Larvicidal efficacy of Diospyros kaki fruit extracts against Culex Vishnui mosquito

The study aims to assess the larvicidal efficacy of Diospyros kaki fruit extracts (crude and solvents) against the rice field mosquito, Culex vishnui, which is the vector of Japanese encephalitis. Under simulated semi-field conditions, the larvicidal property of the most effective extract was tested against third instar Cx. vishnui larvae. The crude extract of fruits has a strong larvicidal effect. The larvicidal bioassay with chloroform: methanol extractive outperformed the other solvent extractives of fruits. After 72 h of exposure in a larvicidal bioassay, chloroform: methanol extractive had the lowest LC50 and LC90 values, which were 46 ppm and 186 ppm, respectively, against 1st instar larvae. The semi-field results showed that chloroform: methanol extract was likewise highly effective against third instar Cx. vishnui larvae, with the maximum mortality rate of 100% at 400 ppm concentration after 72 h of exposure. Three major bioactive compounds were identified namely 2,7-dibutoxy-fluoren-9-one- oxime, Pthalic acid, and Tris (2,4-ditert-butylphenyl) phosphate. Non-target organisms, such as Diplonychus annulatum nymphs, were found to be unaffected by the said extracts. Thus, we can claim that the fruits of D. kaki exhibit outstanding larvicidal efficacy against Cx. vishnui mosquito.