Urban landscapes affect wild bee maternal investment and body size

Urbanization is considered one of the major threats to biodiversity worldwide, with a special concern for native species decline, including wild bees. Through the increase of impervious surfaces, urbanization diminishes, fragments, and warms city environments, significantly reducing nesting and foraging resources for bees. Understanding the response of wildlife to urbanization in terms of reproduction, foraging efficiency, and offspring provisioning is important to species conservation in the face of continued urban development. In this study, we investigated how different levels of urbanization affect individual foraging effort, survival, brood productivity, and fitness in Ceratina calcarata. Our findings show that low urbanization levels favour larger-bodied adults, but foraging efforts (determined by wing wear) were higher at moderate disturbance levels. Larger-bodied mothers produced more numerous offspring (clutch size), mainly in medium disturbance sites. Likewise, larger-bodied mothers produced a larger-bodied offspring at low urbanization levels. Our results indicate that wild bees benefit from low and medium levels of urbanization indicated by maternal and offspring fitness in terms of body size and the number of brood, respectively. This suggests significant effects of urbanization on the fitness and stability of wild bee populations. This study provides novel insights into the impact of urban land use and highlights the importance of conserving and providing green spaces for pollinators.

Automated summary

Urbanization is a major threat to biodiversity worldwide, especially for native species decline, such as wild bees. This study investigates how different levels of urbanization affect individual foraging effort, survival, brood productivity, and fitness in Ceratina calcarata (a species of wild bee). The results show significant effects of urbanization on the fitness and stability of wild bee populations, highlighting the importance of conserving and providing green spaces for pollinators.