English Grain AphidMacrosiphum avenae
Class Insecta, order Homoptera, suborder Aphidinea, superfamily Aphidoidea, family Aphididae, subfamily Aphidinae, tribe Macrosiphini, subtribe Macrosiphina, genus Macrosiphum.
Oligophagous cereal pests.
Morphology and biology.
Apterous female with green or yellow-brown fusiform body and long legs. Its length varies from 2.7 to 2.9 mm. Antenna is longer than body. Siphunculi are black (1.5 times as long as light-green tail). Winged female has red-brown thorax and green abdominal segments. Eggs are oval and black. Over-wintering takes place during the egg phase on winter cereals, and also on cereal weeds. In the southern areas it takes place during the adult phase. Sexual agamous generations are present during the aphid life cycle. Larval period lasts 8-12 days. In the zone of strong harm the hatching of larvae giving fundatrices is observed in April. Life span of apterous parthenogenetic females is about 30-60 days and they produce 20-40 larvae. The pests feed on winter cereals at first and later on spring crops. The insects prefer the upper part of the ears of plants. The aphids are active and they do not form big colonies. In September, when the sprouts of winter cereals appear, the aphids migrate from summer reservations. At the end of September and the beginning of October viviparous individuals (viginoparae) appear, giving birth to females and males. The eggs are laid at the end of October-November. The female produces 6 to 12 eggs.
The insect is widespread throughout Europe, Asia, West Africa, America and Japan. Within the territory of the Former Soviet Union the species occurs widely northward to Khibiny, in Siberia, Primorskii Territory, the Caucasus, Transcaucasia, Middle Asia and Kazakhstan. It causes the greatest harm in the steppe and forest-steppe zones.
Embryo development occurs at 5 degrees Celsius. The air temperature required for development of the first generation varies from 63 to 75 degrees Celsius. In the areas where the insect causes the greatest harm the intensive migration of aphids to cereals takes place at the end of May and in June. The borders of fields are populated at first and then the pest penetrates deep into the cereal field. The aphid.s infestation is very dangerous when the plants are in the phases of ear emergence, milk and dough development. The most favorable conditions for the insects are at temperatures of 16-20 degrees Celsius and a relative humidity of 65-80%. The greatest harm caused by this insect occurs after years with moderately warm and damp summers and also damp autumns. Within the territory of the Former Soviet Union the species produces 14-20 generations during a year. Its most important predators are insects of the families Coccinellidae (Coccinella septempunctata L., C. notata Host., C. axiridis Pall., also representatives of the genera Adalia, Semiadalia, Adonia etc.), Syrphidae (the genera Syrphus, Melanostoma, Scaeva, Eupeodes, Paragus), Chrysopidae (C. carnea Steph., C. formosa Br.). Most important parasites are representatives of the family Braconidae (the genera Aphidius, Lysiphlebus, Ephedrus).
The pest causes the greatest damage to summer and winter wheat, summer and winter barley, rye, oats, sorghum and maize. Among the wild cereal grasses it prefers Phleum pratense L., Avena fatua L., Agropyrum repens P.B., Dactylis glomerata L., Bromus mallis L., Bromus secalinis L., Festuca pratensis Huds. Control measures include timely forecasting of the pest appearance and numbers, eradication of weeds and insecticide treatments at the end of May and in June. Insect population may depend on activity of entomophages.