Sitona lineatus

Pea Leaf Weevil

Synonym(s): Circulio lineatus
Class: Insecta
Order: Coleoptera
Family: Curculionidae


Photographer: Pest and Diseases Image Library
Source: Pest and Diseases Image Library

Description

Adult Description: The adult Pea Leaf Weevil (Sitona lineatus) is typically 3-5mm in length, brown in color with longitudinal stripes of two shades, and has never been sited with spots. The adult has flat lying bristles beneath the wings.

Larva Description: Pea Leaf Weevil eggs are small, smooth, and white when laid, but turn black just before hatching. Larvae are milky white in color with a brown head and are about 1/4 in in length. Long setae or hairs protrude from each segment of the body which flatten in the adult form.

Host Plant: Cultivated peas and other leguminous crops and grasses

Ecological Threat: Both adult and larval stages of S. lineatus can be harmful to crop yields. The adults feed on foliage while the larvae feed on root nodules reducing nitrogen fixation for the plant. An outbreak in the Soviet Union recorded a density of 50-70 specimen per square centimeter.

Biology: Mating and laying of eggs occurs from spring to late June after which the Pea Leaf Weevils die off. Maximum clutch size is 3,600 eggs which are laid on the plant itself or on the soil surface. The larvae eat the plant root from the inside out and emerge as adults beginning in July into August. Warm and humid weather without sudden temperature fluctuation is ideal for S. lineatus.

History: The Pea Leaf Weevil was first noted in North America in 1936 in Vancouver Island, British Columbia. In 1970 the weevil was found in Eastern Washington. From there the weevil spread south down the coast and can now be found anywhere peas or other leguminous crops are grown.

U.S. Habitat: Peas, beans, sweet peas, alfalfa, various clover varieties, chickpea, and cultivated oats

Distribution

Native Origin: Europe

U.S. Present: Virginia, Florida, Texas, and British Columbia

Resembles/Alternatives

Clover root curculio can be mistaken for the Pea Leaf Weevil as both may be found in clover fields and contain flat lying bristles. The Pea Leaf Weevil can be distinguished by its large inner wings and stronger ability to fly.

Management

Sowing annual leguminous plants as early in the season as possible, use leaf accelerator fertilizer for the first five weeks of growth and plow fields after harvesting. Use insecticide treatment on plants when needed.

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References

Bardner, R., and K. E. Flether. (1979). Larvae of the pea and bean weevil, Sitona lineatus, and the yield of field beans. Journal of Agricultural Science 92 (1).

Cárcamo, H., & Vankosky, M. (2011). Managing the pea leaf weevil in field peas. Prairie Soils and Crops, 4, 77-85.

Smart, Lesley. (1994). Development of field strategies incorporating semiochemicals for the control of the pea and bean weevil, Sitona lineatus. Science Direct 13 (2) 127-135.

Internet References

http://bugguide.netv
http://www.agroatlas.ru
http://cru.cahe.wsu.edu

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