Monitoring mice in Australia – October 2018

Update #17

Summary

  • Mouse numbers are low in all areas (Figure 1) – There is a low risk of damage of crops leading up to harvest.
  • Mice began breeding in spring, but mouse populations are starting from a low base. Mouse numbers are not likely to increase rapidly because of the generally dry conditions.
  • Growers should actively monitor mouse activity (mouse chew
    cards or active burrow counts). Take a walk through paddocks.
  • Please report and map mouse activity using MouseAlert (www.mousealert.org.au) so other growers can see what mouse activity is being observed in their neighbourhood. Follow on twitter using @MouseAlert.

Management Recommendations

Mouse numbers are currently very low, but will increase through spring into summer. It is unlikely that economic damage will occur as crops mature. See GRDC Mouse Control website for more details about control options.

  1. Baiting with zinc phosphide is reasonably effective providing there is little alternative food available for mice. Once seeds have developed on heads, mice are reluctant to go for zinc phosphide baits, so if need be, bait well before seed set. Be aware of the 14 day withholding period before harvest.
  2. Harvest as cleanly as possible to minimise grain spillage. Whatever food resources are left in the paddock could sustain mouse breeding and lead to higher mouse numbers at sowing next year..

Current situation

Mouse numbers are low across Western, Southern and Northern regions, largely because of very dry conditions (Figure 1). Mice started to breed in early spring and will slowly increase through spring and summer to reach a peak in late autumn 2019. Growers should remain vigilant and act accordingly if damage is likely. Because of patchy activity between paddocks, growers are advised to monitor across multiple paddocks to gauge mouse numbers and inform their management decisions. Please continue to report activity on MouseAlert (www.mousealert.org.au).

South Australia: Mouse numbers are very low in North Adelaide Plains, Mallee, Eyre and Yorke Peninsulas (Figure 2). Trap success at Mallala (north of Adelaide) was 8% in September (Low). There was some activity on some sites, but Low overall.

Victoria: Mouse abundance are very low in all locations. Mouse numbers are Low across Mallee and Wimmera regions (Figure 2). Trap success was 1% at Walpeup in September (Very Low). There was some activity on some sites, but Low overall.


Figure 2 Monitoring of mouse populations across Australia – October 2018

Queensland: Mouse activity is very low: No mice were caught at the Benchmark site near Brookstead (Darling Downs), and no activity on cards or active burrows on the Chinchilla to Moree transects.

Northern, Central & Southern NSW: Mouse numbers are low in Southern, Central & Northern locations. Very few sites with chew card activity.

Western Australia: Mouse activity is low in Ravensthorpe and Esperance areas.

The ‘Mouse Forecast’

Northwest Victoria: There was a low likelihood of an outbreak for autumn 2019. Model predictions are variable because of uncertainty about November-December rainfall. Peak abundance in autumn 2019 will be low (<30 mice/ha).

  • If Nov-Dec rainfall is low, then mouse abundance will be <10 mice/ha (outbreak probability of 0.12).ï‚· If Nov-Dec rainfall is low, then mouse abundance will be <10 mice/ha (outbreak probability of 0.12).
  • If Nov-Dec rainfall is average, then mouse abundance will be 10-15 mice/ha (outbreak probability of 0.22).
  • If Nov-Dec rainfall is high, then mouse abundance will be 15-30 mice/ha (outbreak probability of 0.38).

Central Darling Downs (QLD): The density index for the mouse population is currently very low (<1%), but are likely to remain low in May 2019. The probabilities for May 2019 are High (0.01-0.03), Moderate (0.04-0.34), Low (0.33-0.55) and Very Low (0.62-0.08).

Future activities

The next scheduled monitoring is set for December 2018 across all sites. Please continue to report mouse abundance on your farm (presence and absence!) using MouseAlert (www.mousealert.org.au) on your smart phone, tablet or computer and to check what other mouse activity is being reported locally and regionally. We welcome any information at any time. You can also follow progress on Twitter  (@MouseAlert). Download the MouseAlert App from iTunes app store or Google play (click on hyperlink to download).

MouseAlert Smartphone app www.mousealert.org.au

Background

This is an update on surveillance of mice across the grain-belt of Australia for September/October 2018. Mouse populations were monitored in typical grains farming systems in WA, SA, Vic, Qld and NSW during spring 2018 (September/October). The monitoring provides data on the size (abundance) of mouse populations, their breeding status and overall activity.

This information is used in models that have been developed progressively over the last 20-30 years to predict mouse outbreaks. Monitoring was conducted on a range of sites (Figure 3):

  • Benchmark sites: live trapping data collected for use
    in models in Adelaide Plains (SA), Walpeup (Vic) &
    Darling Downs (Qld).
  • Quantitative rapid-assessment sites: mouse chew
    cards & active mouse burrows assessments on 110
    transects across 11 sites.
  • Qualitative monitoring networks: from farmers and
    agronomists in 11 local areas.

This is part of a study funded by the GRDC to monitor
mouse populations and forecast the likelihood of mouse
outbreaks. This project has been funded by GRDC until Dec 2021.

Further information

Dr Peter Brown – (Peter.Brown@csiro.au) CSIRO Agriculture & Food, Canberra
Steve Henry – (@MouseAlert) (Steve.Henry@csiro.au) CSIRO Health & Biosecurity, Canberra

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