The selective feeding of cotton bollworms (Helicoverpa armigera) on transgenic and non-transgenic cotton leaves from consecutive cultivation fields

Abstract

The aim of this study was to determine whether target-insects selectively feed on transgenic or non-transgenic crops after consecutive cultivation in fields. We sampled leaves from insect-resistant single-transgenic cotton (expressing Cry1Ac gene), pyramided-transgenic (expressing Cry1Ac and CPTI genes) and conventional cotton that were consecutively cultivated for three years in a field. Cotton bollworm (Helicoverpa armigera) collected from the cotton field was reared and its next-generation larvae were fed the three types of cotton leaves in a laboratory. The leaf area damaged by the cotton bollworm larvae was not significantly different among single-transgenic, pyramided transgenic and conventional cotton leaves. There was no significant difference found in the leaf damage among the combination groups of the three cotton types. The survival rate of the bollworms was comparable among the combination groups. The results demonstrated that the cotton bollworms did not selectively feed on transgenic or non-transgenic cotton leaves after consecutive cultivation, which may be due to the resistance evolution of the target-insects and decreased Bt content in transgenic cotton leaves.