Ivermectin impacts on dung beetle diversity and their ecological functions in two distinct Brazilian ecosystems

Abstract

1. The indiscriminate use of Ivermectin is becoming a frequent scenario in Brazil, oneof the largest beef cattle herds in the world, and the second-highest commercialproduction, despite this product having harmful effects on non-target organisms.Among these organisms, dung beetles are essential for the maintenance of ecosys-tem functioning in introduced pastures. 2. This study evaluated the effects of Ivermectin on dung beetle assemblage attributes(species richness, abundance, species composition, functional groups and indicatorspecies) as well as their ecological functions (dung removal and soil bioturbation) inintroduced pastures with different priorities for livestock intensification in Brazil;Amazon (high) and Pantanal (low). 3. We found a negative response of dung beetle assemblages to Ivermectin in bothBrazilian ecosystems, where these negative effects were more pronounced in thePantanal. Tunneler beetles are the functional group most negatively affected in bothecosystems. Finally, the Ivermectin reduces the ecological functions performedby dung beetles, with a dung removal reduction of ca. 50% and 70% in the Amazonand Pantanal, respectively. 4. The most negative impacts in the Brazilian Pantanal reflect the long-term conse-quences due to a long history of Ivermectin use than in the Amazon. However,these results also indicate a drastic future for dung beetles in Amazonian pastures. 5. Thus, a sustainable cattle production system reducing Ivermectin use will be impor-tant for conserving dung beetles on introduced Brazilian pastures and the ecologicalfunctions that these insects provide in livestock-dominated landscapes.