Solitary bees in Pampean agroecosystems: A review about current status of knowledge

Abstract

The Pampean region constitutes one of the most extensive and productive grasslands in the world and experienced an abrupt agricultural expansion in the 20th century, which transformed the landscape into a mosaic of agricultural fields, extensive pasture lands for cattle, and scarce semi-natural habitats. These anthropic modifications strongly impact biodiversity, including solitary bees. In Pampean agroecosystems, the ecology of these important insects has been poorly studied. Here, we synthesise the information from our studies in four Argentine Pampean agroecosystems. Our aims are to present a reliable portrait of the diversity of solitary bees, provide a short overview of the current state of knowledge, compare our results with other studies carried out in the Pampean agroecosystem, and discuss the biological and anthropic threats. We analysed ca. 3500 individuals belonging to 82 wild bee species/morphospecies in 31 genera of five families, however, this does not represent the total richness, but serves as a baseline. Additionally, we analysed a total of 20 cleptoparasite bee species and other predator organisms (wasps, flies, and beetles). We found that low floral diversity (mainly exotic species), and the use of agrochemicals could be limiting solitary bee populations. In this current agricultural scenario, solitary bee species face a complicated situation as the crop homogenization and the low availability of semi-natural habitats play against their survival. We are facing a pivotal moment in which we must rethink how to produce food and other resources, adopting a more environmentally friendly management approach that considers all participants (animals, plants and ourselves).