Natural habitat cover and fragmentation per se influence orchid-bee species richness in agricultural landscapes in the Brazilian Cerrado

Habitat loss and fragmentation in the human-modified landscape affect bee assemblages by reducing the available natural resources. The life history features and adaptations of bees to environmental conditions affect how they perceive and interact with landscape structure. Therefore, it is crucial to quantify the magnitude of the effects of the landscape structure on this group at multiscale. We address the relative contribution of landscape structure in explaining the abundance of orchid bees, richness, and diversity in landscapes of Brazilian Cerrado. We mapped the surrounding landscape around 18 focal patches and sampled male orchid bees attracted by chemical baits. We used VIF and generalized linear models (GLM) to evaluate the effects of landscape structure (composition and configuration) at different spatial scales. We sampled 658 euglossine bees from five genera and 12 species. The savanna cover, forest cover, and fragmentation per se (i.e., the number of patches) were the best predictors of the richness of euglossine bees. The abundance of bees was explained by the savanna cover. The increase in natural habitat area and the reduction in landscape fragmentation favoring the assemblages of orchid bees are supported by our results. Savanna cover also modulates the abundance of euglossine bees, confirming that the habitat amount is essential for maintaining the populations of these bees. Our results reinforce the importance of habitat loss and fragmentation effects on the richness, abundance, and composition of euglossine bees, particularly in the naturally heterogeneous landscapes.