Bioassay-guided isolation of dehydrocostus lactone from <i>Echinops kebericho</i> as potential biopesticide against <i>Aedes aegypti</i>

Dengue fever is the most prevalent viral infection, which transmits by the vector mosquito <i>Aedes aegypti</i> and <i>Aedes albopictus</i>. The development of an effective dengue vaccine is still challenging. Thus, the prevention and control of dengue depend on controlling the transmitting vectors. Traditionally, <i>Echinops kebericho</i> roots are known to have mosquito-repellant properties. Dehydrocostus lactone, one of the major constituents of the roots extract, showed similar larvicidal activity as the standard pesticide permethrin (100% mortality) against the larvae of <i>A. aegypti</i> at 10 µg/mL concentration at 24 h exposure. The derivative compound (13-methoxy dehydrocostus lactone) was inactive against the larvae of <i>A. aegypti</i>. The structure-activity relationship (SAR) suggested that the presence of α- methylene and γ- lactone moieties are responsible for the larvicidal activity of dehydrocostus lactone against the larvae of <i>A. aegypti</i>. Overall, dehydrocostus lactone can be a potential biopesticide against the dengue vector mosquito, <i>A. aegypti</i>.