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.
Keywords: Blattella germanica; Chenopodium ambrosioides; Contact toxicity; Essential oil; Fumigant.