Mosquitocidal Activity Of Three Monoterpenoids And Their Optical Isomers Against Culex Pipiens Pallens

Hygienic insecticide is mainly used in places where human lives in,so they must meet the requirement of safety.At present,pyrethroid pesticide is widely used as hygienic insecticide,but they exert high toxicity to human and animals.Monoterpenes are the main component of essential oils with many advantages,such as low residual,low poisonous,easy to degrade,difficult for insects to develop resistance,safe for human and animals.So they meet the needs of human for hygienic insecticide.In this study,fumigation and repellent activity of three monoterpenoids and their optical isomers were tested against adult Culex pipiens pallens.The single compounds with better activity were further developed into vaporizing mat.The main results were as follows:1.The fumigation activity of three monoterpenoids and their optical isomers against C.pipiens pallens were determined.The fumigation activity include toxicity and knock down activity.The result showed that all eight compounds had a certain degree of fumigation activity against C.pipiens pallens.Compared with other compounds,L(-)-carvone,D(+)-carvone and DL-terpinen-4-ol had better toxicity,with the LC50 of 0.263 ?l/L,0.427?l/L and 0.818 ?l/L,respectively.L-terpinen-4-ol,DL-terpinen-4-ol and L(-)-carvone possessed better knock down activity,with the KT50 of 6.60 min?6.78 min and 9.75 min,repectively.2.The method of Erler et al.(2006)with minor modifications was used to determine the repellent activity of three monoterpenoids and their optical isomers against C.pipiens pallens The result showed that five monoterpenoids all had good repellent activity at the dose of 0.5 ul.DL-terpinen-4-ol and D(+)-carvone showed better repellent activity,with the repellent rate of 100%lasting for 15 min and 10 min,repectively,at the dose of 0.2 ?l.D-terpinen-4-ol and D(+)-carvone showed better repellent activity,with the 100%repellent rate lasting for 5 min at the dose of 0.1 ?l.3.The activity of four kinds of vaporizing mat with L-terpinen-4-ol,L(-)-carvone,DL-terpinen-4-ol and D(+)-carvone as the active ingredient were evaluated against C.pipiens pallens at the dose of 200 ?l.L(-)-carvone had the best activity after heating for 1 h,with the KT50 of 13.70 min.followed by L-terpinen-4-ol and D-carvone,with the KT50 of 15.98 min and 17.90 min,repectively.L-terpinen-4-ol and L(-)-carvone had better activity after heating for 2 h,with the KT50 of 13.08 min and 14.33 min.L-terpinen-4-ol and L(-)-carvone also had some activity after heating for 3 h with the KT50 of 18.45 min and 17.23 min,repectively,but they showed almost no activity after heating for 4 h.In summary,terpinen-4-ol,carvone,menthol and their optical isomers exerted fumigation and repellent activity against C.pipiens pallens.L-carvone and L-terpinene-4-ol had the potential to be developed into hygienic insecticide.