Australia is the last major grain growing country in the world which is free of Russian wheat aphid. Its preference for drier climates indicates it would thrive in the Western Australian wheatbelt.
It is widespread in southern Europe, Central Asia, the Middle East, North America and parts of Africa. It has been found in one region of the People's Republic of China for about 70 years, but has not spread to the major wheat-growing areas. It has recently been found in Chile and Argentina but has not yet become a serious pest.
Russian wheat aphid is a small lime-green coloured aphid with an elongated body. Adults are 1.4-2.3mm in length, the antennae are short, as are the cone-shaped siphunculi (sometimes called cornicles). Supracaudal process is present, giving the appearance of a double tail.
This aphid has a history of severe economic impact. Analysis has indicated that there is a high risk of severe losses in many Australian wheatgrowing areas. Since its appearance in Texas in 1986, Russian wheat aphid has become a major pest of wheat and barley in the United States, causing over $850 million in direct and indirect losses from 1987 to 1992.
Russian wheat aphid is a serious pest of wheat and barley. Limited problems also have been noted in triticale, oats and rye.
Season of occurrence
Russian wheat aphid would occur throughout the year. Infestation of wheat and barley would start from the emergence of the crop in autumn and extend to crop maturity. During wet summers self-sown wheat and barley would serve as a 'green bridge'.
As a result of salivary toxins injected as the aphids feed, plants become purplish and leaves develop longitudinal yellowish and whitish streaks. Tillers of heavily infested plants often run parallel to the ground, giving them a prostrate appearance. In the spring, as wheat stems begin to elongate, the aphids move upward to infest the new leaves. Eventually the aphids reach the flag leaf, causing it to roll and "trap" the emerging head and awns. The "trapped" head then curls, resulting in poor pollination.