Anisoplia austriaca Hrbst. - Wheat Grain Beetle, Wheat Chafer.
Taxonomic position.Class Insecta, order Coleoptera, family Scarabaeidae, subfamily Rutelinae, genus Anisoplia.
Biological group.Pests of cereal crops.
Morphology and biology.The beetle body length is 13-16 mm. Body and legs are black with green shine. Elytra are yellow-brown or red-brown, deeply striated, with black square spot near shield in females. Egg is white, nearly globose, to 2 mm in diameter. Larva is white, with yellow-brown head and legs, to 35 mm long. Pupa is yellow-brown, 15-17 mm long. The Wheat Grain Beetle is a biennial species. Beetles fly from June until July, living openly on ears of grain cereals. In July females lay eggs in soil at a depth of 8-20 cm. Fertility reaches 50 eggs which are laid over 2-3 sittings. The eggs, larvae, and pupae develop in soil. Eggs develop over 2-4 weeks (in July and August) depending on soil temperature. Larvae develop over 22-23 months, and they winter twice at a depth of 30 to 80 cm. The older larvae (after the second wintering) pupate in May at a depth of 8-15 cm in soil. Pupae develop over 10-20 days from May until June.
Distribution.Steppes of Europe are native lands for the species. The pest lives in southeastern part of Western Europe; in steppe, forest-steppe, and in the south of forest zones of Moldova, Ukraine, and European part of Russia; in steppe zone of Ural, Altai, and Kazakhstan, and in the Caucasus, Turkey, and Iran (northern districts). The beetle is most harmful in black-earth steppes of Ukraine and southern Russia, in western and eastern regions of Kazakhstan, and in Azerbaijan.
Ecology.Thermophilous. Emergence of young adults from soil is possible when the temperature is 17°C and higher, and female maturation is possible at 20°C and higher. Beetles are active and feed only during the daytime, especially on hot sunny days. At night they migrate from plant ears to ground surface, remaining there also on cool cloudy days. In this connection, the pest population density increases during warm dry years, greatly decreasing during cool rainy summers. Larvae are relatively hygrophilous; they migrate into deep soil layers during drought periods. The Beetle imagoes feed on cereal plants (of the family Poaceae), preferring wheat, barley and rye cultivars (especially their summer cultivars), and also on wild cereal species, such as timothy grass, couch-grass, etc. The beetles colonize grain-crop fields near borders mainly, eating soft unripe grains of the plants. Larvae during the first year of life feed on soil humus and small roots of different plants; older larvae during the second year of life predominantly eat the roots of grain crops and sugar beet. The Wheat Grain Beetle has natural entomophages, e.g., some wasps, such as Tiphia femorata F., T. morio F. (Hymenoptera, Tiphidae), Scolia quadripunctata Dr. (Hymenoptera, Scoliidae) parasitize beetle larvae. Also, various birds actively exterminate beetles and larvae of the pest.
Economic significance.Both the beetles and larvae of A. austriaca are harmful. Each beetle eats 7-8 g of grains during its life, but it also knocks out many grains from ears. In total, each beetle destroys 9-10 ears of grain cereals. Larvae feeding in soil on roots and seedlings of cereals can cause thinning of young crops. The economic threshold for this pest is 3 beetles per sq.m. If the pest population density is more than 10 beetles per sq.m, and the thickness of sowing is not more than 250 stems per sq.m, then losses of grain yield reach up to 50%. Sometimes the real pest population density in favorable seasons can reach to 60-100 beetles per sq.m at field borders. Control measures: vernalization and early sowing of cereal grain crops; soil cultivation and inter-row treatment on plantations of tilled crops in spring and in early summer as a method of mass extermination of pupae; quick two-phase harvesting at the beginning of grain ripening; early post-harvesting plowing of soil; treatments of plants by insecticides against the beetles if their population density is higher than economical threshold.
Reference citations:Borisenko N.Kh. 1973, The influence of abiotical factors on Anisoplia austriaca. In: Litvinov B.M., ed. Proceed. of Kharkov Agricultural Institute. Kharkov: Kharkov Agric.Inst., vol. 182, p. 67-74 (in Russian).
Chenkin A.F., Grivanov K.P., eds. 1974. Reference Book for plant protection. Moscow: Rosselkhozizdat, 400 p. (in Russian).
Ermolenko V.M. 1971. Atlas of insect pests of field crops. Kiev: Urozhai, 176 p. (in Ukrainian).
Kryzhanovskii O.L., ed. 1974. Insects and mites - pests of agricultural plants, V. 2. Coleoptera. Leningrad: Nauka. 335 p. (in Russian).
Pavlov I.F. 1987. Field crops protection from pests. Moscow: Rossel'khozizdat, 256 p. (in Russian)
Sagitov A.O. & Ismukhambetov Zh.D., eds. 2004. Reference book on plant protection. Almaty: ROND, 320 p. (in Russian).
Volodichev M.A. 1974. About food relations of Anisoplia beetles. In: Semakov V.V., ed. Proceed. VNIIZR. Voronezh: Agric. Ministry of RSFSR, vol. 3, p. 13-24 (in Russian).