The effect of thioredoxin-gene-expressed transgenic soybean on associated non-target insects and arachnids

The evaluation of genetically modified (GM) crops regarding their effect on non-target organisms is necessary to safeguard ecosystem components. In this study, we assessed the effects of transgenic soybean events TRX (expressing the human thioredoxin gene under the control of the β-conglycinin promoter with tolerance to the herbicide glufosinate, PPT) on plant-dwelling non-target insects and arachnids compared with those of a non-GM parental cultivar, Gwangan soybean. Field surveys of soybean fields were carried out at Ochang and Jeonju, Korea, in 2016 and 2017. We found that the number of captured individuals was higher at Ochang in 2017 on both TRX and Gwangan soybean plants. From 2016 to 2017, the average population density of the insect pests and natural enemies decreased; however, in the case of other insects, the population density remained unchanged. The dominance index of the captured non-target insects and arachnids decreased, whereas the diversity and richness indices increased over time on the genotypes at both regions. The evenness index of non-target insects and arachnids decreased at Jeonju but showed no change at Ochang, regardless of the genotype. Hemiptera, Hymenoptera, and Diptera were the most dominant orders of the insect pests, natural enemies, and other insects, respectively. The score from PROXSCAL multidimensional scaling using combined data showed that insects and arachnids in different natural environments differed due to their cultivation regions and years, irrespective of soybean cultivars. Overall, the results indicated that the GM soybean TRX did not negatively affect the community of plant-dwelling non-target insects and arachnids.