7: Proportion of commodity crop pollens in honey bee diets in two landscapes

Honey bees are important managed pollinators in commercial agriculture.  Mixed agricultural landscapes in the mid-south can be vital to maintaining commercial honey bee operations during prolonged nectar dearth.  Declines in bee populations generate concerns about the relationship of pesticide-treated crops and honey bee health.  To investigate the role of pollen from treated crops as a component of bee diet, colonies were established in both agricultural and urban areas.  The agricultural site was surrounded by a mixture of soybeans, corn, cotton, grain sorghum.  Urban hives were located within a large urban community garden, containing diverse fruit, vegetable and ornamental plants, as well as pasture, woodland, wild areas, and residential lawns.  Pollen loads were collected directly from retuning foragers, approximately every two weeks for an entire honey production season (March- September). Pollen collection began before seed-treated crops were planted, and continued until crops had ceased blooming.  Pollen was visually identified to lowest taxonomic level possible, to determine the proportion of the bees’ pollen diet that was derived from agricultural crops for each sample.  Results suggest that the proportion of pollen from crop sources was negligible during most of the bloom period, but was significant for a brief period when other wildflower sources may have been unavailable.  Pollen samples were also screened for pesticide residues.  Very little insecticide or fungicide residues were detected in pollen samples, except for the brief period when bees collected crop pollens.  Herbicide residues were detected throughout the season, and often at very high levels.