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Integrated pest management (IPM) in rice

The indiscriminate use of pesticides for pest control has led to disturbances in natural ecosystem leading to resurgence of pests, secondary pests outbreak, toxic hazards and residues besides environmental pollution. This has led to major emphasis on integrated pest management and gained greater momentum. Integrated pest management programmes promote favourable, ecological, economic and sociological outcome, which is accomplished by the best mix of pest control tactics. The use of appropriate scouting tactics, proper diagnosis of pest, the use of economic thresholds and conservation of naturally occurring biocontrol agents are fundamental components of a sound Integrated pest management programme. The use of chemicals is restricted. It is used only if it is absolutely essential based on surveillance. The important components in the IPM are the use of tolerant/resistant varieties, regulating planting density, adjusting the time of planting / sowing, group farming practices, cultural management of pests, integrated nutrient management, removal of weeds, use of botanical pesticides and preservation of natural enemies. For the preservation of natural enemies, collect the egg masses of pests in perforated polythene bags and keep them in the field so that the parasites that emerge can establish in the field effectively.

Trichogramma chilonis and Trichogramma japonicum are egg parasitoids which effectively control egg mass of leaf roller, stem borer, skippers and cutworms. The parasitoids have to be released 15-30 days after transplantation or 25-30 days after sowing or immediately after noticing moth activity in the field. The release rate is 1 lakh parasitoids/ha of both size (5cc/ha). The release has to be carried out at weekly intervals. The trichocard have to be cut into small pieces (minimum 10 pieces) and released in main field, 6-8 releases is necessary to control the pest.

Precaution : If larval attack is observed in the field, necessary organic/inorganic insecticides have to be used and a gap of 7 days has to be given before next release. The trichocards have to be placed during early morning or late evening hours and should not come in direct contact with sunlight.

Common natural enemies of insect pests found in rice ecosystem 

A. Predators Description of biocontrol agents
Characters Pest attacked
1 2 3
Spiders
1. Wolf spider
2. Lynx spider
3. Jumping spider
4. Long jawed spider
5. Dwarf spider
6. Orb spider
Female lays 200-800 eggs in life-time of 3-4 months. Both nymphs and adults are voracious feeders. It consumes 5-15 insect pests in a day depending up on the size Leaf and plant hoppers, leaf feeding caterpillars and adult stem borers.
Damsel and dragon flies Multi-coloured with transparent narrow wings. Nymphs are aquatic and can climb up rice stems to search food. Adults fly normally below the rice canopy in search of flying insects Stem borers, hoppers and other flying insects.
Mirid bugs Adults are green and black at the shoulder. Nymphs are greenish. They can consume 7-10 eggs or 1-5 hoppers a day Leaf hoppers and plant hoppers
Water bugs Broad shouldered adults can be either winged or wingless. Each female lays 20-30 eggs in rice stumps above the water level. Life span 1-2 months. Winged adults disburse when rice plants dry up. Plant hopper and other small soft-bodied insects
Water treaders They are solitary feeders Stem borer larvae and hoppers that fall on water surface
Water striders Each strider takes 5-10 prey daily. They live for 1-1.5 month; lay 10-30 eggs Rice hoppers, moth and larvae that fall on the water surface
Ground beetle Hard bodied insects. Larvae are shiny black and adults are reddish brown. Active predators, which pupate in the soil. Consume 3-5 larvae /day Plant hoppers and larvae of leaf folders
Rove beetle 7mm long with short elytra and blue tip of abdomen. Found on rice plant, water and ground surface; active during night. Leaf hoppers, plant hoppers and larvae of leaf folder and hairy caterpillar.
Lady bird beetles Active during daytime.Found in the upper half of rice canopy. Feed on small and slow moving prey as well as on exposed eggs. Grubs are more voracious than adults and consume 5-10 prey. Produce 150-200 offsprings in 6-10 weeks Plant hoppers
Crickets, Sword tailed crickets Egg predators Eggs of stripped borer, leaf folder, armyworm and nymph of plant hoppers and leaf hoppers.
Grasshoppers, Meadow grass hoppers Distinguished from true grasshoppers by its long antennae, which are more than twice as long as its body length. Active at night and abundant in older fields. Can consume 3-4 yellow stem borer egg masses per day Eggs of rice bug and stem borer, nymphs of plant hoppers and leaf hoppers
B. Parasitoids
1. Egg parasitoids
Trichogramma japonicum Telenomus chilonis Tetrastychus sp. Dark coloured tiny insects. Female wasp lays 20-40 eggs in the host egg. Development from egg to adult stage takes 10-40 days. Stem borers and leaf folders
Gonatocerus sp. Anagris sp. Brown to dark yellowish brown tiny wasp. Females can reproduce without mating. Adults live 6-7 days and parasitise on an average 8 eggs/day Plant hoppers and leaf hoppers
2. Larval parasitoids
Cotesia sp. 
Stenobracon sp. Macrocentrus sp. Xanthopimpla sp. Charops sp.
Dark coloured wasp. Lives for 4-7 days Larvae feeding on stem, leaf and other parts of rice plant

C. Birds

a. Install artificial nesting sites viz., wooden nest boxes in the rice fields (@ 12 nests/ha) for colonization by cavity nesting birds (magpie robin, common myna, barn owl, etc) which play a vital role in managing a variety of insect and noninsect pests. The nest boxes should be installed at a height more than 8 feet on wooden pole, tree trunk, etc.

b. Installation of bird perches @ 50/ha increases the activity of insectivorous birds and reduces the pest population in rice fields. The perches should have a minimum height of 75 cm above the crop canopy for better visibility for the birds.

c. Tying metalised reflective ribbon @ 20 - 25 rolls/ha at 75 cm above the canopy of the vulnerable stage of the crop on bamboo poles, 2.5 – 3.0 m apart at convenient length, twisted at every 1 m length scares away the depredatory birds.

Effective and eco-friendly pest management in wet land rice ecosystem

1. Cultivate tolerant varieties

2. Monitor the field at least at weekly intervals

3. Pest and natural enemy population should be monitored for deciding spraying schedule.

4. Spraying should be avoided during the reproductive phase.

5. Spot application of insecticide may be adopted in heavily infested pockets to control further spread of the pest and to conserve the existing natural enemy population in rice ecosystem.

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