Parasiticidas sintético e natural em bovinos: escarabeíneos como indicadores de impactos ambientais sobre pastagens do Cerrado

Abstract

With the largest commercial cattle population in the world, Brazilian territory harbors more cattle than humans. The Cerrado (Brazilian Savannah) is responsible for 34% of total beef production, which is managed in native and exotic pasture. Such a big cattle population has been a scenario for indiscriminate use of synthetic parasiticides, commonly known as veterinary pharmaceutical, to control pests in cattle, resulting in great incidence of residues in meat and milk. The importance of food security and environmental risks associated to veterinary pharmaceutical residues has increased the demand for low-impact alternatives of food production. Here, I assessed, using dung beetles as an indicator group, the environmental risks associated to use of two veterinary pharmaceutical (Neem plant and Ivermectin) in native and introduced pastures in the Cerrado. In the first chapter we performed free choice tests with dung contaminated with Neem, Ivermectin residues and free residues, in eight introduced and eight native pastures. We evaluated the consequences of veterinary pharmaceutical over ecological functions of burial dung and soil bioturbation, and community attributes (richness, abundance, biomass and composition) of dung beetles. Both pasture system and veterinary pharmaceutical type affected all aspects of dung beetles community. The dung beetles performed more ecological functions in dung contaminated with Neem and Ivermectin, than in free residues dung. In addition, the community attributes (richness, abundance, biomass and composition) of dung beetles captured in dung with Neem and Ivermectin is distinct between native and introduced pastures. Our findings highlight that veterinary pharmaceutical and pastures systems must to be considered as synergic factors for assess the risks of use veterinary pharmaceutical in non-target fauna. In the second chapter, we performed a non-choice laboratory test using Dichotomius nisus Oliver, 1798 a dung beetle species widely found in Brazilian pastures. We evaluated the effects of veterinary pharmaceutical residues (Neem and Ivermectin) on the ecological functions performed by dung beetles. Additionally, we performed extraction of the dung beetles fat amount in order to evaluate the physiological status of adult dung beetles exposed to the different types of residues. D. nisus do not alter their behaviour in the presence of Ivermectin and Neem residues when compared with control, but the individuals exposed to Ivermectin have 5% more fat. Our findings stresses the need for multiple tests (i.e. ecology, behaviour and physiology) to assess the risks of veterinary pharmaceuticals in non-target fauna. I conclude that the assessment of environmental risks of the veterinary pharmaceutical to dung beetles must include pasture system as a synergic factor. In addition, Neem can be considered less-impactant than Ivermectin, since does not alter the fat amount in D. nisus. Also, dung with Neem residues has more ecological functions performed by dung beetles than dung with Ivermectin, which can be beneficial to cattle producers.