Effects of neonicotinoids on putative escape behavior of juvenile wood frogs (Lithobates sylvaticus) chronically exposed as tadpoles

Abstract

Neonicotinoids are water‐soluble neurotoxic insecticides widely used in agriculture that are being detected in nontarget aquatic environments. Nontarget aquatic wildlife, such as amphibians, may be at risk of exposure. Studies using larval stages suggest neonicotinoids are a minor concern to amphibians; however, behavioral effects manifesting later in life are not often considered. Behavioral endpoints could further our understanding of potential sublethal neurotoxic effects after exposure has ended. Using juvenile wood frogs (Lithobates sylvaticus), we investigated the effects of chronic larval exposure to 3 concentrations (1, 10, and 100 μg/L) of formulations containing imidacloprid or thiamethoxam on the putative escape response to a simulated heron attack. We found that control frogs actively responded (i.e., moved or jumped) to the simulated predator attack but frogs exposed to imidacloprid at 10 and 100 μg/L were less likely to respond. The exposed frogs, specifically from the imidacloprid treatment at 10 μg/L (tendency at 100 μg/L) were less likely to leave the attack area compared with controls. However, frogs used refuge similarly among all treatments. Finally, there were no differences in locomotor performance, as measured by total number of jumps and distance traveled during a trial among treatments. In conclusion, our study suggests that exposure to neonicotinoids during amphibian larval development may affect a juvenile frog's ability to perceive or respond to a predator, potentially increasing their vulnerability to predation. Future studies should validate and explore this potential effect further. Environ Toxicol Chem 2018;37:3115–3123. © 2018 Crown in the right of Canada. Published by Wiley Periodicals Inc. on behalf of SETAC.

Detecting Amphibians in Agricultural Landscapes Using Environmental DNA Reveals the Importance of Wetland Condition

“…This is likely attributable to spray drift from nearby agricultural activities, but even at the St. Denis National Wildlife Area there is prescribed use of herbicides to control alien plant species (Environment Canada ). However, we found little evidence for negative effects of the most commonly detected pesticides here, namely 2,4‐D, MCPA, and imidacloprid (Relyea ; Johnasson et al ; Robinson et al ; Lee‐Jenkins and Robinson ). Without detailed, field‐based investigation into the single and combined effects of chronic agrochemical exposure to wood frogs, we caution that these results are preliminary and correlative.…”

Embryonic Exposure to Thiamethoxam Reduces Survival and Alters Neurobehavior of Fathead Minnows

“…The predator escape response is a reflexive and innate behavior that occurs through the detection of water flow at the lateral line, which allows larvae to escape predators (McHenry et al, 2009). Changes to predator escape behaviors in response to toxicant exposure can indicate neurotoxicity, as demonstrated in larval frogs and zebrafish exposed to another neonicotinoid, imidacloprid (Crosby et al, 2015; Lee‐Jenkins & Robinson, 2018). The changes seen in the latency and burst speed parameters after embryonic stage exposure to thiamethoxam indicate that complex behaviors such as predator escape may also be affected by chronic exposure to sublethal concentrations of thiamethoxam.…”

Performance studies on jumping behaviour in froglets exposed to commercial grade malathion

“…In rainbow trout, exposure to AChE inhibitor showed hyperactivity (Beauvais et al, 2000) and in salamander such exposure did not show any significant changes in their behaviour (Baker, 1985). In other neurotoxic chemical exposure (neonicotinoids), Lee-Jenkins and Robinson (2018) found no considerable difference in locomotor performance. On the contrary, in the present study the neurotoxic chemical (Malathion) had produced clear increase in jumping performance at higher concentrations.…”