Effect of diapause induction temperatures on the fitness of Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae)

Trichogramma wasps have been the subject of intensive research because of their wide application in biological control programs since the past decades. Increasing the fitness of Trichogramma during their production and storage was one of the points that have always attracted the attention of researchers, producers and consumers of these biological control agents. Temperature as one of the main environmental factors that influence all life stages has always been effective on the fitness of insects. We investigated the effect of temperatures (10, 14 and 20°C) on the emergence rate, sex ratio, fecundity and mortality of different developmental stages of Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae) in order to examine the response of parasitoid to low temperatures. Based on the obtained results, larvae and pre-pupae were the most sensitive and resistant life stages of T. brassicae to low temperatures, respectively. A direct relationship was observed between both emergence rate and fecundity of T. brassicae with temperature. The proportion of emerged females did not show a statistically significant difference when parasitoid was exposed at low temperatures. According to the results, T. brassicae can enter dormancy (diapause-quiescence) using cold storage although the diapause incidence through low temperature exposure is associated with reduced fitness of T. brassicae.