History
Russian wheat aphid is indigenous to central Asia and southern Russia. It was considered a minor pest until it was reported 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 is one of the last major grain producing countries to remain free of the pest.
Risk to Tasmania
Tasmania already has Import Requirements in place that reduce the likelihood of Russian Wheat Aphid entering Tasmania on live plants, which are treated with insecticide, or on agricultural machinery, which must be clean on arrival. Additional requirements are not required. There is a possibility that the aphid will blow naturally across Bass Strait in the future. Russian Wheat Aphid is not moved via harvested cereal grain.
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, will be much less than in the dry wheat belt areas of the mainland.
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 thePoaceae family, such as oats (Avena satvia), tall wheat grass (Agropyron elongatum) and Indian rice grass (Oryzopsis hymenoides).
Although rye and triticale are moderately resistant, and oats is resistant, to serious damage from the aphid all three crops act as a harbour and a food source for the aphid without showing symptoms.