Fertilização nitrogenada em pastagens: impactos sobre o escarabeíneo Dichotomius bos (Blanchard, 1846)

Abstract

Natural habitat conversion to agriculture and pasturelands, associated to the use of inorganic fertilizers, are among the major causes of biodiversity loss and, consequently, reduction on the ecosystem services. Several studies have demonstrated the negative effect of the use of nitrogen fertilization on edaphic diversity. Thus, in order to verify the effects of nitrogen fertilization on, survival, weight, body fat amount, and ecological functions performed by dung beetles, we conducted field and laboratory experiments using the beetle Dichotomius bos, an abundant and widely distributed Brazilian pastures. In the first experiment, we verified the ecological functions performed by the beetles in a pasture in function of the presence of urea. Secondly, we used mesocosms in the laboratory to evaluate the ecological functions due to prolonged exposure. In the third, we use mesocosms in the laboratory to evaluate the survival, the variation in weight and body fat of beetles. Our results indicate that the commercial dosage of urea does not interfere on the performance of ecological functions by beetles, both in the field under natural conditions and in the laboratory under controlled conditions. This may be associated to the reaction time of the agrochemical in soil, which occurs very quickly; to the dosage of urea used, being too low to be felt by the beetles; and the single dose application of urea; and the possibility of sublethal effects occurring. When the dosage is increased, the survival, weight, and body fat accumulation of the beetles are altered. Thus, we conclude that the management practices with proper use of urea, the main fertilizer applied to pasture Brazilian not interfere with the operation of these ecosystems, referring to the ecological functions performed by scarabaeinae beetles, since it is used at recommended dosages.