Diversity of cavity-nesting Hymenoptera and their parasitoids in subtropical forests, southeastern China

Abstract

Backgruound & Aims: Cavity-nesting Hymenoptera are both predators and pollinators and provide key services for ecosystem functioning. Previously, there have been few studies on cavity-nesting Hymenoptera in subtropical forests. This study contributes to a greater understanding of the diversity and biology of cavity-nesting Hymenopterans in subtropical forest in China. Ultimately, a greater understanding of these organisms will help to better protect the resources wild cavity-nesting Hymenoptera use for their ecological services. Methods: Trap nests are used to study the biology, life history, diversity and ecology of solitary bees and wasps. We used this method to collect cavity-nesting Hymenoptera in 88 plots. Based on five years of long-term monitoring and sampling on Biodiversity–Ecosystem Functioning Experiment China (BEF-China) platform, we recorded the species diversity of cavity-nesting Hymenoptera and relevant occurrence patterns of solitary bees and wasps. Results: We found 3 orders, 25 families and 129 species in the trap nest system. Pollinators accounted for 26.6% of the diversity, mainly including Colletidae and Megachilidae with 12 species in 2 families. Predators represented 73.4% of the diversity, mainly including Eumeninae, Sphecidae, Pompilidae and Crabronidae with 44 species in 4 families. There were 73 species of parasitoids in 19 families, mainly including Sarcophagidae, Bombyliidae, Chrysididae, Trigonalyidae, and Eulophidae. Conclusion: For species composition, we found the diversity of pollinators was significantly less than that of predators. Meanwhile, we noted the protandry was common in cavity-nesting Hymenoptera and more obvious in overwintering individuals. In addition, we also found variable occurrence patterns in different species. The occurrence time of Megachilidae and Crabronidae were more concentrated than that of Eumeninae and Pompilidae. Finally, by constructing the interaction relationship between host and parasitoids, we explain the abundance and richness of parasitoids to be regulated by the bottom-up effect of lower trophic hosts.