Russian wheat aphid
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Figure 1. Russian wheat aphid (approx. 2 mm long)
(Image: Kansas Department of Agriculture, Bugwood.org)
Russian wheat aphid (RWA) has been confirmed to be present in NSW following detections in South Australia in May and Victoria in June 2016. Grain growers and consultants across NSW are urged to monitor cereal paddocks for signs of RWA, and report suspect aphids or symptoms to NSW DPI.
Russian wheat aphid
Russian wheat aphid (RWA) (Diuraphis noxia) is a major field pest of wheat and barley in many grain producing countries. Yield losses of up to 80% in wheat and 100% in barley have been reported overseas. RWA injects toxins into the plant during feeding which stunts plant growth. Heavy infestations may kill plants.
Russian wheat aphid can spread by wind, movement of machinery and vehicles and on people’s clothing.
RWA has a wide host range on grasses (Poaceae family). Primary hosts for RWA support the entire lifecycle and allow reproduction to occur. These include wheat (Triticum aestivum), barley (Hordeum vulgare), and durum wheat (Triticum durum).
Secondary hosts are plants that support adults and final instars only. These hosts allow the aphid to survive but not to reproduce. Secondary hosts include oat (Avena sativa), rye (Secale cereale) and triticale (X Triticosecale).
While many grass species are considered hosts of RWA it is not known which native Australian grasses are suitable hosts.
What to look for
Detection of RWA is most likely to occur with the observation of symptomatic plants. Scout for symptomatic tillers in host crops and inspect for aphids. Russian wheat aphid is very small (less than 2 mm) and a 10x magnification hand lens can be used to examine them.
Russian wheat aphid may be present in mixed populations. If aphids which are commonly found in cereals are observed it should not be assumed these are the only ones present.
Symptoms associated with the presence of RWA include:
- Leaves with white, yellowish and red streaks
- Leaf rolling along margins
- Awns trapped by rolled flag leaves
- Heads with a bleached appearance
If you think you have found Russian wheat aphid, or have observed symptoms associated with the aphid, take a sample for identification and report it to NSW DPI by calling the Exotic Plant Pest Hotline 1800 084 881. There are a number of entomologists throughout NSW who can provide identification. Upon reporting NSW DPI will provide details on where to send the sample.
Photographs of symptoms can also be sent to: firstname.lastname@example.org
Aphid sampling guidelines
An aphid sample may be required for accurate identification.
- Leave aphids on host leaves where possible to reduce damage to aphids during transportation
- Sample suspect plants, ensuring they are infested with aphids. Remove roots and soil.
- Samples should be placed in sealed container, vial or plastic ziplock bag with triple packaging (e.g. vial with 2 layers of plastic ziplock bags)
- All samples should be accompanied by a Russian wheat aphid diagnosis request form (PDF, 28 KB)
- Samples should be sent by express post.
It is important to put hygiene practices into place to reduce the risk of transporting pests and diseases on clothing, footwear, vehicles and machinery when moving between paddocks and farms.
If symptoms of suspected RWA are observed it is important to change clothing (including hats) and clean footwear and vehicles before entering another paddock or farm. People entering crops should consider wearing disposable coveralls and changing these between farms. Used coveralls should be bagged and securely disposed of. Clothing worn in a suspected infested crop should be bagged, sealed and washed before being worn again.
Russian wheat aphid management
If chemical control is required, The Australian Pesticides and Veterinary Medicines Authority (APVMA) has issued an emergency permit [#82792] (PDF, 114.6 KB) for the control of Russian wheat aphid.
Chemical control should consider economic thresholds, insecticide resistance in other crop pests, natural pest enemies and beneficial insects as part of integrated pest management.
See the GRDC website for the latest nationally developed RWA management guidelines.