Chapter 9: Mortality Induced by Mixtures of Pesticides in Tadpoles from the Pampas Region of Argentina

Habitat degradation is a hazard to global biodiversity. Specifically, amphibian populations have been declining for the last 30 years worldwide, a phenomenon that can be partially explained by the extension of agriculture and the high rate of pesticide application that modern agriculture requires. Moreover, pesticides are often applied in the form of mixtures, which interact with and affect non-target organisms in different ways, altering both their survival and/or fitness. The Pampas region of Argentina has not been exempted from this situation, and studies involving amphibians and mixtures of pesticides have increased in the last decades. Most of these studies have been performed in laboratory conditions employing the South American common frog Rhinella arenarum (Anura, Bufonidae), a ubiquitous toad of the region. As far as we know, only one work has been performed in field conditions evaluating mixtures of commonly employed pesticides in four species. Different interactions were detected among the mixture studies, with variations among the formulations employed, developmental stages of individuals exposed and time of exposure. These facts highlight the importance of extending the studies to the most commonly employed mixtures together with native fauna to minimize negative effects on the native biota.