Bacillus thuringiensis subsp. israelensis at the Public Health–Ecology–Biotechnology Nexus: From Larvicidal Precision to Protein Delivery Platform Potentials

This review examines Bacillus thuringiensis subsp. israelensis (Bti) as both a highly selective microbial larvicide and a biological platform for protein storage and delivery, enabled by the structural features of its prokaryotic insect larvicidal organelle (PILO). Bti remains the most widely deployed biological agent for mosquito control. Decades of operational use demonstrate substantial public health benefits and only limited, manageable ecological tradeoffs within integrated vector management programs (IVMP). Its narrow host range underlies an excellent safety record for humans and other vertebrates. Moreover, laboratory and field studies consistently show that collateral effects are minimal, context dependent, reversible, and largely restricted to closely related non-target aquatic dipterans. These attributes have established Bti as a cornerstone of environmentally sustainable IVMP worldwide. Here, we synthesize current knowledge on Bti biology, ecological selectivity, field performance, and the resistance-management properties embedded in the molecular architecture of the PILO. Finally, we assess emerging opportunities and technical constraints in repurposing the PILO as an in vivo microbial factory for packaging heterologous proteins with potential pharmaceutical and industrial applications.