Résumé
Temperature is a key factor influencing insect performance and host-parasitoid interactions. Knowing how hosts and parasitoids respond to temperature variations is crucial for predicting the success of biological control strategies, especially in the context of climate change. We investigated how developmental temperature affects the interaction between the fall armyworm (FAW) Spodoptera frugiperda, a major invasive pest, and the larval endoparasitoid Hyposoter didymator. FAW caterpillars were reared under three fluctuating temperature regimes centered at 20°C, 25°C, and 30°C (± 5°C of daily variation), and were either left unexposed to parasitism or were exposed to H. didymator. We analyzed host survival, developmental time, and body mass, as well as the success of the parasitoid. In unparasitized FAW, higher temperatures accelerated development and increased pupal survival but reduced larval survival and adult body mass. In parasitized FAW, the rate of escape from parasitism increased at the highest temperature of 30°C. For H. didymator, temperature accelerated development but had negative effects at 30°C, leading to reduced survival during the endoparasitic phase and impaired cocoon formation. The responses of the host and parasitoid produced opposite trends: the multiplication rate of FAW increased with temperature, while that of the parasitoid decreased at the highest temperature of 30°C. This study underscores the importance of considering the thermal sensitivity of both FAW and its potential parasitoids when evaluating biological control options. This type of studies will be critical for designing effective and sustainable pest management strategies.