Tehran University of Medical Sciences Journal of Arthropod-Borne Diseases 2322-1984 6 2 2015 10 14 90 97 EN Wei Xiang-Zhu Department of Entomology, China Agricultural University, Beijing, China Kun Zhao Department of Entomology, China Agricultural University, Beijing, China Sha Sha-Chu Department of Entomology, China Agricultural University, Beijing, China Zhi Long-Liu Department of Entomology, China Agricultural University, Beijing, China 2015 10 14 2015 10 14 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 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. https://jad.tums.ac.ir/index.php/jad/article/view/160 https://jad.tums.ac.ir/index.php/jad/article/download/160/144