INSECTICIDE EFFECT ON 3 TEPHRITID FRUIT-FLIES AND ASSOCIATED BRACONIDPARASITOIDS IN HAWAII

Laboratory bioassays were conducted to determine the effect of insecti cides on three species of tephritid fruit flies and associated parasit oids. First, topically applied malathion, carbaryl, and permethrin wer e tested against the Mediterranean fruit fly, Ceratitis capitata (Weid emann), the oriental fruit fly, Bactrocera dorsalis (Hendel), the melo n fly, B. cucurbitae (Coquillett), and their corresponding parasitoids , Diachasmimorpha tryoni (Silvestri), D. longicaudata (Ashmead), and P sytallia fletcheri (Silvestri). Second, the effects of toxic baits on the three fruit fly species were tested by mixing insecticides with a protein hydrolysate bait. Insecticides used were malathion, naled, car baryl, and permethrin. In a third test, we determined the effects of n aled and malathion added to Staley's bait on C. capitata and D. longic audata. Parasitoids were more susceptible to insecticides than the res pective host fruit fly species. For example, D. longicaudata was 663 t imes more susceptible to permethrin than B. dorsalis, and D. tryoni wa s 680 times more susceptible to carbaryl than the C. capitata. Parasit oid response to insecticides varied by parasitoid species. The B. cucu rbitae parasitoid, P. fletcheri, was less susceptible to these insecti cides than the other two species. Topical and feeding tests showed tha t carbaryl was ineffective against fruit flies. Malathion was the most effective of the three materials tested topically against fruit flies . Naled was the most toxic insecticide in the protein bait tests. Stal ey's bait did not attract D. longicaudata, and this parasitoid was not as susceptible to malathion as C. capitata. However, D. longicaudata and C. capitata were equally susceptible to naled. Application of thes e results to integrated pest management of fruit flies is discussed.