Neonicotinoid insecticides have been studied as possible contributors to bumble bee declines in North America and Europe. This has potential significance in corn agro-ecosystems since this crop is frequently treated with
neonicotinoids and dominates much of the agricultural landscape in North America and Europe where bumble bees and other pollinators are commonplace. We conducted an experiment where commercial bumble bee (Bombus impatiens)
hives were placed during pollen shed next to corn (Zea mays) fields that were grown from "conventional" seed that was treated with
neonicotinoids, or "organic" seed that was not treated with pesticides. Samples of pollen were collected from corn plants for
neonicotinoid residue analysis, pollen types carried by worker bees returning to
hives were determined, and in autumn
hives were dissected to measure various endpoints that serve as markers of colony vigor.
Clothianidin was detected (0.1-0.8 ng/g) in pollen collected from all conventional fields, but was not detected in pollen from organic fields. Corn pollen was only rarely collected from bumble bee foragers and the vast majority of pollen was from wild plants around the corn fields. All
hives appeared healthy and
neonicotinoid seed treatments had no effect on any hive endpoints measured, except the number of workers, where significantly fewer workers were recovered from
hives placed next to conventional fields (96 ± 15 workers per hive) compared to organic fields (127 ± 17 workers per hive). The results suggest that exposure during pollen shed to corn grown from
neonicotinoid-treated shed poses low risk to B. impatiens.