rootworm

Rootworm is the common name for the larval stages of several beetles in the leaf beetle family that feed on the roots of crops, most notably corn. The term is most often applied to the corn rootworms, of which the western, northern, and southern forms are the primary agricultural pests. Adults are typically striped beetles that feed on corn silks and foliage, while larvae tunnel through and feed on the root system.

The western corn rootworm (Diabrotica virgifera virgifera) is native to North America and has become invasive in Europe and parts of Asia. The northern corn rootworm (Diabrotica barberi) and southern corn rootworm (Diabrotica undecimpunctata howardi) are mainly found in North America. These species differ somewhat in life cycle timing and host preferences but share a reliance on corn roots for larval development.

Biology and life cycle: Eggs overwinter in soil and hatch in warm spring conditions. First-instar larvae feed on root tips, then move into deeper roots and eventually pupate in the soil. Adults emerge in summer and may feed on foliage and reproductive structures before laying eggs to begin a new generation. Most populations produce one generation per year, though warmer areas can support additional rounds.

Damage and impact: Larval feeding on developing roots reduces plant stability, water and nutrient uptake, and overall vigor, which can increase lodging and reduce yield. Adult feeding on silks or leaves may also affect kernel set. Economic losses are most pronounced in corn production systems with high rootworm pressure.

Management: Integrated pest management combines crop rotation away from corn, use of soil-applied or seed treatments, and deployment of resistant Bt corn varieties. Insecticide applications are used selectively, and ongoing monitoring helps guide timely interventions. Refuge strategies and stacked traits help delay resistance development.