BIOLOGIA E ECOLOGIA DE VESPAS E ABELHAS SOLITÁRIAS (INSECTA, HYMENOPTERA) EM FRAGMENTOS DE FLORESTA OMBRÓFILA MISTA

Abstract

Before current global scenarios of biodiversity loss, human activities have been responsible for most environmental changes that compromise the persistence of species, alter their distributions, and bring about changes in antagonistic and mutualistic interactions. Natural enemies are important components in communities of solitary wasps and bees that nest in preexisting cavities, since they act as a relevant mortality factor and may help regulating the growth of the host population. However, the natural interaction of the host remains little investigated. In this study we investigated whether the cluster of wasps and bees nesting in preexisting cavities and associated natural enemies differ in two fragments of Atlantic Forest and two adjacent matrices areas. For the sampling of these insects, trap nests made of wood and bamboo were installed in two fragments of forest and in their adjacent matrix areas. A total of 580 trap nests were collected in the studied areas. Seven species of wasps were common to forest and matrix areas, and the highest nests abundance was found in the matrix (350 nests), where there were 22 species of wasps and seven species of bees. The richness estimator Chao1 indicated that the expected richness was very close to the one observed for all areas. Although we did not verify significant differences for the diversity indexes between forest fragments and adjacent matrices, it was possible to observe that the composition of the species changes with the forest withdrawal. It was observed a greater number of interactions occurring in the adjacent matrix area, where 11 species of wasps and bees were attacked by 19 species of natural enemies, whereas in forest fragment, seven species of wasps and nine species of natural enemies were observed. Interaction networks presented a more general and modular pattern with low connectivity and nesting, while robustness values indicated that host species are stronger to resist secondary extinctions, making the network more stable for host species.