Evaluation of Essential Oil and its Three Main Active Ingredients of Chinese Chenopodium ambrosioides (Family: Chenopodiaceae) against Blattella germanica

BACKGROUND The efficacy of essential oil of Chenopodium ambrosioides flowering aerial parts and its three main active ingredients was evaluated against Blattella germanica male adults. METHODS Composition of essential oil was determined by GC-MS. Topical application bioassay was used to evaluate contact toxicity of essential oil and three main components. Fumigant toxicity of essential oil and its main components was measured using a sealed space method. RESULTS Twenty-two components were identified in the essential oil and the main components were (Z)-ascaridole (29.7%), isoascaridole (13.0%), ρ-cymene (12.7%) and piperitone (5.0%). The essential oil and (Z)-ascaridole, isoascaridole and ρ-cymene possessed fumigant toxicity against male German cockroaches with LC(50) values of 4.13, 0.55, 2.07 and 6.92 mg/L air, respectively. Topical application bioassay showed that all the three compounds were toxic to male German cockroaches and (Z)-ascaridole was the strongest with a LD(50) value of 22.02 μg/adult while the crude oil with a LD(50) value of 67.46 μg/adult. CONCLUSION The essential oil from Chinese C. ambrosioides and its three main active ingredients may be explored as natural potential insecticides in the control of cockroaches.