Biochemical Responses of Anopheles spp. Larvae to a Novel Brazilian BR101 Bacillus thuringiensis var. israelensis Formulation: Oxidative Stress, Detoxification Enzymes, and Safety for Nontarget Notonectidae and Gerridae Aquatic Insects

Despite its proven efficacy, Bacillus thuringiensis israelensis (Bti) has not yet been incorporated into Brazilian Ministry of Health programs targeting Anopheles spp., the primary malaria vectors. This study evaluated the larvicidal potential of the Brazilian strain BR101. The strain displayed significant activity, with mortality rates ranging from 11% ± 2% to 91% ± 5% (LC 50 = 3.13 µg/mL), accompanied by increased reactive oxygen species (54.67 ± 3 µmol H 2 O 2 ), lipid peroxidation (57.33 ± 4.5 ηmol), and oxidative protein damage (16.67 ± 2.1 nM reactive carbonyls/mg). Biochemical responses included elevated activities of superoxide dismutase (29.00 ± 3 mU/mg protein), catalase (17.00 ± 1 µmol H 2 O 2 ), glutathione peroxidase (29.00 ± 3 mmol NADPH/min/mL), mixed‐function oxidases (11.00 ± 3 nmol cytochrome/mg protein), and esterases ( α : 20.67 ± 2; β : 25.67 ± 1 µmol/min/mg). Acetylcholinesterase activity was slightly reduced (80.33 ± 7 µmol/min/mg). Ecotoxicological assays revealed no lethal effects on nontarget aquatic predators (Notonectidae, Gerridae), with 100% survival over 30 days, equivalent to controls. These findings demonstrate that Bti BR101 is effective against Anopheles larvae while being safe for nontarget organisms.