Colony Development and Reproductive Success of Bumblebees in an Urban Gradient

Urban Farm DB summary

A study placed experimental bumblebee nests at 10 sites (nine of them community gardens) across an urbanization gradient (0-99% urbanization) in the United States to assess the effects of urbanization on colony development and reproductive success. Reproductive success and colony size were positively correlated with the nests' cumulative weight gain (p < 0.05), but the degree of urbanization had no significant effect on population growth rate or forager activity (p > 0.05). Growth rate was strongly negatively affected by the abundance of wax moth larvae (p < 0.05) and positively correlated with parasite diversity (p < 0.05) and the number of foragers entering the nest (p < 0.01). The study concludes that both bottom-up and top-down effects are equally important for pollinator population dynamics.