Impact of marking dye, transport and irradiation on eclosion of mass produced Queensland fruit fly Bactrocera tryoni (Froggatt) (Diptera Tephritidae)

In Sterile Insect Technique (SIT) programs, released flies are commonly marked with fluorescent dye prior to irradiation to assist subsequent identification. The impacts of dye, transport and irradiation on adult eclosion of Queensland fruit fly were investigated. Eclosion in the non-dyed, non-transported, nonirradiated pupae was 84.64%. Dyeing, transport and irradiation processes significantly reduced the adult eclosion rate to 72.88%. This reduction in adult eclosion was accompanied by a 10.2% increase in partially eclosed adults. In an additional treatment, the dye was removed from pupae following irradiation by rinsing with water. These pupae were allowed to eclose in a humid container, whereas the pupae from the other treatments were allowed to eclose in glass Petri dishes. The percentage of fully eclosed flies was 81.54% - a significant improvement compared with standard dyed transported irradiated pupae and very close to that found in untreated controls - and the percentage of partially eclosed flies was not significantly different from the control pupae. Both irradiation treatments had more uneclosed pupae compared to the control treatment although the three treatments differed by only 2.1% variation. Based on these results, it appears that dye and/or the eclosion environment have considerable impacts on the viability of Queensland fruit flies produced for SIT. There appears to be substantial room for improvement in either the marking system and/or the eclosion environment used prior to release.