Pesticide Contamination in Native North American Crops, Part I—Development of a Baseline and Comparison of Honey Bee Exposure to Residues in Lowbush Blueberry and Cranberry.

Simple Summary: Working in two native berry crops, we trapped honey bee pollen as foragers entered the hive. We then obtained grower records of the pesticides that were applied on the farm. We analyzed the pesticide residues in each pollen sample and established a baseline for real-world exposure levels and combinations to contaminated pollen. Between the two crops, the number of pesticides, total residue concentrations, and risk of exposure varied. The blueberry residue array was dominated by fungicides and miticides and cranberry was dominated by insecticides and herbicides. In most cases, pesticide residue concentrations were of low risk (low risk quotient) to honey bees in these crops. We documented that there were many residues that foragers would have picked up "off-farm." The reports from growers regarding their pesticide application dates allowed estimates of field decay rates of several common pesticides. Some compounds were detected in pollen many days after application. Taken together, our findings may be key to future work aimed at reducing risk to bees. A pesticide exposure baseline for honey bees was compiled for two New England cropping systems, the native North American plant species consisting of lowbush blueberry (Vaccinium angustifolium Aiton) and cranberry (Vaccinium macrocarpon Aiton). More unique pesticide compounds were applied in blueberry than cranberry, but the numbers of pesticides discovered in trapped honey bee pollen were similar between the two crop systems. Not all pesticides found in pollen were the result of the applications reported by growers of either crop. When comparing residues, number of pesticides detected, total concentration, and risk quotient varied between the two crops. Also, blueberry was dominated by fungicides and miticides (varroacides) and cranberry was dominated by insecticides and herbicides. When comparing reported grower applications that were matched with detection in residues, the proportion of pesticide numbers, concentrations, and risk quotients varied by crop system and pesticide class. In most cases, pesticide residue concentrations were of low risk (low risk quotient) to honey bees in these crops. Estimation of decay rates of some of the most common pesticide residues under field conditions could aid growers in selection of less persistent compounds, together with safe application dates, prior to bringing in honey bees for pollination. [ABSTRACT FROM AUTHOR]