Hypera postica

(Gyllenhal, 1813)

Alfalfa Weevil

, the , is a small to Europe and a major pest of alfalfa in North America following accidental introductions. measure 4–5.5 mm and are with a dark mid- stripe; are yellowish-green with a black and dorsal stripe, reaching about 1 cm before . The causes significant through larval of alfalfa foliage, with yield reductions up to 15%. Multiple agents, particularly in the Bathyplectes, have been to manage .

Hypera postica P1400593a by
xpda. Used under a CC BY-SA 4.0 license.

Hypera postica P1650314a by
xpda. Used under a CC BY-SA 4.0 license.

Hypera postica 01 by AfroBrazilian. Used under a CC BY-SA 3.0 license.

Pronunciation

How to pronounce Hypera postica: /haɪˈpɪərə ˈpɒstɪkə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from the closely related clover (Hypera ) by its smaller size (H. punctata is nearly twice as large) and the black of its (H. punctata larvae have tan heads). may be separated from other small in alfalfa by the combination of short broad , half as wide as rostrum, and the dark mid- stripe. sampling or beat bucket methods are standard for ; larvae are found between folded leaves when young, and on open leaflets when older.

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Habitat

Primarily associated with alfalfa (Medicago sativa) cropping systems. overwinter in alfalfa crowns, coarse vegetation in ditches, fence , or nearby woodland edges. develop within alfalfa stems and on foliage. In summer, adults undergo in protected areas away from fields, returning in fall.

Distribution

to Europe, with established across much of the continent including Britain, France, Germany, Italy, Spain, and Scandinavia. and established in North America (United States, Canada), where it is a major pest. Also recorded in Asia (Afghanistan, India, Iran, Iraq, Israel, Lebanon, Pakistan, Saudi Arabia, Turkey), North Africa (Algeria, Egypt, Libya, Morocco, Tunisia), and the Canary Islands.

Seasonality

Activity varies by region. In Illinois and similar temperate zones: become active in March–April after . laid in alfalfa stems in batches up to 25. Larval feeding occurs over 3–4 weeks with three molts. lasts 1–2 weeks, with new adults emerging in late spring. Adults feed briefly then enter summer , returning to fields in fall. Some occurs in late fall or winter when weather permits. In the southern United States, may be present from early February through March, with activity extending over 6–8 weeks.

Diet

Both and feed on alfalfa foliage. Young larvae feed on leaf and between folded leaflets, creating puncture marks. Older larvae leaves by feeding between , leaving a grayish- appearance from a distance. Adults feed on leaf edges, producing a characteristic feathery appearance. Also recorded feeding on clover (Trifolium spp.) and vetch.

Host Associations

Medicago sativa - primary alfalfa; main economic
Trifolium spp. - secondary clover

Life Cycle

with four stages. laid in batches of up to 25 inside alfalfa stems. through three over 3–4 weeks, feeding on foliage. Mature larvae drop to ground and spin silken in leaf litter. Pupal stage lasts 1–2 weeks. emerge, feed briefly, then may enter summer with dampened metabolic, respiratory, and activity. adults resume activity in spring. Some fall/winter egg-laying occurs in mild conditions.

Behavior

feeding activity for both and . Adults demonstrate summer () in response to hot, dry conditions, seeking shelter in protected vegetation. When disturbed, adults may drop from plants. of the Bathyplectes anurus (associated with this ) can 'jump' several centimeters when disturbed, though this is a parasitoid trait rather than of the itself.

Ecological Role

Major in alfalfa agroecosystems. Larval feeding significantly reduces and forage quality. Serves as for multiple agents including Bathyplectes anurus, B. curculionis, and Microctonus aethiopoides. may be killed by the Zoophthora phytonomi, particularly in warm, humid weather.

Human Relevance

Significant agricultural pest of alfalfa, a major forage for dairy and livestock industries. Yield reductions up to 15% documented. Management relies on including early cutting, with , and when thresholds are exceeded. guide treatment decisions: approximately 0.5–2.0 per stem depending on height and proximity to harvest. has been documented in western United States . Subject of ongoing research for improved .

Similar Taxa

Hypera punctataClover ; nearly twice as large as H. postica, with tan-headed versus black-headed larvae of H. postica; seldom causes significant alfalfa damage

More Details

Biological Control History

Multiple accidental introductions to North America occurred, followed by deliberate introduction of several agents. Bathyplectes anurus is generally considered superior to B. curculionis due to higher . The jumping of B. anurus aids in avoiding .

Insecticide Resistance

in the western United States have developed to certain , prompting ongoing research into resistance and management strategies.