Destruction or regulation or suppression of undesirable insects,other animals or plants by the introduction, encouragement or artificial release of their natural enemies. Biological suppression involves the action of parasitoids, predators or pathogens in maintaining another organism's population density at lower average than would occur in their absence. It includes the use of natural or modified organisms, genes, gene products etc., to reduce the effects of undesirable organisms (pests), so as to favor desirable organisms such as crops, trees, animals, beneficial insects and micro organisms.
Agents of Biological control
1. Parasitic insects –
- Living organisms remaining in close association with their hosts and gradually derive their food from the host. They live and feed internally or externally on the host e.g. Trichogramma chilonis , Epiricania Melanoleuca
2. Predatory insects- Insects which catch, kill & devour prey e.g.Chrysoperla carnea , Cryptolaemus montrouzieri
3. Pathogens - Micro-organisms causing diseases in pests & inhibiting the harmful fungi.
e.g. Bacteria - Bacillus thuringensis
Fungi - Trichoderma, Nomuraea, Paecilomyces,Verticilium,Metarrhizium
Viruses – N.P.V.(Nuclear polyhedrosis virus)
Parasitic insect - Trichogramma chilonis
- Egg parasite of over 200 insect pests
- Females lay their eggs within the insect eggs
- Completes the larval and pupal stages within the insect eggs
- Total destruction of insect eggs and emergence of Trichogramma adults from the eggs
- Multiplication of Trichogramma and simultaneously pest management through egg
destruction
-One Trichogramma adult can parasitize 90-100 eggs
Field application of Trichogramma
- Mass multiplication of Trichogramma on host eggs (Rice moth eggs) - One Trichocard contains 20000 parasitized eggs - Rate of application – 40000 adults/acre i.e. 2 trichocars/acre
- 3-4 releases at 12-15 days interval after irrigating the field - Avoid insecticidal spray after releasing Trichogramma in the fields
Epiricania Melanoleuca -
- Adult parasite of sugarcane pyrilla - Caterpillar sticks to the ventral side of adult pyrilla - Cocoon of Epiricania are released in the field - Sugarcane leaves containing egg masses and cocoons are stapled on lower side of leaves - Rate of application – 1000 Cocoons/ha
Predators
Chrysoperla carnea
- Predator of soft bodied insects like aphids, white flies, jassids, mealy bugs & scales - Consumption of eggs of caterpillar pests. - Chrysopid larvae are released in the field and feed on soft bodied insects - Rates of applicationr – 8000- 10000 larvae/acre
Cryptolaemus Montrouzieri
- Predator of mealy bugs on citrus, grapes, pomegranate - Besides feeding on mealy bugs, lay their eggs near the mealy bug colonies - Beetles feed on all stages of mealy bugs - Rate of application - 1000-1500 adults/acre
Pathogenic micro-organism
Fungus – Trichoderma viride -Antagonists against pathogenic fungi like
-Fusarium oxysporum – Wilt of cotton, Pigeon pea,tomato Sclerotium rolsfi - Stem rot of g.nut, soybean,ginger Rhizoctonia solani – Root rot of vegetables and pomegranate Pithyum debaryanum – Wilt in gram and pulses
Mode of Action of Trichoderma
1. Mycoparasitism - - Attaching & coiling around the host hyphae - Growing within the host hyphae & destroyng its protoplas 2. Antibiosis – - Release of antagonistic chemical products in the environment namely viridin & gliotoxin. - Suppresssing the growth of harmful fungi by destroying their cell wall. 3. Competition for substrate - High competition habit for nutrition space directly suppresses the pathogen activity.
Field Application
1. Seed treatment-
For pulses and oliseed crops 10 gm Trichoderma powder per kg of seed before sowing.
2. Soil application-
For fruit crops 8-10 kg/ha through organic matter
3. Drenching –
For vegetables drenching the plants by solution of Trichoderma by dissolning it in water @ 10 gm/lit
4. Aerial spray –
5 gm/lit as a preventive measure against air borne diseases
Fungus - Paecilomyces lilacinus
-Fungal bioagent of plant parasitic nematode - Root knot nematodes is the major pests of fruit and vegetable crops -Parasitization of nematode eggs by Paecilomyces fungus -Suppression of nematode hatching -Rate of application 3 kg/acre through organic matter - Need of organic matter and proper soil moisture during application
Verticilium lecani - Pathogenic fungus of mealy bug & white fly
- Management of mealy bug in citrus, grape, pomegranate by developing disease in these pests. - Easily mass multiplied on crushed and moist sorghum grains in laboratory - Rate of application – 1kg/acre through water suspension
Fungus – Nomuraea rileyi -Entomopathogenicfungus. - Spore germination on cutlele & penetration through cuticle - Multiplication in hoemocoel
- Produces toxic metabolite Inhibition of metabolic enzymes & thereby causing paralysis and ultimately death of insect Target Pests - Helicoverpa, Spodoptera, white fly -Rate of application – 1 kg/acre through water suspension