Bacillus thuringiensis subsp. israelensis strain AM65-52

Bacillus thuringiensis subsp. israelensis (Bti) strain AM65-52 is a highly specific biological larvicide used globally for the control of mosquito and black fly larvae. This strain is prized in agriculture and public health for its ability to target specific dipteran pests without harming non-target organisms, including beneficial insects, aquatic wildlife, and mammals.

The mode of action of this biological agent relies on the production of parasporal crystalline inclusions (delta-endotoxins) during the sporulation phase of the bacterium. Once ingested by the larvae, these crystals are dissolved in the alkaline environment of the larval midgut. The released toxins bind to specific receptors on the gut lining, causing cellular lysis, intestinal paralysis, and the eventual death of the target pest.

This active substance is primarily employed in aquatic environments, including stagnant waters, irrigation ditches, ponds, and floodplains. In agricultural settings, it is applied to water bodies near crop fields to mitigate the nuisance and health risks posed by adult mosquito populations emerging from these habitats. It is an essential component of integrated pest management (IPM) programs.

Application strategies require targeting the early larval stages (instars I–III) for maximum efficacy. Factors such as water temperature and the presence of organic debris can influence the persistence and bioavailability of the spores. Proper formulation selection, such as liquid concentrates for surface spraying or granules for deep-water penetration, is critical to ensuring the toxin reaches the larval feeding zone.

Safety precautions for handling Bacillus thuringiensis israelensis are minimal due to its excellent toxicological profile. It is non-toxic to humans, pets, livestock, and aquatic vertebrates. Users should follow standard label instructions regarding protective gear to avoid skin or eye irritation during the preparation of the spray mix. There are no restrictions on the subsequent use of treated water for crop irrigation.