Chemical composition and fumigant toxicity of three citrus essential oils against eggs, larvae and adults of Callosobruchus maculatus (Col.: Bruchidae)

The fumigant toxicity of volatile fractions of peel essential oils of the Rutaceae species of Citrus reticulata Blanco, C. limon L. and C. aurantium L. was studied against eggs, larvae and adults of Callosobruchus maculatus (F.) at 27 ± 1 ºC and 65 ± 5% RH in darkness. The oils were extracted from the fruit peels using water steam distillation. The essential oils were characterized by a combination of GC and GC/MS analyses. Limonene was the major constituent of the three essential oils. The effect of different concentrations of the essential oil vapors on egg hatchability as well as larval and adult mortality was found to be significant. Citrus reticulata and C. aurantium oils were more toxic on egg hatchability than C. limon extract and caused higher mortality on larvae as well. There was no significant difference between essential oils in terms of adult mortality. The adult beetles were also exposed to the concentrations of 18.5, 37, 55.5 and 74 μl/l air. At the highest concentration (74 μl/l air), C. aurantium oil caused 100% mortality after a 6 h exposure, but the oils from C. reticulata and C. limon caused 38% and 62% mortality, at the identical exposure time, respectively. The results suggest that citrus peel oils can be effectively used as botanical fumigants against various life stages of Ca. maculatus.