Trapping grid insights

The Goulburn Murray Valley (GMV) Fruit Fly Area Wide Management program monitors trapping grids in urban, peri-urban and rural locations across the region. These grids are essential to identifying Queensland fruit fly hot spots, timing of management activities and evaluating the effectiveness of programs such as the release of sterile Qfly in Cobram.

Populations on the move

Fruit fly numbers peaked in urban sites during December 2020, while last year’s peak occurred unusually in March 2020.

Queensland fruit fly peaks appear to occur early in urban areas, mid-season in peri-urban locations and later in rural sites. One conclusion is that fruit fly move from urban, through peri-urban and into rural locations during the season, due to fruit availability.

Hot spot activity

The following locations show the average number of Queensland fruit fly trapped over the current fruit fly period from 1 July 2020 to 21 May 2021 in urban/peri-urban areas of the GMV, from highest to lowest.

  • Nagambie
  • Merrigum
  • Numurkah
  • Euroa
  • Congupna
  • Tatura
  • Mooroopna
  • Shepparton

While some areas have high averages, Queensland fruit fly is not evenly spread over these ‘hot spots’. Of the 16 traps servicing Merrigum and Nagambie, only 3 account for 67 per cent of trappings during 2020/21.

Of the Queensland fruit fly trapped in the GMV during May 2021, 45% were from just 7 of the 395 traps on the grid. If you live in proximity to any of these critical ‘hot spots’ a Project Field Officer may make contact with you to offer advice, support and assistance. Project staff can be contacted for advice by phoning 03 5871 9222.

Weather conditions ideal

If the coming winter is not cold or dry enough fruit fly will survive the winter by taking refuge in warm spots and become problematical in the coming spring and summer.

Queensland fruit fly must mate to lay eggs into ripe and ripening fruit, however only need to mate once to be able to lay eggs into many fruit over a period of up to two months. Fruit fly mate at dusk and only when the temperature is higher than about 16˚C. The current weather conditions have contributed to large numbers of fruit fly found in the GMV and points to the probability of the survival of large numbers through winter and into spring.