Evaluation of toxicity and environmental safety in use of spinosad to rationalize control strategies against Aedes aegypti

Abstract

Spinosad is a naturally-occurring insecticide used for the management of Ae. aegypti larvae. The assessment of ecotoxicological parameters of spinosad is required for verifying the environmentally-friendly behavior of the compound and for evaluating toxicity values on non-target species. Thus, the aim of the study was to conduct toxicity tests using Daphnia magna as model organism after exposure to different concentrations of spinosad. Immobility effects were observed in both acute and chronic toxicity tests at the concentration of 2.5 μg/L, and D. magna exhibited an EC50-48 h of 4.1 μg/L and EC_50-7d of 9.3 μg/L. Also, the reproductive test showed a significant increase in the time of first reproduction and decrease in the number of neonates per female. However, due to the rapid decay of spinosad, other reproductive parameters were not markedly affected. Thereby, considering the satisfactory control performance against Aedes aegypti, a 100-fold lower concentration of spinosad can be used against the larvae, and owing to the residual efficacy observed, the application of the pesticide in the field may be rationalized while offering environmental safety.

Keywords: Daphnia magna; Ecotoxicology; Environmental health; Larvicide.