Queensland Fruit Fly Workshop Notes

Queensland_Fruit_Fly_-_Bactrocera_tryoniThe evening of Thursday the 19th of March saw a full venue of people turn out to hear The Seymour Agricultural & Pastoral Society’s guest speaker Russell Fox give a talk on Queensland Fruit Fly. People from right across the region attended including, farmers, orchardists, home and community gardeners and many interested persons. Russell gave an interesting and informative talk including an overview and brief history of detections in Victoria, work being done in Cobram, the life cycle of the Queensland Fruit Fly and the variety of control options available. My notes follow and I must advise that these contain only some of the information made available on the evening and I apologise for any errors I may have inadvertently made. Following the workshop notes I have also included a number of websites worth visiting for further information.

Queensland Fruit Fly Workshop Notes
Seymour Agricultural & Pastoral Society
March 19th 2015, Guest Speaker: Russell Fox

Australia is home to 100’s of different fruit fly species but the Queensland species is the only problem one.

In the years 1990/91 Queensland Fruit Fly was first found in Murray valley at Cobram. By 2011/12 the area had an annual report of 138 detections. Owing to the numerous increasing and widespread detections Queensland Fruit Fly has now been declared endemic so there is little or no government activity, support or funding to act against it.

This year the spread of Queensland Fruit Fly has taken off due to high humidity and relatively few 40c plus days.

Life-cycle-fruit-fly

Life stages: Adult injects into fruit > maggots grow > emerge > drop to soil & pupate > new adult emerges. The life cycle takes three weeks.

Management is aimed to stop “fruit stinging” (egg laying into fruit). Maggots will come up from inside the fruit and form a C on the surface then jump in a wide spread to the soil in order to pupate. Chooks in the garden can help with reducing fruit fly numbers. Stung fruit can be bagged & disposed of. Attracting male flies in and killing with Queensland Fruit Fly bait has proven helpful. Unfortunately funding is not really available to run control programs so communities are largely on their own.

Control options


 

Trapping & scouting

Most traps are designed for the male fruit fly. Females only need to mate once to produce viable larvae for the season. Both sexes require a protein feed on emerging so the traps aim to catch the fruit fly before mating. Once mated a single female can lay 8000 eggs in a season which is why they can spread out of hand so effectively.

One type of trap holds a protein source, but is a cost prohibitive item at $30 to $40 per trap (available at Bunnings). To use traps they need to be put out early and keep out all year and at a distribution of at least one trap per tree, CeraTrap is one name brand. Traps are not a control by itself but can help.

Protein mixes can be home made for use in a trap. Vegemite can be used as the protein source in a homemade mix with insecticide added or used in a trap. The key factor with traps is to get them and the bait out early.

Scouting

Have a look for damage, citrus are susceptible and can also harbour the insect during cold periods. Stone fruits, soft fleshed fruits such as figs and loquats are among the many and varied prime targets, also egg plant, tomatoes etc. Pomegranates can even be attacked when they split. Fruits with high acid content (e.g. apples) will also be stung but although the acidity will kill maggots bacteria left behind by the adult female at injection will still cause browning of the fruit flesh around the injection site.

MAT (Male Annihilation Technique)

Is a specific hormone attractant with insecticide in a wick format. Buying Queensland Fruit Fly MAT wicks for home gardens can be a waste of time. But they are good to raise awareness of the Queensland Fruit Fly problem.

Protein Baits

Protein baits are the preferred commercial treatment. A “splash” mix of protein & insecticide (Malathion) is applied. Queensland Fruit Fly is attracted to the protein and takes up insecticide while feeding. To be effective Splash Treatment MUST be carried out on every tree, every week at a rate of 50-100 ml placed on the foliage and or trunk. Repeated application is necessary as the protein quickly breaks down. One product name is Yates Success another is Bugs Once. Some insecticides are pre-mixed others need to be made up. If it rains reapplication is needed. Organic bacteria mixes are also available. If making you own traps Queensland Fruit Flies are attracted to the colour yellow.

Cover Spraying

Cover spraying utilises a knock down insecticide so is really not an effective option as it will only work on any adult fruit fly it happens to contact at the time of spraying.

Garden Hygiene

Garden hygiene is also an important factor. In the case of Councils, RTA & the like and also home gardeners it’s highly advisable to be careful what you plant, particularly to avoid planting amenity trees that will harbour Queensland Fruit Fly.
General good garden hygiene of picking up fruit etc. is helpful. (An attendee mentioned putting spoiled produce into drums of water and the fermentation process will stop the fruit fly from pupating.)

Exclusion Netting

Exclusion netting is the best option. Different types of purpose made bags & nets are available. Place individual bags over fruit. Some are cloth bags. www.greenharvest.com.au is one supplier of products.

Diggers & other companies supply frames & the fine insect netting required.
It’s a good idea to bring or keep trees to manageable heights in order to facilitate netting.

Exclusion Netting factors:

  • Low impact organic approach
  • Damage free crops produced
  • Effectiveness in low to high fruit fly pressure areas
  • Assists protecting from nearby sources of infestation
  • Some physical work and diligence required
  • Bags most suitable for small to medium crop – Use netting for a large crop

Days with temperatures over 40c will kill out many maggots, as will minus 7c but remember temperatures in harbour trees (e.g. Citrus) will be warmer. Citrus fruits are usually attacked at colour change with lemons being one of the worst effected as they can hold fruit all year. People sharing fruits from different regions add to the spread of Queensland Fruit Fly and although there are many good and beneficial things about farmers markets sadly they can also add to spread of Queensland Fruit Fly.


 

Successful tackling of Queensland Fruit Fly requires a whole community approach- Everyone in an area must participate to make it work. The Seymour & district local contact for reporting Queensland Fruit Fly detections to is John Dalziel (former President of the Seymour Agricultural & Pastoral Society). Carolyn generously made her home made bait recipe freely available.

Carolyn’s home made fruit fly bait recipe:

1 tsp Vegemite
100g sugar
Dissolve in 1 Lt. Of warm water add:
1tsp dish washing liquid
1/2 tsp vanilla essence
1/2 Tbsp cloudy ammonia

Some links:

http://www.depi.vic.gov.au/agriculture-and-food/pests-diseases-and-weeds/pest-insects-and-mites/queensland-fruit-fly/about-queensland-fruit-flies

http://www.bugsforbugs.com.au/skin/pdfs/Fruit_Fly_Brochure500Kb.pdf

http://preventfruitfly.com.au/about-fruit-fly/life-cycle/

http://www.bugsforbugs.com.au/shop/fruit-fly-control/

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