Pests

Agrotis segetum (Denis & Schiffermueller) -Turnip Moth

Systematic position.

Class Insecta, order Lepidoptera, family Noctuidae, genus Agrotis.

Synonyms.

Euxoa segetum Denis & Schiffermueller, Scotia segetum Denis & Schiffermueller.

Biological group.

Polyphagous pest.

Morphology and biology.

The size and color of moths are varied. This species expresses sexual dimorphism. Body length is 18-22 mm, wing span 34-45 mm. Female forewings are yellowish-gray, brown, or almost black; round, reniform, and cuneiform spots are surrounded by thin black limbation. Second and third diametrical bands are represented as double curved lines. Marginal line is represented as a number of black striae. Males have lighter forewings. Female hind-wings are light-gray with gray band along external edge; male hind-wings are white, sometimes with dark veins. Females have setaceous antennae, males have comb-like antennae. Imago life span is 5 to 25 days (at the most, 40 days) depending on the temperature. Fecundity varies in the range of 400-1000 (maximum 2200) eggs. Eggs are laid one by one, occasionally in groups of 2-3 on plant residues, on the ground, and on the lower side of weed leaves adjoining soil surface or aggregating in a rosette. Development of eggs lasts 3 (at +29-30°C) to 24 days (at +10-12°C). Eggs have spherical shape (0.5-0.6 mm in diameter) and costate surface; color is white, later with reddish pattern. Larvae develop in 24-40 (sometimes 90-100) days, reaching 40-52 mm in length at the last 6th instar. Larvae are greenish-gray to 5th instar and later become glossy dark-gray with dark stripes extending along dorsal and lateral sides. Ventral part of larvae is lighter. Head is orange with dark stripes on frons. The 5-6th instar larvae over-winter in soil at a depth of 10-25 cm; in southern regions larvae of 3rd-4th instar can winter. Larvae pupate in soil at a depth of 1-6 cm (in "cavities"); here pupae develop over 25-30 (in spring) or 10-15 days (in summer). Pre-pupal stage lasts 2-10 days. Pupae are red-brown in coloration. Body length is 16 to 20 mm.

Distribution.

West Europe, Africa, Middle East, Mongolia, China, Japan, Hindustan, Nepal, Baltic States, Byelorussia, Ukraine, Moldavia, Armenia, Azerbaijan, Georgia, Kazakhstan, Middle Asia, Russia. In the territory of the former USSR the Turnip Moth area occupies the European part to the Polar circle, the North Caucasus, southern Ural, also South of Siberia and the Far East.

Ecology.

Polycyclic species; types with one generation develop in the northern regions of Russia, types with 2 generations develop in the central regions of Russia, 2-3 in the North Caucasus, 2 in Byelorussia, Ukraine, and Moldavia, 3 in Azerbaijan, Armenia, Georgia, and Kazakhstan, 3-4 generations in Middle Asia. Degree-days for one generation development are 550° at threshold +10°C. Adult emergence begins at +12°C average daily temperature for northern populations and at +15°C for southern populations: in the south of Tajikistan it begins in the last days of March; in Middle Asia, southern Kazakhstan and Transcaucasia in the middle of April; in Moldavia, Byelorussia and Ukraine in the middle of May; in north-west regions of Russia and in Baltic States in the middle of June. Emergence lasts more than a month. Moth flight of different generations usually overlap and continue into October. Females need nectar for the beginning of oviposition. Moths are active at twilight and night. Insect development depends on temperature and amount of precipitation, particularly in winter-spring period. Insect population density depends on activity of entomophages (parasites and predators) and entomopathogens. Larvae feed on plantlets (cotyledon leaves, first true leaves) and cause damage to root collars and young stems, often destroying them completely. The species is considered a broad polyphagous insect. In Russia and adjacent countries the larvae populate more than 160 plant species; in nature they prefer weeds, such as clover, lambs quarter goosefoot, trailing bindweed, garden orach, horse sorrel (dock), and common plantain.

Economic significance.

The greatest damage is caused to cotton, tomatoes, maize, grain legumes, tobacco, sunflower, sugar beet, and winter cereals during the first generation of pest development. It is capable of causing injury to soy bean, pea, pumpkin, squash, potato, vegetables, castor-oil plant, hemp, jute. The damage has been observed on grape, tea, seedlings of arborescent species. Over the last decades the Turnip Moth level of harm has decreased considerably. Economic threshold of harmfulness is 2-3 larvae per sq. m on winter wheat plantlets, 0.5-2 larvae per sq. m on maize, 1-2 larvae per sq. m on sugar beet, 1.5-2 larvae per sq. m on cotton, 0.5-1 larvae per cabbage plant. Control measures include: cultivation of resistant varieties, weeding, removal of crop residues from fields, deep autumn plowing, inter-row cultivations, optimal dates of early sowing, including vetch-oat sown fallows in crop rotation, digging defensive ditches and furrows, watering, application of green poisonous baits, insecticide treatments of seeds and plantlets, release of such entomophages as Trichogramma spp., application of such bio-preparations as Lepidocide, Virin, Dendrobacillin and Bitoxibacillin. Monitoring is possible by use of sex pheromone traps.

Reference citations:

Bryantsev B.A. 1973. Agricultural entomology. Leningrad: Kolos. 336 p. (In Russian)
Druzhelyubova T.S. 1975. Turnip Moth (Agrotis segetum Schiff.). In: Polyakov I.Ya., ed. Distribution of the main pests of agricultural crops in the USSR and efficiency of their control (Methodical instructions). Leningrad: VASKHNIL, VIZR. 42-44 p. (In Russian)
Kononenko V.S. 2003. Noctuidae. In: Ler P.A., ed. Keys to the insects of the Russian Far East. V. 5(4). Trichoptera and Lepidoptera. Vladivostok: Dalnauka. 688 p. (In Russian)
Nikitin I.V. 1937. Turnip Moth. Review of pests and diseases development on agricultural crops for 1936 year. Part III. Pests of sugar beet. Leningrad-Moscow: VASKHNIL. 219-235 p. (In Russian)
Pospelov S.M. 1989. Noctuids - pests of agricultural crops. Moscow: Agropromizdat. 112 p. (In Russian)
Sakharov N.L. 1930. Injurious noctuids and their control. Saratov: Gos. izd., Nizhnevolzhskoe kraevoe otd. 80 p. (In Russian)
Shchegolev V.N., Znamenskii A.V., Bei-Bienko G.Ya. 1934. Insect pests on field crops. Leningrad-Moscow: Selkhozgiz. 364 p. (In Russian)
Sukhareva I.L. 1999. Noctuidae. In: Kuznetsov V.I., ed. Insects and mites - agricultural pests. V. 3, part 2. Lepidoptera. St. Petersburg: Nauka. 332-378 p. (In Russian)
Volkov A.N., Gerasimov B.A., Zaring P.V., Mushinkova K.S., Nikiforov A.M., Popov S.D., Chuvakhin V.S. 1955. Textbook on control of pests and diseases of agricultural cultivars. Moscow: Sel'khozgiz. 687 p. (In Russian)
Zakharenko V.A., Chenkin A.F., Cherkasov V.A., Martynenko V.I., Polyakov I.Ya. 1985. Reference book on plant protection. Moscow: Agropromizdat. 415 p. (In Russian)
Zubenko V.F., Petrukha O.I., Pozhar Z.A., Shevchenko V.N., Matushkin S.I. 1976. Measure system improvement against pests, diseases on sugar beet crops. Problems of plant protection from pests, diseases and weeds. Moscow: Kolos. 100-104 p. (In Russian)

© Chumakov M.A., Kuznetsova T.L.

 

Web design —
Kelnik studios