AbstractThe development and survival of mountain pine beetles axenically reared on standardized diet at 8 constant temperatures (10°–35 °C) were observed. At 32 °and 35 °C, 22 and 18% of the eggs hatched and all larvae died within 10 d of hatching. At the lower temperatures, 60–70% of the eggs hatched. The highest survival for all developmental stages was at 24 °C. At 10° and 15 °C development of all beetles reared in bolts of lodgepole pine or on axenic diet stopped when larvae were fully developed, whereas at 24 °and 27 °C all of the beetles developed normally to the adult stage. Larvae that had stopped developing during rearing at 15 °C resumed development after being transferred to 24 °C, indicating that pupation was limited by temperature. Although mean development times to the larval, pupal, and adult stages all decreased with increasing incubation temperature, heat-unit requirements above a base temperature of 5.6 °C were lowest for individuals reared at 27 °and 24 °C for all developmental stages. At these temperatures, an estimated average of 673 and 674 degree-days above 5.6 °C were required for development from egg to the tanned (dark) adult stage, respectively. The average widths of the prothorax and the sex ratios of axenic beetles were within published ranges. Mean development times and heat-unit requirements at constant temperatures for development to various life stages agreed well with published field and laboratory studies from western Canada.
Autumn shifts in cold tolerance metabolites in overwintering adult mountain pine beetles