Larvicidal activities of wood and leaf essential oils and ethanolic extracts from Cunninghamia konishii Hayata against the dengue mosquitoes.

摘要

Aedes aegypti and Aedes albopictus are considered to be the main vector of a group of arboviruses responsible for dengue and yellow fever. Natural products derived from plant extracts were tested in a discovery program for effective, environment friendly mosquito control agents. Screening for mosquito larvicidal activity of plant extracts could lead to the discovery of new agents for mosquito larvae control. The mosquito larvicidal activities of the wood and leaf essential oils and ethanolic extracts from Cunninghamia konishii Hayata against A. aegypti and A. albopictus were investigated in this study. Results obtained from the mosquito larvicidal assay showed that wood and leaf essential oils possessed the activity against fourth instar larvae of A. aegypti and A. albopictus. Using gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) analyses, twenty-seven and twenty-five compounds were identified, representing 100.0% and 98.1% of the wood and leaf essential oils. The main constituents of wood essential oil were cedrol (53.03%) and alpha -pinene (25.57%); of leaf essential oil were alpha -pinene (34.89%), p-cymene (16.66%) and gamma -muurolene (11.35%). Among ten pure constituents tested, beta -myrcene, p-cymene, (+)-limonene and sabinene exhibited significant larvicidal activity, with LC₅₀ values of 35.8, 69.4, 71.9 and 74.1 micro g/ml against A. aegypti larvae and 27.0, 68.3, 41.2 and 39.5 micro g/ml against A. albopictus larvae, respectively. These results clearly revealed that the essential oils from C. konishii leaf and wood and their effective constituents served as a potential, eco-friendly mosquito larvicide against the dengue mosquitoes.