Larvicidal activity of an Origanum majorana plant in two mosquito species: Culex pipiens and Culiseta longiareolata (Diptera : Culicidae)

This study aims to test the effect of essential oil extracted from Origanum majorana against two species of mosquitoes, Culex pipiens and Culiseta longiarealata. The essential oil of O. majorana was obtained by hydrodistillation with a yield of 0.50 ± 0.13% of the dry matter. Toxicological tests show larvicidal activity of this essential oil with a concentration-response relationship. Sublethal and lethal concentrations for Cx pipiens (LC₂₅ = 10.79 μL/mL, LC₅₀ = 14.86 μL/mL and LC₉₀ = 28.18 μL/mL) and C. longiareolata (LC₂₅ = 4.15 μL/mL, LC₅₀ = 5.89 μL/mL and LC₉₀ = 11.89 μL/mL). A significant delay in development time, when larvae of both species were exposed to al LC₅₀. This essential oil would be an alternative to chemical larvicides.