The effect of urbanisation and seasonality on wild bee abundance, body size and foraging efforts

Abstract

1. Anthropogenic changes highly impact the world's biodiversity. An important human-driven change to natural environments is increasing urbanisation, which is responsible for decreasing suitable habitats for many wild species, including bees.2. In this study, we investigate if three levels of urbanisation (low, medium and high) affect body size, foraging efforts and abundance of the sweat bee Agapostemon virescens. Overall, A. virescens was more abundant in medium-urbanised sites.3. Second-generation females (summer bees) were more abundant than overwintered (spring bees) at all levels of urbanisation. According to body size, female bees were larger in highly urbanised sites and male bees were larger in medium-urbanised sites. According to foraging efforts, we observed an increase in wing wear during spring and a decrease during summer.4. It was also found a female-biased sex ratio under high urbanisation and a malebiased in low urbanisation sites. Our results suggest that highly urbanised sites can still provide sufficient nesting and foraging resources for A. virescens.5. In addition to our findings of higher bee abundance in low and medium urbanised sites, we suggest that maintaining different levels of urbanisation and heterogenous landscapes within a populous city might have a more positive impact on wild be sustainability.

Insect ecology and conservation in urban areas: An overview of knowledge and needs

“…Urban density may also select for dispersal-enhancing morphologies within populations or species assemblages, which has been proposed for flight-related traits of aquatic beetles (Liao & Lin, 2024), as well as body size of wild bees (Brasil et al, 2023) and macro moths (Merckx, Kaiser, & Van Dyck, 2018). These patterns, which are also considered a form of ecological filtering, may reflect changes in the costs and benefits of dispersal in urban environments (Ancillotto & Rocco, 2024;Jones & Leather, 2012), although they may also reflect traits of founder individuals in low-dispersal systems, and conclusions are largely uncertain (see also genetics section below) (Federico et al, 2024).…”

Local factors influence the wild bee functional community at the urban-forest interface

“…Bees were designated to functional guilds. In the present study, we consider the following functional traits of wild bees per (Danforth et al, 2019;Fortuin and Gandhi, 2021;Braman et al, 2023;Brasil et al, 2023).…”