Insecticidal activity of Citrus aurantium peel extract against Bactrocera oleae and Ceratitis capitata adults (Diptera: Tephritidae)

Citrus aurantium (L.) peel extracts in petroleum ether were evaluated for toxicity against olive fruit fly, Bactrocera oleae (Gmelin) and medfly, Ceratitis capitata (Wiedemann) adults. Bactrocera oleae flies were more susceptible to the extract than C. capitata in contact and residual bioassays. Fumigation bioassay had no effect. Both sexes of B. oleae were equally susceptible in both types of bioassays. However, males of C. capitata were more susceptible than the conspecific females. LD50 values (concentration causing 50% mortality) after 96 h for the males and females of B. oleae were 44.8 and 40.1 mu g/insect in contact bioassay through topical application. Whereas, LD50 values for the males and females of C. capitata were 38.8 and 67.8 mu g/insect respectively. LC50 values after 96 h for the males and females of B. oleae were 18.8 and 17.8 mu g/cm(2) in Petri dish residual bioassay. Whereas, LC50 values for the males and females of C. capitata were 70.6 and 147.1 mu g/cm(2) respectively.Fractionation of the extract on a silica gel column with three different polarity solvents resulted in three fractions with only the intermediate polarity solvent fraction having substantial insecticidal activity. Toxicity of the mixtures of active and inactive fractions was equal to the original extract. Our results indicate that C. aurantium has potential for controlling insect pests.