Bacillus thuringiensis serovar israelensis (Bti) is a group of bacteria used as biological control agents for larvae stages of certain Dipterans. Bti produces toxins which are effective in killing various species of mosquitoes, fungus gnats, and blackflies, while having almost no effect on other organisms. Indeed this is one of the major advantages of B. thuringiensis products in general is that they are thought to affect few non-target species.
Bti strains possess the pBtoxis plasmid which encodes numerous Cry and Cyt toxins, including Cry4, Cry10, Cry11, Cyt1 and Cyt2. The crystal aggregation which these toxins form contains at least four major toxic components but the extent to which each Cry and Cyt protein is represented is not known and likely to vary with strain and formulation. Both Cry and Cyt proteins are pore forming toxins; they lyse midgut epithelial cells by inserting into the target cell membrane and forming pores.
Commercial formulations include "Mosquito Dunks"/"Mosquito Bits". It is also available in bulk liquid or granular formulations for commercial and public agency use.