It is possible to get first-class management of Queensland Fruit Fly (Qfly) in areas where the pest is endemic, with a low-cost systems-based approach, according to Queensland entomologist Dan Papacek.
Dan has helped run the Area Wide Management (AWM) programme in the fruit fly-endemic area of the Central Burnett in south east Queensland for more than 10 years, through his concultancy Bugs for Bugs. He told growers at the Fruit Growers Victoria conference in Shepparton on Thursday that management in this district had been so effective, that Qfly was now ‘actually almost not an issue’.
He said while it would always be preferable NOT to have Qfly in orchards, for those growers in areas where the pest was already endemic, it could be managed quite effectively at a reasonable cost. He estimated the cost of protein-based baiting at around $6-8/ha a week.
“Growers need to realise that the Government is not going to fix it, they have to address it themselves,” he said. “It is a nasty pest and it is here to stay, you have to learn to live with it, but the sky has not fallen. It can be managed and good results are possible.”
But Dan stressed it would also require urban management as the widespread practice of neglected fruit trees in urban back gardens acted as a pest reservoir.
“Some people think it’s a God-given right to have a fruit tree in the back yard and that needs to be sorted out. If you are not able to manage fruit fly in your back yard fruit tree then it should go.”
He said Queensland growers had brought Qfly to a manageable level by a systems-based approach using four main tools:
- Protein baiting
- Male Annihilation Technique (MAT)
Of these, far the most important was protein bait spraying which is directed at newly-hatched flies before they are able to develop eggs and sting fruit.
While many other potentially exciting tools are being developed (including Sterile Insect Technology (SIT), female traps and biological control), Dan said the above tools were available now and effective if applied properly.
He said growers had 5-7 days from when the flies hatched before they would damage the fruit.
Bait spraying needed to be started early (before fruit was susceptible), applied regularly (typically weekly), with no missed treatments, applied to foliage or trunk (not ground or grass), reapplied after rain and applied fresh.
“If you do nothing else right, get your protein bait spraying right,” he said.
Emerging flies actively seek out protein, without which their eggs will not mature. They are highly attracted to the protein bait which works in much the same way as do cockroach baits in the kitchen.
“Fruit flies are fundamentally lazy (just like people),” Dan said. “If we put a protein source close so they don’t have to travel, they will take it.”
While monitoring served as a useful indicator of population trends, Dan warned against modifying baiting based on flies trapped.
“Trapping does not replace going out and checking the orchard,” he said. “You should be doing a field assessment once a week, (even twice a week in the critical periods), looking for adult flies and evidence of fruit stinging.”
He said although initially sceptical of Male Annihilation Technique (MAT), which had been introduced as part of Area Wide Management (AWM) as a way of reducing the male population, it had proved a very valuable tool. “The use of MAT as an adjunct to an effective protein baiting program serves to reduce population pressure even further and offers a cumulative effect over time,” he said.
Dan said the focus on removing fruit on the ground was a ‘bit misleading’ as it was not an issue if those fruit had not been stung.
“We have found with our (QLD) growers, that if they are doing everything right, they won’t see fruit on the ground due to Qfly,” he said. “It is important however to remove fruit from the tree after harvest as blocks with residual mature fruit could serve as a breeding site for the pest.”
So successful had the AWM been in southern QLD that some growers reported not having used a cover spray for 20 years and had to be reminded not to drop their guard.
“It is actually almost not an issue,” he said. “We have to remind our growers that even though they are doing a great job, it is because everyone is doing it right.”
Area Wide Management of Fruit Fly – Central Burnett (Dr Annice Lloyd, Final Project Report, 2007)
New website for Qfly management (Dr Penny Measham, May 2018)
Area Wide Management for Qfly (Dr Penny Measham, April 2016)