Impacto do algodoeiro geneticamente modificado (Bollgard®) sobre a biodiversidade de artrópodes

Abstract

The impact of transgenic cotton NuOpal® (Bollgard®) which expreses the Cry1Ac gene of bacteria Bacillus thuringiensis (Bt), producing insecticidal protein against the lepidopteran target-pests Alabama argillacea (Hübner, 1823), Heliothis virescens (Fabricius, 1781) and Pectinophora gossypiella (Saunders, 1844) was evaluated in field conditions during crop season 2006/2007 in Dourados/MS, Brazil. We compared the effect of NuOpal® with non-transgenic isogenic DeltaOpal®on the biodiversity of target-pests, the nontarget pests and the natural enemies (mainly predators) to a non-treated crop. Two methodologies of visual sampling were evaluated: whole plant observation and beatsheet. Bollgard® technology presented efficient control on the target-pests. The average number of species was significantly lower in Bt-cotton than in non-Bt cotton. In the whole plant sampling, pests the average number of specimes of non-target pests was significantly higher in NuOpal® than DeltaOpal®. This difference was not observed with beatsheet sampling. The diversity of nontarget pests characterized by Shannon-Wiener index was higher in NuOpal® than DeltaOpal® in the whole plant observation. The average number of specimes and the diversity of natural enemies also characterized by Shannon-Wiener index did not differ significantly between Bt-cotton and non-Bt cotton in both sampling methods.