Diversity and spatial distribution of predacious Dolichopodidae (Insecta: Diptera) on organic vegetable fields and adjacent habitats in Brazil

摘要

Adults of the fly family Dolichopodidae (Diptera) are general predators on small soft-bodied invertebrates, and often are abundant in agroecosystems. However, information about their diversity and spatial distribution in agricultural landscapes are scarce. Using structured sampling, we identified the species of Dolichopodidae associated with organic vegetable crops, fallow, agroforestry, and native vegetation in the Federal District of Brazil, and evaluate their richness and abundance. We collected 70 species Dolichopodidae distributed in 17 genera and 9 subfamilies. Of these, some 80% of the specimens belong to the following 5 taxa: Chrysotus spectabilis (Loew), Thrypticus violaceous Van Duzee, Condylostylus depressus (Aldrich), Condylostylus “caudatus group” females, and Condylostylus erectus Becker (all Diptera: Dolichopodidae). Habitats with vegetable crops harbored a higher abundance and number of species (diversity α), with a gradual reduction towards more forested environments of native vegetation. This is an inverse gradient with the general patterns of community studies with other taxa. We also verified the importance of less disturbed habitats over time in the agricultural landscape, such as agroforestry and native vegetation, as complementary habitats for the maintenance and conservation of dolichopodid species in particular, a scenario to be tested for other insect groups.