Influência de condições pós-queimada sobre o comportamento e a realização das funções ecológicas em besouros escarabeíneos (Coleoptera: Scarabaeinae)

Abstract

Fire is an ecologically and evolutionarily important natural disturbance for the Cerrado ecosystem. Due to historical-evolutionary relation between the fire and the Cerrado, its flora and fauna this environment have been considered resistant and/or resilient to this kind of disturbance. Dung beetles are conspicuous faunal components of the Cerrado and appear to be quite resilient to fire this environment. However, despite of the understanding advances on the dung beetles’ response to the fires, there are still many gaps in the knowledge about the effects this disturbance on the behavior and post -fire survival of these organisms. Thus, this study aimed to evaluate the effects on the post -fire conditions on the foraging behavior and on the ecological functions performed in dung beetles of the Cerrado. In chapter one, were evaluated: the influence of the ashes on the volatiles compounds concentrations emitted by pig dung; and the influence of the ashes add ed to faeces on the food resource perception by Dichotomius bos beetles species. The volatiles profiles emitted by faeces and faeces with ashes samples were characterized through of analysis on a gas chromatograph with flame ionization detector (GC-FID). To evaluate the olfactory response of beetles, two behavior independents experiments was conducted using a four -armed olfactometer. The D. bos were introduced at the olfactometer in groups of four individuals. The first experiment, was composed by: three control arms (without odor source) and one arm containing pigs dung. And the second experiment was composed by: pigs dung; mixture of the faeces and ashes; ashes; and control. The results of the chromatographic analyzes showed that the ashes drastically decreases the volatiles compounds concentration emitted by faeces. However, despite the decreasing of compounds concentration, the ashes did not' influence the attractiveness of faeces, and the individuals of D. bos were equally attracted by the odors of faeces with and without ashes. In chapter two, were evaluated: the influence of the ashes’ presence on the performance of functions of dung burial and soil revolving by Phanaeus palaeno beetles species, besides that was also evaluated the effects of the sex and weight of the individuals about these functions performance. The ecological functions were measured in laboratorial experiments, composed by: treatment I, (control buckets without ashes on the soil); treatment II (bucket containing ashes on the soil in bo th sides); treatment III (bucket containing ashes on the soil in one side). The individuals of P. palaeno did not have their functions affected by the presence of ashes. Besides that, both clean and faeces mixed with ashes was the explored equally. Only the sex of the individuals was significantly related to the performance of the functions, the females buried more faeces and revolved more soil than males. This work showed the dung beetles are well adapted to the post burned conditions found in Cerrado areas, and their behavior is not affected by the presence of ashes, the main by-product generated from the burning of vegetation. These results contribute important information about the resilience of fauna to fire from Cerrado environments.