Improved pheromone-based trapping systems to monitor Toxotrypana curvicauda (Diptera: Tephritidae)

A membrane-based formulation method that provided a constant release rate of synthetic pheromone for the papaya fruit fly, Toxotrypana curvicauda Gerstaecker, was developed. Release rate measurements over 23 days indicated that lures loaded with 5, 15, 25, and 50 μl of synthetic pheromone released an average of 120, 360, 580 and 1120 ng per hr and the half-life of the lures was estimated to be 67, 184, 300 and 48 days, respectively. Field tests conducted in Mexico compared efficacy of blank and pheromone-baited sticky green spheres, cylindrical traps made from green opaque plastic that either contained a toxicant or were coated with sticky material, and cylindrical traps prepared from green sticky paper. Green opaque traps containing a toxicant and sticky paper traps captured approximately five times more papaya fruit flies than either the sticky-coated green opaque traps or the sticky-coated green spheres, and the presence of pheromone did not affect numbers of flies captured. Thus, the combination of the green color and the cylindrical shape provided a visual cue sufficient for papaya fruit fly capture. The pheromone lure significantly increased trap capture in similar tests conducted in Guatemala. Capture was highest in the sticky paper traps and in sticky-coated spheres. Use of the membrane-based synthetic pheromone in a cylindrical trap may provide an effective tool for monitoring papaya fruit flies.