Research is being conducted on how the Russian wheat aphid is surviving between winter cropping seasons after the pest was discovered in South Australia in 2016.
Understanding how the aphids use weeds and volunteer cereals (known as the green bridge) to survive should help farmers and agronomists determine the risk of infestation and potential damage the pest could cause.
The Grains Research and Development Corporation (GRDC) has invested in field research at sites across South Australia, as well as Victoria, Tasmania and New South Wales, with the insect present in those states.
The research is being led by the South Australian Research and Development Institute, a division of Primary Industries and Regions SA in partnership with sustainable agriculture research organisation Cesar.
Cesar research scientist Dr Elia Pirtle said samples taken from paddocks were being used to identify the Russian wheat aphid’s favoured weed hosts and food sources, particularly during summer.
She said information collected on the sample sites included crops and grass species present, irrigation, waterways, topography, aphid growth stages and the presence of parasitoid wasps and beneficial insects.
At an irrigated site we visited recently, there was a lot of healthy-looking barley grass and the site was swarming with aphids,” Dr Pirtle said.
“But it was also swarming with beneficials – there was more lady bug larvae than I’ve ever seen in one spot and they were really going to town on the aphids.”
Farmers can also perform their own Russian wheat aphid surveillance by unfurling leaves and partially emerged heads of grasses and checking inside for the insects.
The GRDC has an acronym for farmers to follow in the detection of the pest. FITE the Russian wheat aphid stands for -
Find – Look for aphids and the characteristic plant symptoms of infection including leaf streaking or leaf rolling on cereal crops and grasses;
Identify – Positively identify RWA by consulting with an industry specialist;
Threshold approach – Consider thresholds for control, the presence of natural aphid enemies in the crop, crop growth stage and potential yield losses;
Enact – Take appropriate action: Manage next steps including encouraging beneficial insects and protecting honeybees before implementing control options.
Findings from the research will be used to update the GRDC tips and tactics guide on the aphid, meanwhile grain growers can stay up-to-date with the research through fact sheets, webinars and trial site visits.
Growers and advisers should report occurrences to the GRDC’s PestFacts services and take advantage of pest identification services provided by cesar and SARDI.
For information visit https://grdc.com.au/resources-and-publications/resources/russian-wheat-aphid