This objective is the detailed understanding of the resistance mechanism occurring in insect strains resistant to Bt toxins, either in spray formulations or in Bt-crops. We have been pioneers in demonstrating the key role of membrane receptors in the biochemical bases of resistance. Most resistant strains of many different insect species have been found to have an alteration in a receptor binding site and this type of alteration generally confers extremely high levels of resistance. In such a case resistance is mainly due to a major gene, recessive and autosomal.

Some proteins have been proposed as Bt toxin receptors and some genes have been linked to resistance. We are interested to determine if mutations in them are the responsible in the resistant strains we study and the role they play in the mode of action.

We have worked with our own resistant strains, though much of the work in this line has been carried out through collaborations with foreign laboratories of entomology. We continue to offer our collaboration to any laboratory in the world that may want to know the biochemical basis of resistance to Bt toxins in a determined insect pest. As a matter of fact, we have collaborated with CSIRO (Australia), the Auburn University (Alabama), the University of Tennessee (Tennessee), the Cornell University (New York), the University of Hawaii (Hawaii), the Lincoln University (Nebraska), the U.S. Department of Agriculture (USDA, Kansas), the North Carolina State University (North Carolina), and the Imperial College (U.K.), among other public organizations.

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