Abstract
Bacillus thuringiensis (Bt) Cry1A toxins are known for their effectiveness against lepidopteran insects. In this study, the entomopathogenic activity of Cry1Aa was investigated against two lepidopteran larvae causing serious threat to various crops, Spodoptera littoralis and Tuta absoluta. Contrarily to S. littoralis, which showed low susceptibility to Cry1Aa (40% mortality with 1μg/cm2), T. absoluta was very sensitive to this delta-endotoxin (LC50 of 95.8ng/cm2). The different steps in the mode of action of this toxin on the two larvae were studied with the aim to understand the origin of their difference of susceptibility. Activation of the 130kDa Cry1Aa protein by T. absoluta larvae juice generated a 65kDa active toxin, whereas S. littoralis gut juice led to a complete degradation of the protoxin. The study of the interaction of the brush border membrane vesicles (BBMV) with purified biotinylated Cry1Aa toxin revealed six and seven toxin binding proteins in T. absoluta and S. littoralis BBMV, respectively. Midgut histopathology of Cry1Aa fed larvae demonstrated approximately similar damage caused by the toxin in the two larvae midguts. These results suggest that the activation step was strongly involved in the difference of susceptibility of the two larvae to Cry1Aa.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
