Ostrinia nubilalis (Hübner)
Taxonomic placing: Insecta, Holometabola, Lepidoptera, Pyralidae.
Common name: European corn borer.
Geographical distribution: North America, North Africa, Europe, Asia.
Morphology: The female is pale yellow to light brown, with dark, wavy bands across the dark-yellow forewings, length about 12-15 mm. The larva is 15-25 mm long, usually flesh-colored to light brown, with small brown spots on each segment.
Host plants: Corn (maize), potato, sorghum, pepper, beans and about 200 other plants.
Life cycle: The adults are active at night, remaining on the plants during day. On corn females deposit in clusters of about 20 eggs on the lower sides of leaves, each female producing about 600 eggs. Fecundity is increased by multiple mating. Initially the young larvae feed on the upper part of maize plants, their damage evident by leaf whorling; later they tunnel into the stem internodes, excavate many galleries and consume corn ears and stalks. They pupate in the stalks. The average adult lifespan is 10-15 days and annyally the pest raises 4-5 partially overlapping nerations. The larvae are resistant to cold and undergo a winter diapause in the crop debris. In various parts of the world the pest occurs in several sympatric pheromone and/or host-plant races.
Economic importance: This insect is a major pest of corn in many parts of the world, and annually its economic losses can amount to many hundred million dollars. The feeding of the larvae results in the breakage of the tassel, causing the the entire plants to fall over, damage sometimes reaching 100%. Heavy injury may occur in corn grown for seed, silage and grain, as well as in sweetcorn. Potatoes can also be heavily damaged.
Monitoring. Early scouting is conducted by searching for whorl damage, and later for egg masses. The moth may be monitored by sampling adults with a sweep net, black light traps and by sex pheromone traps. Various models, intended to predict pest emergence from diapause, and based on regional temperature data, were developed in different regions of the world.
Horticultural methods: Ploughing at the end of the maize-growing season, in order to kill the diapausing larvae, is compulsory in some countries.
Plant resistance: Some degree of resistance to the corn borer is now common in commercial maize hybrids. Many of these contain DIMBOA, present in immature maize plants, adversely affects O. nubilalis. In addition, transgenic hybrids expressing toxins from Bacillus thuringiensis (Bt) have been incorporated into commercial varieties and protect the plants. However, the pest is developing resistance to the toxin.
Chemical control. Due to environmental and health concerns chemical control is not usually considered against the corn borer. Formulations of B. thuringiensis provide good control, particularly if aimed at the pest’s first-stage larvae. However, the control efficacy of several formulations is unequal and larvae feeding within the stalks are hard to kill.
Biological control: Many arthropods, predators and parasitoids, as well as diseases contribute to suppressing the pest populations. These include the hymenopterous egg parasitoids Trichogramma spp., the entomopathogenic fungus Beauveria bassiana and protozoa. Applications of entomopathogenic nematodes reduced corn borer damage from 20% to 5% in Israel. The integration of microbial control with augmentative releases of egg parasitoids is nowadays being carried out successfully. Several biofactories produce and sell these egg parasitoids by rearing them on unnatural hosts.
Ben-Yakir, D., Efron, D., Chen, M and Glazer, I. 1998. Evaluation of entomopathogenic nematodes for biocontrol of the European corn borer, Ostrinia nubilalis, on sweet corn in Israel. Phytoparasitica 26: 101-108.
Coates, B.C., Johnson, H., Kim, K.-S., Hellmich, R. L., Mason, C.. and Sappington, T.W. 2013. Frequency of hybridization between Ostrinia nubilalis E-and Z-pheromone races in regions of sympatry within the United States. Ecology and Evolution 3: 2459–2470.
EPPO, 2013. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Laurent P. and Frérot B. 2007. Monitoring of European corn borer with pheromone-baited traps: review of trapping system basics and remaining problems. Journal of Economic Entomology 100: 1797-807.
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Özpinar, A., Uzun, S. and Hassan, S.A. 1999. A research on selection of the most effective species or strains of 7 Trichogramma for biological control against Ostrinia nubilalis Hübner. Turkish Journal of Agriculture and Forestry 23: 83-86.
Siqueira, H.A., Moellenbeck, D., Spencer, T. and Siegfried, B.D. 2004. Cross-resistance of Cry1Ab-selected Ostrinia nubilalis (Lepidoptera: Crambidae) to Bacillus thuringiensis delta-endotoxins. Journal of Economic Entomology 97: 1049-1057.
Yan, T., Bethenod, M.-T., Pelozuelo, L., Frerot, B, and Bourguet, D. 2003. Genetic isolation between two sympatric host-plant races of the European corn borer, Ostrinia nubilalis Hubner. 1. Sex pheromone, moth emergence timing, and parasitism. Evolution 57: 261–273.
Web site https://www.google.co.il/search?q=Ostrinia+nubilalis+image&biw=1280&bih=687&tbm=isch&tbo=u&source=univ&sa=X&ved=0CB8QsARqFQoTCLmY7_ur3cgCFYG0Ggod620B1Q