Pakistan Sugar Journal April-June, 2013 (28)

TRICHOGRAMMA WASPS(EGG PARASITOIDS)

Saadia Rizwana and Asia Naheed

Natural enemies of croppestsThe genus Trichogramma iscosmopolitan in distributionand present in all terrestrialhabitats and is one of 80genera in the familyTrichogrammatidae.Trichogramma are primaryparasitoids eggs ofLepidoptera but parasitismalso occurs in eggs of otherorders such as Coleoptera,Diptera, Hemiptera,Hymenoptera andNeuroptera.

Trichogramma species arethe most studied groupworldwide of egg parasitoidsfor biological control due totheir efficiency and easymaintenance underlaboratory conditions. Thesenatural enemies are used inmore than 30 countries inbiological control programsagainst insect pests. Becausethese species can be found inthe majority of ecosystems

where they can suppressmany pests, these naturalenemies are favored in manycommercial biologicalcontrol programs.Trichogramma chilonis Ishii(Hymenoptera:Trichogrammatidae) hasbeen used as a biologicalcontrol agent against variousinsect pests attacking cropsworldwide, including sugarcane borers, corn borers, andcotton bollworms.

Biological Control Lab ofShakarganj SugarResearch Institute (SSRI)IntroductionSSRI established a Bio-control Laboratory in 1995for rearing of Trichogrammachilonis for control of borercomplex of sugarcane crop.Under laboratory conditionT. chilonis is mass multipliedby using stored grain pest(Sitotroga cerealella) as ahost. The production

involves the multiplication ofhost insect on wheat grains,allowed to be parasitized byTrichogramma. Then eggsare clued in cards as "Trichocards".

Two to three lacs cards arereleased in field every yearfor betterment of farmers,

crop and society. A goal ofthis biological programme isto establish a self sustainingsystem. For example, anatural enemy introduced inan area with the hope that itwill establish, cause the pestto fluctuate below theeconomic injury level.

What is Integrated PestManagement (IPM)?"IPM is a sustainableapproach to managing pestsby combining biological,cultural, physical andchemical tools in a way thatminimizes economic, healthand environmental risks."

IPM

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Biological ControlBiological control involvesuse of a specially chosenliving organism to control aparticular pest. This chosenorganism might be apredator, parasite, or diseasewhich will attack the harmfulinsect.

ParasitoidsParasitoids are insects thatprey on other insects and thuscan be benefit to cropgrowers. Their eggs or larvaeare usually found in or on asingle insect host. Theimmature parasitoid developswithin or on its host,ultimately killing the pest.Most parasitoids are wasps orflies.

What to look forTrichogramma wasps areused worldwide as effectivebiological control agent. Thefemale drills a hole throughthe chorion and deposits itseggs within the egg of the

host. Larvae emerged fromTrichogramma egg and feedon host insect. Venominjected by the female at thetime of oviposition isbelieved to cause thispredigestion of the egg’scontents. Pest eggs turnblack. No pest larvae willemerge. One femaleparasitizes from one to teneggs per day or from ten to190 during her life. Thenumber of eggs laid per hostegg may vary from 1 to 20 ormore depending upon thesize of the host egg.AppearanceAdults are very small 1/32inch long, they have a yellowblack compact body, red eyesand short antennae.

Taxonomic Rank & LifeCycle of Trichogrammachilonis

Common Name:Trichogramma, TriconTechnical Name:Trichogramma chilonis

Family: TrichogrammatidaeOrder: HymnopteraPests AttackedTwo hundred hosts havebeen recorded worldwide,primarily in Lepidoptera andalso Diptera, Coleoptera, andNeuroptera. Some of themajor pests against which ithas been used / recorded inIndia include sugarcaneborers (Chilo infuscate-llus, Chilo sacchariphagusindicus, C. auricilius,Emmalocera depressella,Raphimetopus ablutellus,Acigonasteniellus, Scirpophaga excerptalis), ricestemborer (Scirpophagaincertulas),leaffolder (Cnaphalocrocis medinalis), coconutblackheaded caterpillar(Opisina arenosella),diamond back moth (Plutellaxylostella), cotton bollworms(Earias vittella, E. insulana,Helicoverpaarmigera, Pectinophora gossypiella), variousspecies of moths andbutterflies.

Trichogramma Parasitizing pest Eggs Cabbage Moth Eggs Parasitized by Trichogramma

Pakistan Sugar Journal April-June, 2013 (30)

Heliothis (American Bollworm) Eggs Parasitized by Trichogramma

Time of ApplicationAs or when required whenyou see pests, cards are takento the field and punched onthe under side of the leavesto avoid the direct exposureto sun. Trichogrammareleases in field on cards arein pupal stage. In two to three

days Trichogramma adultsemerge, search out pests eggsand destroy them byparasitism. In favorableenvironments, 70-80% boreregg parasitism is noticedwhich bring down pestpopulation less thaneconomic injury level.

RecommendationRelease of Trichogrammachilonis egg parasitoid fifteento twenty cards at fortnightlyintervals six timescommencing from Aprilonwards effectively checksthe incidence of pests.

Release Rates on Different Crops

Crop Trichogramma Population/Acre No. of Cards/AcreSugarcane 50,000-200,000 15-20Cotton 50,000-200,000 15-20Maize 50,000-200,000 15-20Tree and Vine Crops 30,000-60,000 8-10Vegetables 50,000-200,000 15-20Enclosed Areas 10,000-20,000 5-8

Precautionary Measures1. Observe field carefullyprior to release cards thatthere is no dangerouschemical in field damagingTrichogramma cards.i. Handle cards carefullywhile shifting from lab tofield.ii. When you get cards fromlab then you must release infield immediately.

iii. Don't press cards, ifpressed then cards will expireand no Trichogrammaemergence took place.Advantages of Biocontrol1. Biological control is an

environment friendlymethod and it does nothave adverse effects onhuman and animals health.

2. Biological control is along term control.

3. In biological control cropsbeneficial insects are save.

4. Insect pests developresistance in response tocontinuous use of certainchemicals. In case ofbiological control no suchresistance could be seen.

Crops ProtectedSugarcane, cotton, maize,orchids and vegetables.

SUGAR INDUSTRY ABSTRACTS