Larvicidal and deterrent activity of Umbellularia californica Nutt. essential oil against Aedes aegypti
Aedes aegypti is a vector of dengue fever and yellow fever, and is the cause of high rates of human morbidity and mortality worldwide. There is a tremendous need for new efficacious compounds to protect humans from mosquito bites. Natural repellents from essential oils have the advantage of potential low mammalian and environmental toxicity. Umbellularia californica Nutt. was well known from the first European settlers as a spice and antibacterial, but also for its insecticide properties. Also known as “California bay laurel”, it is a strong aromatic shrub belonging to the monotypic genus Umbellularia. The insecticidal activity of the essential oil against Ae. Aegypti was investigated by bio-guided assays. The essential oil of U. californica leaves was obtained by steam distillation and its chemical profile was determined using GC-FID and GC-MS. Umbellulone was isolated as one of the major constituents in very high yield (36.7%). Mosquito deterrent and larvicidal activities against Aedes aegypti L were evaluated. The oil showed higher activity against Ae. aegypti larvae than deterrent activity. Therefore, bioassay-guided isolation studies were performed on U. californica oil using larvicidal activity.