Diabrotica virgifera zeae

The Mexican corn rootworm is morphologically similar to the western corn rootworm (D. v. virgifera) and is distinguished primarily by geographic distribution and subtle biological differences rather than obvious external features. Adults are small beetles, typically yellowish-green with black markings on the wing covers. Larvae are slender, white to cream-colored with a brown head capsule and three pairs of thoracic legs. The subspecies status is confirmed through examination of male genitalia and geographic origin. In areas where both subspecies occur, identification to subspecies level requires taxonomic expertise.

Corn agroecosystems, specifically fields planted with Zea mays. The species is associated with continuous corn production systems and can persist in areas where crop rotation with non-host crops is practiced less effectively than western corn rootworm. In South Central Texas, has been observed damaging corn following sorghum, indicating potential adaptation to local cropping systems.

Central Mexico; southern United States including Texas, particularly the South Central and Coastal Bend regions. The subspecies occurs in areas where its range overlaps with or replaces that of the western corn rootworm.

Eggs hatch beginning mid-April in South Texas and mid-May in the High Plains, with hatching continuing for several weeks. Adult activity peaks during summer, with egg-laying occurring shortly after corn silking. One generation per year.

Larvae feed exclusively on roots of corn (Zea mays), including root hairs, smaller roots, and primary roots. Adults feed on corn silks, pollen, tassels, and leaves, with a preference for silks during the green silk stage.

• Zea mays - obligate hostOnly known host for larval development; feeding on roots is required for survival. Adults feed on above-ground plant parts but do not complete development on other plant species.

One generation per year. Adults lay eggs in soil within cornfields, typically in the upper 2 to 8 inches. Eggs overwinter and hatch the following spring when soil temperatures rise and corn roots are available. Larvae progress through three instars while feeding on corn roots, then pupate in soil. Adults emerge in summer, feed on corn plant parts, and begin egg-laying shortly after silking. If corn roots are unavailable at egg hatch, larvae die.

Adults tend to remain in the same field where they developed as larvae, contributing to localized population buildup. Adults are active fliers and feed on exposed corn silks, with heavy silk feeding during pollination potentially causing poor ear fill. In South Central Texas, has shown behavior of damaging corn following sorghum rotation, unlike typical western corn rootworm populations.

Agricultural pest; no known significant ecological role in non-agricultural ecosystems. Population dynamics are driven entirely by corn production practices.

Major economic pest of corn production in Mexico and parts of the southern United States. Larval root feeding reduces yield, causes stunting, and can lead to plant lodging ('goosenecking'). Adult silk feeding can interfere with pollination. Management relies on crop rotation, Bt corn hybrids (with variable efficacy), soil-applied insecticides, and seed treatments. Resistance to Bt toxins has been documented in related subspecies, with cross-resistance patterns between Cry3Bb1 and mCry3A toxins. As of early 2016, resistance had not been documented in Mexican or western corn rootworm in Texas, though resistance monitoring is ongoing.

• Diabrotica virgifera virgifera (western corn rootworm)Overlapping distribution and morphological similarity; distinguished by geographic range and that D. v. virgifera is more effectively controlled by crop rotation, while D. v. zeae has shown ability to damage corn following sorghum in some areas.
• Diabrotica barberi (northern corn rootworm)Similar life history and pest status; distinguished by geographic distribution (northern corn rootworm occurs in more northern regions) and that northern corn rootworm has extended diapause variants with eggs hatching after two winters.
• Diabrotica undecimpunctata howardi (southern corn rootworm)Similar larval feeding damage; distinguished by having multiple generations per year, laying eggs after corn seedling stage (making crop rotation ineffective), and being relatively unaffected by Bt corn hybrids targeted at rootworms.

• agricultural pest
• corn rootworm
• Bt resistance
• crop rotation
• integrated pest management
• Chrysomelidae
• Coleoptera
• subspecies
• Mexico
• Texas
• Zea mays
• soil insect
• larval root feeder
• single generation
• overwintering eggs

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• UC Davis Researcher and Colleagues Target 'Billion-Dollar Pest' | Bug Squad
• Pre-emergence insect control - AgriLife Extension Entomology
• Appendix - AgriLife Extension Entomology
• Managing Insect and Mite Pests of Texas Corn - AgriLife Extension Entomology
• For Western Corn Rootworm, Combo of Management Methods Critical to Slow Insecticide Resistance
• Farmer Feedback: Needs Assessment Reveals Growers' Views on Corn Insect Pests in Iowa
• Field Biology of Mexican Corn Rootworm, Diabrotica virgifera zeae (Coleoptera: Chrysomelidae), in Central Mexico