Low temperature storage of larvae and synchronization of adult emergence in the predatory midge Aphidoletes aphidimyza

Diapause larvae of Aphidoletes aphidimyza were stored at a temperature of 3 degreesC under continuous darkness for up to 7 months with survival rates above 50%; after storage for I year the survival rate dropped to 12%. Diapause was terminated in the majority of individuals within 120 days uf chilling under storage conditions. Brief exposure ( 10-60 s) to the vapor of n-hexane appeared to be a useful alternative to chilling for the termination of diapause. The larvae with terminated diapause required, on average, an additional 31 days at 22 degreesC and long-day conditions in order to reach the adult stage. The 10-90% adult emergence spanned a period of 21.1 days. When the larvae with terminated diapause were exposed to 30 degreesC for 1 week after the end of low temperature storage, the survival rate was not affected. the average time-to-adult shortened moderately to 28 days, and the synchrony of adult emergence improved considerably to 10 days. Low temperature storage of nondiapause larvae resulted in a decrease in survival from 98 to 31% during the first 60 days of storage. Nondiapause larvae did nut enter diapause during low temperature storage and, as a consequence, the;adults emerged relatively rapidly (after 14-15 days) and synchronously (within 2-3 days) after the end of storage. Directions for future research, which might bring further improvement in low temperature storability and synchrony of adult emergence in A. aphidimyza, are proposed. (C) 2001 Academic Press.