Aerial Releases of Sterile Mediterranean Fruit Fly (Diptera: Tepbritidae) by Helicopter: Dispersal, Recovery, and Population Suppression

Abstract

Sterile Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were released by helicopter over commercial coffee ( Coffea Arabica L.) fields and nearby habitats on the island of Kauai, Hawaii. Temporal and spatial dispersal patterns of released flies were expressed effectively by both asymptotic and exponential decay models. Approximately 90% of the captured flies were located within 100 m of the release line. Sterile flies remaining in coffee fields declined rapidly, with <15% remaining within 5 d. Flies released by helicopter dispersed throughout a narrower band than those released at higher altitudes by the standard airplane method. Our studies suggest that flight line intervals of 200 m every 3-4 d should provide adequate coverage and numbers of sterile flies in target areas. An 8-mo program of sterile fly releases (52 releases, total = 208 million flies) by helicopter was conducted throughout an interior 15-km2 area to evaluate the effectiveness of the helicopter. A small C. capitata population in coffee patches throughout the under story of a watershed forest was targeted. Fruit collections from the treatment area indicated a 90.6% reduction of the larval infestation rate. Higher levels of control or eradication of C. capitata in riparian forest areas would probably require sterile fly releases throughout surrounding areas to prevent reinfestation. Helicopters appear to be well suited for sterile fly releases in mountainous areas where terrain and unpredictable weather conditions are unsuitable for airplanes.