Microbial symbionts of hymenopteran parasitoids: an effective tool for next-generation crop protection

Parasitoids, a distinct group of insects, rely on other insects for their offspring’s development, depositing their eggs within or atop a host insect, which is then consumed during the juvenile phase. These insects possess a wide array of microbial symbionts, including viruses, bacteria, and fungi. Unlike the symbionts in herbivorous and blood-feeding insects that supply nutrients, those associated with parasitoids are crucial for the reproduction of the parasitoid, the suppression of the host’s immune system, and the alteration of the host’s behaviour, including disrupting metamorphosis and affecting the metabolism of fats in herbivorous hosts. Additionally, recent research has shown that interactions between herbivores and parasitoids within plant-associated communities at different trophic levels can be influenced by parasitoid symbionts such polydnaviruses. This suggests that the role of these symbionts is significantly broader than previously understood. This review examines the influence of parasitoid symbionts on both direct and indirect interactions among species and its implications for the dynamics of ecological communities, particularly in terms of evolutionary processes and species interactions.