What was it all about?
This project saw the first trial of area-wide integrated pest management (AW-IPM), including the sterile insect technique (SIT), for control of Queensland fruit fly. The study was carried out in south-eastern Queensland, near Stanthorpe, on properties ideal for this pest management approach due to their isolation from each other as well as from urban centres.
In Australia, the SIT has been used to manage Queensland fruit fly in pest-free areas for nearly two decades using a bisex strain which involves both male and female sterile flies. The technique has not yet been shown to be effective in suppressing wild endemic populations.
In this study, two properties were set up using the general principles of AW-IPM (using cover sprays when required), while two others had the same treatment plus the release of sterile male flies. The aim was to control the fly year-round, not just during the production season.
The results showed that Queensland fruit fly numbers were better controlled with the addition of the SIT to area-wide integrated pest management, however both methods were able to minimise fruit infestation. This shows that the principles of an AW-IPM approach can be applied effectively, with or without SIT.
As well as demonstrating for the first time in Australia that AW-IPM SIT is effective, the researchers also investigated the impacts of the mass-rearing, handling and irradiation processes on fruit fly fitness.
The researchers concluded that in order for SIT to be an effective control, sterile flies need to be of a high quality. The colony needs to be renewed each year with wild collected flies, flies must be irradiated at the lowest dose needed to make them sterile, and flies need sufficient cushioning and insulation during transport to keep them in good condition.
They also found that mass-reared larvae benefited from being fed bacterial probiotics, with fitter flies as a result.