Insecticidal Activity and Synergistic Effect of Gundelia tournefortii L. (Asteraceae:Compositae) Extracts and Some Pure Constituents on Drosophila melanogaster Meigen (Drosophilidae: Diptera)

Laboratory bioassay experiments were conducted using Gundelia tournefortii L. (Asteraceae: Compositae) plant as a source of active ingredients against the vinegar fly Drosophila melanogaster Meigen (Drosophilidae: Diptera) as a model insect. Extracts of all plant parts except roots were tested using seven solvents; acetone, benzene, chloroform, ethanol, ether, methanol and water. Seeds and flowers gave the highest percentages of extracted yield than leaves and stems. Chloroform seed-extract showed the highest toxicity to D. melanogaster larvae with the lowest LC50 value (119.95 ppm), followed by the chloroform leaf and the ether leaf and seedextracts. Mortality percentages to fly larvae due to both carbaryl and imidacloprid insecticides were increased from 10-20% to 40-70% with synergistic factors of 3-4 times after acetone and chloroform seed-extracts had been added. α-Terpinyl acetate and oleic acid of the G. tournefortii were responsible for 80% and 70% of larval mortalities with LC50 of 22.98 and 23.15 ppm, respectively. Therefore, both chemicals can be further investigated as bioactive insecticides and could be incorporated into IPM programs of insect pests.