Pacific Pests, Pathogens and Weeds

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Summary

• Restricted. South and Southeast Asia, North America (Hawaii), Oceania. In Guam, Papua New Guinea, Solomon Islands.
• Minor pest of rice, attacks usually late and only if maize or sugarcane nearby. Also pest of millet, wheat, many grasses, some sedges.
• Larvae tunnel through internodes of stem to the growing point, killing it; stems pull out easily (‘deadhearts’). Panicles fail to emerge, or emerge with unfilled grain (‘whiteheads’).
• Eggs (up to 100) between leaf sheaths and stem, in rows. Mature larvae deep pink with orange-red heads, 25-30 mm long. Adults have brown hairs over the head and thorax, light-brown forewings, whitish hindwings, 28-35 mm wingspans. Strong flyer. Nocturnal.
• Natural enemies: many egg and larval parasitoids and predators.
• Biosecurity: introduction possible on produce contaminated with infested stems of host plants.
• Cultural control: handpick in nursery; plough land well (burying larvae/pupae of previous crop); 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; use resistant (short, high tillering, early maturing) varieties.
• Chemical control: unlikely to be needed. Use abamectin. Avoid broad-spectrum insecticides to preserve natural enemies.