VISUAL CUE AND CHEMICAL CUE INTERACTIONS IN A DRY TRAP WITH FOOD-BASED SYNTHETIC ATTRACTANT FOR CERATITIS-CAPITATA AND ANASTREPHA LUDENS (DIPTERA, TEPHRITIDAE)

Several modifications of a plastic dry trap baited with synthetic lure s (ammonium acetate and putrescine) were field tested in Guatemala for capture of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann ), and the Mexican fruit fly, Anastrepha ludens (Loew). The cylindrica l plastic dry trap has 3 holes for release of internally placed chemic al lure as well as for insect access into the trap, and a painted band that provides a visual cue. Fruit flies entering the trap move to int ernally placed toxicant-sugar panels, causing insect death after they feed. Visual cue modifications in traps painted green or orange includ ed comparisons between shiny or dull trap exteriors and among a range of widths of the painted band on the trap body (3-15 cm wide). Chemica l cue modifications included 3 versus 6 access holes in the body of th e cylindrical dry trap and tests of 2 doses of a new putrescine formul ation. The greatest amount of discrimination among the tested modifica tions was demonstrated by female C. capitata, The highest capture of f emale C, capitata was in green 3-hole traps with dull exteriors and wi th visual cues 12-15 cm wide. Variation in the width of the visual cue and in the number of access holes had less effect on capture of male C. capitata than on females, but capture of males was the lowest in or ange traps with shiny exteriors. Capture of female A. ludens was relat ively unaffected by the modifications tested, although highest capture was obtained with the green visual cue of 3-7.5 cm and the orange vis ual cue of 7.5-12 cm. Male A. ludens response was similar to that obse rved in females, although the capture of males among the modifications tested was more variable. There were interactions between visual cues associated with the trap body and the dose of putrescine, thus optima l dose of putrescine may vary with visual cue used in the trap design. Results from this study indicate that modifications in the plastic dr y trap can be used to improve the capture of female C. capitata and to develop more cost-effective dry traps for field use against pest Teph ritidae.