Effect of Overwintering on Fecundity and Sex ratio of Trichogramma brassicae (Hymenoptera: Trichogrammatidae)

عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) is a key natural enemy of Lepidopteran key pests in Iran. Here, we investigated fecundity and sex ratio of 30 overwintered T. brassicae females which were exposed under outdoor conditions between 8 October and 11 December 2014 in central Alborz Mountains (35°48′14″ N, 50°59′55″ E; 1,346 m. above sea level), in comparison with 30 females which were kept under laboratory conditions (25 ± 1°C). We found significant differences in fecundity and sex ratio of females which survived during harsh conditions compared to those kept under controlled conditions. Based on our results, the fecundity of overwintered females (10.3 eggs per each female) decreased in comparison with control females (26.73 eggs per each female) which were reared under optimal conditions at 25 ± 1°C. Furthermore, T. brassicae females which survived under natural conditions produced less female progenies, which is influenced by the fact that overwintered T. brassicae spend so much energy for surviving during cold conditions and lose part of their energy to produce female progenies. The results of this study could be useful in applied biological control (long-term storage of Trichogramma wasps) because they showed negative effect of overwintering (lower fecundity and lower female progenies) on T. brassicae females.
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