Bee and wasp responses to a fragmented landscape in southern Brazil

The available studies on Hymenoptera assemblages in fragmented landscapes have shown that these insects are sensitive to fragmentation, besides some different conclusions which are possibly linked to different landscape attributes and sampling designs. The present objective is to determine the correlation among the descriptors of bees and wasps assemblages with fragment predictors (size, connectivity and edge effect) within a fragmented landscape of Semidecidual Seasonal Forest (Paraná State, Brazil). For this purpose five forest fragments, from three to 484 hectares, were sampled during a year, summing up 480 samples of baited traps and 3,480 of bowl traps. We have found that abundance of Apinae and oligolectic bees increase and the richness of Augochlorini bees decreases with increasing fragment size. Connectivity has positively influenced bee richness and edge effect has positively influenced the abundance of oligoletic bees. Orchid bees also respond to the site predictors, especially for the Eufriesea violacea, which abundance was positively correlated with fragment size and connectivity, however negatively with edge effect, and Eufriesea nigrita which abundance was negatively correlated with fragment size, but positively with edge effect. Composition of bees, Crabronidae and Pompilidae wasps were influenced by fragment size. Plebeia droryana and Tetrapedia diversipes could be considered as indicators, according to their sensitiveness to habitat predictors. Our results are congruent with previous studies which found that bees are sensitive to landscape fragmentation, we suggest that the group be used in ecological indicator and monitoring studies.