Efficacy of 4-methyl-7-hydroxy coumarin derivatives against vectors <i style="">Aedes aegypti </i>and <i>Culex quinquefasciatus</i>

Abstract

4-Methyl-7-hydroxy coumarin is considered as a lead molecule as a biopesticide. Its mono bromo and tribromo derivatives were synthesized. Two more derivatives were synthesized by acylation. Compound 1 (3,6,8-tribromo-7-hydroxy-4-methyl-chromen-2-one) was found to be the most potent against IV^th instar larvae of <i style="">C. quinquefasciatus</i> and <i style="">A. aegypti</i> <i> </i>the<i> </i>LC₅₀ being 1.49 and 2.23 ppm respectively. It showed 100% larval mortality at 25 ppm against <i style="">A. aegypti</i> and at 10 ppm against C<i style="">. quinquefasciatus</i>. Compounds 1 and 2 (3,6,8-tribromo-7-hydroxy-4-methyl-chromen-2’-oxo-2H-chromen-7-yl acetate) showed remarkable ovicidal activity. Significant reduction of 80-85% hatching of eggs of both mosquito species was observed at the highest dose of 100 ppm. The hatched larvae showed 100% mortality in the successive instars. Compounds 3 and 4 (3-bromo-7-hydroxy-4-methyl-chromen-2-one and 3-bromo-4-methyl-2’-oxo-2H-chromen-7-yl acetate) showed moderate activity against both mosquito species.