Abstract
* Hymenopteran parasitoids are crucial in regulating host population dynamics and acting as natural pest control agents in agroecosystems. Despite their acknowledged importance, they are to this day largely understudied, especially concerning their community ecology.
* We compared communities of pentatomoid bugs, representing many pest species, and their respective egg parasitoids between farmland ecotones—comprising the initial rows of apple orchard and bordering hedges—and semi-natural ecotones. A focus was laid on Trissolcus japonicus, an exotic and newly introduced parasitoid of Halyomorpha halys. We also investigated the total communities of hymenopteran parasitoids and potential arthropod hosts, expecting increased diversity in semi-natural ecotones for both.
* Trissolcus japonicus was not detected, whereas Trissolcus mitsukurii, another exotic parasitoid of Halyomorpha halys, was found only in farmland ecotones, reflecting its host's primary distribution. Pentatomoid bugs were more abundant in farmland ecotones, while their specialized parasitoids were equally distributed between both ecotones. Arthropod richness was higher in semi-natural ecotones, while parasitoid diversity scored higher in farmland ecotones, suggesting that farmland ecotones represent a suitable environment for diverse parasitoid communities. Furthermore, the communities of both potential hosts and parasitoids were correlated, as evidenced by parasitoid-host co-occurrences in both habitats.
* Our study emphasizes the role of different habitat types in maintaining diverse parasitoid communities and underlines the high value of hedges along field margins in agroecosystems. Further research on species–habitat networks, as well as parasitoid-host co-occurrences, is needed for optimizing habitat management and ensuring sustainable pest regulation.