Cry11Aa

Cry11Aa is a delta-endotoxin produced by Bacillus thuringiensis subsp. israelensis (Bti). It is one of several mosquitocidal crystal proteins generated by Bti during sporulation and is commonly present in commercial biopesticide formulations alongside Cry4Aa, Cry4Ba, and Cyt1Aa. Cry11Aa is ingested by mosquito larvae and, after proteolytic activation in the larval midgut, the active toxin binds to gut receptors and inserts into epithelial cell membranes to form pores. This disrupts ion homeostasis, causes cell lysis, compromises the gut barrier, and leads to larval death. Its activity is primarily directed at Dipteran mosquito species, including Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus; susceptibility can vary among species and strains of mosquitoes.

Mechanism and interactions: Cry11Aa belongs to the three-domain family of Cry toxins, which execute toxicity via pore formation in midgut membranes. Receptor interactions involve midgut proteins such as aminopeptidase N and alkaline phosphatase. Cry11Aa can act in concert with Cyt1Aa, which can enhance toxicity and help overcome resistance by providing alternative binding pathways, contributing to more robust mosquitocidal activity when used in combination formulations.

Applications and safety: Cry11Aa is deployed in Bacillus thuringiensis israelensis-based formulations for aquatic larval control in vectors and disease prevention programs. The toxin is part of pyramid strategies that reduce the likelihood of resistance development compared with single-toxin products. Regulatory use emphasizes limited non-target toxicity and environmental safety when applied according to label directions.