Landscape Structure Effects on Bee and Wasp Assemblages in a Semiarid Buffer Zone

Understanding the effects of anthropogenic changes on groups that perform key ecosystem services, such as pollination and pest control, is essential for conservation and maintenance of these groups in landscapes. We aimed to understand how landscape heterogeneity and the natural vegetation loss affect the diversity of bees, wasps and their parasitoids in a resource limited semiarid environment. We sampled bees and wasps that nest in pre-existing cavities in 20 landscapes, for two years, in Ubajara National Park, in northeastern of Brazil. We recorded eleven species of bees, nine of wasps and six of parasitoids in 657 trapnests. Landscape heterogeneity had different effects on bees, wasps and their parasitoids. Landscape configuration had stronger effect than composition. Bee abundance decreased according to the complexity of the spatial arrangement of landscape units, while wasp abundance increased. Our study shows that in semiarid regions some species may have different responses to landscape structure from those found in other regions. The spatial patterns described here have important implications for conservation of these essential biological groups, indicating that conservation actions for these groups should associate both landscape composition and configuration to increase the provision of resources and to facilitate the access to resources throughout the year.