Comprehensive Evaluation of Bacillus thuringiensis subsp. israelensis: From Molecular Profiling to Ecotope-Specific Larvicidal Efficacy Against Laboratory Aedes aegypti and Wild Mosquito Populations

The escalating challenge of managing vector-borne pathologies necessitates the advancement of vector control strategies that are both highly potent and environmentally benign. This research evaluates the insecticidal efficacy and environmental plasticity of three Bacillus thuringiensis subsp. israelensis (Bti) H14 strains 33, 87/1, and 7-1/3 against laboratory and wild mosquito populations. In controlled laboratory assays, cultures with a spore density of 4.0–4.4 × 109 spores/mL demonstrated significant larvicidal activity against larvae of all instars (L1–L4) of Aedes aegypti. The median lethal concentration (LC50) was established between 1.15 and 1.48 µL/L, resulting in cumulative mortality rates of 95–96% within a 48 h exposure window. Proteomic profiling via SDS-PAGE and Western blotting validated the robust synthesis of the signature δ-endotoxin complex, specifically verifying the presence of Cry4Aa, Cry4Ba, Cry11Aa, and Cyt1Aa. Field applications in specific forest (Polissya) and steppe (Forest–Steppe) aquatic biotopes of Ukraine—characterized by distinct physicochemical profiles (differing significantly in light exposure, water hardness, salinity, and suspended solids)—substantiated the stability of the liquid formulations, achieving larval suppression rates of 95–100% within 48 h against wild Aedes-dominated assemblages at application rates of 0.25–1.0 mL/m2 (equivalent to 2.5–10.0 L/ha). The demonstrated environmental adaptability suggests these novel strains are viable candidates for broad-spectrum ecological engineering applications. Their integration into sustainable vector control strategies offers a mechanism to enhance biosecurity without compromising the ecological balance of local biocenoses.