Insecticidal activities of leaf essential oils from Cinnamomum osmophloeum against three mosquito species

The larvicidal activities of leaf essential oils and their constituents from six chemotypes of indigenous cinnamon (Cinnamomum osmophloeum Kaneh.) trees were evaluated against three mosquito species. Results of larvicidal tests demonstrated that the leaf essential oils of cinnamaldehyde type and cinnamaldehyde/cinnamyl acetate type had an excellent inhibitory effect against Aedes albopictus larvae, and their LC50 values in 24 h were 40.8 lg/ml (LC90 = 81.7 lg/ml) and 46.5 lg/ml (LC90 = 83.3 lg/ml), respectively. Results of the 24-h mosquito larvicidal assays also showed that the effective constituents in leaf essential oils were trans-cinnamaldehyde and benzaldehyde and that the LC50 values of these constituents against A. albopictus larvae were below 50 lg/ml. In addition, cinnamaldehyde type leaf essential oil and trans-cinnamaldehyde have also exhibited great larvicidal formance against Culex quinquefasciatus and Armigeres subalbatus larvae. Comparisons of mosquito larvicidal activity of trans-cinnamaldehyde congeners revealed that a-methyl cinnamaldehyde, benzaldehyde, and trans-cinnamaldehyde exhibited strong mosquito larvicidal activity.

本研究评估了6种化学型本土肉桂（Cinnamomum osmophloeum Kaneh.）叶片精油及其成分对3种蚊虫的杀幼虫活性。幼虫毒杀试验结果表明，肉桂醛型及肉桂醛/乙酸肉桂酯型叶片精油对白纹伊蚊（Aedes albopictus）幼虫具有优异的抑制效果，其24小时半数致死浓度（LC50）分别为40.8 lg/ml（LC90=81.7 lg/ml）与46.5 lg/ml（LC90=83.3 lg/ml）。24小时蚊虫杀幼虫试验结果还显示，叶片精油中的有效成分为反式肉桂醛与苯甲醛，二者对白纹伊蚊幼虫的LC50值均低于50 lg/ml。此外，肉桂醛型叶片精油及反式肉桂醛对致倦库蚊（Culex quinquefasciatus）及骚扰阿蚊（Armigeres subalbatus）幼虫亦表现出良好的杀幼虫活性。对反式肉桂醛同系物的蚊虫杀幼虫活性比较研究发现，α-甲基肉桂醛、苯甲醛及反式肉桂醛均表现出较强的蚊虫杀幼虫活性。