Mode of action of mosquitocidal Bacillus thuringiensis toxins

• Published in: Toxicon (Oxford) 2007-04, Vol.49 (5), p.597-600
• Main Authors: Soberón, Mario, Fernández, Luisa E., Pérez, Claudia, Gill, Sarjeet S., Bravo, Alejandra
• Format: Article
• Language: English
• Subjects: Animals; Bacillus thuringiensis; Bacillus thuringiensis - chemistry; Bacterial Toxins - chemistry; Bacterial Toxins - toxicity; Biological and medical sciences; Control; Cry; Culicidae; Culicidae - drug effects; Cyt; Fundamental and applied biological sciences. Psychology; Integrated pest control; Larva - drug effects; Lepidoptera; Lepidoptera - drug effects; Medical sciences; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Mode of action; Models, Biological; Models, Molecular; Pesticides, fertilizers and other agrochemicals toxicology; Phytopathology. Animal pests. Plant and forest protection; Protozoa. Invertebrates; Receptor; Synergism; Toxicology; Vectors. Intermediate hosts
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2006.11.008

Cry toxins from Bacillus thuringiensis (Bt) are used for insect control. Their primary action is to lyse midgut epithelial cells. In lepidopteran insects, Cry1A monomeric toxins interact with a first receptor and this interaction triggers toxin oligomerization. The oligomeric structure interacts then with a second GPI-anchored receptor that induces insertion into membrane microdomains and larvae death. In the case of mosquitocidal Bt strains, two different toxins participate, Cry and Cyt. These toxins have a synergistic effect and Cyt1Aa overcomes Cry toxin-resistance. We will summarize recent findings on the identification of Cry receptors in mosquitoes and the mechanism of synergism: Cyt1Aa synergizes or suppresses resistance to Cry toxins by functioning as a Cry membrane-bound receptor.