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.