The most northerly case of redlegged earth mites (RLEM) resistant to bifenthrin insecticide in Western Australia has been recorded on a property in the Dandaragan/Badgingarra area.
Department of Agriculture and Food, WA (DAFWA), researchers detected the resistant insects after sampling paddocks where a grower had reported bifenthrin failures.
DAFWA senior technical officer Peter Mangano urges growers in the area to monitor their paddocks for signs of resistance, although no further cases have been found to date.
Since it was first discovered in Australia at Esperance in 2006, RLEM resistance to bifenthrin and other synthetic pyrethroid insecticides has been found on 26 farms at Esperance, Green Range, Cranbrook and Boyup Brook.
However, Mr Mangano says growers can use products from the organophosphate insecticide group, such as omethoate, dimethoate and chlorpyrifos, to help control RLEM resistant to synthetic pyrethroids.
“Early awareness of resistance to synthetic pyrethroids can lead to effective control in limiting their potential spread,” Mr Mangano says.
DAFWA is continuing to study the problem and management options as part of the GRDC-funded National Invertebrate Pest Initiative project.
Growers are encouraged to contact Mr Mangano, who is based in Perth, and DAFWA entomologist Svetlana Micic, who is based in Albany, to report suspected resistance and receive advice on control measures.
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