Diabrotica virginifera (the western corn rootworm), along with its closely related sister taxon Diabrotica barberi (the northern corn rootworm), are chrysomelid beetles that together have been labeled the most destructive pests of dent corn (as opposed to table corn, dent corn is used for grain and animal feed rather than as a vegetable) in the corn producing states of North America and Canada. The cost of damage and control of these pests is estimated at upwards of one billion dollars annually. While D. barberi occurs mainly in the north central United States, D. virginifera is found more broadly, including most of the US, central America, and since several introductions in the 1990s is now widespread in central Europe, threatening all maize-growing areas of Europe and Asia.
The larvae of the western and northern corn rootworms tunnel through root systems and the base of their primary host, corn (Zea mays) plants, as well as other grass and grain species. Adults will eat almost every other part of the corn plant, but are especially troublesome in eating the silks because in so doing they challenge fertilization and productivity of the corn. Other beetles in this genus also are threats to other crops, especially the cucumber family (Cucurbitaceae).
Control is a major problem. Pheromone traps are widely used to monitor populations, especially in Europe with the aim to contain the beetle’s spread. Soil insecticides are applied at planting, and sprays are used to control adult beetles. Crop rotation, nematodes, host plant resistance (using genetic modified plants, such as Bt-corn), biological control, pheromone-laced insecticide baits are other wide-spread approaches. Although spread of these beetle pests is slow, occurring mainly by flight of the adult beetle, the spread of D. virginifera throughout North America demonstrates its potential and is of great concern in Europe.
(CABI 2011; EPPO 2011; Wikipedia 2011)
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