Ecotoxicological and behavioural responses of aquatic model organisms to the MosChito raft bioinsecticide delivery system

MosChito raft, a Bacillus thuringiensis (Bti)-based formulation, represents a promising device for mosquito larvae control in domestic environments. Its chitosan matrix and active component, the commercial Bti product VectoBac 12AS, ensure high specificity and minimal environmental impact. This study evaluates the ecosafety of MosChito raft by assessing their effects on two aquatic model organisms, Daphnia magna and Danio rerio embryos. Both organisms were exposed to different MosChito rafts (Matrix, Yeast, Bti, Bti + Yeast). Embryos and larvae of D. rerio were monitored to assess acute toxicity, changes in swimming behavior, and alterations in key biochemical markers (ROS and AChE). Daphnids were exposed from hatching to 14 days, and the same markers as in D. rerio were evaluated, as well as their fertility. Across all tests, MosChito raft showed no acute toxicity. Behavioral assays in D. magna revealed a slight but statistically significant reduction in swimming activity after exposure to specific formulations. Biochemical analyses revealed mild oxidative stress in D. magna, although cholinergic signaling remained unaffected. No significant impact on D. magna fertility was found. Overall, our findings suggest that MosChito raft exerts negligible toxic effects on non-target aquatic species, supporting its use as an environmentally safe mosquito control tool, consistent with integrated pest management strategies aimed at minimizing ecological impact.