Mosquito larvicidal bioassay with the fruit extracts of Diospyros kaki on filarial vector Culex quinquefasciatus

Abstract

Due to the emergence of resistance of the commonly used synthetic pesticide, vector control is in grave danger. Application of biocontrol agents may be a suitable alternative approach in vector control. The purpose of this study was to evaluate the larvicidal effectiveness of crude and methanolic fruit extracts of Diospyros kaki against Culex quinquefasciatus, the carrier of human filarial worm. The methanol extract showed promising result in biocontrol assay than crude extract. The methanolic extract had the LC50 and LC90 values of 46 ppm and 186 ppm, respectively against 1st instar larvae after 72 hours of exposure, The rate of mortality was positively associated with the solvent extracts in increasing concentrations, having a regression coefficient value near to 1 in each case, showing a definite positive dose-dependent mortality. During chemical characterization of the solvent extract by GC-MS and FT-IR studies, some bioactive compounds like 5,8,11,14,17-Eicosapentaenoic Acid, Methyl 4,7,10,13,16,19-Docosahexaenoate, cyclotrisiloxane hexamethyl and Arsenous acid, tris(trimethylsilyl) ester were identified that showed the larvicidal activity against mosquito larvae either singly or jointly. Thus, D. kaki fruit extract showed excellent potential as a bio control agent for Cx. quinquefasciatus and the isolated bioactive phytochemical may be utilized as a source of a powerful insecticide.

Keywords

• bioactive compounds
• Culex quinquefasciatus
• Diospyros kaki
• FT-IR
• GC-MS
• LC50 and LC90 values