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 com-ponents 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%), ?-cymene (12.7%) and piperitone (5.0%). the essential oil and (z)-ascaridole, isoascaridole and ?-cymene possessed fumigant toxicity against male german cockroaches with lc50 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 ld50 value of 22.02 ?g/adult while the crude oil with a ld50 value of 67.46 ?g/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.