Diapause-induced transgenerational performance of Trichogramma ostriniae exploiting Corcyra cephalonica eggs

Diapause induction is a crucial method widely used for storage in commercial production of Trichogramma, which may affect biological traits of parasitoids significantly. However, whether the diapause-induced biological changes persist across generations has never been determined. In a preliminary experiment, we found that diapause-exposed females of Trichogramma ostriniae showed a positive effect interpreted as increased oviposition.

In the present study, we compared the diapause-exposed and unexposed T. ostriniae individuals by measuring a diversity of essential biological parameters in a transgenerational manner across four consecutive generations (F₀-F₃). Our results showed much higher numbers of parasitized eggs on Corcyra cephalonica eggs and significantly longer longevity in the diapause-exposed T. ostriniae than in those of diapause-unexposed. Most importantly, the above advantages of biological characteristics were shown in the F₀-F₂ generations of adults which went through diapause, and then returned to diapause-unexposed levels until the F₃ generation. Additionally, no quality reduction of T. ostriniae appearance were induced by diapause exposure, which was expressed as no significant differences in female rate, body and hind tibia length between the diapause-exposed and unexposed treatments across F₀-F₃ generations.

Our study is the first report that reveals the transgenerational plasticity of the enhanced parasitism resulting from diapause. These findings are important for designing optimal storage methods for T. ostriniae and developing efficient pest biocontrol strategies. © 2025 Society of Chemical Industry.