Evaluation of Cry1Ac and Cry2Aa Toxin Binding to Two Important Beneficial Cotton Field Insects, Harmonia axyridis and Orius similis

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Abstract or Summary

Transgenic crops expressing Cry toxins are effective and considered environmentally friendly alternatives to synthetic pesticides, but assessment of environmental risks of their application on nontarget organisms is ongoing. The main risk is the transfer of Cry toxins to natural enemies through the food chain. There is reported evidence supporting that Cry toxins can be detected in the body and gut of some natural enemy insects. Considering that binding of Cry toxins to insect proteins is an essential step in the intoxication process, this work was conducted to evaluate interactions between Cry1Ac and Cry2Aa toxins with proteins from larvae/nymphs and adults of two important predatory natural enemies in cotton fields, Harmonia axyridis and Orius similis. Results support the absence of Cry1Ac or Cry2Aa binding proteins in immature stages of H. axyridis and O. similis, as well as in imaginal stage of H. axyridis. One same binding band about 70 kDa was found in imaginal total protein of O. similis when probed with the two Cry proteins, with the best match to Hsc70 of O. sauteri in the Uniprot database. However, nonspecific binding was verified by following competitive binding assays between the two Cry proteins and imaginal total protein of O. similis. From these results, we may infer that Cry1Ac and Cry2Aa have no likely detrimental effects on H. axyridis and O. similis.

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Evaluation of Cry1Ac and Cry2Aa Toxin Binding to Two Important Beneficial Cotton Field Insects, Harmonia axyridis and Orius similis (held on an external server, and so may require additional authentication details)

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