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

The effects on adult Ceratitis capitata of the ingestion of formulations containing different concentrations of some essential oils were examined. The bioassays were carried out using groups of C. capitata adults fed for 3 days with formulations containing a known concentration (0.25%, 0.5%, 1.0%) of essential oils. The oils, of different chemical composition, were obtained by steam distillation from aromatic plants collected during the balmy period. The essential oils of Rosmarinus officinalis and Salvia officinalis, which are rich in monoterpenic hydrocarbons and monoterpenic ketones, respectively, 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 quantities of essential oils was a depressive effect on the nervous system. Dissection of dead flies showed marked differences compared with the controls and microscopic examination revealed anomalies in the gut region.