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Comprehensive Description

provided by Memoirs of the American Entomological Society
Spodoptera exigua (Hiibner)
Figs. 151-152, 471^73
Diagnosis. — General ground color is variable and can be yellow, green, or brown. Head color can be pale (yellow or green) to brown, with dark submedial reticulate patterns on pale heads and light reticulations on dark heads. The body is usually patterned with white dots and short lines. Paired dorsal markings on mesothorax round when present. The dark triangular subdorsal markings common in most species of Spodoptera are usually absent, if present, they are not triangular, but more elongate or round (Levy & Habeck 1976). Total number of crochets on all 5 pairs of prolegs on one side of body is less than 106.
Description of preserved specimens. — Head: Color pale to black; reticulate; frons pale to black; cutting edge of mandible serrate; P2 setae farther apart than PI setae; ratio ecdysial line: frons height, averages less than 0.62. Thorax: Pronotum with dorsolateral stripe conspicuous, either solid or consisting of closely spaced spots and dashes; middorsal stripe narrower than dorsolateral stripe. Mesothorax segmental spot absent (can be present in heavily marked specimens (Levy & Habeck 1976)); with lateral dark spot present. Metathorax with segmental spot absent; lateral dark spot absent. Abdomen: Body smooth; setal pinacula minute. Middorsal stripe inconspicuous, narrower than dorsolateral stripe. Segmental spots on abdomen absent (can be present on
heavily marked specimens (Levy & Habeck 1976)). Segment 1 with lateral dark spot absent. Segments 2-6 with lateral dark spots in spiracular band absent. Spiracular band reticulate; spiracular band on segments 1-6 with white or light colored spot caudal to spiracle present. Spiracle with black border and pale center; not stalked. Subspiracular stripe inconspicuous, concolorous below spiracular band. Crochets uniordinal; total number on one side of body less than 106 (range: 77-88; mean: 84.5; n=10).
Color description. — Mature larvae range from 25-30 mm in overall body length. Head pale, with broad submedian arcs, reticulation, and a solid area posterior to ocelli fuscous or black. Pronotal shield infuscated. Ground color varies from green to soft shades of gray and brown to pinkish brown. Middorsal stripe pale, nearly absent on anterior and posterior portions of each abdominal segment by more intense fuscous markings anteriorly. Segmental spots black when present. Lateral band darker than dorsum. Lateral stripe white. Spiracular band a shade of lavender to black. Spiracles pale yellowish with dark rims. Venter green flecked with white (Swezey 1906; Fletcher 1914; Crumb 1927, 1956).
Plant hosts. — S. exigua is an important economic pest throughout the world. Hosts include many crops in the Fabaceae (peanuts, peas, beans, soybeans, lentils, alfalfa) and Poaceae (corn, millet, oats, wheat, rice, sorghum). Larvae also feed on a variety of horticultural crops including many species of cut flowers.
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bibliographic citation
Pogue, M.G. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society vol. 20. Philadelphia, USA

Beet armyworm

provided by wikipedia EN

The beet armyworm or small mottled willow moth (Spodoptera exigua) is one of the best-known agricultural pest insects. It is also known as the asparagus fern caterpillar. It is native to Asia, but has been introduced worldwide and is now found almost anywhere its many host crops are grown.[1] The voracious larvae are the main culprits. In the British Isles, where it is an introduced species and not known to breed, the adult moth is known as the small mottled willow moth.[2]

Discovery

Thought to have originated in south-east Asian countries, it was first discovered in North America about 1876, when it was found in Oregon, and it reached Florida in 1924.[3]

Larva

Description

The adult is a drab brown or grey moth with a wingspan of 26–32 millimetres (1–1+14 in). Forewing is greyish ochreous in color, washed with dull yellow and sprinkled with black scales. Inner and outer lines are double, indistinct, filled in with pale yellowish color. A dark waved median shade visible before lower half of outer line. Cell is dark brown. Orbicular stigma is pale or bright yellow, and round, whereas reniform has a curved brown lunule in centre. The submarginal line is pale grey. There is the darker shade preceding it with dark streaks between the veins. Terminal spots are black. Hindwings semihyaline are white, with the veins dark brown. All three margins are shaded with fuscous color.[4]

Larvae are pinkish brown, clotted with black. Spiracular line pale ochreous, with dark upper edge. They are greenish-brown cutworms, soft and bulging caterpillars with dark longitudinal stripes.[5]

Damage

The larvae feed on the foliage and fruits of plants, and can completely defoliate small ones. Smaller larvae devour the parenchyma of leaves, so all that remains is the thin epidermis and veins. Larger larvae tend to burrow holes through thick areas of plants. For example, they will burrow straight into a head of lettuce rather than neatly removing tissue from one particular leaf, rendering the produce unmarketable. Larvae also attack buds and new growth on plants, preventing flowers from opening, new leaves from sprouting, and vegetables from developing. As the smaller larvae move about they leave strands of silk behind, netting the leaves with a silvery film.[3]

Illustration

Ecology

The wide host range of the beet armyworm includes asparagus, beans and peas, sugar and table beets, celery, cole crops, lettuce, potato, tomato, cotton, cereals, oilseeds, tobacco, cannabis, many flowers, and a multitude of weed species.[6] The beet armyworm does not tolerate cold. It can overwinter in warm areas, such as Florida and Hawaii, but in colder areas, it dies off during the winter and the region is reinvaded by the adult moth as the weather warms and crop plants sprout.[3]

Control

Pheromone traps and mechanical hand picking of adults and caterpillars are extensively used. Parasitoids such as Chelonus insularis, Cotesia marginiventris, Meteorus autographae, Lespesia archippivora lay eggs on the caterpillars, and their larvae feed and emerge. Predators like Orius sp., Geocoris sp., Nabis sp., Podisus maculiventris are also effective controlling measures. Pupal stages can be eliminated by introducing Solenopsis invicta to the field.[3]

Apart from biological control, many chemical pesticides are extensively used. Larvae are susceptible to neem products. Eggs can be killed by using petroleum oil concentrations. Applying cottonseed oil to leaves can eliminate both eggs and larvae.[3]

See also

References

  1. ^ "Spodoptera exigua (Hübner)". ICAR-National Bureau of Agricultural Insect Resources. Retrieved 3 August 2016.
  2. ^ "beet armyworm (Spodoptera exigua)". Plantwise Technical Factsheet. Retrieved 3 August 2016.
  3. ^ a b c d e "beet armyworm". University of Florida. Retrieved 3 August 2016.
  4. ^ Hampson, G. F. (1894). The Fauna of British India, Including Ceylon and Burma: Moths Volume II. Taylor and Francis – via Biodiversity Heritage Library.
  5. ^ Seitz, A. Ed., 1914 Die Großschmetterlinge der Erde, Verlag Alfred Kernen, Stuttgart Band 3: Abt. 1, Die Großschmetterlinge des palaearktischen Faunengebietes, Die palaearktischen eulenartigen Nachtfalter, 1914
  6. ^ "Robinson, G. S., P. R. Ackery, I. J. Kitching, G. W. Beccaloni & L. M. Hernández, 2010. HOSTS – A Database of the World's Lepidopteran Hostplants. Natural History Museum, London".

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Beet armyworm: Brief Summary

provided by wikipedia EN

The beet armyworm or small mottled willow moth (Spodoptera exigua) is one of the best-known agricultural pest insects. It is also known as the asparagus fern caterpillar. It is native to Asia, but has been introduced worldwide and is now found almost anywhere its many host crops are grown. The voracious larvae are the main culprits. In the British Isles, where it is an introduced species and not known to breed, the adult moth is known as the small mottled willow moth.

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cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
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wikipedia EN