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

Abstract

Abstract 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. 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. 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. It was also found a female‐biased sex ratio under high urbanisation and a male‐biased in low urbanisation sites. Our results suggest that highly urbanised sites can still provide sufficient nesting and foraging resources for A. virescens. 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.