Dispersal of mass-reared sterile, laboratory-domesticated and wild male Queensland fruit flies C. Weldon* & A. Meats Fruit Fly Research Centre, School of Biological Sciences A11, University of Sydney, Sydney, NSW 2006, Australia Introduction Dispersal of insect species is of critical importance for understanding their spread and effective control (Stinner 1983). Dispersal can influence the effective release rate required for insect biological control agents, because release rates below a critical thresh- old may lead to an Allee effect (Hopper and Roush 1993; Grevstad 1999). Dispersal is also relevant to the population control of pest fruit flies through the mass release of sexu- ally sterilized conspecific individuals (the ‘sterile insect technique’, SIT). Too little dispersal could result in uneven coverage or no coverage of some patches of the target area (Meats et al. 2006; Meats 2007) whereas too much could mean that sterile individuals would be wasted if they rapidly left the target area. Analogous considerations apply to the ability of an array of surveillance traps to detect an infestation, and this determines the choice of effec- tive trap density. This is because the probability of trapping is related to both insect and trap density and therefore to the probability of a trap being close enough to the centre of an incipient population (Cunningham and Couey 1986; Lance and Gates 1994; Meats 1998a; Meats and Clift 2005). The release rates necessary for successful suppression of Q-fly populations using SIT are also partly deter- mined by their ability to survive to a mature age, at which time they also start to respond to traps (Fletcher 1974; Meats et al. 1988; Meats 1998b; Weldon et al. 2008). Dispersal studies on wild and sterile Mediterra- nean fruit fly (Medfly) Ceratitis capitata (Wiede- mann) (Diptera: Tephritidae) have been reviewed by Meats and Smallridge (2007) whereas Q-fly data were reviewed by Meats and Edgerton (2008). However, so far there has been no comparison of the dispersal of sterile Q-flies with either normal laboratory flies or wild flies on the same trap array. The objective of the present study was to compare dispersal of wild male Q-flies with that of labora- tory-reared and sterile (gamma-irradiated) male Q-flies. Keywords Bactrocera tryoni, cue-lure, monitoring, sterile insect technique, Tephritidae Correspondence C. Weldon (corresponding author), Fruit Fly Research Centre, School of Biological Sciences A11, University of Sydney, Sydney, NSW 2006, Australia. *Present address: Department of Brain, Behaviour and Evolution, Macquarie University, North Ryde, NSW 2109, Australia. E-mail: chris.weldon@mq.edu.au Received: January 8, 2009; accepted: June 15, 2009. doi: 10.1111/j.1439-0418.2009.01436.x Abstract Queensland fruit flies, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) (‘Q-flies’) were released as sexually immature adults from a point within an orchard. Marked male Q-flies were recaptured in the trap furthest from the release point (1087 m) by 2 weeks after release, although 98.25 Æ 1.04% of recaptured males were trapped <500 m from the release point. Comparison of gamma-irradiated (sterile), laboratory- adapted and wild male Q-flies indicated that dispersal distance was not significantly affected by fly type. There was no significant correlation between temperature and mean dispersal distance, but total recaptures were significantly negatively correlated with increasing daily maximum, minimum and average temperature. J. Appl. Entomol. 16 J. Appl. Entomol. 134 (2010) 16–25 ª 2009 Blackwell Verlag, GmbH