Dual resistance to Bacillus thuringiensis Cry1Ac and Cry2Aa toxins in Heliothis virescens suggests multiple mechanisms of resistance.

Evidence for multiple mechanisms of resistance to Cry1Ac and Cry2A toxins from Bacillus thuringiensis in Heliothis virescens

Genetic basis of resistance to Cry1Ac and Cry2Aa in Heliothis virescens (Lepidoptera: Noctuidae).

The development of pest resistance to transgenic crop plants producing insecticidal toxins from Bacillus thuringiensis Berliner (Bt) poses a major threat to their sustainable use in agriculture. "Pyramiding" two toxins with different modes of actions in the same plant is now being used to delay the evolution of resistance in the insects, but this strategy could fail if a single gene in a pest c...

The Heliothis virescens cadherin protein expressed in Drosophila S2 cells functions as a receptor for Bacillus thuringiensis Cry1A but not Cry1Fa toxins.

Genetic knockout of the BtR4 gene encoding the Heliothis virescens cadherin-like protein (HevCaLP) is linked to resistance against Cry1Ac toxin from Bacillus thuringiensis. However, the functional Cry1Ac receptor role of this protein has not been established. We previously proposed HevCaLP as a shared binding site for B. thuringiensis (Bt) Cry1A and Cry1Fa toxins in the midgut epithelium of H. ...

Importance of Cry1 delta-endotoxin domain II loops for binding specificity in Heliothis virescens (L.).

We constructed a model for Bacillus thuringiensis Cry1 toxin binding to midgut membrane vesicles from Heliothis virescens. Brush border membrane vesicle binding assays were performed with five Cry1 toxins that share homologies in domain II loops. Cry1Ab, Cry1Ac, Cry1Ja, and Cry1Fa competed with (125)I-Cry1Aa, evidence that each toxin binds to the Cry1Aa binding site in H. virescens. Cry1Ac comp...

Cry toxin mode of action in susceptible and resistant Heliothis virescens larvae.

Many pest insect species are effectively controlled by Bacillus thuringiensis (Bt) Cry toxins delivered in plants and biopesticides. Since the insect midgut epithelium contains receptors and other molecules that determine Bt toxicity, characterization of these molecules is necessary for sustained usage of Bt toxins. Studies of Bt susceptible and resistant strains of Heliothis virescens have pro...