Cold storage of Trichogramma nerudai using an acclimation period

Low temperature induced quiescence in parasitoids Trichogramma evanescens Westwood and Trichogramma chilonis Ishii reared on Plodia interpunctella (Hübner): Its utilization as quality control for mass rearing

“…In our case, we did not measure survival of the host, in terms of P. interpunctella egg hatch, but our data show that both T. evanescens and T. chilonis were able to survive long periods at low temperature, at percentages of emergence that were generally lower than those of individuals that were not exposed to cold, suggesting that even an exposure as short as 15 d can cause some parasitoid morality. It is generally considered that exposure, and thus preservation from a practical point of view, of parasitoids at low temperature may be subjected to considerable fitness costs, including increased mortality [16,38,39], which stands in accordance with the present findings. However, Cagnotti et al [38] reported that Trichogramma nerudai Pintureau (Hymenoptera: Trichogrammatidae) prepupae, that had been stored at suboptimal temperature were not affected when the storage was 10 or 20d.…”

“…This may be attributed to the initiation of a cold-hardening procedure that might have been triggered at these conditions, switching eventually the adaptation of the parasitoids. The increased adaptation, through improved cold-hardening that is exposed more vigorously in long exposures, has been also identified in other parasitoids [38,40].…”

“…This direct response to non-suitable environmental conditions, and the subsequent response with the return of the favorable conditions, i.e. increase of temperature and host availability, may mostly suggest quiescence rather than diapause [8,38,39]. Andreadis et al [39] found that the parasitoid was generally more susceptible than the host while following a similar protocol with low temperature or the exposure of the endoparasitoid Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) on larvae of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepipdoptera: Pyralidae).…”

“…However, Cagnotti et al [38] reported that Trichogramma nerudai Pintureau (Hymenoptera: Trichogrammatidae) prepupae, that had been stored at suboptimal temperature were not affected when the storage was 10 or 20d. In this context, preconditioning may play a positive role [38,39].…”

“…Among the various insect egg parasitoids, Trichogramma (Hymenoptera: Trichogrammatidae) species are widely used for pest management throughout the world [1,2]. The most common species of this genus are Trichogramma minutum Riley, T. evanescens Westwood, T. chilonis Ishii, T. pretiosum Riley, T. deion Pinto and Oatman and T. dendrolimi Matsumura [3].…”