Genera-specific analysis of wild bees in an urban ecosystem
Wednesday, August 4, 2021
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Matthew Healy, Adam Germaine, Prisca Sanon, Christina Orazine, Andrew Oguma and Michael Bankson, Division of Science and Mathematics, Massasoit Community College, Brockton, MA
Division of Science and Mathematics, Massasoit Community College Brockton, MA, USA
Background/Question/Methods Reports of declines in pollinators, including wild bees, suggest the need to investigate the cause of these declines. Urbanization is thought to contribute to pollinator loss by reducing habitat and/or foraging resources. Studies at the community level measuring overall bee abundance may fail to fully characterize the impact of urbanization on individual bee genera. Monitoring the success of individual bee genera in an urban to suburban ecosystem may provide insight into the long-term relationship between various aspects of urbanization and the bee community. Therefore, this study investigated how individual bee genera react to three proxies of urbanization: percent impervious land cover, percent forest cover, and forest fragmentation index (area/edge), across six study sites in Southeastern Massachusetts over four years (2016-2019). Results/Conclusions A total of 10,939 bees from 39 genera were sampled over four years. Five genera, comprising 5% or more of the total abundance, were included in the analysis with Apis (10% of total) excluded due to their domestic status. Abundance consisted of 36% Lasioglossum, 10% Agapostemon, 8% Ceratina, 7% Halictus, and 7% Bombus. Analysis of mean bee abundance per sample showed a significant main effect of genera ( p<0.01 ) but not year (p=0.73). There were significant interactions between genus and percent impervious land cover as well as percent forest cover (p<0.01 for each) but not between genus and forest fragmentation index (p=0.26). Noticeably, Bombus abundance had a positive relationship with impervious land cover (r=0.47, p=0.02) and edge ratio (r=0.53, p<0.01) while other genera had negative relationships with both proxies. Bombus showed a negative relationship with percent forest cover (r=-0.69, p<0.01) while Lasioglossum had a positive relationship (r=0.43, p=0.036), suggesting that Bombus may be better adapted to urbanized environments than other genera in southeastern Massachusetts. These results suggest that genera interactions may vary in urban ecosystems.