Flower plantings support wild bee reproduction and may also mitigate pesticide exposure effects

1. Sustainable agriculture relies on pollinators, and wild bees
benefit yield of multiple crops. However, the combined exposure to
pesticides and loss of flower resources, driven by agricultural
intensification, contribute to declining diversity and abundance of many
bee taxa. Flower plantings along the margins of agricultural fields offer
diverse food resources not directly treated with pesticides. 2. To
investigate the potential of flower plantings to mitigate bee pesticide
exposure effects and support bee reproduction, we selected replicated
sites in intensively farmed landscapes where half contained flower
plantings. We assessed solitary bee Osmia lignaria and bumble bee Bombus
vosnesenskii nesting and reproduction throughout the season in these
landscapes. We also quantified local and landscape flower resources and
used bee-collected pollen to determine forage resource use and pesticide
exposure and risk. 3. Flower plantings, and their local flower resources,
increased O. lignaria nesting probability. Bombus vosnesenskii
reproduction was more strongly related to landscape than local flower
resources. 4. Bees at sites with and without flower plantings experienced
similar pesticide risk, and the local flowers, alongside flowers in the
landscape, were sources of pesticide exposure particularly for O.
lignaria. However, local flower resources mitigated negative pesticide
effects on B. vosnesenskii reproduction. 5. Synthesis and applications.
Bees in agricultural landscapes are threatened by pesticide exposure and
loss of flower resources through agricultural intensification. Therefore,
finding solutions to mitigate negative effects of pesticide use and flower
deficiency is urgent. Our findings point towards flower plantings as a
potential solution to support bee populations by mitigating pesticide
exposure effects and providing key forage. Further investigation of the
balance between forage benefits and added pesticide risk is needed to
reveal contexts where net benefits occur.