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

If they have, research organisation cesar is again making available to growers and advisers a screening service to test for insecticide resistance in RLEM.

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

Dr Paul Umina of cesar says a major concern facing the Australian grains industry is the reliance on three registered chemical classes to control this insect pest – neonicotinoids as a seed dressing, and synthetic pyrethroids (SPs) and organophosphates (OPs) as foliar insecticides.

“Insecticide resistance in RLEM to both SPs and OPs has been confirmed in multiple populations from South Australia,” Dr Umina says. “Resistance had previously only been detected in Western Australian populations.”

RLEM populations from South Australia, Victoria, Tasmania and New South Wales are being screened by cesar.

The research group is interested in hearing from growers or advisers who have had noted recent or past failures in paddocks that are continually needing to control RLEM with pesticides.

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

Although insecticide options are limited, Dr Umina says it is still crucial to minimise chemical use and rotate chemical groups to curb the spread of insecticide resistance.

He says the screening service will not only help detect any resistance before it becomes widespread but will also assist in identifying the best control options for growers. A kit can be provided containing the necessary equipment to send mites in if required.

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

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