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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
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A. Predators
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Description of biocontrol agents
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Characters
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Pest attacked
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1
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2
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3
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Spiders
1. Wolf spider
2. Lynx spider
3. Jumping spider
4. Long jawed spider
5. Dwarf spider
6. Orb spider
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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
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Leaf and plant hoppers, leaf feeding caterpillars and adult stem borers.
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Damsel and dragon flies
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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
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Stem borers, hoppers and other flying insects.
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Mirid bugs
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Adults are green and black at the shoulder. Nymphs are greenish. They can consume
7-10 eggs or 1-5 hoppers a day
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Leaf hoppers and plant hoppers
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Water bugs
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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.
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Plant hopper and other small soft-bodied insects
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Water treaders
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They are solitary feeders
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Stem borer larvae and hoppers that fall on water surface
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Water striders
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Each strider takes 5-10 prey daily. They live for 1-1.5 month; lay 10-30 eggs
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Rice hoppers, moth and larvae that fall on the water surface
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Ground beetle
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Hard bodied insects. Larvae are shiny black and adults are reddish brown. Active
predators, which pupate in the soil. Consume 3-5 larvae /day
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Plant hoppers and larvae of leaf folders
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Rove beetle
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7mm long with short elytra and blue tip of abdomen. Found on rice plant, water and
ground surface; active during night.
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Leaf hoppers, plant hoppers and larvae of leaf folder and hairy caterpillar.
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Lady bird beetles
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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
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Plant hoppers
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Crickets, Sword tailed crickets
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Egg predators
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Eggs of stripped borer, leaf folder, armyworm and nymph of plant hoppers and leaf
hoppers.
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Grasshoppers, Meadow grass hoppers
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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
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Eggs of rice bug and stem borer, nymphs of plant hoppers and leaf hoppers
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B. Parasitoids
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1. Egg parasitoids
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Trichogramma japonicum Telenomus chilonis Tetrastychus sp.
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Dark coloured tiny insects. Female wasp lays 20-40 eggs in the host egg. Development
from egg to adult stage takes 10-40 days.
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Stem borers and leaf folders
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Gonatocerus sp. Anagris sp.
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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
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Plant hoppers and leaf hoppers
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2. Larval parasitoids
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Cotesia sp.
Stenobracon sp. Macrocentrus sp. Xanthopimpla sp. Charops sp.
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Dark coloured wasp. Lives for 4-7 days
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Larvae feeding on stem, leaf and other parts of rice plant
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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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