Introduction

Introduction Natural ecosystems have abundance of natural enemies of pests. Natural enemies keep pest populations in check, where man does not interfere. Greatest harm to these farmers’ friends is caused by indiscriminate use of pesticides.Pest management thus lays emphasis on conservation of natural enemies. Natural enemies are also compatible with resistant varieties.

Bio-control and Bio-pesticides in IPM

Conserve non- target organisms

In fact, biological control along with cultural methods should form the core of any IPM programme. Natural enemies are a gift of nature to farmer and they need to be conserved for taking their advantage. 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

DB-Cultural methodsDB-Mechanical

Methods

DB-Physical methods

DB-Bio-control methods

DB-Chemical methods

Multipest-modules

Dissemination

insect Disease

nematode weeds

ETL

Multiple pest management programmesIPM Concept

Biological control refers to use of natural enemies of pests such as parasitoids, predators and pathogens to suppress pest populations. Crop ecosystems are replete with natural enemies but these need to be conserved against harmful effect of pesticides.

Likewise, bio-pesticides 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

Biological Control

PredatorsSpiders, predatory bugs, predatory

beetles such as lady bird beetles, rove beetles and ground beetles, syrphids, predatory crickets and grasshoppers take heavy toll of crop pests. Vertebrate predators such as birds, fish and ducks also feed on crop pests.

Spiders: Spiders are dominant and most common predators in rice ecosystem. Spiders consume 5-15 insects a day depending upon their size. Moths and flies are also ensnared and eaten by spiders.

Spider with egg case

Ground beetle

Lady bird beetlesLady beetles are very important predators of aphids and other sucking pests and can be seen in large number especially on rabi crops like mustard, wheat, coriander etc. Both grubs and adults feed voraciously on pests.While spraying pesticides, care should be taken to spare these useful predators through selective application.

SyrphidsMaggots of hoverflies also feed on aphids.

Adult of lady bird beetle

Grub of lady bird beetle

Rove beetlesRove beetles feed on larvae of leaf folder and hairy caterpillar, and planthoppers.

Ground beetles feed on larvae of leaf folder, and planthoppers. Each predator can consume 3-5 larvae per day.

Lace wingsLace wing grubs also feed on aphids and thus help in reducing crop losses due to pests.

Rove beetle

Grub of lace wing

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.

Dragon and Damsel fliesDragon and damsel fly adults also feed on flying insects, thereby aiding in their biological control. They are found in abundance near water bodies.

Predatory cricket

Dragon fly

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. Birds also follow the plough or tractor and pick up exposed soil pests.

Sparrow

Crows feeding soil pests

ParasitoidsParasitoids 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

Inundative releases (Table 1) of insectary reared egg parasitoid Trichogramma (Trichocard) are also undertaken to contain stem borers in rice, maize and sugarcane, cotton bollworms, rice leaf folder. Trichogramma spp. are released @ 1-1.5 lakh/ha/week for variable number weeks depending upon need. These releases act like application of insecticides and control is achieved through released individuals only and not through their progeny.

Braconid wasp

Trichocards

Pest Natural enemy Release/application

Rice yellow stem borer & leaffolder

Trichogramma japonicum & T. chilonis

Inundative release @50,000- 100000/ha/week for 5 weeks

Sugarcane pyrilla

Epiricania melanoleuca

Periodic release @8000-10,000 cocoons or 800,000-1000,000 eggs/ha

Maize stem borer

T. chilonis Inundative releases @ 100,000/ha/3 days - 5 times

Tobacco caterpillar

Telenomus remus (egg parasitoid)

3 fortnightly releases @ 40,000/ha

Cotton bollworms

T. chilonis,

Chrysopa carnea

@ 1,50,000/ha/7-10 days during egg laying period@ 2 larvae/plant during peak egg hatching

Table 1 Inundative releases of natural enemies against pests

Pathogens Entomopathogenic fungi like Beauveria, Metarhizium, Entomophthora also play important role in suppressing populations of planthoppers and other pests. Likewise, entomogenous nematode, Steinernema carpcapsae also help to control crop pests. Nucleopolyhedrosis virus (NPV) have been found to be effective against tobacco caterpillar (Spodoptera) and gram pod borer (Helivoverpa).

NPV infected insect larvaCourtesy: http://butterflybreeders.com

NPV infected larva haging upside down

Biopesticides Bacteria, Bacillus thuringiensis (Bt) is effective against lepidopteran pests.Neem products like neem seed kernel extract (NSKE) is effective against suckng pests and other foliage feeders.Conservation of natural enemiesEnsure need based application of pesticidesAvoid use of broad spectrum pesticidesDon’t treat area having natural enemy abundance.

Conserve spiders

Let’s Sum upBiological control refers to use of natural enemies of pests to suppress pest populations.

Predators like spiders, predatory bugs, lace wings, predatory beetles, predatory crickets, grasshoppers and birds take heavy toll of crop pests.

Parasitoids are tiny insects which feed on eggs, larvae or pupae of pests. Trichogramma is an important egg parasitoid of stem borers, bollworms and leaf folders.

Inundative releases of insectary reared Trichogramma (Trichocard) are also undertaken to contain stem borers, cotton bollworms and leaf folders.

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 pests like tobacco caterpillar and gram pod borer.

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.