Effects of the Neonicotinoid Insecticide Clothianidin on Southern Leopard Frog (Rana sphenocephala) Tadpole Behavior.

Neonicotinoid insecticides are highly water soluble with relatively long half-lives, which allows them to move into and persist in aquatic ecosystems. However, little is known of the impacts of neonicotinoids on non-target vertebrates, especially at sublethal concentrations. We evaluated the effects of the neonicotinoid clothianidin on the behavior of southern leopard frog tadpoles (Rana sphenocephala) after a 96-h exposure at 6 concentrations, including 0 (control), 0.375, 0.75, 1.5, 3.0, 6.0 µg/L. We quantified total displacement, mean velocity, maximum velocity, and time spent moving of tadpoles for 1 h post-exposure. Total displacement and mean velocity of tadpoles decreased with clothianidin exposure. Maximum velocity decreased linearly with concentration, but there was no relationship between time spent moving and clothianidin concentration. Our results suggest exposure to clothianidin at sublethal concentrations can affect movement behavior of non-target organisms such as tadpoles.