Effect of natural predators on Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae) control by sterile insect technique (SIT)

BACKGROUND: Queensland fruit fly (Q-fly) is a destructive insect pest that infests a wide variety of agricultural plants in Australia. The sterile insect technique (SIT) is used to manage Q-flies, but the effectiveness of SIT has not been tested in the presence of natural predators. The objective of this study was to investigate the effect of natural predators and SIT on the survival and reproduction of laboratory reared Q-flies under semi-natural conditions. We altered the presence of predators and irradiated Q-fly males, and measured survival, number of eggs laid and egg-hatching rate. 

RESULTS: The presence of natural predators significantly affected the survival of Q-flies and appeared to decrease the number of eggs laid. Interestingly, we found that both sterile and fertile males were more prone to predation than females, but we found no difference among males. The presence of sterile males significantly reduced Q-fly fertility, but the interaction of natural predators and sterile males did not significantly reduce the number of fertile eggs. 

CONCLUSION: Our findings highlight the important role of natural predators in controlling Q-flies together with SIT and provide a solid foundation for similar large-scale field trials using wild counterparts.