Increased Accuracy in Discrimination Between Captured Wild Unmarked and Released Dye-Marked Adults in Fruit Fly (Diptera: Tephritidae) Sterile Released Programs

Abstract

Decision making in large fruit fly sterile insect technique (SIT) programs, a process that involves massive releases of sterile flies, depends largely on a continuous feedback on the area-wide achievement of sterile to wild ratios. Uncertainties faced in these programs have often focused on the adequacy of the marking system and the availability of an accurate technique to discriminate between marked sterile and unmarked wild flies captured in monitoring traps. In the study described here, data were collected over several years by the Mexico! United States Mediterranean fruit fly eradication/containment program (Programa Moscamed) in southern Mexico and Guatemala, we compared the traditional system of detecting marked sterile flies with a UV lamp with a system based on fluorescent microscopy. Our results indicate that fluorescent microscopy is more accurate, faster, and less expensive than use of traditional UV light system. Numbers of sterile flies without discernible dye per million flies captured decreased by ≈75%, representing a 4-fold reduction in dissection costs. Use of fluorescent microscopy also reduced uncertainty due to unidentifiable flies and therefore reduced the potential of declared outbreaks that require disruptive and costly emergency action. Success in large scale SIT eradication/containment programs is ultimately determined by the detection of pockets of few remaining wild flies among thousands of recaptured mass released sterile flies. Thus use of fluorescent microscopy will allow for a more rapid and accurate diagnosis and results in a more effective reaction to real fly outbreaks in eradication or fly free zones.