Insecticide resistance in fall armyworm (FAW) remains at low levels in central and northern Queensland grain growing regions, but experts warn that ongoing vigilance is key to maintaining efficacy and control.
This has been a key finding from a GRDC investment with New South Wales Department of Primary Industries and Regional Development (NSW DPIRD) in collaboration with the Department of Primary Industries Queensland (DPIQ) focusing on insecticide resistance surveillance in FAW and Helicoverpa armigera.
FAW, a serious pest of cereals and pulses, was detected in Australia in February 2020 and has since established populations in northern areas of Queensland, the Northern Territory and Western Australia. Seasonal outbreaks have also impacted some growing regions of northern NSW.
Dr Lisa Bird with fall armyworm samples at the Tamworth laboratory. Photo: NSW DPIRD
NSW DPIRD Senior Research Scientist Dr Lisa Bird said the resistance surveillance work had a strong focus on the cropping regions of central and northern Queensland where there was a high risk of FAW incursions.
"FAW is a tropical pest, so it is exposed to a lot of selection pressure from insecticide use in those areas," she said.
"Our collaboration with researchers from DPIQ provides essential field capacity for collecting and sending samples from northern regions to the testing laboratory in Tamworth.
"Our aim is to track any changes in insecticide resistance frequency so we can extend those messages back to industry in a timely manner to raise awareness of potential resistance outbreaks and provide information to help maximise the effectiveness of spray applications.
Dr Bird said it was 'fantastic news' that there had been no changes in resistance since the discovery of FAW in Australia, particularly given its strong track record of developing insecticide resistance overseas.
Global reliance on chemical control of FAW has resulted in resistance to at least 29 insecticide active ingredients in six mode-of-action groups.
"We use an F2 screening method in our resistance testing, which enables us to pre-emptively detect resistance at very low frequencies," she said.
"It also enables us to detect recessive resistance genes which can lie dormant in populations. In other words, we have the capacity to identify and predict resistance risks before spray failures occur in the field.
"This proactive approach delivers an early warning systems to industry and growers so they have the opportunity to adapt their chemical control strategies to minimise impacts on productivity."
FAW can be an extremely challenging pest to manage with insecticides due to the frequency of egg lays and concealed feeding sites of larvae (in the whorl, silks and cobs of maize), rendering chemical control only partially effective.
