Evaluation of resistance to different insecticides against field populations of Bactrocera zonata (Saunders) (Diptera: Tephritidae) in Multan,Pakistan

Bactrocera zonata (saunders) (diptera: tephritidae) is a serious pest of fruits and vegetables in pakistan. the cover sprays against control of fruit flies are being extensively used in pakistan. for evaluation of resistance to insecticides lc 50 of six commonly used insecticide trichlorfon,bifenthrin,malathion,methomyl,λ-cyhalothrin and spinosad was determined in fifteen field populations of b. zonata in multan,pakistan. susceptible to high resistance was recorded for trichlorfon (1.00-fold to 41.82-fold). susceptible to moderate resistance level was observed for bifenthrin (1.39 to 13.59-fold),cyhalothrin (1.07 to 18.24 fold),spinosad (1.15 to 14.08-fold) and for malathion (1.07 to 19.36-fold) while the fly was susceptible to methomyl. the results suggest that b. zonata has developed resistance to trichlorfon,malathion,bifenthrin,λ-cyhalothrin and spinosad and there is need of resistance management programs for restoring the efficacy of insecticides based control measures. copyright 2012 zoological society of pakistan.