Insetos e outros artrópodes de importância agrícola associados à semeadura direta da cultura da soja (Glycine max (L.) Merr.)

Abstract

Pests and natural enemies populations on the soil surface in different soybean no tillage cultivation systems were evaluating during the growing season of 2006/2007, in Dourados town, Mato Grosso do Sul state, Brazil, at 22o 11’ of latitude South and 54o 56’ of longitude West. The experimental area was constituted by three cover conditions of the soil surface: sorghum, pearl millet, spontaneous vegetation, with posterior soybean direct seeding. Four and two evaluations, using pifall traps, were made, respectively, at the pre-sowing and at the early season periods of soybean seeding. Data were analyzed as measures repeated in time, with posterior comparison between means. The abundance and relative frequency were calculated for the two evaluation periods. Gryllus assimilis (Orthoptera: Gryllidae) and Lagria villosa (Coleoptera: Lagriidae) were, respectively, the most abundant pest species, before and after soybean seeding. Solenopsis sp. (Hymenoptera: Formicidae) was the most abundant natural enemy before and after soybean seeding. The sorghum/soybean and pearl millet/soybean systems significantly modified the population density of these species and of the predators Galerita collaris (Coleoptera: Carabidae) and Calosoma granulatum (Coleoptera: Carabidae). G. collaris accompanied the population dynamic of G. assimilis in the pearl millet/soybean system before soybean seeding. When the capture of Solenopsis sp. was expressive, G. assimilis and L. villosa were less captured.