Bee reproduction on farms relative to honey bee hives, wildflower plantings, and seminatural habitat

Planting wildflower meadows on farms and preserving natural/seminatural habitat surrounding farms are strategies aiming to mitigate wild pollinator declines and promote crop pollination services. It is unclear, however, whether or how these aims are impacted by managed honey bee (Apis mellifera L.) hives on farms. In a previous study examining how wildflower plantings and honey bee hives and/or their interaction influence wild bee communities and the fruit count of two pollinator-dependent crops across 21 farms in the Mid-Atlantic U.S., we found that the presence of hives decreased wild bee abundance and species richness as well as strawberry and winter squash fruit count and that the benefits from wildflower plantings did not offset these decreases. To examine how bee reproduction varied on this network of farms relative to honey bee hives, wildflower plantings, and seminatural habitat, we measured the fecundity (offspring production) of solitary cavity nesting bees, the reproductive potential (body weight) of female alfalfa leafcutter bees (Megachile rotundata F.), and colony growth (maximum weight change) of the common eastern bumble bee (Bombus impatiens Cresson). We found that farms with hives generated lower solitary cavity nesting bee fecundity and alfalfa leafcutter bee reproductive potential, while bumble bee colony growth was unaffected. Wildflower plantings and seminatural habitat enhanced leafcutter bee reproductive potential and solitary bee fecundity, respectively, but neither offset the decreases associated with hives. Overall, this work shows that honey bee hives could reduce the conservation value of wildflower plantings or habitat preservation on farms.