Comparative field studies of Bactrocera oleae baits in olive orchards in Crete

Abstract

Protein-based food attractants are used in Bactrocera oleae (Gmelin) (Diptera: Tephritidae) management for monitoring populations, estimating the time of bait sprays and for Mass Trapping. McPhail traps loaded with two trophical attractant solutions (two formulations of hydrolysed proteins equal to 55% and 75% w/w) at 0.5, 1, 2, 4 and 8% concentrations were tested for their attractiveness, which was indicated by the captures of flies in McPhail traps during two periods in successive summers. The results indicated that lower concentrations than the 2% concentration recommended for both tested proteins (highest captures of 31.4 olive fruit flies/trap/week were recorded at 1% for protein equal to 55% and 28.5 at 0.5% for protein equal to 75%) were also attractive to olive fruit flies, whereas 8% was the least attractive concentration for both attractants (18.7 and 9.9 olive fruit fly/trap/week respectively). In addition, the 2% attractant concentration for both proteins was evaluated for attractiveness over time compared with ammonium sulphate; three-day-old solution of the protein equal to 75% was significantly more attractive to flies (at least twice) than 7-, 10-, 14-, 17-, 20- or 24-day-old solutions while the 7-day-old solution of the protein equal to 55% did not display differences compared with other solution ages. The attractiveness of ammonium sulphate weakened as time passed (below 5 olive fruit flies/trap/week). On the other hand, olive stems sprayed with the tested proteins under field conditions attracted approximately 0.6–1.0 adults per day, as indicated by captures in yellow sticky panels, with the highest number of flies recorded on the first day (0.9–1.4 adults). Finally, changes of pH values of these trophical attractants after dilution to the water are also reported.