Interação entre o algodoeiro bollgardtm, o ácaro rajado, Tetranychus urticae Koch (Acari: Tetranychidae) e o predador Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae)

Abstract

Cotton plants have been genetically transoformed with genes from the bacterium Bacillus thuringiensis Berliner (Bt) which confers the plant resistance against certain lepidopoteran pest species. The Bt-cotton carries genes that express the toxin Cry1Ac. This creates new interactions in the agroecossystems encouraging researches to answer the questions about the potential impact on nontarget organisms. In the cotton ecosystem, the two spotted spider mite, Tetranychus urticae Koch, acquires and mantain in its body high concentrations of Cry toxins (Cry1Ab from Bt-corn and Cry1Ac from Bt-cotton). This finding leads to the question about the potential long term impact on the phytophagous minte, a nontarget, and their predators. Thus, this work investigated the biology and behavior of T. urticae and its predatory mite, Phytoseiulus macropilis (Banks) on Bt-cotton. The results obtained during three successive generations showed that the Bt-cotton does not affect negatively its development, viability of immature stages and reproductive output. Furthermore, the preference for feeding and oviposition of T. urticae and its predator, P. macropilis, were similar on both cotton types. In addition, P. macropilis exhibited similarpredatory behavior on T. urticae fed on both cotton types. Despite of similar results, T. urticae acquired about 3.97 times more Cry1Ac than that expressed in the Bt-cotton plants.