Interaction network and niche analysis of natural enemy communities and their host bees (hymenoptera: Apoidea) in fragments of cerrado and atlantic forest

Abstract

Natural enemies are important components of solitary bee communities that nest in preexisting cavities because they act as a relevant mortality factor and can regulate host population growth. Nevertheless, the natural enemy-host interaction remains poorly investigated. This research aimed to determine the composition of the community, the structure of the interaction network, and niche overlap and breadth of natural enemy species in areas of Cerrado (Brazilian savanna) and Semideciduous seasonal forest (Atlantic Forest) in the state of São Paulo, Brazil. Trap-nests made of black cardboard and bamboo canes were provided in the field and inspected monthly in each area, from August 2001 to July 2003 at Cerrado and from June 2006 to May 2008 at the Semideciduous seasonal forest. A modular structure in the interaction network was observed for both areas with the populations of natural enemies showing high degrees of specialization. This structure confers higher stability against disturbances than less specialized webs since these adversities spread more slowly through the network. The niche analysis showed low degrees of overlap for both, trophic and temporal, among the natural enemy populations.