RLEM resistance management strategies
The National Insecticide Resistance Management working group of the Grains Pest Advisory Committee has just finalised the first Resistance Management Strategy for redlegged earth mites (RLEM) in grain crops and pastures.
The RLEM is a major pest of grain and livestock enterprises in Australia and can be particularly damaging to emerging crops. Mite feeding can lead to distortion or shrivelling of leaves and affected seedlings may die at emergence with high RLEM populations.
The use of chemicals to target RLEM in grain crops and pastures continues to grow in Australia, exerting strong selection pressure for the development of resistance. High levels of resistance to synthetic pyrethroids (for example, bifenthrin, alpha-cypermethrin) are becoming more common across the Western Australian grainbelt. Additionally, localised resistance to organophosphates (for example, omethoate, chlorpyrifos) has recently been discovered on multiple WA properties.
At present, there is no confirmed resistance to any insecticide outside of WA.
Growers need to understand how to minimise the further development of resistance.
This strategy aims to conserve the effectiveness of the limited insecticide options for this pest. To do this, industry needs to minimise the selection pressure for resistance to the same insecticide group across consecutive generations of RLEM. As with other pest (and weed) resistance-management strategies, the rotation of different groups of chemicals is central to this strategy.
Differences in the distribution of resistance have meant regionally relevant strategies have been developed: one specifically for WA, the other for eastern Australia (South Australia, Victoria, Tasmania and New South Wales). Because resistance is thought to be absent outside WA, growers in eastern Australia have greater flexibility around the choice of insecticides.
In addition to chemical rotation, the success of this strategy will depend on the uptake of integrated pest management tactics and the use of economic pest thresholds before making spray decisions.
More information:Dr Paul Umina, cesar,
03 9349 4723,
Growers across Australia are encouraged to adopt the recommendations of this new Resistance Management Strategy. The strategy has the endorsement of CropLife Australia.
GRDC Project Code UM00043, UM00048