Testing the dermal and oral toxicity of selected chemicals to brown treesnakes

Dermal and oral toxicity tests were conducted on brown treesnakes (Boiga irregularis) with active ingredients and insecticide formulated products registered with the U.S. Environmental Protection Agency (EPA). Over-the-counter drugs approved by the U.S. Food and Drug Administration (FDA) were evaluated for oral toxicity. Dermal applications of pyrethrin and pyrethroid commercially formulated aerosol insecticides containing the synergists piperonyl butoxide and n-octyl bicyloheptene dicarboximide were toxic to the snakes. The lowest oral gavage dose that resulted in 100% mortality for rotenone, pyrethrins, propoxur, and aspirin was 2.5, 40, 40, and 1,280 mg/kg, respectively; but, when these chemicals were consumed by snakes in bait matrices at doses several times higher than the gavage doses, mortality was greatly reduced. Uncoated tablets of aspirin (150 and 300 mg), ibuprofen (100 and 200 mg), acetaminophen (100 and 200 mg), and commercial over-the-counter tablet formulations of 80 mg and 325 mg acetaminophen were offered to snakes in a dead mouse bait matrix. The mortality with aspirin ranged from 67% to 100%. No mortality was observed with ibuprofen. Acetaminophen resulted in 100% mortality for each of the doses tested. Overall, these dermal and oral toxicity results indicate that some EPA-registered pesticides and drugs approved by FDA may have use as toxicants for brown treesnakes.