The occurrence of pesticidal pollution in the environment and the resistance in the mosquito species makes an urge for the safer and an effective pesticide. Permethrin, a poorly water-soluble pyrethroid pesticide, was formulated into a hydrodispersible nanopowder through rapid solvent evaporation of pesticide-loaded oil in water microemulsion. Stability studies confirmed that the nanopermethrin dispersion was stable in paddy field water for 5 days with the mean particle sizes of 175.3 ± 0.75 nm and zeta potential of −30.6 ± 0.62 mV. The instability rate of the nanopermethrin particles was greater in alkaline (pH 10) medium when compared with the neutral (pH 7) and acidic (pH 4) dispersion medium. The colloidal dispersion at 45°C was found to be less stable compared with the dispersions at 25 and 5°C. The 12- and 24-h lethal indices (LC50) for nanopermethrin were found to be 0.057 and 0.014 mg l−1, respectively. These results were corroborative with the severity of damages observed in the mosquito larvae manifested in epithelial cells and the evacuation of the midgut contents. Further, the results were substantiated by the decrease in cellular biomolecules and biomarker enzyme activity in nanopermethrin treated larvae when compared to bulk and control treatment.

An acetone extract of Solanum trilobatum leaves was evaluated for its ovicidal activity on the mosquito species Culex quinquefasciatus and Culex tritaeniorhynchus, by exposing eggs ranging in age from 0 to 18 h to concentrations of 50–200 ppm of the extract, and assessing their percent hatchability. A 100-ppm dose of the extract killed all of the eggs from both species aged between 0 and 6 h. The 50- and 75-ppm concentrations were also highly effective against young eggs; the effect declined in older eggs. The extract was more ovicidal towards C. quinquefasciatus than C. tritaeniorhynchus. On a testé l'activité ovicide d'un extrait à l'acétone de feuilles de Solanum trilobatum sur les deux espèces de moustiques, Culex quinquefasciatus et Culex tritaeniorhynchus, en exposant des œufs âgés de 0 à 18h à des concentrations de l'extrait compris entre 50 et 200ppm et en évaluant le pourcentage d'éclosions. La concentration à 100ppm de l'extrait tue tous les œufs d'âge compris entre 0 et 6h des deux espèces de moustique. Les concentrations à 50 et 75ppm sont également très efficaces contre les jeunes œufs, mais l'effet diminue avec l'âge des œufs. L'extrait est plus efficace vis à vis de C. quinquefasciatus que de C. tritaeniorhynchus.