Chemical composition and insecticidal activity of Anacyclus pyrethrum essential oil from the Bensliman area against Culex pipiens

Anacyclus pyrethrum is a herbaceous plant that belongs to the Asteraceae family. The focus of the present study is to extract the essential oil from this plant, to determine its chemical composition and to evaluate its insecticidal activity against the larvae of the mosquito Culex pipiens. The essential oil from A. pyrethrum collected from the region of Bensliman in Morocco was extracted by hydrodistillation and analyzed by gas chromatography coupled to mass spectrometry were studied. Essential oil yield obtained by hydrodistillation was 0.09%. The major aroma constituents were Spathulenol (20.47%), Germacrene D (16.48%), Caryophyllene oxide (13.20%), 4(14)-Salviale-1-one (8.27%) and Caryophyllene 4(14),8(15)-dien-5α-ol (7.30%). The larvicidal test carried out according to a methodology based on the standard protocol of the World Health Organization was studied on 4th instar larvae of C. pipiens and showed that A. pyrethrum essential oil possesses remarkable insecticidal properties. After 24 hours of exposition, larvicidal assays revealed a 100% mortality of C. pipiens larvae. The dose of 40 μL/mL was toxic enough to cause 100% larval mortality of C. pipiens. The lethal concentrations LC50 and LC90 calculated for the essential oil studied were of the order of 14.79 μL/mL and 19.95 μL/mL, respectively. To control mosquitoes, this essential oil extracted from A. pyrethrum might be used as a natural insecticide and therefore could be an alternative to synthetic insecticides already present on the market.