European corn borer
|European corn borer|
| Ostrinia nubilalis |
The European corn worm or European corn borer (Ostrinia nubilalis), also known as the European high-flyer, is a pest of grain, particularly maize. The insect is native to Europe, originally infesting varieties of millet, including broom corn. The European corn borer was first reported in North America in 1917 in Massachusetts, but was probably introduced from Europe several years earlier. Since its initial discovery in the Americas, the insect has spread into Canada and westward across the United States to the Rocky Mountains.
European corn borer caterpillars damage the ears of corn, as well as the stalks, by chewing tunnels, which cause the plants to fall over. Biological control agents of corn borers include the hymenopteran parasitoid Trichogramma spp., the fungus Beauveria bassiana and the protozoa Nosema pyrausta.
Bt corn, a variety of genetically modified maize, has had its genome modified to include a gene from the Bacillus thuringiensis ssp. kurstaki. As a result, the corn variety produces a toxin which affects the corn borer.
Immature maize shoots accumulate a powerful antibiotic substance, DIMBOA that serves as a natural defense against a wide range of pests and is also responsible for the relative resistance of immature maize to the European corn borer.
The corn borer moth is about one inch long with a one-inch wingspan. The female moth is light yellowish-brown with dark, irregular, wavy bands across the wings. The male is slightly smaller and darker in coloration. The tip of its abdomen protrudes beyond its closed wings. The fully-grown larva is three-quarters to one inch in length. This borer is usually flesh-colored, but may range from light gray to faint pink, with conspicuous small, round, brown spots on each segment.
Female corn borer moths lay clusters of eggs on corn leaves, usually on the undersides. The egg masses, or clusters, are laid in an overlapping configuration and are whitish-yellow in color. As the larvae develop inside their eggs, the eggs become more and more transparent and the immature caterpillar black heads are eventually visible. The caterpillars hatch by chewing their way out of the eggs.
- Female, dorsal view
- Female, ventral view
- Male, dorsal view
- Male, ventral view