Chemical composition and larvicidal evaluation of marjoram and bitter orange volatile oils against Culex pipiens (Dipetra: Dulicidae)

Author(s): K.S.Khater, Mohamed H.M.Abd El Azim

In this study; the two oils were analyzed by GC/MS. About 20 and 32 volatile compounds were identified from the volatile oils of O. majorana and C. aurantium respectively. Terpinen-4 –ol and terpinene were the major isolated constituents of O. majorana, while limonene and 2-methyl- 5-(1-methyl ethenyle)-2-cyclohexene-1-one were themajor compounds of C. aurantium oil. Larvicidal activity of marjoram (Origanum majorana), (family: Verbenaceae) and bitter orange (Citrus aurantium), (family: Rutaceae) volatile oils were tested against the early fourth instar larvae of Culex pipiens. The larval mortality was observed after 24 hours of exposure. Both of the two oils showed high larvicidal effects; however, the highest larval mortalitywas found in the treatment with marjoramvolatile oil. The LC50 values are 188.5 ppmand 251.4 ppmfor marjoramand bitter orange respectively.

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