Pesticides in the real world: The consequences of GMO-based intensive agriculture on native amphibians.

Abstract

Pesticide use has been suggested as one of the major drivers of the global amphibian decline. Laboratory andmesocosm studies have addressed several questions to understand the mechanism by which pesticides causedetrimental effects on amphibians. However, the extrapolation of those results to natural populations may not beadequate to predict environmental impacts or to understand the role of pesticides in the amphibian decline. Byusing in situ enclosures, we evaluated the effects (survival and mobility) of common pesticides applied byfarmers (cypermethrin, chlorpyrifos, endosulfan, glyphosate, and 2,4-Dichlorophenoxyacetic acid) on tadpoles.We assessed these effects in four common amphibian species from South America across 91 ponds located in thePampas of central Argentina. We found that survival decreased in 13 out of 20 pesticides applications concomitantlywith detection of pesticides in water ponds. 48 h after applications, mixtures containing endosulfanor chlorpyrifos reduced tadpole survival to<1% while the cypermethrin mixtures reduced survival to 10%. Inaddition, we found impairment of mobility in all combination of pesticides, including glyphosate. The ecologicalcontext involved in our study represents the common exposure scenarios related to GMO-based agriculturepractices in South America, with relevance at regional levels. We emphasize that multifaceted approaches developedto understand the role of pesticides in the amphibian decline need a conservation perspective. This willbe achieved by work focusing on the integrated use of state-of-the-art techniques and resources for documentingpesticide effects over wild amphibians´ populations, allowing conservation scientists to generate better managementrecommendations.