S. Ya. Reznik and N. P. Vaghina. 2006. Heat Shock Influences on Parasitization of the Angoumois Grain Moth Sitotroga cerealella Oliv. (Lepidoptera, Gelechiidae) Eggs by the Egg Parasitoid Trichogramma principium Sug. et Sor. (Hymenoptera, Trichogrammatidae) Females.

Entomological Review, 2006, Vol. 86, No. 8, pp. 861–865. 

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Experiments have showed that heat shock (45°C during 30 min) caused a twofold increase in mortality of T. principium females recorded during two days after the shock. The percentage of females that have started parasitization of the grain moth eggs (among all survived females) sharply decreased (40–50% and 30% in controls and in treated females, respectively). Thus, the switch from egg retention to parasitization of less preferred hosts was not the result of “pathological” changes in a senescent or dying wasp, but a “normal” stage of adult life. Females that have already started parasitization before the heat shock, continued to parasitize after the shock (differences between treatments and controls were not significant). Obviously, the heat shock influence on oviposition was mostly indirect (as a cue factor) and the wasps that have already started parasitization, were insensitive to this cue. These data resemble the loss of sensitivity to the diapause-inducing factor which was often observed after reactivation. We conclude that the results of our study confirm analogies between egg retention and reproductive diapause.