SUPPRESSION OF A MEDITERRANEAN FRUIT-FLY (DIPTERA, TEPHRITIDAE) POPULATION WITH CONCURRENT PARASITOID AND STERILE FLY RELEASES IN KULA, MAUI, HAWAII

Irradiated adult Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were released at an average rate of 3 million per week for 5 mo in a sterile insect technique (SIT) program to suppress a wild C. capitata population in the 13-km2 area of Kula, Maui, HI. Concurrent with sterile fly releases, the braconid larval parasitoid Diachasmimorpha tryoni (Cameron) was released at an average rate of 388,000 per week. The average weekly overflooding ratio was 76.0 +/- 4.8 sterile/wild flies. Mean number (+/-SEM) of male C. capitata trapped per day was significantly reduced to 0.15 +/- 0.05 in Kula compared with 1.30 +/- 0.17 in a nearby control area. The mean percentage of C. capitata eggs hatching was significantly lower in Kula (22.9 +/- 4.2%) than in the control area (90.2 +/- 0.9%). The overall mean percentage parasitism of C. capitata in fruit samples was significantly higher in Kula (47.2 +/- 2.7%) than in the control area (20.3 +/- 3.1%). After the first month of parasitoid releases, D. tryoni became the dominant parasitoid present in Kula, representing 61.6 +/- 6.3% of the parasitoids recovered from C. capitata in fruit samples. The mean number of adult C. capitata recovered per kilogram of fruit was significantly lower in Kula (9.8 +/- 1.3) compared with the control area (92.6 +/- 22.7). This field experiment suggests that the concurrent release of parasitoids and sterile flies represents a valuable approach to eradication of established Mediterranean fruit fly populations.