Effect of adult chill treatments on recovery, longevity and flight ability of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae).

Control of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), populations or outbreaks may be achieved through the mass-rearing and inundative release of sterile B. tryoni. An alternative release method is to release chilled adult sterile fruit flies to decrease packaging and transport requirements and potentially improve release efficiencies. Two trials were conducted to determine the effect of chilling on the performance of two separate batches of adult B. tryoni, fed either a protein and sucrose diet or sucrose only diet. The first trial compared chill times of 0, 0.5, 2 and 4 h; the second trial compared chill times of 0, 2, 4, 8 and 24 h. Overall, there was little or no affect of chilling on the recovery, longevity and flight ability of B. tryoni chilled at 4°C. Recovery time can take up to 15 min for chilled adult flies. There was no effect of chill time on longevity although females generally had greater longevity on either diet compared with males. Propensity for flight was not adversely affected by chilling at the lower chill times in trial 1; however, in trial 2, adults fed on a protein and sucrose diet had a decreased tendency for flight as the chilling time increased. Fly body size did not affect recovery times although the smaller adult B. tryoni in trial 1 had significantly reduced longevity compared to the larger adults in trial 2. Implications of these findings for B. tryoni SIT are discussed.