Area-wide management for fruit fly

Can fruit fly infestations be reduced through area-wide management of mango crops? That is the question Queensland researchers are asking as they look for better ways to protect mangoes from fruit fly.

A systems approach combining male lures, protein baits, monitoring and orchard hygiene is considered a viable alternative to orchard cover sprays for fruit fly control. Bait and lure programs have been set up on mango orchards at the Atherton Tablelands and at Bowen to evaluate whether a concept that has seen success in Indonesia would work in tropical Queensland.

Project leader Stefano De Faveri said that fruit fly populations were successfully reduced to eradication levels in Indonesia and believes these programs are applicable to more regions than first thought.

“Over three years, Indonesian fruit fly populations have been reduced to insignificant levels in areas where lures and baits were trialled, Less than 0.1 flies were caught daily per monitoring trap in the trial area compared with up to 600 flies in the sprayed area. We also saw several occasions where no flies were found in the traps during the weekly monitoring. This was unheard of before we started the program,” he said.

These results mean that fruit fly was at eradication levels within the trial sites from January 2014 to August 2015 according to the internationally accepted Area Indices for Fruit Flies. Maintaining populations at such low levels could satisfy the requirements of an Area of Low Pest Prevalence for fruit flies under the International Standards for Phytosanitary Measures. If this concept is a success in Australia, it will deliver clean fruit that will meet import country Maximum Residue Limits (MRLs).

“Before the Indonesian trials, we were not sure if this concept would work in the tropics where endemic fruit fly populations are high. The increased yield and quality of mangoes at the trial sites resulted in increased profits for the producers involved. We are now trialling the system in north Queensland against local fruit fly species, and hope to see similar benefits passed onto Australian farmers,” Mr De Faveri said.

Areas surrounding the Indonesian trial sites were also observed and showed high populations of fruit fly.

“The low numbers showed that flies appeared not to migrate into the treatment zone from surrounding areas. This suggests that areas of low pest prevalence can be created and maintained in non-isolated crop areas. This is an extremely valuable observation as such a concept has never been demonstrated before in the tropics, although further work is needed on this aspect of fruit fly ecology,” Mr De Faveri said.

An important part of the research is to find yeast products that do not affect the fruit, ways to apply the bait to the tree without contact with fruit, or a method to attract the female fruit fly that does not require foliage sprays. In Australia, protein bait sprays and application methods have been trialled to examine whether they cause blemish to mangoes.

“Commercially available protein baits produce a pink skin blemish when sprayed on mangoes which can lead to downgraded fruit quality. We have tested some promising alternative baits which cause less blemish to Australian mango varieties,” Mr De Faveri said.

Researchers are determined to enhance fruit fly control through acceptable protein bait application methods targeting females.

The project Area-wide management of pest fruit flies in an Indonesian mango production system is funded by the Australian Centre for International Agricultural Research (ACIAR) and the Queensland Department of Agriculture and Fisheries. It is managed by Stefano De Faveri from Queensland Department of Agriculture and Fisheries. ACIAR fund international and domestic research to improve the productivity and profitability of agricultural systems in partner countries as well as providing benefits to Australian industries. The project is supported by project Farm-wide fruit fly management systems for the east coast of Australia which is co-funded by the Queensland Government and Horticulture Innovation Australia.

Read the ABC story: NQ mango farms trial Indonesian fruit fly research

Listen to the ABC story: ABC rural report for north Queensland, Thursday 3rd September 2015