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

Abstract

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 seed-extracts. 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.