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Effects of a Neonicotinoid Insecticide and Population Density on Behavior and Development of Wood Frogs (Rana
J Bouffard1,2, V Careau1, S A Robinson3
1Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
Environmental Toxicology and Chemistry
|September 12, 2022
Summary
This study found that the pesticide imidacloprid and high tadpole density independently reduced wood frogs' freezing response to predators. Interactions between these stressors did not significantly alter amphibian behavior or development.
Area of Science:
- Ecotoxicology
- Amphibian Biology
- Environmental Science
Background:
- Amphibian populations are declining globally due to anthropogenic activities, including pesticide contamination from agricultural runoff.
- Neonicotinoids, such as imidacloprid, are common agricultural pesticides linked to amphibian declines.
- Few studies have examined how neonicotinoids interact with natural environmental stressors, like population density, during amphibian larval development.
Purpose of the Study:
- To investigate the interactive effects of imidacloprid and population density on wood frog (Rana sylvatica) behavior and development.
- To assess how these stressors influence behavioral responses to predation cues across metamorphosis.
- To understand the ecotoxicological impacts of pesticides in the context of natural environmental variability.
Main Methods:
- A fully crossed experimental design exposed wood frog tadpoles to imidacloprid (10 µg/L) and two population densities (0.33 and 1 tadpole/L).
- Behavioral assays, including open-field tests with and without predation cues, were conducted at three developmental stages.
- The study measured activity levels, freezing responses, and the repeatability of behaviors across metamorphosis.
Main Results:
- Imidacloprid did not interact with population density to affect behavior in the absence of predation cues.
- High population density led to increased activity early in development but decreased activity at metamorphic climax.
- Both imidacloprid and high density independently reduced tadpoles' freezing response to predation cues.
Conclusions:
- Imidacloprid and high population density act independently to impair antipredator responses in wood frogs.
- The study underscores the importance of considering natural stressors in ecotoxicological assessments of pesticides.
- Future research should incorporate behavioral assays and multiple stressors to accurately predict environmental risks to amphibians.
