A Purdue University study has found that honeybee pollen is consistently contaminated with a number of agricultural and urban pesticides throughout the growing season.

The study, published by Nature Communications, showed that the highest concentrations of pesticides in bee pollen were pyrethroids. Pyrethroids are found in many pesticides but are typically found in insecticides used to control mosquitoes, wasps and hornets.

Christian Krupke, who authored the May 31 report with Elizabeth Long, now an assistant professor of entomology at Ohio State University, told Bloomberg BNA that the findings indicate that bees are exposed to a variety of pesticides, not just...