Also known as Asian maize borer
Ostrinia furnacali synonym Pyrausta salentialis

Life cycle and description

• Adult stage: Adults are brownish or straw-colored with a wingspan of approximately 30mm. Males are slightly darker than females and have a tapering abdomen. Females deposit eggs in clusters of various sizes on the upper side of leaves or on the husk. In a lifetime a female can deposit up to 1500 eggs. Adults can live for up to 11 days and are prolific fliers, frequently covering up to 1.5km in a lifetime.
• Egg stage: Eggs are light yellow or cream in color, turning black as the time for hatching approaches. Eggs are scale-like and deposited in overlapping clusters (similar to roof tiles or fish scales) in variable sizes. Eggs are deposited on the upper leaf or husks and hatch in 3 to 5 days.
• Larval stage: There are generally 6 larval instars. Young larvae are pink or a yellowish-gray in color. Mature larvae are white with wart-like black spots on each body segment. Mature larvae are up to 50mm long. Larval stages usually last between 17 and 30 days. At the end of the season the final instar will diapause in stem residue or cobs.
• Pupae stage: Pupae are located wherever the last feeding occurred.  They can be found in tunnels in the stem, in the ears, or between the sheath and shank.  Pupation usually lasts for 6 to 9 days.
• In favorable conditions this species has a 30-day lifecycle. Several generations can occur during the growing season, but usually range from 1 to 3.
• In the tropics there can be continuous overlapping generations, provided a suitable host is cultivated continuously.

Confirmation

Identity can be confirmed by inspection of adult moths, larvae, symptoms, and geographic location.  This species is closely related to the European maize borer (O. nubilalis) and hence close inspection of adults reared from larvae or from moth traps may be required.

Problems with similar symptoms

Several maize borers including European maize borer and the Spotted sorghum stem borer cause similar damage to maize.

Why and where it occurs

The pest is a major problem where there is continuous cultivation of hosts throughout the year. Tropical regions of Asia are particularly vulnerable. In more temperate regions, Oriental corn borer is a problem particularly under reduced tillage as larvae are able to over winter in crop stems and debris.

Host range

Maize, sorghum, sugarcane, ginger, millets, Indian hemp, wild grasses, bell peppers, cereals and wormwood (Artemesia).

Geographical distribution

Oriental maize borer is widely distributed in Asia and is a major problem in China, the Philippines, Indonesia, Taiwan, Malaysia, Thailand, Sri Lanka, India, Bangladesh, Japan, Korea, Vietnam, Laos, Burma and Cambodia. The oriental maize borer is very closely related to the European corn borer (O. nubilalis) and both species overlap in their geographic distribution in Central Asia.

Damage

• Mechanism of damage: Boring into the stems and tassel can lead to lodging and broken tassels.  Boring in stems can interfere with the translocation of nutrients and water, resulting in yield loss. Larvae can also bore into ears, causing kernel damage and ear drop.
• When damage is important: Excessive boring in the stem can result in major yield loss due to interference with nutrient and water translocation.  Boring in the ears can also lead to the development of cob rots, which produce mycotoxins.
• Economic importance: Yield losses ranging from 20 to 80% have been reported due to the Asian corn borer.

Management principles

Monitoring

• Moth traps (light and pheromone) can be used to estimate incidence of the pest.
• Leaves should be regularly monitored for presence of egg masses and feeding larvae.
• Control of this species should be implemented if more than 3 egg masses are observed per 100 plants.
• Control measures should be implemented when 3 to 4 egg masses are observed per 100 plants.

Cultural control

• Management of maize stems and crop residue following harvest can reduce the number of larvae that overwinter.
• In temperate regions where cultivation of only one host crop is possible during the season, early planting can reduce yield loss by avoiding periods when pest infestation is high.

Biological control

• Various natural enemies including various predators, parasitoids and pathogens play an important role in controlling populations of Asian maize borers.  In particular, wasps of the Trichogramma species have been introduced to successfully control Asian maize borer infestation. Trichogramma species are egg parasitoids and have a life cycle of 7 to 8 days. Parasitized eggs appear pale, dark and depressed.
• Earwigs (Euborellia annulata), flower bug (Orius tantillus), and Xanthopimpla stemmator are also important parasitoids of Asian maize borers.
• Use of Bacillus thuringiensis (Bt) products can suppress pest infestations. For successful treatment Bt should be applied in the whorl when larvae are at the first instars.

Chemical control

• Chemicals can be used to effectively control severe pest infestations. However, chemical application should be applied to coincide with egg hatch or when the first instar larvae are still exposed. If biological control agents are being used, chemical control may not be compatible.
• Insecticide-treated seed should also be used to protect against stem borer damage.

Host resistance

• Maize varieties with varying levels of resistance to Asian stem borers are available in various regions and offer the most cost-effective means of pest management in areas where Asian stem borers are endemic.

References

CAB International. 2002. Crop Protection Compendium. Wallingford, UK: CAB International.

CSIRO. 2004. Asian Corn Borer. CSIRO and the Australia Government Department of Agriculture, Fisheries and Forestry. http://www.ento.csiro.au/aicn//name_c/a_115.htm (29 November 2006).

Granados, G. 2000. Maize Insects. In R.L. Paliwal, G. Granados, R. Lafitte, A.D. Violic and J.P. Marathee (eds.), Tropical Maize Improvement and Production. FAO Plant Production and Protection Series 28. Rome: Food and Agriculture Organization (FAO).

He, K., Z. Wang, D. Zhou, L. Wen, Y. Song and Z. Yao. 2003. Evaluation of Transgenic Bt Corn for Resistance to the Asian Corn Borer (Lepidoptera: Pyralidae). Journal of Economic Entomology 96: 935-40.

King, A.B. and J.L. Saunders. 1984. The Invertebrate Pests of Annual Food Crops in Central America. London: Overseas Development Admin.

Nafus, D.M. and I.H. Schreiner. 1991. Review of biology and control of the Asian corn borer, Ostrinia furnacalis. Tropical pest management 37: 41-56.

Ortega, A. 1987. Insect pests of Maize: A Guide for Field Identification. Mexico, D.F.: CIMMYT.

Panwar, V.P. 1995. Agricultural Insect Pests of Crops and Their Control. New Delhi, India: Kalyani Publishers.

Umali, M.M. 2005. Management of the Asian Corn Borer. Seedquest News Release 11,444. http://www.seedquest.com/News/releases/2005/february/11444.htm (29 November 2006).

Wakman, W., N. Nonci, M. Yasin, M.S. Pabbage and Surtikanti.  2002. Biological control of Asian corn borer using Trichogramma evanescens and Beauveria bassiana.  Proceedings of the 8th Asian Regional Maize Workshop. Bangkok, Thailand. 5-8 August 2002.  Pp. 413-26.

Contributors: Gabrielle Turner, David Bergvinson, and Biswanath Das