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Identification, symptoms and nature of damage of Stem Borer and Gall Midge

Identification, symptoms and nature of damage of Stem Borer and Gall Midge. End. Previous. Next. Introduction. Rice is the staple food crop of humid and sub-humid Asia, cultivated in 112 countries covering every continent and is consumed by 2500 million people in the developing countries.

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Identification, symptoms and nature of damage of Stem Borer and Gall Midge

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  1. Identification, symptoms and nature of damage of Stem Borer and Gall Midge End Previous Next

  2. Introduction Rice is the staple food crop of humid and sub-humid Asia, cultivated in 112 countries covering every continent and is consumed by 2500 million people in the developing countries. In India, rice is grown on about an area of 44.3 million hectares with a production of 89.09 million tonnes. However, rice productivity in India is inferior to neighbouring countries. Healthy crop of rice End Previous Next

  3. The introduction of fertilizer responsive high yielding varieties of rice following green revolution, has increased the problems of pests and diseases manifold and the continuous use of pesticides led to the outbreak of secondary pests. • Yield loss due to insect pests in rice has been estimated to be around 25%. • Crop productivity can be enhanced by effective management of insect pests. Stem borer damaged crop End Previous Next

  4. 1. Yellow stem borer (Scirpophaga incertulas) Identification • The stem borers are regular pests of rice causing damage during both vegetative and reproductive crop stages. Among five stem borer species distributed in India, yellow stem borer, Scirpophaga incertulas is the dominant and widely distributed. Courtesy: www. knowledgebank.irri.org End Previous Next

  5. Female moth has yellowish forewings with a single dark spot at their centre while the male has numerous small brown spots. • A female lays eggs in batches of 50-80 at leaf tips and eggs are covered with yellow brown hair of female tuft. Therefore, removal of seedling tips before transplanting helps in reducing stem borer incidence in field. Yellow stem borer female Courtesy: www. knowledgebank.irri.org End Previous Next

  6. The fully grown larva is pale yellow in colour with orange yellow head. It passes winter in rice stubbles and destruction of rice stubbles also thus helps in reducing incidence of this pest. • Stem borer completes its life cycle in 40-45 days. Stem borer larva Stem borer pupa Courtesy: www. knowledgebank.irri.org Life cycle of yellow stem borer Courtesy: www. knowledgebank.irri.org End Previous Next

  7. Nature of Damage • Only larva causes damage to the crop. After hatching, larva bores in to stem and damages it • Damage during vegetative stage results in drying of central shoot, damage symptom called “dead heart”. • Damage after flowering results in white empty straight panicles known as “white-ears”. Stem borer damage (white-ears) • As dead-hearts and white-ears harbor larvae, their collection and disposal helps in reducing incidence of this pest. End Previous Next

  8. Economic threshold level (ETL): 5% dead hearts, 2% white ears or 1 egg mass/m2 or 1 moth/m2 Female sex pheromone (Scirpolure) traps are used for monitoring and mass trapping of this pest. Likewise light traps can also be utilized for monitoring purpose. Pheromone traps Light trap End Previous Next

  9. Gall Midge, Orseolia oryzae Identification The adult fly is a small mosquito like insect with long legs. The female has bright yellow abdomen whereas the male is dark in colour. The female lays reddish elongated eggs on leaf blade or sheath. Life cycle of rice gall midge Courtesy: www. knowledgebank.irri.org Gall midge adult Courtesy: www.cbit.uq.edu.au End Previous Next

  10. Damage This insect infests the crop from seedling stage in nursery to maximum tillering stage. It does not occur in north India but causes serious damage in eastern, southern and central India. Maggots (larvae) after hatching enter the leaf sheath and convert it in to galls (tubular structures) resembling shining onion leaf. These symptoms are thus called “silver shoot”. Early incidence of this pest results in to profuse tillering and stunting. Removal of silver shoots helps in reducing damage of this pest. Economic threshold level (ETL) 1 gall/m2 or 5% infested tillers Rice gall midge damage (silver shoot) www.africarice.org End Previous Next

  11. Let us sum up • Stem borer is regular pest of rice causing damage during both vegetative and reproductive crop stages. • Only larva of stem borer causes damage to the crop. Damage during vegetative stage results in drying of central shoot called “dead heart”. Damage after flowering results in white empty straight panicles known as “white-ears”. • Female sex pheromone (Scirpolure) traps are used for monitoring and mass trapping of this pest. • Gall midge adult is small mosquito like insect with long legs. This pest does not occur in north India. • Gall midge infests the crop from seedling stage in nursery to maximum tillering stage. • Maggots (larvae) after hatching enter the leaf sheath and convert it in to galls (tubular structures) resembling shining onion leaf. These symptoms are thus called “silver shoot”. Previous

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