Diapause and cold tolerance of larvae of Ephestia elutella

Abstract

Larvae of the warehouse moth Ephestia elutella were exposed to low temperatures within the range of +5°C to −10°C after different procedures of acclimation. Diapausing larvae of E. elutella were highly tolerant of low temperature exposure, requiring 4 weeks at −10°C or 12 weeks at −5°C for control. Non-diapausing larvae were much less tolerant but able to survive several weeks at O°C and up to 2 weeks at −5°C. Accelerating the rate of temperature fall during acclimation increased the effectiveness of low temperatures in achieving kill. A 12-week exposure to a temperature cycling between 0 and −5°C caused little mortality. The survivors of low-temperature exposure emerged faster and with increased synchrony over those in control batches. To achieve control in practice, temperatures need to be reduced to well below −5°C for several weeks and to avoid insect acclimation, the fall needs to be rapid.