Common names:Sugarcane borer, Sugarcane stalk borer, Sugarcane moth borer, American sugarcane borer, Small moth borer, Small sugarcane moth borer
Latin name: Diatraea saccharalis (Fabricius)

Life cycle and description

• Adult stage: Adult moths are yellowish or straw colored with several narrow brown lines running along the length of the forewing. Hindwings in females are white but slightly darker in males. Wingspan of females ranges from 25 to 40mm and in males from 18 to 30mm.  Adults are nocturnal and remain hidden in vegetation during the daytime.  The adult stage usually lasts between 3 to 8 days. Females deposit eggs in the evenings for up to 4 days. Females can deposit up to 700 eggs in a lifetime.
• Egg stage: Eggs are deposited in clusters of up to 50 on both the upper and lower surfaces of leaves.  Eggs are oval (1.2mm in length and 0.8mm in width), scale-like, and deposited in an overlapping fashion similar to roof tiles or fish scales. Eggs are white when deposited, turning reddish or black close to the time of hatching. Often the dark larval head capsule can be seen just before hatching. Eggs hatch in 4 to 9 days.
• Larval stage: Larvae tend to hatch simultaneously and migrate to the whorl to feed. The number of larval instar stages is highly variable - there are usually 6 instar stages, although 3 to 10 can occur. Young larvae are white in color with black heads and 1 to 2mm long. Later stage larvae burrow into the stems, ears, and tassels and are creamy in color with prominent dark brown spots bearing stout hairs on each body section. Overwintering larvae lose their brown spots and are predominantly creamy in color. Mature larvae are up to 30mm long. Larval development can take between 25 and 35 days depending on weather conditions. Development is faster in warmer conditions.
• Pupae stage: Pupation occurs wherever larvae of the final instar happen to be feeding, usually in the stem, ear shanks or ears. Larvae will prepare an exit ‘window’ prior to pupation to allow the adult moth to emerge.  Pupae are brown in color and 16 to 20mm long. Pupation generally takes seven to nine days, but can take up to 22 days in cool conditions.
• In warm conditions, the sugarcane stem borer can complete its life cycle in 25 days, although with cool conditions the life cycle can last up to 200 days.
• 4 to 5 generations are possible per growing season depending on prevailing weather conditions.
• Larvae enter a diapause and overwinter in maize stems.

Confirmation

Moth traps can be used to confirm the identity of adult moths during the growing season.  Larvae of sugarcane stem borer are similar to those of southern maize stalk borer and discrimination between the two is achieved by microscopic examination of mouthparts.

Problems with similar symptoms

Several stem borers cause similar symptoms, including the Neotropical maize borer, Spotted stem borer, and Southwestern maize borer.

Why and where it occurs

This pest is most prevalent in areas with a warm growing season and moderate rainfall. Reduced tillage agriculture will encourage overwintering of larvae, resulting in increased incidence of the pest.

Host range

Primarily sugarcane although many species in the family Gramineae are hosts including maize, sorghum, rice and wild grasses.

Geographical distribution

Sugarcane stem borer is associated with Gramineae species of the Americas and occurs from the southeastern United States to the Argentinean corn belt, including the Caribbean.

Damage

• Mechanism of damage: Larval feeding in the whorl can lead to destruction of the growing point (dead heart), leading to stunted growth or plant death. Boring in the stems weakens the plants making them susceptible to lodging.  Stem boring also interferes with translocation of nutrients and water. Boring in the ears leads to kernel damage, ear drop, and favors development of ear rots that produce mycotoxins.
• When damage is important: High pest infestation at early maize growth stages can lead to severe damage of growing points and stunted growth.  Infestation in later growth stages can result in lodging and increased incidence of cob rots.
• Economic importance: Considerable losses can be experienced under heavy infestation which can result in dead heart, lodging and ear rot.

Management principles

Monitoring

• Moth traps (light and pheromone) can be used to determine incidence of adult moths.
• Maize plants should be inspected for the presence of eggs and larvae feeding in the whorl.
• Control measures should be implemented when egg clusters are observed on 25% of plants.

Cultural control

• Management of infested crop residue following harvest will reduce the amount of overwintering larvae.
• In irrigated fields, flooding following harvest can kill overwintering larvae in crop debris.
• Rotation with a non-graminaceous species can reduce pest infestation.

Biological control

• Several natural predators and parasitoids including Trichogramma wasp species help maintain pest populations in various parts of the Americas. However, deliberate introduction of these species as biological control agents has met with limited success.

Chemical control

• Insecticides can be used to provide effective control of sugar cane borer under heavy infestation.  Chemicals should be applied to coincide with egg hatching or when larvae are still exposed in the whorl. Granular application of insecticides in the whorl can limit damage due to sugar cane borers.

Host resistance

• Some maize varieties show good levels of resistance to sugarcane borers and should be cultivated in areas that are prone to high pest infestation.

References

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

Capinera, J.L. 2001. Sugarcane borer.  University of Florida Institute of Food and Agricultural Services. http://creatures.ifas.ufl.edu/field/sugarcane_borer.htm (4 December 2006).

Davidson, R.H. and W.F. Lyon. 1987. Insect Pests of Farm, Garden and Orchard. Hoboken, NJ: John Wiley & Sons.

Flynn, J.L., T.E. Reagan and E.O. Ogunwolu. 1984. Establishment and damage of the sugarcane borer (Lepidoptera: Pyralidae) in corn as influenced by plant development. Journal of Economic Entomology 77: 691-7.

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).

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

Maredia, K.M. and J.A. Mihm. 1991. Sugarcane borer (Lepidoptera: Pyralidae) damage to maize at four plant growth stages. Environmental Entomology 20: 1019-23.

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

Contributors: Gabrielle Turner, David Bergvinson, and Biswanath Das