RESEARCHERS have made the troubling discovery that green peach aphid (GPA) populations in Western Australia are starting to form resistance against one of Australia's most effective registered controls against aphids and white flies.
GPA, which is a major pest in broadleaf crops such as canola and pulses and can spread unwanted viral diseases such as turnip yellows virus, which sprung to prominence in 2014 under its former name beet western yellows virus, is evolving resistance to sulfoxaflor which is the active ingredient in Transform insecticide.
Australia's agronomic community is concerned about the news as Transform is regarded as one of the most important insecticides for control of aphids, where there are limited options available.
The low level resistance was discovered near Esperance, in Western Australia's south-east, as part of joint research by CSIRO, cesar and the WA Department of Primary Industries and Regional Development (DPIRD) with funding from the Grains Research and Development Corporation (GRDC) and Corteva Agriscience, which makes Transform.
It is yet to be fully understood how the resistance is occurring but it is believed that a metabolic response is responsible.
Project leader Paul Umina, cesar, said the finding showed how important insecticide rotations were.
"This discovery serves as an important reminder to use all products judiciously."
He said farmers needed to weigh up whether an insecticide application was necessary.
He said there are unlikely to be yield losses from turnip yellows virus after the rosette stage in canola and direct feeding damage is also generally fairly low in canola apart from isolated seasons where numbers build up to high levels.
When a spray is needed, Dr Umina said it was critical to consider what modes of action had been used in the past, even though there are limited options available.
Proactively, Dr Umina also recommended integrated pest management (IPM) techniques such as green bridge control and sowing into standing stubble as means to keep aphid numbers down.