Sublethal Effects of Sulfoxaflor Pesticide on Physiology and Behavior of Daphnia magna

by Mary Hoffman

Faculty mentor: Dr. Tyler Frankel

Insect pests are a major concern for large-scale agriculture as a result of increasing insect resistance to pesticides, driving a need for the development of new pesticides. Sulfoxaflor, a sulfoximine pesticide recently approved for use by the USEPA, was developed in order to replace neonicotinoid use and has shown to have high efficacy in the field. It is used in rotation with other pesticides, with environmental introduction caused primarily by wet spray application or agricultural runoff. In insects, sulfoxaflor binds to nicotinic acetylcholine receptors, triggering over-activation that leads to paralysis and death. Preliminary exposure studies have shown neonatal effects and development of liver tumors in rats and mice, and moderate oral toxicity in bobwhite quails and fathead minnows. Little research into the effects of the chemical on aquatic non-target invertebrates has been conducted; as such, this research aims to identify potential physiological and behavioral impacts of sulfoxaflor on adult Daphnia magna at concentrations of 0, 0.1, 1, 10, 100, and 1000 µg/L. Impacts on mobility were determined using top-down recordings and behavioral analysis software ToxTrac (v2.84). Heart rate was analyzed through analysis of minute-long heart recordings to quantify beats per minute. While this research is currently ongoing, it is expected that these treatment levels are sub-lethal at 24 hours, and that exposure to sulfoxaflor at higher concentrations will inhibit heart rate and mobility in adult Daphnia magna. The research aims to help elucidate the potential sub-lethal impacts of sulfoxaflor on non-target aquatic invertebrates.