Diversidade e abundância de artrópodes edáficos em agroecossistemas de agricultura familiar na Amazônia

Abstract

The Amazon is a valuable ecosystem that is home to a wide variety of flora and fauna species. The latter, having arthropods as an essential component for achieving ecological processes. Thus, understand and measure the diversity of arthropods in natural and anthropogenic ecosystems is extremely important for the consolidation of these. Thus, this work aims to assess the diversity and abundance of arthropods in agroecosystems of family farming in the Amazon. The work was carried out on a family farm establishment in João Vaz settlement, in the southeast of Pará. For the sampling of arthropods were used four pitfall traps, distributed to 20 m from each other in the form of a square in each area, remaining in the field for seven days. Sampling was carried out depending on regional climatic seasonality, three in the dry season and three in the rainy season, the 2012/2013 cycle in agroecosystems Cassava (Manhihot esculenta C.), cowpea (Vigna unguiculata (L.) Walp.), Grassland and forest area. The arthropod were taken to the laboratory for screening and identification of individuals in morphospecies. The diversity index and dominance Simpson, equitability of evenness (J) and estimator wealth of Margalef were calculated using the Past 3:05 software. Simpson diversity index, using the same program, were compared by Student's t test at 5% probability. They collected 24,352 individuals in 13 orders, 50 families and 243 morphospecies. The Hymenoptera orders (57.5%), Acari (19.1%) and Coleoptera (18.4%) had greater abundance. In the dry season the agroecosystem with greater abundance was the manioc and the lowest was the pasture area. In the rainy season the manioc continued with the greatest abundance, however, the smallest found in secondary forest. In total, the cassava was the most abundant, statistically different from the others, and the lowest abundance was found in secondary forest. The latter showed higher species richness, which favored the increase of ecological indices evaluated. Overall, all agroecosystems showed good diversity getting all with rates above the average rate (0.500). The agro-ecosystem with greater Simpson diversity index was the bean cultivation followed by the area of secondary forest. On the other hand, cassava showed the lowest index of diversity, this was only statistically differing bean cultivation. Thus, it is concluded that seasonality and the structure of agricultural ecosystems influenced on the diversity index.