> The intent of the study was to determine, by ELISA assay, the amount of imidacloprid in water sources that are likely to be visited by honeybees. In rural areas, honeybee water sources were anticipated to include low puddles in fields, small streams, and wetlands, and in residential and urban areas, sources were anticipated to include storm management ponds, street drain puddles, koi ponds, fountains, and potted plant holders. Eighteen distinct sites spanning Maryland’s agricultural Eastern Shore to the Pennsylvania line and including suburban/urban areas in or near Baltimore, Annapolis, and Washington, DC, were chosen which surveyed diverse habitats including livestock and crop farms, residential neighborhoods, and cityscapes.  

> Assessing the exposure levels of IMI on honeybee health is complicated. A sample such as the nursery puddle sample containing 131 ppb may be high enough to kill a small percentage of a nearby population of bees, but IMI concentrations in honeybee water sources seem to exist mostly at low sublethal doses which should pose less risk to the health of the colony. Changes in water movement and volume such as evaporation increasing a puddle concentration or rainfall diluting a concentration would make quantification of a water-soluble pesticide a time- or weather-dependent event. Hives near golf courses and nurseries where IMI is likely to be regularly applied might present the highest risk of exposure. This risk could be mitigated by the presence of alternate pesticide-free water sources provided naturally or by an apiarist.   

Johnson, J. D., & Pettis, J. S. (2014). A Survey of Imidacloprid Levels in Water Sources Potentially Frequented by Honeybees (Apis mellifera) in the Eastern USA. Water, Air, & Soil Pollution, 225(11), 1-6.

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