Print PageHigh pesticide use in the tropics can enhance crop production through pest control, but may also substantially imperil human health and biodiversity. Highly hazardous substances such as DDT, Dieldrin and Heptachlor are still used in many tropical countries. The combination of cheap products from producers in India, Brazil, or Indonesia and illiteracy of local people preventing them from reading manuals often lead to exacerbated pesticide application. Subsequent impact on tropical biodiversity – in particular on vertebrates – and ecosystem services are little studied. Given that ecotoxicological research in temperate regions has advanced rapidly, an important question is whether this knowledge is directly transferable to the tropics. We used a comprehensive literature review and Bayesian mixed effects modeling to quantify non-target effects of pesticides on tropical vertebrate biodiversity and highlight effects on a range of ecosystem services. Given the scarcity of long-term pesticide studies in the tropics, we also conducted a combined correlative-experimental field study on threatened amphibians and little studied reptiles in Sulawesi (Indonesia). In the correlative approach, we monitored diversity changes and increasing pesticide use over three years. In parallel, we experimentally manipulated insecticide, herbicide, and herbicide/insecticide load.
Results/Conclusions
Literature suggest much higher pesticide susceptibility in tropical amphibians compared to temperate congeners. Our correlative and experimental field approach revealed that amphibians are more susceptible to pesticide exposure with dramatic abundance declines even of the most common species. The latter has important implications for biocontrol services potentially affecting cacao yield through an interaction with highly invasive ants that reduce native ant diversity as predators of cacao pest vectors. In summary, we provide an example of how pesticides, initially intended to increase human welfare, compromise vertebrate diversity and ecosystem services. Future research should focus on potential risks of exacerbated pesticide application and provide guidelines including Integrated Pest Management with an emphasis on biological pest control.
