Effects of constant low-temperature storage on the performance of a commercial strain of aphidius colemani

This study determined the effects of cold storage of mummies on the biological characteristics of Aphidius colemani Viereck (Hy-menoptera Braconidae), a solitary, koinobiont endoparasitoid of more than 40 species of aphids. The effects of three constant temperatures (5, 7 and 9 °C) at five time periods (5, 10, 15, 20 and 30 days) were evaluated on eight quality control parameters of the parasitoid (adult emergence, sex ratio, time elapse before emergence, adult longevity, length of the hind tibia, flight capacity, percent parasitism and sex ratio of F1 wasps). The results showed that all parameters except the sex ratio of F1 were negatively affected by cold storage duration in comparison to control treatment (25 °C). Based on the adult emergence and sex ratio, A. colemani could be stored for 15 days at 5 and 7 °C and for 10 days at 9 °C but it is important to consider other quality control parameters (time elapse before emergence, adult longevity, adult size, flight capacity and percent parasitism). However, when the mummies of A. colemani were stored for longer than 10 days, their quality criteria were more negatively affected at all three temperatures. The results are discussed in order to facilitate the planning of A. colemani mass rearing and aphid biocontrol programs.