Exposure to Ginger Root Oil Decreases Capture of Male Mediterranean Fruit Flies (Diptera: Tephritidae) in Trimedlure-Baited Traps

Detection programs for pestiferous tephritid fruit flies rely on traps baited with either natural or synthetic food substances, or so-called male lures. While studies on several tephritid species have demonstrated that protein feeding reduces subsequent attraction to protein food baits, comparable data for male lures are scant and largely restricted to the genus Bactrocera. Ginger root oil (GRO) is attractive to males of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and males exposed to this oil’s scent exhibit heightened mating competitiveness. Because of this increased mating success, several sterile male release programs against C. capitata now include pre-release, GRO exposure as part of their standard operating procedures. However, the impact of such exposure on subsequent trap capture has received little study. The purpose of the present study was to measure the effect of GRO exposure on subsequent capture of sterile male medflies in trimedlure-baited traps in two fruit orchards in Hawaii. At each study site, 600 control (non-exposed) and 600 treated (GRO-exposed) males from a mass-reared, genetic sexing strain were released per replicate from a central release point, and trap captures were scored 2 d post-release for eight trimedlure-baited Jackson traps placed in a circular array around the release point. At both orchards, control males were, on average, captured in significantly greater numbers than treated males. This result did not appear to reflect differential mortality between the male types: mortality in screen cages under field conditions was similar over a 48 h period for control and treated males. Implications of these findings for sterile release programs are discussed.