Russian Wheat Aphid

Images left to right: 1. Russian Wheat Aphid on wheat near Cressy. 2. Russian Wheat Aphid feeding symptoms on wheat near Cressy. 3. Feeding symptoms on barley near Launceston. Photos: Guy Westmore, Biosecurity Tasmania​​​

​​Detection of a New Pest in Tasmania

Russian wheat aphid, a new pest of wheat and barley was first detected in Australia, at Tarlee in South Australia, in May 2016. A national management committee determined it was beyond eradication and expected to spread rapidly. By October 2016 it occurred across much of the wheat and barley belt of South Australia, Victoria and southern New South Wales.

Russian Wheat Aphid was first detected in Tasmania in January 2017. It is likely to have arrived naturally on northerly airflows.​​

History

Russian wheat aphid is indigenous to central Asia and southern Russia. It was considered a minor pest until it appeared in South Africa in 1978 where it became a major pest of wheat. In the last 30 years it spread to other parts of the world including North and South America. Australia was one of the last major grain producing countries to remain free of the pest.


Risk to Tasmania

Tasmania has Import Requirements in place that reduce the likelihood of various pests including Russian Wheat Aphid entering Tasmania on live plants, which are treated with insecticide, or on agricultural machinery, which must be clean on arrival.  Russian Wheat Aphid is not moved via harvested cereal grain. It does however disperse widely on the wind.

Impact

Russian Wheat Aphid, Diuraphis noxia, is a small green aphid whose feeding produces strong plant symptoms due to the injection of saliva into the plant. Symptoms include rolled leaves, chlorotic spots, leaf streaking, trapped awns giving a hooked appearance and a stunted crop.

The presence of the aphid is unlikely to seriously impede market access for Australian exports of grain but feeding by the aphid will reduce yields and may increase crop management costs.

Russian Wheat Aphid is best adapted to the dry climate of the mainland Australian wheat belt and not well adapted to the moist Tasmanian climate. Its impact in Tasmania, although undesirable, is anticipated to be less than in the dry wheat belt areas of the mainland. However, the lack of a gap between summer and spring cereal crops in Tasmania may foster the pest.

Russian Wheat Aphids spend their entire life on cereals and grasses. They survive only a few days without feeding on suitable plants. The hosts that are most severely affected are barley (Hordeum vulgare) and wheat (Triticum aestivum). Other primary hosts include durum wheat (Triticum durum), field broom grass (Bromus arvensis), Elymus sp. and jointed goatgrass (Triticum cylindricum).

Secondary hosts are plants that only support adults and older juveniles. They allow the aphid to survive but not reproduce. Secondary hosts include cereal rye (Secale cereale), triticale (Triticum aestivum x Secale cereale) and various grasses in the Poaceae family, such as oats (Avena satvia), tall wheat grass (Agropyron elongatum) and Indian rice grass (Oryzopsis hymenoides).

Identification and Reporting

​Reporting of suspect occurrences of Russian wheat aphid is encouraged. The Entomology Team in Plant Diagnostic Services of DPIPWE will identify aphids suspected of being Russian Wheat Aphid at no fee. For an initial opinion, photos (with location) can be sent to 0429 852 886 or emailed to Guy.Westmore@dpipwe.tas.gov.au. Guy may request specimens before making a final identification.
Alternatively, specimens can be submitted to the Devonport (Stony Rise) or New Town Laboratories in person or by post. Samples of plants bearing aphids should be secured in sealed double plastic bags along with some absorbent paper towel.
Alternatively contact 1800 084 881 to report a suspect occurrence of this aphid and direction to an entomologist in Plant Diagnostic Services.

An expert national working group is generating information on management of this pest. Their information on the Russian Wheat Aphid can be found at the Plant Health Australia website.

Initial Management Advice

If you face a heavy infestation, seek advice from a commercial agronomist.

In many cases growers will not need to spray to control Russian Wheat Aphid.  Sprays are not preventative. Spraying low populations of Russian Wheat Aphid or other pests will kill predators and other beneficial insects, potentially causing resurgence to higher levels of Russian Wheat Aphid and other aphids later in the life of a crop.  Save pesticide options until you need to protect the flag leaf to maximize grain fill. If spraying is warranted aim to use softer chemistry to encourage natural predators and beneficial insects.  

Consider the economics of control.  International advice supports an economic threshold of 20% of plants infested up to the start of tillering and 10% of plants infested thereafter. 

Future Management Advice

This new pest affects a major Australian industry. A technical group has been established by Plant Health Australia to assist growers.  The Russian Wheat Aphid Technical Group comprises representatives from several major industry and government organisations.  Updates from the group will follow as more is known.  

Trial work is underway in South Australia to develop a range of insecticide options. 

More information on future management of the Russian Wheat Aphid can be found on the Plant Health Australia website.

Identification of Russian Wheat Aphid

Monitor crops for signs of Russian Wheat Aphid.

Learn to recognize the symptoms in wheat and barley plants., which can resemble herbicide damage. Symptoms include rolled leaves, chlorotic spots, leaf streaking, trapped awns giving a hooked appearance and a stunted crop.

The aphid itself has diagnostic features as in this image: 

Image: Key identifying features of Russian wheat aphid (D. noxia). Photo: Nicholas A. 2011 (Oklahoma)

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Contact

Entomologist
Lionel Hill
1 Rundle Road
DEVONPORT TAS 7310
Phone: 03 6421 7636
Fax: 03 6424 5142
Email: Lionel.Hill@dpipwe.tas.gov.au

Entomologist (Northern Tasmania)
Guy Westmore
Mt Pleasant
Launceston TAS 7250
Phone: 6777 2150
Mobile: 0429 852 886
Email: Guy.Westmore@dpipwe.tas.gov.au

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