Mosquito Larvicidal Potentiality of <i>Holoptelea integrifolia</i> Leaf Extract against Japanese Encephalitis Vector, <i>Culex vishnui</i> Group

Abstract

Vector control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative in future. Holoptelea integrifolia distributed in many parts of India is a medicinal plant. During the present study, larval mortality of Culex vishuni group was observed after 24 h, 48 h and 72 h of exposure with five concentrations of crude extract (0.1%, 0.2%, 0.3%, 0.4% and 0.5%) and four concentrations (100 ppm, 200 ppm, 300 ppm and 400 ppm) of acetone extract of leaf of the plant. Respective lethal concentrations were determined by log-probit analysis (at 95% confidence level). Effects of acetone extract of H. integrifolia leaves were tested against non-target predatory fishes and insect larvae. During the present study, the mortality rates of all larval instars at 0.5% concentration were significantly higher (p < 0.05) than at 0.1%, 0.2%, 0.3% and 0.4% concentrations of crude leaf extract. Highest mortality was observed at 400 ppm concentration of acetone extract. Phytochemical analysis of crude extract revealed the presence of tannin, saponin, steroid and phenol as major bioactive secondary metabolites. No nontarget mortality was observed.