Date of Award

January 2023

Document Type


Degree Name

Master of Science (MS)



First Advisor

Jefferson Vaughan


Lyme disease affects tens of thousands of people every year in the United States, causing serious illness and even death. It is caused by the bacterium, Borrelia burgdorferi, through infected black-legged tick bites. The range of these ticks is expanding, causing Lyme disease cases to increase. Considerable effort has been put toward research and eradication of Lyme disease, with limited success. Isoxazoline drugs, commonly used to prevent flea and tick infestations in dogs, could be dispatched in the field to keep black-legged ticks off the reservoir host of Lyme disease, the White-footed mouse. Little research has been done on these drugs, so their environmental impact is unknown. This study aimed to test how isoxazoline drugs (lotilaner, fluralaner and afoxolaner) affect non-target species. Lotilaner-treated mouse carcasses were left outside for 27 days to observe decomposition and infestation. Carcass invertebrates and soil samples were collected. Neurotoxic effects of fecal pellets from isoxazoline-treated white-footed mice on Culex pipiens mosquito larvae were also tested. Mosquito larvae were exposed to lotilaner, fluralaner, and afoxolaner-treated mouse fecal pellets to find the percent mortality. Fathead minnows were exposed to lotilaner contaminated water to see if the drug could leech out of the fecal pellet, pass through the gills and be toxic to the fish. The results showed that treated mouse carcasses decompose slightly slower than control carcasses, but there is no effect on the invertebrates on or under the carcasses. Lotilaner is toxic to mosquito larvae for almost two months. Afoxolaner is toxic for about a week while fluralaner is not toxic whatsoever to Culex pipiens mosquito larvae. Finally, lotilaner had no effect on fathead minnows, suggesting that lotilaner could be used around aquatic habitats and pose little to no danger to fish.