Diabrotica undecimpunctata

Mannerheim, 1843

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

Diabrotica undecimpunctata is a to North America and a major agricultural pest. are greenish- with twelve black spots on the . The exhibits broad polyphagy, feeding on over 200 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 (Erwinia tracheiphila) and Pantoea ananatis, contributing to spread in 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.

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 (Acalymma vittatum) by spotted rather than striped elytral pattern. Differs from the banded cucumber beetle (Diabrotica balteata) by having discrete spots rather than broad . Superficially similar to some and 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.

Images

Habitat

Agricultural fields, particularly those containing , corn, beans, and other ; 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

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 across approximately 50 plant . Strong preference for (Cucurbitaceae). feed on leaves, flowers, stems, pollen, and fruit. 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 ; feed on foliage and fruit, on roots
Zea mays - cause primary damage to roots; feed on leaves
Glycine max - feed on foliage
Arachis hypogaea - damage roots and pods; feed on vegetation
Ipomoea batatas - feed on marketable roots causing direct damage
Erwinia tracheiphila - Transmits bacterial in , particularly in eastern U.S.
Pantoea ananatis - Late-Season Decline in corn; acquired and transmitted through feeding wounds and deposition

Life Cycle

. 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; are yellowish and wormlike, feeding on roots. occurs in soil for 6–10 days; measure 6.25 mm by 3.5 mm with abdominal . 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 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 for various including , wolf , birds, mammals, and amphibians; preyed upon by spiders, , , and .

Human Relevance

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

Similar Taxa

Acalymma vittatumStriped cucumber ; distinguished by three black stripes on rather than twelve spots; more specialized on
Diabrotica balteataBanded cucumber ; has greenish with broad black rather than discrete spots; more tropical distribution
Diabrotica virgifera; similar larval damage in corn but lack distinct spotted pattern; more specialized on corn