Consumption of Bt Maize Pollen Containing Cry1Ie Does Not Negatively Affect Propylea japonica (Thunberg) (Coleoptera: Coccinellidae).

Yonghui Li,Yanmin Liu,Lili Geng,Yufa Peng,Xiuping Chen,Xinming Yin,Jörg Romeis,Yunhe Li,Xinyuan Song

doi:10.3390/toxins9030108

Abstract

Propylea japonica (Thunberg) (Coleoptera: Coccinellidae) are prevalent predators and pollen feeders in East Asian maize fields. They are therefore indirectly (via prey) and directly (via pollen) exposed to Cry proteins within Bt-transgenic maize fields. The effects of Cry1Ie-producing transgenic maize pollen on the fitness of P. japonica was assessed using two dietary-exposure experiments in the laboratory. In the first experiment, survival, larval developmental time, adult fresh weight, and fecundity did not differ between ladybirds consuming Bt or non-Bt maize pollen. In the second experiment, none of the tested lethal and sublethal parameters of P. japonica were negatively affected when fed a rapeseed pollen-based diet containing Cry1Ie protein at 200 μg/g dry weight of diet. In contrast, the larval developmental time, adult fresh weight, and fecundity of P. japonica were significantly adversely affected when fed diet containing the positive control compound E-64. In both experiments, the bioactivity of the Cry1Ie protein in the food sources was confirmed by bioassays with a Cry1Ie-sensitive lepidopteran species. These results indicated that P. japonica are not affected by the consumption of Cry1Ie-expressing maize pollen and are not sensitive to the Cry1Ie protein, suggesting that the growing of Bt maize expressing Cry1Ie protein will pose a negligible risk to P. japonica.

Highlights

Maize (Zea mays L.) is one of the most important cereal crops in the world and plays a decisive role in food and feed production
When fed with maize pollen, over 73% of the P. japonica larvae developed to adults, and the pupation rates and eclosion rates did not significantly differ between the Bacillus thuringiensis (Bt) and the non-Bt maize pollen treatments (Table 1)
The cry1Ie gene has been identified from Bacillus thuringiensis isolate Btc007 and is a relatively new gene used for plant transformation [23]

Summary

Introduction

Maize (Zea mays L.) is one of the most important cereal crops in the world and plays a decisive role in food and feed production. In China, it is mainly grown for food, feed, and ethanol production [1]. The yield of maize can be reduced heavily by insect pests. China is the Asia maize borer, Ostrinia furnacalis Guenée (Lepidoptera: Crambidae). The Asia maize borer was estimated to cause approximately 10% of yield loss each year and more than 30% in years of heavy infestations [2].

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Conclusion