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Growers urged to test redlegged earth mite for resistance

Grain growers and farm advisers are being encouraged to send in samples of redlegged earth mites (RLEM) to Cesar Australia if they notice a chemical failure or suspect insecticide resistance.
Photo: Supplied

Grain growers and farm advisers are being asked whether they have noticed a chemical control failure or suspect insecticide resistance in redlegged earth mites (RLEM).

If they have concerns, research organisation Cesar Australia is encouraging them to send in RLEM samples for testing for insecticide resistance.

This no-cost screening service is made possible through a GRDC investment being led by Cesar Australia in collaboration with the University of Melbourne, the Western Australian Department of Primary Industries and Regional Development (DPIRD) and CSIRO.

Associate Professor Paul Umina, director of Cesar Australia, says a major concern facing the Australian grains industry was the heavy reliance on three registered chemical classes to control RLEM – neonicotinoids as a seed dressing, and synthetic pyrethroids (SPs) and organophosphates (OPs) as foliar insecticides.

“Insecticide resistance in RLEM to both SPs and OPs had previously only been detected in Western Australian populations, but since 2016 has been confirmed in multiple populations from South Australia and Victoria,” Assoc. Prof.  Umina says.

Cesar Australia is actively screening populations from South Australia, Victoria, New South Wales and Tasmania where control failures to SPs and/or OPs may be occurring.

The research team are interested in hearing from growers or advisers who have experienced recent or past chemical control failures or have paddocks that continually require control of RLEM with pesticides.

“RLEM populations from paddocks which are frequently impacted by the mites, and often require spraying, are ideal candidates for resistance testing,” Assoc. Prof. Umina says.

Cesar Australia will be undertaking field trips to collect RLEM for resistance screening, so get in touch if you would like to discuss RLEM collection from your area.

Although insecticide options were currently limited, Assoc. Prof. Umina says it was still crucial to minimise chemical use and rotate chemical groups to reduce the spread of insecticide resistance.

He says the screening service would help detect any resistance before it became widespread and would also assist in identifying the best control options for growers.

“We encourage growers and advisers to make use of this service, and also refer to the National RLEM Resistance Management Strategy to help avoid control failures.”

More information: about the resistance testing service contact Dr Aston Arthur, Cesar Australia, 0427 875 040,

The RLEM Resistance Management Strategy can be found on the GRDC website, as well as the IPM Guidelines for Grains website.

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