The effect of release method and trial site on recapture rates of adult sterile Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

The Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae) is Australia's worst pest of edible fruit. The Fruit Fly Exclusion Zone (FFEZ) in south-eastern Australia encompasses some of the country's most valuable horticultural production areas and is recognised nationally and internationally as free of B. tryoni. Outbreaks of B. tryoni in the FFEZ are controlled, in part, with the inundative release of sterile B. tryoni. To determine whether release method and trial site affected trap recapture rates of sterile B. tryoni, four sterile B. tryoni releases were conducted simultaneously at two sites: Wagga Wagga, New South Wales (NSW) and Unley, South Australia (SA) from December 2007 to April 2008, using both a plastic adult rearing container (PARC) and a bin release method. PARC or bin did not affect the number of B. tryoni recaptured. Trap recapture rates of released sterile B. tryoni were higher in NSW than SA throughout the trial, and peak recapture rates occurred 1 week earlier in NSW. Humidity was higher inside the bins compared with the PARCs in three of the four releases; temperature was higher in PARCs compared with bins in two of the releases. For the only fly batch tested, emergence and flight were higher in the PARCs compared with the bins. Quality control and recapture studies showed that dye pigment was not a confounding factor in recapture rates of the main studies.