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

If they have, research organisation cesar is again making available to growers and advisers a screening service to test for insecticide resistance in RLEM, with an additional resistance screening service now on offer for Lucerne flea.
 

These no-cost screening services are 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 both of these insect pests – neonicotinoids as a seed dressing, and synthetic pyrethroids (SPs) and organophosphates (OPs) as foliar insecticides.

“Insecticide resistance in RLEM to both SPs and OPs was recently confirmed in multiple populations from South Australia,” Dr Umina says.

“Resistance had previously only been detected in Western Australian populations. There are also now emerging resistance concerns involving Lucerne flea, which often occurs in the same location as RLEM.”
 

For RLEM, cesar is screening populations from all over Australia where control failures to neonicotinoid seed treatments are suspected; and populations from South Australia, Victoria, New South Wales and Tasmania where control failures to SPs and/or OPs are suspected.

For Lucerne flea, cesar is screening populations from all over Australia where control failures to foliar insecticides or seed treatments are suspected.

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.

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

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