No impact of transgenic cry1Ie maize on the diversity, abundance and composition of soil fauna in a 2-year field trial.

Soil fauna play an essential role in the soil ecosystem, but they may be influenced by insecticidal Cry proteins derived from Bacillus thuringiensis (Bt) maize. In this study, a 2-year field trial was conducted to study the effects of transgenic cry1Ie maize, a type of Bt maize (Event IE09S034), on soil fauna, with the near-isogenic line non-Bt maize (Zong 31) as a control. The soil animals were collected with Macfadyen heat extractor and hand-sorting methods, respectively, and their diversity, abundance and community composition were calculated. Then, the effects of maize type, year, sampling time and soil environmental factors on the soil fauna were evaluated by repeated-measures ANOVA, redundancy analysis (RDA) and nonmetric multidimensional scaling (nMDS). Repeated-measures ANOVA showed that the diversity and abundance of the soil fauna were not affected by maize type, while they were significantly influenced by year and sampling time. Furthermore, for both the Macfadyen and hand-sorting methods, RDA indicated that soil fauna community composition was not correlated with maize type (Bt and non-Bt maize) but was significantly correlated with year, sampling time and root biomass. In addition, it was significantly related to soil pH according to the hand-sorting method. nMDS indicated that soil fauna community composition was significantly correlated with year and sampling time; however, it was not associated with maize type. In this study, we collected soil faunal samples according to the Macfadyen and hand-sorting methods and processed the obtained data with ANOVA, RDA, and nMDS in three ways, and our data indicate that transgenic cry1Ie maize (Event IE09S034) had no substantial influence on the diversity, abundance or community composition of the soil fauna.

Use of Taxonomic and Trait-Based Approaches to Evaluate the Effects of Transgenic Cry1Ac Corn on the Community Characteristics of Soil Collembola.

Nontarget soil fauna in fields planted with transgenic Bt crops may be influenced by the Bt protein following crop establishment. Here, we investigated the effects of transgenic Cry1Ac corn Bt-799 on soil Collembola using both taxonomic and trait-based approaches in an experimental field in northeast China from 2014 to 2015. The relationship between the collembolan community and environmental variables (including corn type) was investigated using redundancy analysis (RDA). In May 2015, we found that collembolan species richness, Shannon-Wiener's index, and all trait values examined in transgenic Cry1Ac corn (Event Bt-799, Bt corn) were lower than in its near isoline (Zheng 58, non-Bt corn). However, this significant influence did not persist in the subsequent corn growth period. For all other sampling periods over 2-yr study, all indices based on taxonomic (abundance, species richness, and Shannon-Wiener's index) and trait-based (number of ocelli, body size, pigmentation, furcula development, and antennae length) approaches in Bt corn were not significantly different from non-Bt corn. The results showed no significant difference between the two corn types in the repeated-measures analysis of variance (ANOVA). Moreover, redundancy analysis (RDA) showed that corn type only explained 1% of the variation in the collembolan community. These results suggested that Bt corn did not affect collembolan community characteristics in the short term.