Field Capture of Male Mediterranean Fruit Flies (Diptera: Tephritidae) in Traps Baited with Varying Amounts of Trimedlure

Detection of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), relies heavily on traps baited with the male attractant trimedlure. This lure is dispensed from solid polymeric plugs (2 g a.i.) that are changed out every 6 wk, because beyond this interval their attractiveness drops significantly below that of fresh lure. Existing data suggest that plugs loaded with 4 g of trimedlure may have longer attractancy, which would allow for longer servicing intervals with associated reductions in material and labor costs. The objective of the present study was to gather additional data on the effectiveness of plugs having trimedlure loadings greater than 2 g. In 4 field experiments conducted in Hawaii, the capture of male medflies was compared over 10 or 12 wk periods between control traps baited with 2 mL fresh liquid trimedlure on a cotton wick and treatment traps baited with aged plugs containing 2 to 4 g of the lure. In all experiments, 6-wk-aged plugs, regardless of the specific loading, attracted similar numbers of males as the fresh liquid lure. Conversely, in 3 of the 4 experiments, plugs aged for 10 or 12 wk attracted significantly fewer males than the fresh lure. The performance of plugs aged 8 wk was inconsistent, showing similar attractiveness as fresh lure in certain cases but not others. Based on these findings, we conclude that, counter to our expectations, the use of 4 g trimedlure plugs would not allow effective trapping over longer inter-servicing intervals.