Screening of larvicidal activities and potential mode of action of Citrus limon (Rutaceae) and Salvia rosmarinus (Lamiaceae) essential oils against Aedes aegypti and Aedes albopictus.

With the increase in dengue fever cases, the control of dengue vector Aedes mosquito is crucial. The current study was designed to evaluate the larvicidal activity of essential oils of Citrus limon L.; Rutaceae and Salvia rosmarinus (Spenn 1836); Lamiaceae against Aedes aegypti L., and Aedes albopictus (Skuse 1894) mosquitoes. The essential oils were extracted by steam distillation and their component analysis was conducted. The larvicidal activities were assessed by exposing fourth instar larvae to various concentrations of essential oils for 24 h. The mode of action of essential oils was assessed by analyzing their inhibitory activities against key mosquito enzymes including acetylcholinesterase and α-amylase. The major constituents identified from both plant essential oils were 1,8-cineole, limonene, camphor, α-pinene, β-pinene, α-terpineol, and linalool. Moreover, the C. limon and S. rosmarinus essential oils exhibited significant larvicidal activities against Aedes larvae. The LC50 values of C. limon essential oil for Ae. aegypti and Ae. albopictus larvae were 33.43 and 38.01 mg/liter, respectively, as compared to the LC50 of S. rosmarinus essential oil that were 44.96 and 49.53 mg/liter, respectively. Furthermore, both plant essential oils significantly inhibited the activities of acetylcholinesterase and α-amylase. The camphor and limonene were the major essential oils components with highest binding affinities against acetylcholinesterase (-6.3 and -6.4) and α-amylase (-5.9 and -5.2) enzymes. Therefore, it can be concluded that the essential oils of C. limon and S. rosmarinus with diverse compositions possess significant larvicidal activities as well as inhibitory activities against acetylcholinesterase and α-amylase. Therefore, these essential oils can be used for Aedes mosquito control.