The major insect pests of rice, their nature of damage and appropriate control measures are given below:
1. Yellow Stem Borer (Trypoeyza Incertulas):
In the northern regions, the yellow stem borer is active from April-October, while in southern states, it multiplies throughout the year.
Nature of Damage:
Caterpillar bore into central shoot of paddy seedling and tiller producing “dead heart” in young plants. After panicle initiation the damage by caterpillar’s results in chaffy panicles called “white ears”. The ETL for the pest is 5 % dead hearts during vegetative stage and 2% white ears during flowering.
Control:
Grow resistant varieties like Ratna, Jaya, MTU 5849, etc. Avoid close planting and continuous water stagnation. Pull out and destroy the affected tillers. Set up light traps to attract and kill the moths. Harvest the crop up to the ground level and disturb the stubbles.
Release the egg parasitoid, Trichogramma japonicum on twice @ 5 cc/ha followed by monocrotophos 36 SL spray thrice @ 1000 ml/ha on 58, 65 and 72 DAT. Apply Bacillus thuringiensis var kurstaki and neem seed kernel extract. Spray Monocrotophos 36 SL 1000 ml/ha or Endosulfan 35 EC 1000 ml/ha or Quinalphos 25 EC1000 ml/ha.
2. Gall Midge (Orseolia Oryzae):
Infestation of gall midge occurs in southern and eastern India. Adult is small mosquito like fly with long legs.
Nature of Damage:
Infestation of gall midge starts in nursery and continues till maximum tillering stage of the crop. Maggot feeds at the base of the growing shoot causing formation of a tube like gall that is similar to “onion leaf” or “Silver-shoot”. Infested tillers do not produce any panicles. Infestation in early stages of crop induces profuse tillering and results in stunted plants. The economic threshold level (ETL) for gall midge is 5% silver shoots.
Control:
Early planting in July, use resistant varieties such as IR 36, Phalguna, Shakthi, Vikram and Surekha. Harvest the crop and plough immediately. Remove the alternate hosts and adjust the time of planting (early). Use early maturing varieties. Optimum recommended doses of potash fertilizer. Setup light trap and monitor the adult flies.
3. Swarming Caterpillar (Spodoptera Mauritia):
Nature of Damage:
Larvae cut the seedlings in large scale. Severe infestation results cattle grazing appearance in the field. They feed gregariously and march from field to field.
Control:
Kerosenate the water while irrigation for suffocation. Allow ducks into the field. Drain the water from nursery. Spray chlorpyriphos 20 EC 80ml or endosulfan 35 EC 80ml + 20 lit of water for 8 cents.
4. Leaf Folder (Cnaphalocrocis Mainsails):
Nature of Damage:
Leaves fold longitudinally and larvae remains inside. Larvae scrapes the green tissues of the leaves and becomes white and dry. During severe infestation the whole field exhibits scorched appearance. The ETL for the pest is 4% folded leaves.
Control:
Adopt resistant varieties like Cauveri, Akash, TKM 6, etc. Clipping of the affected leaves. Keep the bunds clean. Avoid excessive nitrogenous fertilizers. Set up light traps to attract and kill moths. Release Trichogramma chilonis @ 1,25,000/ha thrice. Spray carbaryl 50 WP 1 kg or chlorpyriphos 20 EC 1250 ml/ha.
5. Yellow Hairy Caterpillar (Psalis Pennatula):
Nature of Damage:
Caterpillar causes defoliation.
Control:
Spray endosulfan 35 EC 1000 ml/ha or monocrotophos 36 WSC 500 ml/ha.
6. Short Horned Grasshopper (Oxya Nitidula):
Nature of Damage:
Irregular feeding on seedlings and leaf blade. Cutting of stem at panicle stage. Completely defoliate the plants leaving only the mid ribs.
Control:
Expose the eggs to be picked up by birds after ploughing and trim the bunds. Dusting the crop with methyl parathion 2% @ 25-30 kg/ha or malathion 5% @ 20 kg/ha.
7. Rice Hispa (Dicladispa Armigera):
Nature of Damage:
The pest is active from May-October. Adults and grubs feed on chlorophyll by scraping and causing white parallel streaks and white patches along with long axis of leaf. Grubs mine into the leaves and make blister near leaf tips. The ETL for this pest is 2 adults or 2 damaged leaves per hill.
Control:
Leaf tip containing blotch mines should be destroyed. Manual collection and killing of beetles using hand nets. Spray endosulfan 35 EC @1000ml/ha.
8. Green Leafhopper (Nephotettix Virescens):
Nature of Damage:
Both nymphs, and adults suck sap from leaves. Affected leaves turn yellow/brown from the tip downwards. It also transmits tungro virus disease. The disease is characterized by slight stunting and reduced tillering. Young leaves are often mottled with pale-green to shitish stripes. Infected plants bear a few light spikelets. The ETL for this insect is 2 hoppers per hill in tungro endemic areas and 10 hoppers per hill in other regions.
Control:
Use resistant varieties like IR 20, CR 1009, IET 301, IET 303 etc. Apply neem cake @ 12.5 kg/20 cent nursery as basal dose .The vegetation on the bunds should also be sprayed with the insecticides. Set up light traps. Spray the crop with phosphamidon 85 SL (Dimecron)@ 1000 ml/ha or carbaryl (sevin) 50 WP @1000 ml/ha twice, 15 and 30 days after transplanting.
9. Brown Plant Leafhopper-BPH (Nilaparvata Lugens):
BPH has become a severe pest of high yielding rice in almost all the rice growing areas of the country. Large scale infestation of this pests occurred during mild winter followed by a hot summer with little rain during May-June. The nymph and adults of BPH are brown in colour and the adults get attracted to light during night. The ETL for BPH is 5-10 hoppers per hill.
Nature of Damage:
Nymphs and adults congregate at the base of the plant above the water level. Affected plant dries up and gives a scorched appearance called “hopper burn”. Circular patches of drying and lodging of matured plant. It is vector of grassy stunt, ragged stunt and wilted stunt diseases.
Control:
Use resistant/tolerant varieties like Aruna, ADT 36, IR 36, IR 72, etc. Clean cultivation. Make allies of 25-30 cm at 2-3 m interval. Avoid close planting. Avoid use of excessive nitrogenous fertilizers and folio split applications .Control irrigation by intermittent draining. Set up light traps during night. Yellow pan traps during day time. Conserve natural enemies like Lycosa pseudoannulata, Cyrtorhinus lividipennis.
Avoid synthetic pyrethroids, methyl parathion, fenthion and quinalphos causing resurgence. Drain the water before the use of insecticides. Apply Phosphamidon 40 SL@ 1000 ml/ha, or Monocrotophos 36 SL @ 1250 ml/ha or Carbofuran 3 G @ 17.5 kg/ha or Dichlorvos 76 WSC @ 350 ml/ ha or Neem oil 3% @ 15 lit/ha.
10. White Backed Plant Hopper (Sogatella Furcifera):
Nature of Damage:
Suck the sap and cause stunted growth. “Hopper burn” is caused in irregular patches. The ETL for the pest is 5-10 hoppers per hill.
Control:
Avoid use of excessive N fertilizers. Control irrigation by intermittent draining. Apply Phosphamidon 40 SL@ 1000 ml/ha or Monocrotophos 36 SL @ 1250 ml/ ha or Carbofuran 3 G @ 17.5 kg/ha or Dichlorvos 76 WSC @ 350 ml/ ha or Neem oil 3% @ 15 lit/ha.
11. Mealybug (Brevennia Rehi):
Nature of Damage:
Large number of insects remains in leaf sheath and suck the sap. Plants become week, yellowish and very much stunted in circular patches. Presence of white waxy fluff in leaf sheaths
Control:
During field preparation – remove the grasses from the bunds and trim the bunds. Remove and destroy the affected plants. Spray dimethoate 30 EC 500 ml/ha or methyl demeton 25 EC@ 500 ml/ha in the initial stage of infestation. Conserve the natural enemies like Scymnus sp., Anatrichus pygmaeus, and Mepachymerus ensifer.
12. Rice Earhead Bug (Leptocorisa Acuta):
Nature of Damage:
Sucking the sap from individual grains, which are in milky stage. Individual grains become chaffy. Black spots on the grains at the site of feeding puncture. Buggy odour in rice field during milky stage.
Control:
Dust Quinalphos 1.5 D or Carbaryl 10 D or Malathion 5 D at 25 kg/ha twice, the first during flowering and second a week later. Spray Fenthion 100 EC @ 500 ml/ha or Malathion 50 EC @ 500 ml/ha or Neem seed kernel extract 5% @ 25 kg/ha twice as above.
13. Thrips (Stenchaetothrips Biformis):
Nature of Damage:
Laceration of the tender leaves and sucks the plant sap. Yellow or silvery streaks on the leaves of young seedlings. Terminal rolling and drying of leaves from tip to base. It causes damage both in nursery and in main field.
Control:
Spray Phosphamidon 40 SL 50 ml or Monocrotophos 36 SL 40 ml or Endosulfan 35 EC 80 ml in nursery stage and in main field.
To apply the pesticide and insecticide effectively, hand compression sprayer or low volume sprayer (LV) should be used. Low volume sprayer required only 12 litres of water to spray one hectare of land.