Structure and succession in a beetle community inhabiting cow dung

The material included 62,500 individuals of 179 beetle species collected during the whole course of succession (30 days) from droppings exposed in three macrohabitats (field, pine and spruce forest) in three summer months (June, July and August). The collection was divided into coprophages (50 species) and carnivores (129 species), and mean values are given for the lengths and dry weights of all species found. The trophic status of dung-inhabiting beetles is briefly discussed. Coprophages are designated as microhabitat and food specialists, and carnivores as microhabitat generalists. For coprophages the macrohabitat richest in species was the field, and for carnivores the pine forest. Probable reasons are the distribution of suitable microhabitats, and the microclimate and structure of the macrohabitat. For average values per dropping during the first 10 days of succession, carnivores (with 16 species and 191 individuals) outnumbered coprophages (with 11 and 126, respectively) but in total biomass the situation was the opposite (129 and 443 mg weight, respectively). Variation in the numbers of species and individuals, and diversity among individual droppings had a minimum from about the 2nd to the 7th day in the pooled data, including those for the macrohabitat and seasonal gradients. Presumably this reflected a decreased rate of succession and decreased influence of the weather as the surface of the dung dried into a hard cover. Coprophages exemplified a typical heterotrophic succession: after a brief peak (in species, individuals, and diversity) on the 2nd day from the beginning, there was a radical decrease. In the carnivores the peak was broader, and occurred between the 3rd and 8th days, probably because the prey (mainly dipterous eggs and larvae) available to the carnivores does not decrease during the 1st week of the succession. The structure of the community and the succession depended largely on abiotic factors, especially on weather conditions.