Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Rice white stem borer (411)

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Photo 1. Adult rice white stem borer, Scirpophaga innotata.

Photo 2. Adult rice white stem borer, Scirpophaga innotata.

Photo 3. Damage ('deadheart') to rice stem by Chilo auricilius (damage to Scirpophaga innotata is similar).

Photo 4. 'Whitehead' - a symptom caused by stem borers: the base of the panicle is damaged preventing it from emerging or, if already emerged, the grain is unfilled and white.

Summary

• Restricted. Southeast Asia, Oceania. In Australia, Papua New Guinea.
• Severe on rice and wild rice if attack comes at flowering stage.
• Larvae tunnel between stem and leaf sheaths to the growing point, killing it; stems pull out easily (‘deadhearts’). Panicles fail to emergence, or emerge with white unfilled grain (‘whiteheads’).
• Eggs laid up to 100 near leaf tips, covered in hairs. Larvae white to yellowish when mature, 25 mm long. Pupae white. Adults white, wingspans 18-33 mm (males smaller than females). Nocturnal.
• Note, larvae go through resting period (diapause) for several months if conditions unfavourable. Where crops one a year and long-maturing, diapause means many moths emerge at one time.
• Natural enemies: many egg and larval parasitoids and predators.
• Biosecurity: introduction possible on produce contaminated with infested stems of host plants.
• Cultural control: plough land well (IMPORTANT to bury larvae/pupae of previous crop) and direct seed; cut tips of seedling to remove eggs; plant at higher density than normal; rotate, e.g., legumes; synchronise plantings with neighbours; submerge eggs by raising water occasionally; weed; apply split applications N; harvest at ground level to remove larvae; plough in stubble, unharvested plants and weeds; in irrigated rice-rice-fallow systems use medium (135-140 day) varieties so diapause is incomplete when time to replant.
• Chemical control: unlikely to be needed. Use abamectin. Avoid broad-spectrum insecticides to preserve natural enemies.

Common Name

Rice white stem borer

Scientific Name

Scirpophaga innotata. A moth in the Crambidae.

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