Diversity, Composition and Population Dynamics of Arthropods in the Genetically Modified Soybeans Roundup Ready® RR1 (GT 40-3-2) and Intacta RR2 PRO® (MON87701 x MON89788)

Abstract

Knowledge of insect diversity is essential for ecological studies and pest management. The aim of this study was to study the occurrence, abundance of target and non-target pests in genetically modified insect resistant (Bt) and glyphosate-tolerant soybeans (RR1 and RR2), with and without the application of insecticides. Experiments were carried out in the agricultural year of 2011/2012 in four municipalities in the State of Mato Grosso do Sul. The treatments were: 1 -Roundup Ready ® RR1 soybeans without insecticide application; 2 -Roundup Ready ® RR1 soybeans with application whenever the control level was reached; 3 -Intacta RR2 PRO ® soybeans without insecticide application; and 4 -Intacta RR2 PRO ® soybeans with application whenever the control level was reached. The evaluations were initiated soon after emergence of the plants at weekly intervals. In order to obtain representative gradients of species composition, we used the method of ordering by non-metric multidimensional scaling (NMDS) and the Bray-Curtis dissimilarity index. Insects of the order Lepidoptera presented 7547 specimens, composing more than 70% of the insect community. The orders Coleoptera and Hemiptera also stood out, consisting of 2066 and 331 insects, respectively. Most of the samples were recorded in stages V8 to R2 for defoliating caterpillars and between R5.2 and R6 for the phytophagous stink bug complex. The Bt technology significantly reduced the target insect pests and favored populations of natural enemies. The treatments with insecticide application resulted in reduction of arthropods collected and changes in population outbreaks when compared to areas without spraying.

Defoliation of Soybean Expressing Cry1Ac by Lepidopteran Pests

“…A study of diversity, composition, and population dynamics of arthropods in non-Bt soybean and Bt soybean showed that A. gemmatalis , C. includens , C. virescens , and S. frugiperda were significantly controlled by Bt soybean. However, other species of the Spodoptera complex were not controlled by this technology [ 70 ]. Other studies reported that S. cosmiodes was the most abundant species attacking Bt soybean [ 71 ] and that development and reproduction of this species were not affected by the Cry1Ac protein [ 20 ].…”

Antibiosis in Soybean Genotypes and the Resistance Levels to Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae)

“…Ministério da Agricultura and Abastecimento 2013). Although new technologies such as Bt-transgenic soybean expressing the Cry1Ac toxin have been commercially released in Brazil (Justiniano et al 2014), there is little expectation that they will be effective in controlling SAW due to the low toxicity of Cry1Ac to S. eridania larvae (Santos et al 2009, Bernardi et al 2014.…”

Survival and development of Spodoptera eridania, Spodoptera cosmioides and Spodoptera albula (Lepidoptera: Noctuidae) on genetically‐modified soybean expressing Cry1Ac and Cry1F proteins

“…1,2 The main soybean Lepidopteran pests are velvetbean caterpillar, Anticarsia gemmatalis (Hübner), soybean looper, Chrysodeixis includens (Walker), Old World bollworm, Helicoverpa armigera (Hübner), and tobacco budworm, Chloridea virescens (F.). [3][4][5][6] However, outbreaks of Spodoptera species have been reported in soybean fields, including S. frugiperda (Smith), S. eridania (Stoll), S. cosmioides (Walker) and S. albula (Walker). [7][8][9] Of these species, S. frugiperda is an emerging soybean pest due to increased infestations and damage observed on soybean in recent seasons in Brazil.…”