Critical role of native forest and savannah habitats in retaining neotropical pollinator diversity in highly mechanized agricultural landscapes

Increasing food production while preserving natural ecosystem services linked to native biodiversity is one of the most important societal challenges in the 21st-century. Natural pollination performed by bees significantly increases yields even in crops that do not strictly depend on animal pollination, such as soybean. However, several factors, such as habitat loss and degradation, have contributed to the decline in abundance and diversity of bees. Here, we assess the effects of the type, complexity and amount of native habitats on Neotropical bee assemblages within agricultural landscapes. We sampled bees at 43 landscapes in the state of Mato Grosso, Brazil, within a region encompassing Amazonian rainforests, the drier Cerrado savannahs, and transitional vegetation between these biomes. We collected 1359 individuals representing 134 bee species. Bee species richness differed between soybean and core native only in Amazonian forest landscapes, while species composition differed in both forest and transition landscapes. Overall bee species richness did not differ between the three vegetation types, but species composition in forest landscapes diverged from those in transition and Cerrado areas. The amount of native habitat remaining had a positive effect on both species richness and composition. Our results show that the relentless replacement of natural ecosystems with soybean monoculture detrimentally affects bee species richness, and substantially changes the species composition. Pollinator decline has negative consequences for economics and biodiversity conservation. Therefore, we suggest that areas of native vegetation should be protected and monitored due their crucial importance for maintain biodiversity and ecosystem services through the landscape. Ideally, we suggest that strategies for the conservation of bee diversity consider the amount of native habitats at landscape scale.