LAUSR

ABSTRACT: The study of non-target organisms such as mites, can provide information about the possible effects of transgenic maize cultivars on the arthropod community. This study aimed to evaluate the abundance of phytophagous mites in the area of Bt maize and evaluate the instantaneous population growth rate, and food preference of phytophagous mites on Bt maize. We registered the species occurrence and the number of adult mite individuals on four maize cultivars, one non-Bt 30F35, and three containing the proteins Cry1Ab (30F35 Yg), Cry1F (30F35 Hx) and Vip3a (Impacto Viptera). Cry proteins disrupt the midgut epithelium of insect pests. The food preference and instantaneous population growth rate (ri) were evaluated using the two-spotted spider mite Tetranychus urticae as model. The species Catarhinus tricholaenae and Aceria zeala were recorded. The Bt maize cultivars did not significantly affect the average number of C. tricholaenae and A. zeala mites compared to conventional cultivar. The population growth rates of T. urticae were similar for the different maize cultivars. T. urticae showed no preference between the leaf of Bt or conventional cultivars. Bt maize did not affect the abundance of species in phytophagous mite. Key words: plant defense, Non-target organisms, Genetically modified organisms Bt protein, Diptilomiopidae, Eriophyidae, Tetranychidae. RESUMO: O estudo de organismos nao-alvo, tais como acaros, pode fornecer informacoes sobre os possiveis efeitos de cultivares de milho transgenico na comunidade de artropodos. Este estudo teve como objetivo avaliar a abundância de acaros fitofagos na area de milho Bt e avaliar a taxa de crescimento populacional instantânea e preferencia alimentar de acaros fitofagos em milho Bt. Registramos a ocorrencia de especies e numero de individuos adultos de acaros em quatro cultivares de milho, um nao-Bt 30F35, e tres contendo a proteina Cry1Ab (30F35 Yg), Cry1F (30F35 Hx) e VIP3A (Impacto Viptera). A preferencia alimentar e taxa instantânea de crescimento populacional foram avaliadas utilizando femeas adultas do acaro-rajado Tetranychus urticae. As especies Catarhinus tricholaenae e Aceria zeala foram registradas. As cultivares de milho Bt nao afetaram significativamente o numero medio de acaros C. tricholaenae e A. zeala em relacao ao cultivar convencional. As taxas de crescimento populacional de T. urticae foram similares para os diferentes cultivares. T. urticae nao mostrou preferencia entre a folha de milho Bt ou cultivares convencionais. Sugere-se, entao, que o milho Bt nao afeta a abundância de especies, preferencia alimentar e taxa de crescimento de acaros fitofagos.