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- Worms in space |
One of the exciting research topics being studied in the Relyea lab is the impact of pesticides on amphibians. Historically, studying the toxic effects of pesticides on animals (i.e. toxicology) has largely been restricted to laboratory experiments in which most of an animal's natural ecology has been excluded. As a result, it often is unclear whether estimates of lethal concentrations of pesticides are relevant in nature. This is particularly true for studies with amphibians, in which tadpoles are raised in laboratories without any of the biotic or abiotic challenges that tadpoles actually face in nature.
Our current hypothesis is that the two stressors (the fear of predators combined with the pesticide stress) combine synergistically to cause tadpole mortality. We are currently examining many different species of amphibians and a variety of other pesticides to determine if these synergistic interactions are common and whether these pesticide interactions may be responsible for the decline of amphibians around the world.
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Given this perspective, we have begun a research program that asks whether pesticides become more or less lethal to
amphibians when raised under more natural conditions. We are studying the globally-common pesticide carbaryl
(commercial name: SevinŽ). One of the most surprising findings to date is that the presence of predator cues
(chemicals emitted by predators feeding on tadpoles) makes carbaryl much more lethal to tadpoles. In the most extreme case,
carbaryl alone killed only 2% of the tadpoles, the predator cues alone only killed 2% of the tadpoles, but the combination of
carbaryl and predator cues killed 92% of the tadpoles!
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