Bt, Not a Threat to Propylea japonica.

Chenchen Zhao,Xiangzhen Zhu,Linke Wu,Chuanpeng Wang,Junyu Luo,Shuai Zhang,Peng Zhao,Li Wang,Jinjie Cui,Lin Niu

doi:10.3389/fphys.2020.00758

Abstract

Given the ever-increasing commercial planting of transgenic plants across the world, an evaluation of their impacts on non-target organisms is as an important part of the risk assessment process. Propylea japonica is a dominant non-target predator and pollen feeder insect that is prevalent in Bt cotton fields, and it is thus in direct contact with Bt proteins. However, the effect of Bt proteins on P. japonica has not received much attention. In this study, the effects of Cry1Ac and/or Cry2Ab proteins on P. japonica were investigated from three aspects. First, no significant differences in the diversity of the microbiota nor change in species composition and community structure were observed among Cry protein treatments. Firmicutes are the most abundant bacterial phylum present in P. japonica, followed by Proteobacteria and Actinobacteria. The most abundant genus was Staphylococcus. Second, the expression levels of the detoxification and digestion-related genes did not change significantly in any Cry protein treatment. Third, none of the Cry proteins affected the population fitness of P. japonica. These results indicated that P. japonica was not sensitive to Bt proteins, suggesting that growing Bt cotton expressing Cry1Ac and/or Cry2Ab will pose negligible risks to P. japonica.

Highlights

The global cultivation of genetically modified (GM) crops exceeded 191.7 million hectares in 2018, which substantially contributes to both increasing crop production and reducing poverty (ISAAA, 2018)
Bacillus thuringiensis (Bt) proteins were solubilized in a solution of 2M sucrose (Álvarez-Alfageme et al, 2011) at a final concentration of 500 μg/mL, which was at least 10 times higher than that measured in Bt cotton pollen (Knight et al, 2013; Meissle and Romeis, 2018)
We focused on studying the effects of dietary consumption of Bt toxins on P. japonica, an important but non-target insect species, to better evaluate the environmental impacts of the commercial release of transgenic plants expressing Bt toxins in China

Summary

Introduction

The global cultivation of genetically modified (GM) crops exceeded 191.7 million hectares in 2018 (the 23rd year of continuous biotech crop adoption), which substantially contributes to both increasing crop production and reducing poverty (ISAAA, 2018). This phenomenon has been especially true for major commercial crops like cotton (Gossypium hirsutum L.) and maize (Zea mays L.) where genetic engineering has contributed to both increased production and reduced reliance on insecticide treatments (Sanahuja et al, 2015). Bacillus thuringiensis (Bt) insect-resistant transgenic plants are highly popular and widely commercialized. Bt insect-resistant transgenic plants are highly popular and widely commercialized. Numerous studies have shown that Bt-transgenic cotton can suppress populations of a target pest with a narrow host range, resulting in increased yields (ISAAA, 2018) and great economic and ecological benefits (Wu et al, 2008)

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