Performance of diapausing parasitoid wasps, Habrobracon hebetor, after cold storage

Abstract

The ectoparasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is an important potential biological control agent for lepidopterous pests of stored products. We investigated the effects of long-term cold storage of diapausing and nondiapausing H. hebetor on their performance after cold storage. Mortality during storage increased with increasing storage duration, and the mortality of diapausing females was lower than that of nondiapausing females after 8, 12, and 16weeks of storage. Longevity, egg laying, number of progeny produced, and time to 50% egg laying were all reduced, as compared with the culture females when parasitoids were reared at conditions that do not induce diapause. But, for females reared at 20°C at conditions that induce diapause, all of these quality parameters did not differ from those of culture insects when the storage duration was 8weeks or less. The percentage of female F1 offspring was always lower for cold stored insects than for the culture insects. Presence of a male after cold storage did not impact any of the quality parameters measured. Thus, rearing parasitoids at 20°C and 10L:14D and then storing them for up to 8weeks at 5°C would produce parasitoids that are similar to culture parasitoids, except that the percentage of females is lower than that in the cultures (36% vs. 52%).