Artrópodes associados à soja geneticamente modificada Roundup Ready® RR1 (GT 40-3-2) e Intacta RR2 Pro® (MON 87701 x MON 89788)

Abstract

The use of genetically modified plants can interfere with the insect community, causing changes in the insect fauna of agroecosystems. The aim of this work was to study the occurrence, abundance, population fluctuations and outbreaks, and field test on the effectiveness of genetically modified insect resistant (Bt) and glyphosate-tolerant (RR1 and RR2) with and without using insecticides on target pests, as well as its effects on beneficial arthropods. The experiments were carried out in the agricultural year 2011/2012 in four municipalities in the State of Mato Grosso do Sul. The treatments were: 1 - Roundup Ready® RR1 Soybean without insecticide application; 2 - Roundup Ready® RR1 Soybean with application whenever control level was reached; 3 - Intacta RR2 PRO® Soybean without insecticide application; 4 - Intacta RR2 PRO® Soybean with application whenever the control level was reached. Ten samples were taken for each plot. The evaluations were initiated shortly after plant emergence, at intervals of seven to ten days. In order to obtain representative gradients of species composition, we used the method of ordering by non-metric multidimensional scaling (NMDS) and dissimilarity index Bray-Curtis. The number of insect species and specimens collected was given to each collection point sampled, the average per stage of culture were used for preparation of graphs representing the population fluctuation throughout plant development. The total number of insects per species and stage were subjected to analysis of variance and means were compared by Tukey test at 5% significance. The insects of the order Lepidoptera presented 7547 specimens, composing more than 70% of the insect community. Following stood out the orders Coleoptera and Hemiptera, which were, respectively, 2066 and 331 insects. Most of the samples were recorded in the plant stadiums V8 to R2 for defoliating caterpillars and between R5.2 to R6 for phytophagous stink bug complex. Lepidoptera A. gemmatalis and C. includes, targets of Bt technology, were effectively controlled by the soybean field that expresses the Bt toxin Cry1Ac, reducing the number of sprays to control them. The use of Bt technology does not affected the management and control of non-target pests such as stink bug complex, and favors significantly the population of beneficial arthropods in culture.