Hydrolysis of Queensland Fruit Fly, Bactrocera tryoni (Froggatt), Attractants: Kinetics and Implications for Biological Activity

Queensland fruit fly (Q-fly), Bactrocera tryoni (Froggatt), is a major insect pest of horticultural crops in Australia. Cuelure is the most commonly used attractant for monitoring as well as for management of Q-fly populations through the male annihilation technique and mass trapping. There has been some concern that cuelure is susceptible to hydrolysis, which would limit its usefulness under conditions of high humidity and give rise to inconsistent fly population monitoring. To give some insight into the hydrolysis of cuelure and two closely related compounds, melolure and a newly developed lure, 4-(4-(2,2,2-trifluoroacetoxy)phenyl)-2-butanone (RKTA), the kinetics of hydrolysis of these compounds were quantitatively investigated by gas chromatography–flame ionization detection. From the experimental data, we found the hydrolysis half-lives of cuelure, melolure, and RKTA, at a water concentration of 25 mol L–1, to be ~20 days, 22 h, and 1.2 min respectively. When extrapolated to a water concentration of 1.3 mmol L–1, corresponding to atmospheric conditions of 100 % relative humidity at 25°C, the half-lives are ~1660, ~51, and ~1.4 years respectively.