Response of arthropods associated with the canopy of common beans subjected to imidacloprid spraying

Authors


Authors' addresses: Dr F. Marquini, Dr R.N.C. Guedes (corresponding author), Dr M.C. Picanço, Departamento de Biologia Animal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36571-000, Brasil. Dr A.J. Regazzi, Departmento de Informática, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36571-000, Brasil. E-mail: guedes@mail.ufv.br

Abstract

Abstract:  Imidacloprid, the first neonicotinoid of potential use in agriculture, became an important agent for controlling leafhoppers, aphids, thrips and whiteflies. The use of this compound was extended to common beans in Brazil, a crop of great socio-economic value throughout Latin America, and the aim of the present work was to assess the temporal effectiveness and environmental safety of this insecticide to the arthropod community associated with the canopy of this crop plant. Thirty six species of phytophagous and detritivorous species were collected, as well as 37 species of predators and parasitoids. However, there was no significant impact of imidacloprid on species richness. In contrast, the insecticide significantly decrease the arthropod abundance for over a 30-day period. This impact is probably a reflection of the effect of this insecticide on Thrips tabaci and Caliothrips brasiliensis (Thysan., Thripidae) the most frequent and abundant species present in the area, and important pests of common beans in Brazil. Among the other most frequent taxa (present in over 50% of the samples), Araneae (predators) and the green leafhopper Empoasca kraemeri (Hom., Cicadellidae), another important bean pest in Brazil, were not significantly affected by imidacloprid, unlike the thrips species T. babaci and C. brasiliensis which showed decreased population levels until 8 days after imidacloprid application.

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