Effect of Insecticides, Fungicides, and Adjuvant Combinations on Honey Bee Brood Development

Agriculture/Ecological/Environmental Science: 2nd Place (The Ohio State University Denman Undergraduate Research Forum)Honey bees are highly valued in the booming almond industry because they serve as vital pollinators needed to cross-pollinate almond flowers. California’s almond industry produces approximately 80% of the world’s almonds. Therefore, a significant portion of America’s commercial honey bee colonies are transported to pollinate California’s almonds every year. Various fungicides and insecticides, along with adjuvants are used to minimize crop damage from various diseases and pests. Recent research has demonstrated that these preventative treatments negatively impact honey bee colony health. This is problematic for beekeepers and the almond industry who rely on strong, healthy colonies. In this study we investigate the effects of almond pesticides and an adjuvant on larval mortality. Honey bee larvae were artificially reared to adulthood while being fed a treated diet simulating exposure to commonly used products. First, various concentrations of an organosilicone-based nonionic surfactant with methylated seed oil known as Dyne-Amic were added to the diet of young larvae. The results of the brood mortality were used to plot a dose-response curve for Dyne-Amic to determine lethal and sublethal concentrations. To investigate whether Dyne-Amic increases the toxicity of pesticides to honey bee larvae, a sublethal dose of Dyne-Amic was added with various combinations of insecticides and fungicides to observe any compounding effects. Preliminary results suggest that the label recommended application concentration of Dyne-Amic is 1.9X times higher than the maximum sublethal concentration. However, we did not observe an increase in mortality when Dyne-Amic was added to insecticides and fungicides at sublethal concentrations, alone or in combinations. Further trials will expand to evaluate effects of exposure at field-relevant concentrations. The results of this research are incredibly important and helpful for the almond growers in California, as well as any agricultural practice that utilizes combinations of insecticides, fungicides, and adjuvants. Particularly for almond growers, understanding these chemical interactions can help improve the efficiency of bee pollination services and reduce costs. Product label application instructions may be refined for common insecticides, fungicides, and the surfactant Dyne-Amic as a result of these findings.Almond Board of California California State Beekeeper's Association Project Apis m.No embargoAcademic Major: Animal Science