Mosquito larvicidal activity of Alpinia galanga wild (Zingiberaceae) rhizome against third instar larvae of Aedes aegypti and Culex quinquefasciatus

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Mosquitoes are vectors which transmit parasite, nematodes, and viruses that are harmful pathogens responsible for diseases like chikungunya, dengue, yellow fever, Zika, Lymphatic filariasis and malaria etc. Synthetic and chemical insecticides were initially effective for mosquito control; however, prolonged use has led to the development of insecticide resistance in many mosquito species. The extensive use of chemical insecticides has resulted in environmental degradation, pollution, the accumulation of toxic substances in ecosystems, and serious health risks to humans and animals. Phytochemicals obtained from medicinal plants represent environmentally friendly alternatives to synthetic insecticides and have demonstrated significant efficacy in the control of mosquito species. The present research evaluates the potential mosquito larvicidal efficacy of the crude extracts of the rhizomes of Alpinia galanga Wild against the third instar larvae of Aedes aegypti and Culex quinquefasciatus . Significant larvicidal effect was observed in the hexane extract, with LC 50 values of 223.841 ppm and 171.768 ppm followed by chloroform extract with 224.002 ppm and 216.741ppm, and ethyl acetate extract with 275.772 and 382.794 ppm against A. aegypti and Cx. quinquefasciatus respectively. The methanolic extract showed a very minimal activity. Histopathological studies of larvae ( Cx. quinquefasciatus ) exposed to the most active hexane extract revealed severe damage to the peritrophic membrane, brush border cells (BB), and gastric caeca (GC), accompanied by leakage of midgut contents. The GC–MS analysis of the active hexane extract detected 23 compounds, with ethyl p -methoxycinnamate being the most abundant constituent, representing 44.61% of the total composition. The present study demonstrates that A. galanga is a promising botanical agent for the management and control of vector mosquito populations.