Enhanced toxicity of Cry2Ab with cantharidin and its analogues on Mythimna separata

Abstract

The oriental armyworm, Mythimna separata Walker (Lepidoptera: Noctuidae), is a severe pest of graminaceous crops in Asia and Australia. In this study, we investigated the impacts of Cry2Ab, cantharidin and its analogues (cantharidin‐23 and cantharidin‐24) on M. separata growth, hydrolytic enzymes and detoxifying enzymes. Differences in weight gain and enzyme activities among all treatments were observed. Larval and pupal weight gain and hydrolytic enzyme activities declined when larvae were treated with Cry2Ab, cantharidin and its analogues, individually or in combination. The combination of Cry2Ab and cantharidin or cantharidin‐24 had a markedly adverse effect on larval weight gain. Alkaline phosphatase and acid phosphatase were inhibited, whereas glutathione S‐transferase was upregulated in all treatments with sublethal doses. The maximum reduction in alkaline phosphatase activity and increase in glutathione S‐transferase activity occurred after the larvae were treated with a combination of Cry2Ab and cantharidin‐24 over 48 h. The results suggest that the compositions of Cry2Ab, cantharidin and cantharidin‐24 have a potential use in pest management.

Molecular Characterization and Efficacy Evaluation of Transgenic Maize Harboring cry2Ab-vip3A-cp4epsps for Insect Resistance and Herbicide Tolerance

“…In contrast to the broad-spectrum insecticidal properties of chemical insecticides, these Bt proteins exhibited relatively narrow and selective toxicity against only a certain range of pests [ 2 ]. Cry2Ab shares no high-affinity receptors with Cry1A proteins in the insect midgut and displays toxicity against M. separata and H. armigera [ 2 , 14 , 15 , 16 , 17 , 18 , 19 ]. Vip3A does not share homology with Cry proteins, and its binding sites and mode of action are likewise distinct from those of Cry proteins [ 20 , 21 , 22 ].…”