Diversity and host–parasite interactions of cavity-nesting Hymenoptera communities in the Brazilian Savannah

Abstract

Cavity-nesting bees and wasps (Hymenoptera: Aculeata) can be good models for studies on ecology, life history, and environmental changes, especially in ecosystem ‘hotspots’ such as the threatened Brazilian Savannah biome. We aim to study the diversity and interaction networks of cavity-nesting wasps and bees as well as their natural enemies in two physiognomies of the Brazilian savannah: woody savannah and seasonal semideciduous forest. Fieldwork was performed in the Uberlândia region, Minas Gerais State, Brazil, from March 2009 to April 2010. Trap-nests made of bamboo canes and black cardboard tubes of two different sizes were set in one sampling station installed in two areas of each vegetal physiognomy. A total of 857 nests of 34 cavity-nesting wasp and bee species were collected; 302 in the semideciduous forest and 555 in the woody savannah areas. The community sampled in the four areas was characterised by few abundant species and several rare species. The alpha diversity was significantly different between the areas, which also presented a low degree of similarity. The interaction network of the community showed a modular pattern with high specialisation degrees, with almost all sampled natural enemy species attacking one host species. The data presented herein demonstrate, at a small regional scale, the importance of both woody savannah and seasonal semideciduous forest areas to maintain a high beta diversity of cavity-nesting bees and wasps and their natural enemies in the Brazilian savannah.