Investigation of the parasitic effects of trichogramma evanescens westwood (hymenoptera: trichogrammatidae) on ephestia kuehniella zeller (lepidoptera: pyralidae) eggs under increased carbon dioxide (co₂) and different temperature conditions

This study was conducted to determine the parasitism rate of the flour moth eggs by Trichogramma evanescens (Westwood) (Hymenoptera: Trichogrammatidae), which has great global importance as an egg parasitoid, under laboratory conditions at the same temperature but different CO₂ concentrations, using eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae). In this study, four controlled greenhouse chambers with 400, 600, 800, and 1,000 ppm carbon dioxide concentrations were used. Experimental temperature regimes were set at 32/22, 29/19, and 26/16 °C. After maintaining previously prepared T. evanescens-parasitized egg strips for three generations in the greenhouse chambers, the obtained individuals were used to establish the experiment in each climate chamber with five parental tubes, each containing 50 parental individuals. The experiment lasted four days. On the first and second days, strips containing 200 unparasitized E. kuehniella eggs were provided to the parental tubes, whereas on the third and fourth days, strips containing 100 eggs were used. The effects of temperature, CO₂ concentration, and time on the biological performance of the parasitoids were evaluated both individually and interactively. Temperature and day factors had highly significant effects on all examined biological parameters of T. evanescens. The highest parasitoid performance was obtained at 32 °C on the first day, where the number of eggs laid per female and the parasitism rate were significantly higher compared to other temperature treatments. As days progressed, a gradual decrease was observed in the number of parasitized eggs and the proportion of female individuals, with reductions reaching 30–50% in some parameters. The interaction between CO₂ level and day was also statistically significant for all parameters, and the highest values were recorded at 1.000 ppm CO₂ on the first day. These findings indicate that under climate change conditions, biological control strategies should be reconsidered and optimized by taking environmental variables into account.