Efficacy of ethyl acetate extract of Alangium salviifolium fruit pericarp against Culex quinquefasciatus larvae

Abstract

Mosquitoes transmit major human diseases, resulting in millions of fatalities each year and the development of chemical insecticide resistance, leading to a rebound in vectorial capacity. Plants could be used as a mosquito repellent alternative. The purpose of this study was to evaluate the biocontrol potentiality of ethyl acetate extract of fruit pericarp of Alangium salviifolium against Culex quinquefasciatus larvae. 100% larval mortality was recorded after 72 h of exposure with 50, 40 ppm, and 30 ppm concentrations of ethyl acetate extract against 3rd instar mosquito larvae. The bioactive compound responsible for larval mortality was isolated by TLC (Rf value of 0.33). 3rd instar larvae were found to be the most susceptible (LC50 = 3.60 ppm) among all the instars and corresponding LC50 values were 4.45 ppm and 4.52 ppm for 2nd and 4th instars larvae respectively after 72 h of exposure. The mortality rate of all larval instars was directly proportional to the concentration of bioactive compounds. Three-way ANOVA analysis revealed that larval instars, the concentration of bioactive compound, and time of exposure had a significant effect on larval mortality. In the bioactive TLC fraction of A. salviifolium (Rf value of 0.33), FT-IR spectroscopy analysis revealed the presence of numerous functional groups. GC-MS analysis revealed the presence of Benzoyl bromide and 3-Amino -5 (2-Furyl) Pyrazole in the extract. The compounds were also studied on non-target organisms such as Anisops sardea, 4th instar larvae of Chironomus sp. and Diplonychus annulatum, and in all the cases no abnormalities were recorded.