Movement of sterile male Bactrocera cucurbitae (Diptera: Tephritidae) in a Hawaiian agroecosystem.

The melon fly, Bactrocera cucurbitae Coquillett, invaded the Hawaiian Island chain in 1895. In 1999, a program sponsored by the USDA-ARS to control melon fly and other tephritid pests in Hawaii over a wide area was initiated on the islands of Hawaii, Maui, and Oahu. To control these flies in an areawide setting, understanding how flies move within the landscape is important. To explore the movement of this fly, we examined the movement of marked, male, sterile, laboratory-reared B. cucurbitae on the island of Hawaii in an agricultural setting. Two releases of dyed, sterile flies consisting of approximately 15,000 flies, were released 6 wk apart. Released flies were trapped back by using Moroccan traps baited with a male attractant. These two releases suggest that in the Hawaiian agricultural areas where the areawide control is being sought, melon flies do not move extensively when there are abundant larval host and adult roosting sites. Over the course of this study, only one fly made it the maximum distance that we could detect fly movement (approximately 2,000 m in 2 wk). From these data, it seems that the flies dispersed throughout the study area but then moved very little thereafter. This is very apparent in the second release where the recovery rate after the second week was still fairly high, suggesting that if there are plenty of host fields and roosting sites the flies are unlikely to move.