Development of a low-cost pupal release strategy for Sterile Insect Technique (SIT) with Queensland fruit fly and assessment of climatic constraints for SIT in rural New South Wales

Abstract

Sterile pupae of Queensland fruit fly (Qfly) Bactrocera tryoni (Froggatt) were released to suppress wild Qfly populations at 3 sites in New South Wales and to assess a pupal release strategy using the bed technique. Sterile pupae were released from September 1997 to June 1998 from sand and vermiculite beds. A total of 24.6 million pupae were released with a male recapture rate of 0.101% (not corrected for adult emergence rate). Adult emergence rates were 25% at Tullibigeal; 39% at Ungarie and 46, 41, 71 and 54% respectively at 4 locations at Lake Cargelligo (mean 46%). Corrected recapture rates using cue-lure traps were 0.88% at Tullibigeal, 0.08% at Ungarie and 0.15% at Lake Cargelligo (mean 0.21%). When wild fly populations increased at Lake Cargelligo, a bait spraying program was used which substaintially reduced the catches of both sterile and wild flies in traps. Analyses using the CLIMEX model showed that the climate at Lake Cargelligo town (with irrigation) was suitable for fruit flies. CLIMEX indicated that the unmodified rural environment was unsuitable for fruit fly survival due to a summer moisture deficit. The Meats daily survival rate decrement of 58–72% was similar to that found for some similar studies in Australia but lower than for certain other release programs. No significant bird or ant predation was observed.