Long- and short-term changes in social wasp community structure in an urban area

The success of social wasps in anthropic environments is related to their ability to nest both in vegetation and human constructions, and, as humans modify their own environments, wasps community structure may shift as well. Our aim was to assess the diversity of social wasps and their interactions with nesting substrates seasonally in an urban squares area in Southeastern Brazil, 15 years after the first diversity study in this area. We actively searched for nests in the rainy season between 2014 and 2015 and in the dry season of 2015. Although social wasp species richness did not change since the 2000 assessment (13 species in 5 genera), the abundance decreased substantially. Additionally, wasps showed a general trend of nesting on the man-made materials Metal (n = 115, 60%) and Concrete (n = 106, 36%), especially by the two most common species sampled: Mischocyttarus cassununga and Polistes versicolor. We suggest that abundance decrease may correspond to the reduction of green areas in the assayed locations. These results support the well-known importance of maintaining green areas in urban environments to promote the growth and conservation of diverse social wasp communities.