Diabrotica undecimpunctata

Mannerheim, 1843

spotted cucumber beetle, southern corn rootworm, western cucumber beetle, western spotted cucumber beetle

Species Guides

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Diabrotica undecimpunctata is a leaf beetle native to North America and a major agricultural pest. are greenish-yellow with twelve black spots on the . The exhibits broad polyphagy, feeding on over 200 plant species across approximately 50 . Three are recognized, with D. u. howardi (eastern) and D. u. undecimpunctata (western) being the most significant agriculturally. The species bacterial wilt (Erwinia tracheiphila) and Pantoea ananatis, contributing to spread in cucurbits and corn.

Diabrotica undecimpunctata by (c) Catherine C. Galley, some rights reserved (CC BY), uploaded by Catherine C. Galley. Used under a CC-BY license.Diabrotica undecimpunctata by (c) Katja Schulz, some rights reserved (CC BY). Used under a CC-BY license.Diabrotica undecimpunctata by (c) Catherine C. Galley, some rights reserved (CC BY), uploaded by Catherine C. Galley. Used under a CC-BY license.

Pronunciation

How to pronounce Diabrotica undecimpunctata: /di.aˈbɾɔ.ti.ka ʊn.dɛˌkɪm.pʌŋkˈta.ta/

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

Identification

Distinguished from the striped cucumber beetle (Acalymma vittatum) by spotted rather than striped elytral pattern. Differs from the banded cucumber beetle (Diabrotica balteata) by having discrete spots rather than broad bands. Superficially similar to some Meloidae and Cantharidae but has twelve distinct spots and more compact body shape. identification requires geographic location: D. u. howardi occurs east of the Rocky Mountains, D. u. undecimpunctata west of the Great Basin.

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Habitat

Agricultural fields, particularly those containing cucurbits, corn, beans, and other crops; also found in non-crop including sites in protected areas. overwinter in mild climates in field margins, woodlots, and other sheltered locations. Moist soil preferred for deposition.

Distribution

Native to North America. Found throughout southern Canada (British Columbia to Quebec), the continental United States, and the central highlands of Mexico. D. u. howardi ranges east of the Rocky Mountains to southern Nevada, southeastern California, and Alberta. D. u. undecimpunctata occurs west of the Great Basin in California, Oregon, Washington, Idaho, and Baja California Norte. Also present in Central America (Guatemala, El Salvador, Nicaragua) and Bermuda.

Seasonality

active from spring through fall. Overwinter as adults in mild climates. Number of per year ranges from one in northern areas to three in warmer regions. peaks in late summer. Adults disperse northward seasonally from sites.

Diet

feeder consuming over 200 plant across approximately 50 plant . Strong preference for cucurbits (Cucurbitaceae). feed on leaves, flowers, stems, pollen, and fruit. Larvae feed on roots, stem bases, and sometimes fruit rinds in contact with soil. Documented include corn, soybeans, cotton, beans, peanuts, sweet potato, squash, cucumbers, melons, apples, cherries, clover, lettuce, and potatoes.

Host Associations

  • Cucurbitaceae - Primary Strong preference for cucurbits; feed on foliage and fruit, larvae on roots
  • Zea mays - Larvae cause primary damage to roots; feed on leaves
  • Glycine max - feed on foliage
  • Arachis hypogaea - Larvae damage roots and pods; feed on vegetation
  • Ipomoea batatas - Larvae feed on marketable roots causing direct damage
  • Erwinia tracheiphila - Transmits bacterial wilt in cucurbits, particularly in eastern U.S.
  • Pantoea ananatis - Late-Season Decline in corn; acquired and transmitted through feeding wounds and deposition

Life Cycle

Complete . Females lay 150–400 in soil near plants (up to 1,200 recorded). Eggs hatch in 6–9 days under favorable conditions, or up to 30 days in cooler temperatures. Larval stage lasts 2–3 weeks; larvae are yellowish and wormlike, feeding on roots. occurs in soil for 6–10 days; pupae measure 6.25 mm by 3.5 mm with robust terminal abdominal spines. follows. Adult lifespan approximately 60 days in summer, up to 200 days in winter.

Behavior

are strong fliers and disperse readily between fields during the growing season. Thermoregulatory observed: adults bask in direct sunlight to elevate body temperature above ambient when air temperature falls below 13°C, enabling continued activity, , feeding, and mating at otherwise suboptimal temperatures. Males engage in 'antennal stroking' during courtship, using to stroke female's antennae, , and legs. Females may mate with up to 15 males before accepting a reproductive partner.

Ecological Role

Agricultural pest causing economic damage through direct feeding and transmission. Larval root feeding destroys growing points in seedlings and reduces yield in mature plants. feeding damages reproductive structures and foliage. As a disease , facilitates spread of bacterial in agroecosystems. Serves as prey for various including carabid beetles, wolf spiders, birds, mammals, and amphibians; preyed upon by spiders, ground beetles, ants, and crickets.

Human Relevance

Major agricultural pest in North America. Economic damage to cucurbits, corn, beans, peanuts, and sweet potato. of bacterial wilt (Erwinia tracheiphila), which can destroy entire cucurbit crops. Management relies heavily on chemical control, though concerns about neurotoxicity and nontarget effects have reduced available . Cross-attraction to vittatalactone ( of striped cucumber beetle) offers potential for monitoring and attract-and-kill strategies. through conservation shows promise but is understudied.

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