Impacts of Hive Placement on Blueberry Pollination and Pesticide Drift onto Hives

Kayla Lyn Brouwer

doi:10.7273/000006344

Northern highbush blueberry (Vaccinium corymbosum; hereafter “blueberry”) is an economically important crop within Michigan, Oregon, and Washington who collectively produce 64% of all blueberries grown in the United States. Blueberry production relies on insect-mediated pollination to obtain marketable fruits and growers rely upon rented honey bee (Apis mellifera) hives to achieve profitable yields. Blueberry flower morphology is not conducive to efficient pollination by honey bees which can lead to pollination deficits and yield losses. Poor weather can also reduce honey bee activity and pollination. Commercial blueberry production also depends on pesticide inputs during the pollination period to protect flowers and limit the spread of diseases and viruses. This can put rented honey bees at risk of pesticide exposure while hives are stationed in blueberry fields. Honey bees are in high demand as the cultivation of entomophilous crops increases and beekeepers are sometimes hesitant to place their hives in blueberry fields as colony health tends to decrease during and after hives have been stationed in blueberry. Strategic hive placement may be utilized by growers and beekeepers to improve pollination in blueberry and limit honey bee hive exposure to pesticides, but research informing these practices is limited. In this study, commercial fields in Michigan, Oregon, and Washington received either clumped or dispersed hive placement treatments to determine how these placement strategies affect honey bee activity, crop pollination, and the amount of pesticide drift landing on hive boxes. Clumping was characterized by several pallets of hives concentrated in a single or few drop locations around the blueberry field, while the dispersed treatment was characterized by single pallets of hives spread along the field edge. Furthermore, hives in the dispersed treatment were closer to the field edge, while hives in the clumped treatment were further from the field edge. Clumping hives increased honey bee activity but did not improve overall crop pollination. Furthermore, clumping hives did not decrease the overall amount of pesticide drift on hives across all field locations, but the lack of differences may be due to high variability across sites and differences in grower management. Further analysis of a case study in Washington, where management was held more consistent, suggests clumping can reduce pesticide exposure and increasing the distance from field edge to hives can reduce pesticide drift onto hives. Overall, growers and beekeepers can consider clumping as a strategy to reduce potential exposure to pesticides from drift. This placement strategy should also be more efficient for beekeepers without reducing pollination outcomes.

Impacts of Hive Placement on Blueberry Pollination and Pesticide Drift onto Hives

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