Distance-dependent capture probability of male Mediterranean fruit flies in trimedlure-baited traps in Hawaii

Many countries operate regional trapping programs for the detection of exotic tephritid fruit flies, which because of their polyphagous habits pose a serious threat to fruit and vegetable crops. Detection of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), relies primarily on trimedlure (TML), a synthetic male-specific lure, yet few studies have measured the relationship between distance from TML-baited traps and the probability of male capture, and consequently the detection sensitivity of medfly trapping programs is largely unknown. The present study measured distance-dependent capture probabilities for male C. capitata in TML-baited traps using mark–release–recapture procedures. Releases were performed at distances of 25, 50, 100, and 200m at 4 sites in Hawaii, and the resulting capture rates were used to estimate the minimum detectable population size (detection probability>99.9%) for a trapping density of 5 TML traps per 2.59km2 (=1mi2, the density used in California, USA). Capture rates were similar for 3 of the sites (6.5%, 3.8%, 1.1%, and 0.1% for the 4 distances, respectively) and yielded an estimated minimum detectable population of ≈2300 males, a value similar to that obtained in a comparable study conducted in California. For unknown reasons, capture rates were significantly lower at the remaining site (1.8%, 0.6%, 0.1%, 0.04%) and the estimated minimum detectable population was correspondingly much larger (≈10,000 males). Implications of these results for medfly detection programs are discussed. [Display omitted] •Male Mediterranean fruit flies were released to determine capture rates in trimedlure-traps in Hawaii.•At three sites, capture rates varied from 6.5% to 0.1% for males released 25–200m from the traps, respectively.•A fourth site had much lower recapture rates at all distances, and reasons for this are unknown.•The minimum detectable population size was estimated at 2300 male medflies for standard trapping grids in the USA.