Field assessment of current and improved surveillance traps for fruit flies (Diptera: Tephritidae) in Australia

Exotic fruit fly (Diptera: Tephritidae) surveillance in Australia predominantly relies on male-lure trapping. We assessed the performance of 3 traps currently used in Australian fruit fly surveillance: Lynfield, Modified Steiner, and Paton; against 3 improved versions: Enhanced Steiner, Enhanced Paton, and Enhanced Paton-10 mm. Laboratory trials revealed existing traps failed to exclude rain, and drained poorly, which guided our trap modifications. These modified traps were field-tested across 2 seasons and 4 locations in tropical and subtropical areas, with trap efficacy measured by total flies trapped, quality of fly DNA by real-time PCR, and weatherability observations. During the dry season, the Enhanced Paton trap outperformed all other traps in terms of fruit fly catch rates, a trend that continued in the wet season. While there was no discernible variation in DNA quality among flies caught by the 6 trap types, wet trap contents negatively affected DNA quality, with the incidence of wet trap catches influenced by trap design. No wet flies were observed in the Enhanced Paton trap, a result of the modifications made, which included a 3° entrance tube with a 42° angled roof. Overall, the Enhanced Paton trap proved to be a superior alternative to existing designs, offering higher fly capture rates and better-quality specimens for both morphological and molecular identification.