Identification and Control Methods for the Russian Wheat Aphid
Scientific name Diuraphis noxia (Mordvilko), order Homoptera, family Aphididae. Synonym Brachycolus noxius. Also known as the Russian wheat aphid. Distribution in **. In addition, the Liaohe, Yellow River, Huaihe and Haihe river basins are all suitable areas for this insect. Abroad it is mainly distributed in Ukraine, Central Asia, North Africa, Eastern Europe, Nepal, South Africa, Mexico, the United States and Canada. It is a worldwide major pest of wheat. It is a domestic quarantine target.
Hosts @#@245@#@, barley, rye, oats, wild oats, brome and more than 70 other grass-family crops and weeds. It sometimes damages rice.
Damage characteristics: when damaging wheat, it causes the flag leaf to curl longitudinally and prevents normal heading. Yield reduction 30%-60%.
Morphological characteristics: wingless parthenogenetic female body length 1.59 mm, width 0.6 mm, body light green. Mesothoracic ventral fork sessile to arms separated. Antenna length 0.74 mm, length ratio of segments 1-6 being 35, 30, 100, 62, 58, 46+91. Rostrum reaching the middle coxa, length of terminal segment 0.74 times that of hind tarsal segment 2. Tarsal segment 1 chaetotaxy 3, 3, 3. Cornicle shorter than its basal width. The center of the eighth abdominal tergite bears a supracaudal process, 0.55 times the length of the cauda. Cauda with 5 or 6 hairs, supracaudal process with 4-5 short hairs, anal plate with 9 hairs, genital plate with 20 hairs. Winged parthenogenetic female body length 2.46 mm, width 0.82 mm. Antenna length 0.74 mm, length ratio of segments 1-6 being 23, 12, 100, 51, 53, 43+92; segment 3 with 4-6 circular secondary sensoria, segment 4 with 1 or 2.
Life habits: 11 generations per year, with a full life cycle in cold wheat regions. In late autumn and early winter, sexual females and males are produced; after mating, eggs are laid on wheat or grass-family weeds, and the eggs hatch the following spring; on the above hosts there are 3 parthenogenetic generations, with the first and second generations wingless, and the third and fourth generations partly winged, migrating outward or causing damage until wheat harvest. In warm regions it reproduces parthenogenetically with an incomplete life cycle. Natural enemies include Aphelinus asychis, Aphelinus varipes, Diaeretiella rapae, Aphidoletes aphidimyza, and Scymnus quadripustulatus.
Control methods: (1) Select varieties with low susceptibility such as emmer wheat, Mg4537, Mg7458, Mg8786 and Mg8256 to reduce damage. (2) Plant wheat varieties with high susceptibility such as Maodatou, Hongfoer, Modaosui, 7432-15-0-21 and Goumaobai; they can attract large numbers of the pest, which is then concentrated and eliminated, not only reducing pesticide application and saving manpower and materials but also protecting natural enemies and achieving natural control. (3) When planting locally superior varieties, interplant the above susceptible varieties to eliminate the Russian wheat aphid in the trap strips. (4) Prohibit the transport of grass-family seedlings from areas where the pest occurs. Introduced grass-family seedlings should be carefully inspected and disinfected against insects. (5) When necessary, spray 10% pymetrozine (imidacloprid or Yibian