was 60°C (LDSo from 2 to 4 h), and the lower lethal temperature for winter larvae was -25°C (LDSo from 0 to % h). Summer larvae showed significantly increased mortality with repetitive exposures to sublethal temperatures (55OC) whereas winter larval mortality did not increase significantly with repetitive exposures to sublethal temperatures (-20°C). In winter experiments in which the sex of the emerging adult could be measured, no significant difference in survival was found between the sexes. Our results, in conjunction with published field data, strongly suggest that heat kill in the summer may be a significant mortality factor in warmer areas of the parasite's range.
Cherry, Ronald H.; Armbrust, Edward J.; and Ruesink, William G.
"Lethal Temperatures of Diapausing Bathyplectes Curculionis (Hymenoptera: Ichneumonidae) a Parasite of the Alfalfa Weevil (Coleoptera: Curculionidae),"
The Great Lakes Entomologist, vol 9
Available at: https://scholar.valpo.edu/tgle/vol9/iss4/4