Insect Pest Of Rice: Rice Stem Borer

Rice stem borer is a very common insect pest in world, specially in India, Pakistan, Bangladesh regions. Yield reduces due to attack of this insect.
There are mainly three stem borer of rice. They are a) Rice yellow stem borer ( Scirpophaga incertulas), b) Dark headed stem borer ( Chilo polychrysus ) and c) Pink headed stem borer (Sesamia inferens ).
All of them are belong to the Lepidoptera order and Pyralidae family.  At larvae stage they attack the stem of rice.

Nature of Damage:
Only the caterpillar stage of these insects are very destructive in rice field. Adult insects do not harm in crop field. Adult insects hatch eggs on the leaf sheaths and a week after hatching larvae become active for it's destructive activities. From the leaf sheaths larvae moves toward the stems and bore the stems. When larvae stay into the pith, they feed on the inner surface of the stem wall ( mainly soft tissue of the pith ). This feed is stared from the base to the apical part of the plants. The central leaf whorl turns into brownish color and dries off rapidly, if larvae attack at the vegetative stage of  rice plants. But the leaves of the plant remain healthy. This symptom is called dead heart symptom. Tillers can not bear panicles and become dry. Sometimes panicles emerge but do not produce grains on the top of it. As the panicles are empty, they become whitish in color and remain in straight. This symptom is very conspicuous in the rice field. This symptom is known as white heads symptom.

whiteheads symptom

A larvae inside the stem

Control Measure:
1) Control by cultural practices
a) We have to remove and destroy all the stubble after harvesting the crops.
b) After ploughing a flood irrigation should be given to kill the larvae.
c) Tips of the seedlings should be clipped if eggs are seen on the leaf of seedlings.
d) Application of excess amount of N fertilizer should be avoided.
e) If we apply slag into the field, it will increase the silica into the plans and this will make plants more resistant against rice stem borer.
2) resistant variety ( BR-3 / Biplob ) should be cultivated.
3) Mechanical control
We may use light trap to capture adult moth in the rice field.
4) Biological control
a) Telenomus, Tetrastichus and Trichogramma are the egg parasitoids of stem borer of rice. So we may import these egg parasitoids into the rice fields.
b) Longhorn grasshopper feeds on egg masses of the stem borer, Coccinellid beetles and carabid beetle feed on the larvae of the stem borer.
c) Spider can attack the adult moth ( rice stem borer ) by trapping them in webs.
d) At day time dragonflies ans birds are the predator of rice stem borer.
5) chemical control
As the larvae remain inside the stem, so systemic insecticide is effective to kill the larvae. Monocrotophos may apply 607ml per acre of land, Diazinon may apply 688 ml per acre, Fenitrothion may apply 454 ml per acre, carbofuran may apply 6.8 kg per acre.

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