Integrated Pest Management of insect pests of rice

K Mamocha Singh / M Premjit Singh *

Rice Field at the foot of the Cheirao Ching in October 2008 :: Pix - Marc

In Manipur, one of the major constrains of successful cultivation of rice is the insect pest problems. For successful management of rice pests the following strategies may be followed:

Yellow stem borer (YSB), stripe borer (SB), gall midge (GM), brown plan hopper (BPH), white back plant hopper (WBPH), green leaf hopper (GLH), leaf folders (LFs), Case worm, rice hispa, thrips, termite, gundhi bug, etc. are common insect pest in the rice ecosystem of the state. In any IPM programme, suitable resistant or moderately resistant variety may be selected for cultivation.

The seeds should be pure and free from any insects and diseases. Timely sowing and transplanting should be carried out. Nursery should be healthy and free from weeds. If stem borers and GM infestation reach economic threshold level (ETL), apply carbofuran granules @ 0.333 kg of carbofuran 3G/ 100sq. m area or spray monocrotophos 0.05%. Seedling root dip/ nursery treatment in stem borer and gall midge endemic areas can be carried out to prevent from the pest infestation in the early crop stage in the transplanted field. For seedling root dip, a smooth area of 10X1 m can be bunded on all sides.

A polythene sheet of 10.5X1.5 m should be spread over the area and extended along the bunds. Let in water to a depth of 2 cm and add 200 ml of chloropyriphos 20 EC and mix thoroughly or use chloropyriphos 0.02%. Roots of the uprooted rice seedlings require for transplanting one acre area should be dip overnight (12 hours).

Precautions should be taken while handling/ transplanting the root dip seedlings. Hand gloves or paddy transplanter can be used. Nursery treatment with carbofuran 3G @500g /100sq. m can be carried out as an alternative to root dip and it should be applied 5 days before pulling of seedlings.

If hispa and case worm are observed in nursery, clipping of seedling tips minimized the carryover of pest from nursery to main field. Shades in the paddy field should be removed as it serves as the foci for spread of diseases (bacterial blight) and insect pests (LFs and stem borers). Recommended spacing should be maintained during transplantation.

Fertilizers and micro nutrients should also be applied as per local recommendations. To reduce weed growth maintain a thin layer of water on soil surface. However, alternate drying and wetting of field help in management against planthoppers (BPH, WBPH), bacterial blight and stem rot disease.

Dislodging of caseworm larvae with the help of coir rope after draining out water from the field or pouring a small amount of kerosene oil on water to make a very thin layer over it, help in reducing their population.

Natural enemies like spiders, water bugs, mired bugs, damsel flies, dragon flies, meadow grasshoppers, staphylanid beetles, carabids, coccinellids, Apanteles, Tretastichus, Telenomus, Trichogramma, Bracon, etc, plays a significant role in natural regulation of the rice pests. During the time of field preparation, sheltering site of spiders can be made by putting bundles of paddy straw in upright position inserting on a stick at the bunds of the field.

This will serve as sheltering place for the predators and multiply and spread their population after transplantation of crop. Plants giving nectar and pollens can also be grown at the bunds to attract natural enemies.

If available Trichogramma japonicum or T. chilonis @ 1,00,00/ha can be released for 4-5 times at 10 days interval starting from the day of appearance of the pest for control of stem borers and LFs. Mass trapping of YSB can also be carried out by installing pheromone traps @ 20 traps /ha at 20 days after transplanting.

Lures containing 5 mg pheromone should be replaced 3 times at an interval of 20-25 days during crop season. Rice gundhi bug can also be mass trap using fermented snails/crap/ fish/meat, however, the attracted bugs should not be allowed to move away again.

Under the ambit of IPM, need based, judicious and safe application of pesticides are the most vital segment. It involves crop health monitoring, observing ETL (listed in Table. 1) and conserving natural biocontrol potential before deciding in favour of use of chemical pesticide as the last resort.

The commonly recommended insecticides for management of rice pests are-
carbofuran 3G @ 1kg a.i./ha for thrips, whorl maggot, GM, hispa and stem borers;
monocrotophos 36SL @ 0.5 kg a.i. / ha for LFs, GLH, BPH, WBPH, stem borers, hispa, case worm and cut worm;
imidacloprid 17.8 SL @ 25 g a.i. /ha for GLH, BPH and WBPH;
ethofenprox 10 EC for GLH, BPH and WBPH;
quinalphos 25 EC @ 0.5 kg a.i. / ha for leaf folder, BPH, WBPH, GM, hispa and stem borer;
phosalone35 EC @ 0.5 kg a.i. / ha for stem borer, hispa, GLH and LF;
carbaryl 50 WP @ for thrips, GLH, BPH and WBPH;
chlorpyriphos 20 EC @ 0.5 kg a.i. / ha for LF, BPH, WBPH and hispa;
fenobucarb (BPMC) 50 EC @ 0.5 kg a.i. / ha for GLH and BPH;
Malathion 5DP @ 20 kg/ha for gundhi bug.

Beside these insecticides, some registered insecticides against rice pest are also listed in table 2. Repeated use of same/similar chemicals in the same field should be avoided. Biopesticides like azadirachtin and Bacillus thuriengiensis mentioned in table 2. can be used in organic farming.