1. Bio-control and Biopesticides in Rice IPM
Introduction
Pest management is known as an ecological approach to tackle pest problems because here emphasis is on containing pests in such a way that other biotic components of the system such as natural enemies, human beings and wild life are not harmed and environment is preserved in general. Pest management also underlines that pest control tactics should be socially acceptable and within the reach of farmers.
Earthworms – victims of pesticide use
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2. In IPM different methods of pest control such as resistant varieties, cultural methods, physical methods, Biological and pesticides are integrated to suppress pest populations.
An IPM programme should be basically based on conservation of native natural enemies, cultural methods and resistant cultivars and other management tactics should be incorporated based on availability and need.
IPM Concept
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3. Biological Control
Biological control refers to use of natural enemies of pests such as parasitoids, predators and pathogens to suppress pest populations. Rice ecosystems are replete with natural enemies but these need to be conserved against harmful effect of pesticides.
Likewise, biopesticides like plant extracts or pathogens are also used to contain pests. Parasitoids such as Trichogramma are also used to suppress borer pests.
Spider- Prolific predator
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4. Predators
Spiders, predatory bugs, predatory beetles, predatory crickets and grasshoppers take heavy toll of rice pests.
Spiders: Spiders are dominant and most common predators in rice ecosystem. They are voracious feeders of leaf and planthoppers, leaf eating caterpillars and adult stem borers. Spiders consume insects a day depending upon their size.
Spiderlings in rice field
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5. Water strider
Adults and nymphs of water strider prey on rice hoppers, moths and larvae that drop on to water surface. Each water strider consumes 5-10 prey daily.
Water strider
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6. Predatory beetles
Ground beetles feed on larvae of leaf folder, and planthoppers. Each predator can consume 3-5 larvae per day. Rove beetles feed on larvae of leaf folder and hairy caterpillar, and planthoppers. Likeiwse, lady bird beetles prey on leaf folder larvae and planthoppers.
Rove beetle
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7. Predatory crickets and grasshoppers
Sword-tailed crickets are egg predators and consume eggs of several rice pests. Likewise meadow grasshoppers feed on eggs of rice bug and stem borer, and nymphs of planthoppers.
Predatory cricket
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8. Vertebrate predators Predators like sparrows, mynahs, ducks, frogs and fish are also reared in rice fields and they heavily consume planthoppers and other pests, besides providing extra income to farmers.
Sparrow
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9. Parasitoids
Parasitoids are tiny insects which feed on eggs, larvae or pupae of pests. Eggs parasitoids of stem borer and leaf folder such as Trichogramma, Telenomus and Tetrastchus; egg parasitoids of leaf and planthoppers like Gonatocerus and Anagrus, and larval parasitoids such as Apanteles, Bracon, Stenobracon play very important role in pest suppression under natural field conditions.
Stenobracon parasitoid
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10. Inundative releases of insectary reared egg parasitoid Trichogramma (Trichocard) are also undertaken to contain stem borer and leaf folder incidence. Trichogramma japonicum and T. chilonis is released against yellow stem borer and leaf folder, lakh/ha/week for 6 weeks starting 30 days after transplanting.
These releases act like application of insecticides and control is achieved through released individuals only and not through their progeny.
Braconid wasp
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11. Pathogens
Entomopathogenic fungi like Beauveria, Metarhizium, Entomophthora also play important role in suppressing populations of planthoppers and other pests. Likewise, entomogenous nematode, Steinernema carpcapsae and nucleopolyhedrosis virus (NPV) have been found to be effective against rice pests.
NPV infected insect larva
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12. Conservation of natural enemies
Biopesticides
Bacteria, Bacillus thuringiensis (Bt) is effective against lepidopteran pests.
Neem products like neem seed kernel extract (NSKE) is effective against planthoppers and other foliage feeders.
Conservation of natural enemies
Ensure need based application of pesticides
Avoid use of broad spectrum pesticides
Don’t treat area having natural enemy abundance.
Conserve natural enemies
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13. Let’s Sum up
Biological control refers to use of natural enemies of pests to suppress pest populations.
Predators like spiders, predatory bugs, predatory beetles, predatory crickets and grasshoppers take heavy toll of rice pests.
Parasitoids are tiny insects which feed on eggs, larvae or pupae of pests. Trichogramma is an important egg parasitoid of rice stem borer and leaf folder.
Inundative releases of insectary reared Trichogramma (Trichocard) are also undertaken to contain stem borer and leaf folder incidence.
Fungi like Beauveria, Metarhizium, Entomophthora play important role in suppressing populations of planthoppers and other pests.
Nematode, Steinernema carpcapsae and nucleopolyhedrosis virus (NPV) have also been found to be effective against rice pests.
Biopesticides such as Bacillus thuringiensis (Bt) and neem seed kernel extract (NSKE) are effective against rice pests.
Conservation of natural enemies can be ensured through need-based application of selective pesticides.
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