Natural Enemy communities are more abundant and diverse in heterogeneous landscapes, but not their interactions

Abstract

Context Land use changes have become a major driver of biodiversity loss, impacting natural ecosystems and the species that depend on them. As a result, many species have become isolated from their natural habitats and cannot interact with other species as they would in natural ecosystems. Ecological interactions are crucial for the functioning and stability of ecosystems. Objectives Here, we aimed to evaluate the effects of landscape structure on the natural enemy community and on antagonistic networks consisting of natural enemies and solitary trap-nesting bees and wasps, at two landscape scales. Methods Trap-nests were installed in forest edges in the Cantareira-Mantiqueira Corridor (CCM), Atlantic Forest biome located in São Paulo state, Brazil. Natural enemy community was described using species richness, abundance (number of attacked brood cells), parasitism rate, and taxonomic diversity. While to describe the host-natural enemy network we used the robustness metric, natural enemy’s niche overlap, and linkage density. Results The natural enemy community is richer in species when there is high forest connectivity at the local scale, while landscape heterogeneity increases abundance, taxonomic diversity, and parasitism rate. High similarity between natural enemy species’ trophic niches occurs as landscape heterogeneity increases at the local scale, and the antagonist network is dominated by generalist species of natural enemies. Conclusions Our study presents one of the first results about functional forest connectivity and landscape heterogeneity on natural enemy communities and their antagonistic interactions, highlighting the importance of landscape structure for its conservation and not just insects that respond only to the presence of their hosts in the study region. The presence of specialist species in host-natural enemy networks, both natural enemy species and bee and wasp hosts, may occur through increased functional connectivity of forest patches and landscapes and restored forest fragments.