Pests
Selatosomus latus F. . European Click Beetle
Systematic position.
Class Insecta, order Coleoptera, family Elateridae, subfamily Lepturoidinae, tribe Corymbitini, genus Selatosomus.Biological group.
Polyphagous pests.Morphology and biology.
Beetle is 10-16 mm long and 4.5 mm wide; it is black with dark green, dark blue, or bronze shine. The body of the beetle is flattened, with gray hairs on upper side. Pronotum is wider than long. Legs are dark brown. Eggs are white, nearly globe-shaped, 0.7 mm in diameter. Larva is bright yellow with metallic shine; it is 25 mm long and 3.3 mm wide. The end of last segment of larval body has 2 short projections with sharp-pointed tips. Emargination between these projections is nearly oval. Pupa is white, 16 mm long. The larvae in all the species of Elateridae are hard, nearly cylindrical and shining. They are called "wireworms" because they look like a wire fragment. S. latus has 4-5-year generation development. Beetles fly and reproduce from the middle of April to June in the European part of Russia and from May to July in Western Siberia. They lay eggs only after additional feeding by leaf parenchyma or by flowers of various plants. Females place eggs on radical parts of plants or into soil fissures. The female total productivity is 200 eggs. The eggs, larvae, and pupae develop in soil. The larvae develop during 3-4 years, depending on a climatic zone. During this period, they molt 8-12 times and winter on a depth of 20-50 cm. The adult larvae pupate in June-August on a depth of 10-15 cm. The young imagoes emerge in July-September and stay wintering in soil.Distribution.
S. latus is widespread in the steppes, forest-steppes, and in the southern part of forest zone of Eurasia from the Atlantic Ocean to the Amur Region, including the Asia Minor, the Caucasus, Kazakhstan, Northeastern Mongolia, and Northern China, but absent in the south of Eastern Siberia. The zone of its highest density and harmfulness includes the flat chernozem steppes and the southern part of forest-steppe zone, especially the districts with a predominance of heavy soils.Ecology.
S. latus is the omnivorous, mainly phytophagous species. Its imagoes are light-requiring, living openly; they are active at day time. Their pairing occurs on soil surface. Females select for the oviposition mainly perennial grasses or the fields settled by couch-grass (Agropyrum repens) at a high level, including fallow fields, virgin and long-fallow lands. Eggs develop 20-30 days and pupae develop 14-20 days under the soil temperature 18-23°C. The thermal limits for feeding and development of larvae are 10 to 35°C. The larvae actively move in soil, seeking food or places with optimal thermal and humidity conditions. Natural enemies of all elaterid beetles are ground-beetles of the genera Carabus, Calosoma, Harpalus, Amara (Coleoptera, Carabidae), more than 200 species of birds, and also moles, toads, and lizards. They eat many beetles and larvae on fields after spring and autumn plowings.Economic significance.
The larvae (wireworms) are only harmful in S. latus and other phytophagous beetles of the family Elateridae. They eat seeds, seedlings, and underground parts of various agricultural crops (including perennial crops) and weeds. S. latus larvae are the most harmful for the grain cereals, potato, vegetables, and for the young fruit trees. In arid districts, they are especially dangerous in spring and also in conditions of irrigation. Their harmfulness consists in causing shoot thinning, depression of damaged plants, and deterioration of commercial quality of potato tubers, beet and carrot. The economical threshold of wireworm numbers in major crops (maize, potato, sugar beet) is 3 to 15 larvae per 1 sq. m. The real density of S. latus larvae in the steppe and forest-steppe districts of Europe and Western Siberia is often many times higher than this level. Preventive and protective measures are the extermination of weeds, especially the couch-grass; deep subsurface tillage of fallow fields; cultivation and interrow treatment of soil on tilled crop plantations in spring and in early summer; early post-harvest autumn plowing of soil; extermination of crop plant residues; application of organic fertilizers in high doses; application of soil insecticides in spring before sowing, if the wireworm population density is higher than economical threshold for the crop.Reference citations:
Anon. 2005. Economical Threshold Levels of main pests of agricultural crops. Plant Protection and Quarantine. 10: 36-38; 11: 40-43. (In Russian)Bobinskaya S.G., Grigorjeva T.G., Persin S.A. 1965. The wireworms and control measures against them. Leningrad: Kolos. 223 pp. (In Russian)
Chenkin A.F., Grivanov K.P., eds. 1974. Reference Book for plant protection. Moscow: Rosselkhozizdat. 400 pp. (In Russian)
Cherepanov A.I. 1965. Wireworms of Western Siberia. Мoscow: Nauka, 190 pp. (In Russian)
Dolin V.G. 1964. Elaterid beetle larvae (wireworms) of the European part of the USSR. Kiev: Urozhai. 206 pp. (In Russian)
Ermolenko V.M. 1971. Atlas of insect pests of field crops. Kiev: Urozhai. 176 pp. (In Ukrainian)
Kryzhanovsky O.L., ed. 1974. Beetles. Insects and mites . the pests of agricultural crops. Vol. II. Leningrad: Nauka. 336 pp. (In Russian)
Pavlov I.F. 1987. Protection of field crops from pests. Moscow: Rosselkhozizdat. 256 pp. (In Russian)
Shchegolev V.N., ed. 1955. Glossary-reference Book for Entomologist. Moscow & Leningrad: State Publ. Agricult. Liter., 451 pp. (in Russian).