Effects of essential oil formulations on Ceratitis capitata Wied. (Dipt., Tephritidae) adult flies

The effects on adult Ceratitis capitata of the ingestion of formulations co ntaining different concentrations of some essential oils were examined. The bioassays were carried out using groups of C. capitata adults fed for 3 da ys with formulations containing a known concentration (0.25%, 0.5%, 1.0%) o f essential oils. The oils, of different chemical composition, were obtaine d by steam distillation from aromatic plants collected during the balmy per iod. The essential oils of Rosmarinus officinalis and Salvia officinalis, w hich are rich in monoterpenic hydrocarbons and monoterpenic ketones, respec tively, showed poor activity, whereas the oils of Cinnamomum zeylanicum and Thymus sp. showed a marked toxic effects (over 90% mortality after 72 h). This could be explained by the activity of cinnamic aldehyde (about 80% of the Cinnamomum oil) and carvacrol (68% of Tit. capitatus oil and about 45% of Th. herba barona oil). The first consequence of ingesting even small qua ntities of essential oils was a depressive effect on the nervous system. Di ssection of dead flies showed marked differences compared with the controls and microscopic examination revealed anomalies in the gut region.