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All eyes on lucerne flea and RLEM for suspected control failures

We’ve broadened our insecticide resistance screening efforts to include the lucerne flea as well as the redlegged earth mite.

Since 2016, we have been hot on the trail of suspected cases of insecticide resistance in the redlegged earth mite (RLEM, Halotydeus destructor). These resistance surveillance efforts have yielded some important results for industry, including the detection of insecticide resistance in redlegged earth mite populations in south-east Australia for the first time. This year we will widen our screening process to another invertebrate pest which is at risk of developing resistance - the lucerne flea (Sminthurus viridis).

The lucerne flea (Sminthurus viridis) (Image credit: cesar)

It is likely that most growers and advisers will be familiar with lucerne flea. Small ‘windows’ appearing in the leaves of establishing crops and pastures (particularly legumes) are usually the first sign of their presence. As yet, there have been no formal accounts of resistance issues occurring in lucerne flea. However, over the last few years we have been receiving increasing numbers of control failure reports, the cause of which are not always clear. In addition, lucerne flea is certainly a possible candidate for developing resistance: they are a common pest in most years and occur consistently in many paddocks alongside RLEM and other crop pests, meaning that they are exposed to insecticides frequently.

For RLEM, we are screening populations from all over Australia where growers suspect control failures to neonicotinoid seed treatments; and populations from South Australia, Victoria, New South Wales and Tasmania where growers suspect control failures of synthetic pyrethroids (SPs) and/or organophosphates (OPs). For lucerne flea, we are screening populations from all over Australia where growers have experienced or suspect control failures to foliar insecticides or seed treatments.

Any grower or advisor experiencing a chemical control failure involving lucerne flea (or RLEM), or suspecting issues with insecticide resistance, are encouraged to contact us to discuss the issue and access the free resistance testing service. Remember lucerne flea cannot be controlled by synthetic pyrethroids, so it is primarily control failures involving organophosphates or neonicotinoids that has our interest.

This resistance testing project is funded by the GRDC and is being led by the University of Melbourne and cesar in collaboration with CSIRO and the Western Australian Department of Primary Industries and Regional Development.



Aston Arthur, cesar

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