evaluation of essential oil and its three main active ingredients of chinese chenopodium ambrosioides (family: chenopodiaceae) against blattella germanica

b a ckground: the efficacy of essential oil of chenopodium ambrosioides flowering aerial parts and its three main active ingredients was evaluated against blattella germanica male adults. m e t hods: composition of essential oil was determined by gc-ms. topical application bioassay was used to evalu- ate 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%), ρ-cymene (12.7%) and piperitone (5.0%). the essential oil and ( z )-ascaridole, isoascaridole and r-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 weretoxic to male german cockroaches and ( z )-ascaridole was the strongest with a ld50 value of 22.02 mg/adult while the crude oil with a ld50 value of 67.46 mg/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.