Chemical analysis of essential oils of Thymus Carmanicus Jalas by gas chromatography-mass spectrometry and toxicity activity agains t the major Iranian malaria vector, Anopheles Stephensi

Abstract

In the last few years, using chemical insecticides to control the malaria vector has caused environmental pollution and resistance to chemical insecticides. This study aimed to investigate the chemical analysis of essential oils of Thymus carmanicus Jalas by gas chromatography and mass spectrometry (GC-MS) and toxicity activity against the major Iranian malaria vector, Anopheles stephensi. The essential oil of Thymus carmanicus Jalas was prepared from dried leaves using the hydro-distillation method. Gaschromatography-mass spectrometer (GC-MS) was used to analyze and identify thyme essential oil compounds. Bioassay was performed using World Health Organization (WHO) standard test. The T. Carmanicus Jalas essential oil consisted of 15 compounds, with Carvacrol (61%), Thymol (6%), and β-caryophyllene (5%) being the major components by volume. The LC50 and LC90 of thyme oil were 20.37 and 41.38 ppm at 24h after application, respectively. At 24h after application, significant differences were observed between the toxicity of 5%, 20%, 25%, 40%, 50%, and 80% concentrations of Thyme essential oil (P<0.05). The 80% concentration of Thyme essential oil exhibited 100% toxicity against A.stephensi larvae at 24h after application. T. Carmanicus has a rich source of bioactive compounds for use as a mosquito larvicide.