Repellent Activity Of Elsholtzia Argyi Essential Oil And Its Effective Constituents Against Aedes Albopictus And Culex Quinquefasciatus

This research aimed at evaluating the repellent activity of Elsholtzia argyi essential oil(EO)against two types of mosquito,Aedes albopictus and Culex quinquefasciatus.The EO from the whole plant was extracted by steam distillation.The chemical composition of the EO was analyzed by GC-MS(gas chromatographymass spectrometry),so did the quantitative detection of five kinds of higher levels of terpenoids in it.Then,the high-purity reagents of these terpenoids was used to test the repellent activity against the mosquitoes.The EO of Elsholtzia argyi was a bright yellow oil with a special smell,and its yield(oil weight/fresh plant weight)was 0.52%and density of 0.85 g/mL.The results showed that the 100%protection time of Elsholtzia argyi EO against Aedes albopictus was 4.25 h,the percentage of protection was 79.05%after 6.5 h;the 100%protection time of Elsholtzia argyi EO against Culex quinquefasciatus was 4.35 h,the percentage of protection was 82.31%after 6.5 h.26 kinds of volatile components were detected in the oil.Linalool had the highest relative content among them,38.57%,followed by trans-β-ocimene,13.74%,limonene,11.24%,trans-citral,was 7.41%,β-caryophyllene,7.17%,and cis-citral,5.06%.Five terpenoids in Elsholtzia argyi EO were detected quantitatively,they were linalool,content of 421.61 mg/mL;limonene,content of 54.44 mg/mL;1,8-cineole,content of 8.04 mg/mL,trans-citral,of 78.83 mg/mL and cis-citral,content of 215.12 mg/mL,respectively.100%protection time of these terpenoids high-purity reagents against Aedes albopictus and Culex quinquefasciatus were linalool(content of 98%),3.80 h and 3.88 h;limonene(content of 95%,with 0.03%tocopherol stabilizer),4.73 h and 4.80 h;1,8-cineole(content of 99%),3.65 h and 3.53 h;citral(content was 97%,cis+trans,specific ratio is unknown),3.88 h and 3.78 h,respectively.The percentage of protection after 6.5 h against Aedes albopictus and Culex pipiens were linalool,53.62%and 64.89%;limonene,84.03%and 84.16%;1,8 cineole,62.91%and 61.06%;citral,61.24%and 62.22%.As a control group,10%of DEET were 4.03 h and 4.10 h for 100%protection time for both mosquitoes,percentage of protection after 6.5 h were 48.84%and 44.91%,respectively.Elsholtzia argyi EO showed excellent repellent activity against Aedes albopictus and Culex quinquefasciatus,had the potential to be developed as a great mosquitocide.Limonene showed the best repellent activity among these terpenoids,the worst was 1,8-cineole.The percentage of protection after 6.5h of Elsholtzia argyi EO and these terpenoids against two kinds of mosquito were higher than 10%of DEET.