Mosquitobornediseasescontinuetobeamajorproblem in almost all tropical and subtropical countries.Theyareresponsibleforthetransmissionofthepathogens causing some of the most life - threateninganddebilitatingdiseasesofman,likemalaria,yellowfever,denguefever,chikungunya,filariasis,encephalitis,etc.Environmental protection agencies have banned orplaced severe restrictions on the use of many pesticides,whichwereformerlyusedinmosquitocontrolprogrammes,andtherearenowfeweradulticidesavailable than there have been for the last 20 yr1. Further,manufacturersthemselveshavewithdrawnsomeinsecticidesduetothehighcostofcarryingouttheadditionaltestsnowasperthegovernmentnorms,inaddition to the fact that the production of crop pesticidesfor the agricultural market is much more lucrative1. Theharmful effects ofchemicals in mosquitoes as wellasonnon-targetpopulations,andthedevelopmentofresistance to these chemicals in mosquitoes along withrecent resurgence of different mosquito borne diseases2have prompted us to explore simple sustainable methodsMosquito control by larvivorous fishG. Chandra , I. Bhattacharjee, S.N. Chatterjee & A. GhoshDepartment of Zoology, University of Burdwan, Burdwan, IndiaReceivedJune8,2006Thereisgrowingoftheeffectsofinsecticideusedcontrollingthevectorsofhumandiseases.Manipulating or introducing an auto-reproducing predator into the ecosystem may provide sustainedbiological control of pest populations. The selection of a biological agent should be based on its self-replicating capacity, preference for the target pest population in the presence of alternate naturalprey, adaptability to the introduced environment, and overall interaction with indigenous organisms.Inordertoachieveanacceptablerangeofcontrol,asoundknowledgeofvariousattributesofinteractions between the pest population and the predator to be introduced is desirable. Biologicallarviciding for the control of mosquito borne diseases is feasible and effective only when breedingsites are relatively few or are easily identified and treated. Larval control appears to be promisingin urban areas, given that the density of humans needing protection is higher than the limited numberofbreedingsites.Since1937,fishhavebeenemployedforcontrollingmosquitolarvae.Differenttypes of fish have been used so far in this operational technique. However, use of fish of indigenousorigin is found to be more appropriate in this operation. This review presents information on differentlarvivorous fish species and the present status of their use in mosquito control and provides a readyreference for workers involved and interested in mosquito research.Key wordsBiocontrolagents-larvivorousfish-mosquitocontrol13IndianJMedRes127,January2008,pp13-27ReviewArticleof mosquito control. The eradication of mosquito usingadulticides is not a prudent strategy, as the adult stageoccurs along side human habitation, and they can easilyescaperemedialmeasures3,4.Biologicalcontrol,particularlyusinglarvivorousfish,wasimportanttomalariacontrolprogrammesinthe20thcentury,particularlyinurbanandperiurbanareasforimmediateuseindevelopedanddevelopingcountries5.Ithasaverypositiveroletoplayintheintegratedcontrolmethodologiesinwhichbothpesticides and fish or other biotic agents have their ownroles6.Biologicalcontrolreferstotheintroductionormanipulationoforganismstosuppressvectorpopulations. A wide range of organisms helps to regulatemosquitopopulationsnaturallythroughpredation,parasitismandcompetition.Asbiologicalmosquitocontrol agents, larvivorous fish (i.e., those that feed onimmaturestagesofmosquitoes)arebeingusedextensively all over the world since the early 1900s (preDDTera)7.DuringthepreDDTera,controlofmosquitoes and mosquito vectors of different mosquitoborne diseases was undertaken mainly by environmentalmanagement,pyrethrumspacespraying,useofParisgreen,oilingwithpetrolproductsandintroductionoflarvivorousfish.RecognizingthehighlarvivorouspotentialofGambusiaaffinis,thisfishspecieswaspurposelyintroducedfromitsnativeTexas(SouthernUSA) to the Hawaiin Islands in 1905. In 1921, it wasintroducedinSpain;thenfromthereinItalyduring1920sandlaterto60othercountries8.Beginningin1908,anotherlarvivorousfish,Poeciliareticulata,anativeofSouthAmerica,wasintroducedformalariacontrolintoBritishIndiaandmanyothercountries8.The introduction of the use of DDT in indoor residualspraying for malaria control around the mid - 1940s ledtothegradualdeclineintheuseofconceptsofenvironmentalmanagementandbiologicalcontrolmethods, except in a few programmes in Russia. In thefifties,attentionwasdirectedtoeradicatemosquitoesusing synthetic insecticides until insecticide resistancebegantoassumeprominence.In1969,theWHOchanged its strategy of malaria eradication by sprayinghouses with synthetic insecticides in favour of the morerealistic one for the control of mosquito populations inthe larval stages (post DDT era)7.Theselectionofbiologicalcontrolagentsshouldbe based on their potential for unintended impacts, self-replicatingcapacity,climaticcompatibility,andtheircapability to maintain very close interactions with targetpreypopulations9.Theyeliminatecertainpreyandsustaininsuchenvironments(i.e.,theyeattheprey,when introduced) for long periods thereafter10. However,thiswillonlybepossibleifthepredatorpossessesextraordinarysearchefficiencyirrespectiveoftheilluminatedsituationinresponsetotheemergenceofprey.Itisimportanttohaveasoundknowledgeofpredatorspreyselectivepatternsandparticularlyofits mosquito larval selection in the presence of alternatenatural prey11,12. In addition, the predators adaptabilitytotheintroducedenvironmentandoverallinteractionwith indigenous organisms need to be considered priorto introduction13,14. This review presents a brief accountoflarvivorousfishasmosquitocontrolagentsandpossibleprey/predatorinteractionsinaquaticecosystems.Definition and criteria for species selectionLarvivorousfisharethosethatfeedonimmaturestagesofmosquitoes.AccordingtoJob15,larvivorousfish must be small, hardy and capable of getting abouteasilyinshallowwatersamongthickweedswheremosquitoes find suitable breeding grounds. They mustbe drought resistant and capable of flourishing in bothdeepandshallowwatersaswellaslivingindrinkingwater tanks and pools without contaminating the water.They must have the ability to withstand rough handlingand transportation for long distances. Larvivorous fishmustbeprolificbreedershavingshorterspanoflifecycle.Theymustbreedfreelyandsuccessfullyinconfinedwaters.Larvivorousfishshouldbesurfacefeedersandcarnivorousinhabitandshouldhaveapredilectionformosquitolarvaeeveninthepresenceof other food materials. Another important criterion ofall larvivorous species should be its appearance. Theyshouldnotbebrightlycolouredorattractive.Theyshould be compatible with the existing fish life in thatenvironment. Above all, they should have no food value,so that the fish-eating people discard them. It is difficult to find a species that satisfies all theaboveparameters.Hence,thechoiceusuallydependsupon those, which satisfy as many of the above qualitiesaspossible.CategorizationoflarvivorousfishThepositionofmouthisoneoftheimportantcharacteristicstodeterminethelarvivorouscapabilityofafish.Fromthepointofviewoftheirefficacyincontrollingmosquitolarvae,Hora&Mukherjee16classifiedthelarvivorousfishintothefollowingcategories:(i)Typicalsurfacefeederssuchas14 INDIAN J MED RES, JANUARY 2008AplocheliusandGambusia,whichfulfillthecharacteristicfeaturesoflarvivorousfish;(ii)Somesurface feeders, which are less efficient owing to theirmode of life, e.g., Oryzias, Lebistes (Poecilia), Aphanius,etc.;(iii)Sub-surfacefeederslikeAmblypharyngodonmola,Danio,Rasbora,etc.;(iv)ColumnfeederslikePuntius spp., Colisa, Chanda, Anabas, etc., which feedon mosquito larvae when chance permits; (v) Fry of carpsandmullets,whicharehelpfulincontrollingmosquitolarvae;(vi)PredatoryfisheslikeWallago,Channa,Notopterus and Mystus whose fry may destroy mosquitolarvaebutwhoseadultsmaypredateuponotherfishincluding larvicidal fish species.Potential indigenous larvivorous fishes as biocontrolagents1. Aphanius dispar (Ruppell), 1828 (Common name:Dispartopminnow)Size: Approximately 7.5 cm (3 inches).Distribution:India,Kutch;Pakistan;Sind;Ethiopia:Palestine, along the shores of the Red sea.Ecology: A. dispar is a good larvivorous fish and thrivesboth in fresh and brackish waters where it breeds freely.It is a delicate species and does not stand transport well.Itissuitablefordrainsandpollutedwaterbodiesandusefulforstagnantwaterbodies,disusedwells,cesspools,etc.Fieldtrials:Natural habitats - Shallow channels: In 1981, Ataur-Rahim17 reported the natural occurrence of A. dispar inshallow channels near Riyadh where it was reported tosuccessfully control mosquito larvae. Fish were appliedat about 3 fish per square meter water surface.Man made habitats - Experiments using A. disparin man made artificial containers have shown successfulresults. It has been reported that A.dispar is a suggestedlarvivorous fish for the control of vectors of BancroftianfilariasisnamelyCulexquinquefasciatusSay,1823inanykindofstagnantwatercontainingorganicpollution18.Wells - Louis & Albert19 reported that in an urbanareainDjibouti,theindigenousfish,A.dispar,effectivelysuppressedthebreedingofAnophelesarabiensis and An. gambiae breeding in wells, cisternsandbarrelsandcontainersby97percent.FurtherFletcher et al20 reported that in an urban area in Ethiopia,theindigenousfish,A.dispar,effectivelysuppressedAn. culicifacies adanensis breeding in wells.Cisterns-A.dispareffectivelysuppressedthebreedingofAn.arabiensis andAn.gambiaebreedingincisternswhentheexperimentwasconductedinanurban area in Djibouti19.Barrels and containers - A. dispar effectively reducedthe breeding of An. arabiensis and An. gambiae breedingin barrels and containers by 97 per cent throughout theexperiment in an urban area in Djibouti19. Fletcher et al20whoreportedthatinanurbanareainEthiopia,theindigenousfish,A.dispar,effectivelysuppressedAn.culicifacies adanensis breeding in containers. However,its impact on malaria transmission could not be assessed.2. Aplocheilus (McClelland), 1839(i) Aplocheilus blockii (Arnold), 1911 (Common name:Dwarfpanchax)Size: Approximately 9 cm (3.6 inches).Distribution:EastCoastofIndia,fromMadrasnorthwardsasfarasthePennarsysteminAndhraPradesh.Ecology:Thefishisastrictlyfreshwaterformandinhabits stationary and sheltered waters of tanks, smallstreams and rivulets overgrown with thick vegetation.Suitable for ponds and impounded water bodies wherecarnivorous fish are present, wells and abounded waterbodies. Also useful for introduction in overhead tanks,ornamentalpools,streambedsandmargins,reservoirsand wells for malaria disease vector control.Fieldtrials:Naturalhabitats-StudiesconductedbyKumaret al21 showed that predation by A. blockii reduced thelarval population of An. stephensi by 75 per cent alongthe coastal belt of Goa.Manmadehabitats-A.blockiiisapotentiallarvivorous fish controlling the spread of chikungunyafever by controlling Aedes albopictus Skuse 1894. Theexperiment was conducted in tanks and bigger cisternsandbarrels18.(ii)Aplocheiluslineatus(Valenciennes),1846(Common name: Malabar killie)Size: 10 cm (4 inches).Distribution: Widely distributed in Peninsular India andSri Lanka.Ecology:Commonintanks,paddyfields,canals,andeven in tidal waters. It is suitable for fishponds wherecarnivorousfoodfisharepresentandusefulforCHANDRA et al: MOSQUITO CONTROL BY FISH 15introductioninoverheadtanks,artificialcontainers,cisterns and fountains to control urban malaria, and inpools, streambeds, margins and marshes in rural areas.Fieldtrials:Manmadehabitats-A.lineatusisapotentialbiocontrol agent. It was reported to control dengue fevervectornamelyAe.aegyptiLinnaeus,1762.Theexperimentswereconductedinthebreedinghabitatsofthevector,whichincludedwaterstoragetanks,cistern,andbarrels17.(iii)Aplocheiluspanchax(Hamilton-Buchanan),1822 (Common name: Panchax minnow)Size: Approximately 9 cm (3.5 inches); the average sizein Bengal is about 5 cm (2 inches).Distribution:India:Bengal,Bihar,Orissa,Assam,Punjab, Uttar Pradesh, Madhya Pradesh, Rajasthan; SriLanka; Malaya; Burma (now Myanmar); Thailand; andIndonesia.Ecology:Thespeciesisquitehardyandactiveandinhabits clear shallow fresh and brackish water at lowaltitudes. Suitable for water bodies where carnivorousfishoccur;alsowells,marshes,lagoonsandpollutedstorm water drains and any other stagnant water bodiescontaining organic pollution for filariasis vector control.Fieldtrials:A.panchaxisapotentiallarvivorousfishincontrollingseveralvectorspeciesindifferenttypesofnaturalandman-madehabitats18.ItcontrolledAn.culicifaciesinbreedinghabitatslikerainwaterpools,irrigation channels, sluggish streams with sandy marginsandlittlevegetation,riverbedpools,borrowpits,cemented tanks, swimming pools, freshly laid rice fieldsetc. An. sundaicus was controlled in brackish waters withalgae, behind embankments protecting rice fields, tanks,cleared mangroves and lagoons, ponds, lakes and borrowpitsincoastalareas.A.panchaxalsocontrolledCx.quinquefasciatusincesspools,drains,chockedsevers,stormwaterdrains,ponds,pollutedwaterways,septictanks,disusedwells,well,manurepitsetc.,andCx.vishnuiinricefields,marshes,ponds,pools,streams,ditches, borrow pits, irrigation channels, field wells etc.3. Colisa (Cuvier), 1831(i) Colisa fasciatus (Schneider), 1801 (Common name:Giantgourami)Size: Approximately 12.5 cm (5 inches).Distribution: Assam and Upper Burma (now Myanmar)to Punjab and North West Frontier Provinces (Pakistan)and throughout peninsular India.Ecology:Freshwaterrivers,lakesandestuariesgenerally preferring weedy environment. It is suitableforbrackishwaters,backwatersandlagoonsandespeciallyinlakes,swamps,ponds,etc.,withovergrowth of aquatic plants.Laboratorytrials:C.fasciatus,alocallyavailableindigenousfishcollected from stone quarries of Shankargarh block ofAllahabaddistrictandponds/poolsofDadraulblockofShahjahanpurdistrict(U.P.)22wasevaluatedforcontrolofmosquitobreeding.Thenumberoflarvaeconsumed per day by a fish of an average length of 5.3cm collected from stone quarries ranged from 86 to 96.However, larval consumption rate of a fish of an averagelength of 5.9 cm collected from ponds/pools was 85 to101.Nosignificantdifferencewasobservedinthenumber of larvae consumed with and without fish foodthroughout the study period.Fieldtrials:IthasbeenreportedthatC.fasciatuscontrolsvectorsofbrugianfilariasisandmalarianamelyMansonioidesindianaEdwards,1930andAnopheles(C.) annularis Van der Wulp, 1884 respectively18.Man made habitats:Wells-FieldtrialscarriedoutinthewellsofDadraulPHC22revealedthatexperimentalwellswith50 and 75 larvivorous fish did not attain negativity evenafter three weeks of fish introduction. However, wellswith100larvivorousfishbecomenegativeinonetotwo weeks of fish introduction. The negativity persistedfor 4 months, suggesting that C. fasciatus can be usedfor controlling mosquito breeding in wells if introducedinsufficientnumbers22.(ii)Colisalalia(Hamilton-Buchanan),1822(Common name: Dwarf gourami)Size: Approximately 5 cm (2 inches).Distribution: Northern India, Assam, Bengal, Bihar andUttarPradesh.Ecology: It inhabits slow moving streams, rivulets andlakeswithplentyofvegetation.Suitableforwaterbodies where carnivorous food fish are present. Usefulfor lakes, tanks, etc.16 INDIAN J MED RES, JANUARY 2008Fieldtrials:Naturalhabitats-C.laliaisagoodbiocontrolagent. It has been reported to control An. (C.) annularisVan der Wulp, 1884 thereby preventing the spread ofmalariatoaconsiderableextent.Breedinghabitatofthe vector include clear weed grown stagnant waters,margins of lakes, tanks, dead rivers, borrow pits, andricefield18.(iii)Colisasota(Hamilton-Buchanan),1822(Common name: Sunset gourami)Size:Approximately 4 cm (1.5 inches).Distribution: Northern India, Assam, Bihar, Bengal andUttarPradesh.Ecology: In fresh water rivers and lakes living amidstwaterplantsforprotection.Suitableforfreshwaterbodieswherecarnivorousfoodfisharealsopresent.Alsousefulforintroductioninclearweedgrownstagnant waters for malaria vector control.Fieldtrials:Natural habitats - C. sota is also a potent biocontrolagent with natural habitats similar to C. lalia18.4.Chandanama(Hamilton-Buchanan),1822(Common name: Elongate glass perchlet)Size: Approximately 7.6 cm (3 inches).Distribution:India,BangladeshandBurma(nowMyanmar).Ecology: Widely distributed in fresh waters with thickvegetation and breeds freely in confined waters as wellasrivers.Thespeciesisusefulasalarvicidalfishforintroductionintoforestpools,streams,tanks,ditches,etc., overgrown with vegetation for control of malarialvector.Fieldtrials:Naturalhabitats-C.namahasbeenreportedtocontrol the population of An. (C.) culicifacies Giles, 1901;An.(C.)balabacensisbalabacensisBaisas,1926;andAn. (C.) varuna Iyengar, 1924, which, in turn are potentmalarial vectors inhabiting slow moving fresh water17.5. Oryzias melastigma (McClelland), 1839 (Commonname:Estuarinericefish)Size: 4 cm (1.5 inches).Distribution:Widely distributed in Bengal, Orissa andTamil Nadu.Ecology:Itisacarnivorous,surfacefeederfoundinbothstillandrunningwaters.Thoughprimarilyasestuarine and brackish water fish, it is found inhabitingfreshwaterssuchasponds,lakes,rivers,canalsandcreeks, in large number. An excellent larvivorous formsuitable for open shallow water stretches especially inrice fields for control of mosquitoes causing JapeneseBencephalitis.Laboratorytrials:PredationpotentialofO.melastigma(measuring2.4to2.5cm)wasexperimentedinglasscontainers(measuring 2017 20 cm) against IV instar larvaeofAnophelessp.22.StudyonfoursubsequentdaysrevealedthatO.melastigmaconsumed98IVinstarlarvae of Anopheles per day.Fieldtrials:Naturalhabitats-O.melastigmaisapotentiallarvivorousfish controlling the occurrence of JapenseBencephalitisbyrestrictingpopulationsofCx.(C.)vishnui Theobald, 1901. Breeding habitats of the vectorincludericefields,marshes,ponds,pools,streams,ditches,borrowpits,irrigationchannels,fieldwells,rain water in fallow lands18.A field-based experiment was carried out to evaluatethe efficacy of O. melastigma in controlling mosquitobreeding in rice fields22 rich in Anopheles sp. and Culexsp. The rice field was divided into nine quadrates of asquaremetersurfacewith15cmdeepwater.O.melastigma were released in three quadrates each attherateof5fishperquadrate;threequadratesservedascontrol.Larvaldensityineachquadratewasmonitoredonday2,4,6,12,18,24,30,36and42respectively. Percentage reduction in the density of larvaandpupawascalculated.Onday6,O.melastigmalowered the density of III and IV instar larvae and pupaeby 76.2 per cent and on subsequent days the percentagereduction ranged from 98.3 to 100 per cent. From day12 onwards, 100 per cent reduction in larval and pupaldensitieswasrecorded.6. Danio rerio (Hamilton-Buchanan), 1822 (Commonname: Zebra danio)Size: Approx. 5 cm (2 inch)Distribution: All over northern India, Bangladesh; andBurma (now Myanmar).Ecology:Theyaresurfacefeederbothinslowandmovingstreamsandponds,commoninrivuletsatCHANDRA et al: MOSQUITO CONTROL BY FISH 17foothills; also useful for introduction in clear water, slowmoving stream with grassy margins and shallow earthwells, seepages for control of malaria.Laboratorytrials:Alaboratorybasedexperimentonpredationpotential of D. rerio(measuring 2.4 to 2.5 cm) in glasscontainers (measuring 201720 cm) against IV instarlarvae of Anopheles sp. was done.The trial was repeatedonfoursubsequentdaysandtheaveragenumberoflarvaeconsumedperdaybyeachfishwasrecorded.Study revealed that D. rerio consumed 52 fourth instarlarvae of Anopheles per day22.Fieldtrials:Naturalhabitats-Afield-basedexperimenttoevaluate the efficacy of D. rerio in controlling mosquitobreeding in rice fields rich in Anopheles sp. and Culexsp.wascarriedout21.Onday6,D.rerioloweredthedensityofIIIandIVinstarlarvaeandpupaeby86.8percentandonsubsequentdaysthepercentagereduction ranges from 92.4 to 99.3 per cent. From day12 onwards, 100 per cent reduction in larval and pupaldensitieswasrecorded.7.Macropoduscupanus(Valenciennes),1831(Common name: Spiketailed paradise fish)Size: Approximately 7.5 cm (3 inches).Distribution: Eastern India, Sri Lanka, Western Burma(now Myanmar), Malay Peninsula and Sumatra.Ecology: M. cupanus is a good larvivorous fish thrivingboth in fresh and brackish waters of the low lands; alsofoundinditches,paddyfieldsandshallowwaters.Itbreeds freely in stagnant waters and is tolerant to lowcontent or even deficiency of oxygen. It is also suitablefor brackish waters, marshes, lagoons, polluted canalsandditches.Laboratorytrials:Mathavan et al23 carried out an experiment with M.cupanus collected from paddy fields. The collected fishweregroupedintothreeweight(W)classes(80,270and570mgliveweight)andmaintainedinseparateglassaquaria.Theywereacclimatedtolaboratoryconditions (27 1C) and fed ad libitum on the fourthinstarlarvaeofthemosquitoCx.fatigans.Toevokedifferent levels of hunger, individuals of each W classweredeprivedoffoodfor6,9,12,24or48hbeforecommencingthefeedingexperiments.Significantresultswereobtainedwhichprovedthatfishwhendeprived of food for equal duration, a larger individualbecomes hungrier than the smaller ones. Further, preysearching activities of larger individuals increase theirhunger level.Potential exotic larvivorous fish as biocontrol agents1.Carassiusauratus(Linnaeus),1758(Commonname: Gold fish)Size:200-460 mm.Distribution: Naturally found in China, Korea, Taiwan,Japan, Europe, Siberia, East Asia, Campuchia, etc., andintroduced as an aquarium fish in India.Ecology: Aquariums and ornamental ponds.Laboratorytrials:Chatterjeeetal24reportedthebiocontrolefficacyofgoldfishunderexperimentalconditions.Underlaboratoryconditions,oneC.auratuswasallowedtofeedon200IVstagelarvaeofeachofAn.subpictus,Cx.quinquefasciatusandAr.subalbatusinseparatecontainers.Thenumberoflarvaeconsumedwas193,188 and 132 per day respectively.Fieldtrials:Man made habitats - Unused reservoirs:Under fieldconditions, C. auratus efficiently fed upon An. subpictuslarvaeinunusedwaterreservoirsinHooghly,WestBengal24. There was a remarkable reduction in the perdip density of An. subpictus larvae from 34.5 to 0.02.2. Gambusia affinis (Baird & Girard), 1853 (Commonname: Top minnow)Size: Male - 3.5 cm, Female - 6 cm.Distribution: A native of coastal waters of United StatesfromNewJerseysouthwards,introducedintoIndiaabout 40 years ago from Italy and Thailand.Ecology: Found in freshwater, brackish water and saltmarsheswithhighsalinity.Feedonaquaticandterrestrial insects. Terrestrial insects that fall in the watershow preference to mosquito larvae.Laboratorytrials:Chatterjee&Chandra25reportedthebiocontrolefficacyofG.affinisunderexperimentalconditionsinthe laboratory.G. affinis consumed per day 48, 51 and31 larvae of An. subpictus, Cx. quinquefasciatus and Ar.subalbatus respectively. The fish was more active during18 INDIAN J MED RES, JANUARY 200804.00 - 10.00 h. Feeding rate increased with the increaseinpreyandpredatordensities.Feedingratedecreasedwith the increase in water volume (search area).Fieldtrials:Naturalhabitats-Uncultivatedland:Hackett26described the usefulness of the mosquito predatory fishinmalariacontrolprogrammesinEurope.Accordingto him, G. affinis, when employed in an area of about21 km2 on Istrain peninsula, resulted in the reduction inmalaria rates from 98 per cent in 1924 to 10 per cent in1980. In the same way, Menon & Rajagopalan27 studiedon the habitat predation rate and larvivorous potentialityof14speciesoffishfoundinPondicherry(nowPuducherry).Inthisexperiment,eachGambusiafishshowedanaveragepredationrateof65.7perdayonlarvae of An. subpictus. In an experiment conducted bySingaraveluetal28(wheretheystudiedthepredatoryefficiency of G. affinis on the larvae of Ae. aegypti), theroleofpredationwasfoundtobedependentonpreydensity.Marshy areas - G. affinis holbrooki were introducedfromItalyintotheGhazianmarshesduring1922andwere successful in combating malaria29.Man made habitats:Wells-InHyderabadcity,India,anoperationalrelease of G. a. holbrooki in 1967 controlled the breedingof An. stephensi in hundreds of wells in about 2 years30.Casuarinapits-Raoetal31carriedoutastudytoassess the feasibility of controlling mosquito breedingin casuarina pits in four coastal villages of Pondicherry(now Puducherry) using G. affinis. An. subpictus is thepredominant species breeding in the casuarinas pits. Adrasticreductionwasnotedinthenumberofpitbreeding mosquitoes and the maximum control achievedwas about 96 per cent. In the check villages where nofishwasnoticed,thepercentageofpitbreedingmosquitoes ranged from 55.5 to 91.6 per cent.Overhead tanks - Rajnikant et al32 through a seriesofexperiments,showedthatG.affiniswasthebestpredatorofthelarvaeofAn.stephensibreedinginoverheadtanks.Ricefields-G.affinisisthemostwidelyusedspecies in anti-malarial programmes. It has been usedworldwide. G. affinis, when introduced at a rate of 46fish/m2 water surface in the rice fields, brought aboutasharpreductionintheanophelinelarvaldensitiesandvectorbitingrates33.TheexperimentswereperformedintheKundervalleyofAfghanistan.AccordingtothereportofTabibzadehet al34, Gambusia sp. substantially reduced anophelinelarvae in habitats in Iran and contributed to a reductioninmalariatransmissionandwasfoundtobeanimportantcomponentinmalariaeradication.Whenrice fields had been stocked with 250 to 750 G. affinisper hectare, there was a 95 per cent and a 40 per centreduction in the immature density of An. freeborni andAn.pulcherrimusrespectively.Inanalmostsimilarexperimentalsetup,Das&Prasad35evaluatedthemosquito control potential of G. affinis in the rice fieldsin Shahjahanpur district of Uttar Pradesh, India. At astockingrateof5fish/sq.m,G.affinissignificantlyreduced the larval and pupal densities in experimentalfields as compared to control fields during the entireobservationperiodof42days.Controlofmosquitobreedinginricefieldsthroughfishseemedtobepromising.Prasadetal36reportedthatG.affinissurvivedwellinsubmergedricefieldsandprovided87.8 per cent mosquito larval control in Shahajahanpurdistrict, Uttar Pradesh, during 1991. Rajnikant et al31showedthatmosquitofish,G.affiniswasthebestpredatorofthelarvaeofAn.culicifaciesandAn.subpictus breeding in rice fields.3.Poecilia(Lebistes)reticulata(Peters),1859(Common name: Guppy)Size: Male - 2 cm (0.75 inch); Female - 4 cm (1.5 inch).Distribution: It is originally from tropical America. ThenativedistributionincludesTheNetherlands,WestIndies and from Western Venezuela to Guyana. It wasimported to India more than once, and restricted to southIndia and some other parts.Ecology:Poeciliacannottoleratelowtemperature.Aprolificbreederintropicalwatersrequiringatemperaturebetween22and24C,Poecilialivesonartificial food and prefers mosquito larvae. It has beenfound to tolerate pollution more than Gambusia.Laboratorytrials:According to laboratory experiments, an adult anda fingerling of P. reticulata can consume 32 and 18 IVstage An. subpictus larvae in 24 h37.Fieldtrials:Natural habitats - Menon & Rajagopalan27 studiedthe habitat, predation rate and larvivorous potentialityof 14 species of fish found in Pondicherry (Puducherry).CHANDRA et al: MOSQUITO CONTROL BY FISH 19AveragepredationofP.reticulataperdaywas53.1and range of consumption was from 15 to 100.Rice fields - Nalim & Tribuwono38 studied the ricefieldbreedingmosquitoAn.aconitusincentralJavaandtheireffectivecontrolusingP.reticulatathroughcommunityparticipation.Theyalsonoticedasharpdeclineinthenumberofmalarialcasesafterintroductionofeffectivebiocontrolprocedureswithlarvivorousfishes.Man made habitats:Cisterns and washbasins - Sabatinelli et al39 reportedthatinGrandComoreIsland,theindigenousfish,P.reticulata,effectivelysuppressedlarvalandadultpopulation of An.gambiae in washbasins, and cisternsby 85 per cent in a single year using 3-5 fish in a watersurface of 1 m2.Containers-Guptaetal40reportedthatinIndia,P.reticulataeffectivelyreducedthebreedingofAn. stephensi and An. subpictus population breeding incontainers,by86percentusing5-10fishinawatersurface of 1 m2.Drains - Saha et al41 studied on the use of guppy(P.reticulata)asapowerfulbiocontrolagentinthefieldofmosquitoeradication.TheyselectedtwentymosquitobreedingsurfacedrainsintheoutskirtsofKolkata; ten were observed to contain both mosquitolarvaeandguppyfishesandtheremainingtenwereused as control.Per dip larval and pupal densities ofCx.quinquefasciatusvariedremarkablythanthecorrespondingdensitiesinthedrainswithoutguppyfish.Wells-TheroleofP.reticulatainthecontrolofmosquitobreedinginGhaziabaddistrictvillagesnearDelhiwasjudgedbythedensityofimmaturesandlarvivorousfishes;mosquitobreedingwasfoundeffectively controlled in wells provided the fish did notdie or were not prevented from feeding on larvae dueto debris. Guppies survived and multiplied in wells overthe twenty two week period of observations22. Malariawas a major problem in a sericulture area of Karnataka,south India, where An. culicifacies s.l. and An. fluviatiliss.l.wereconsideredtobethemainvectors.Siblingspecies complexes of these two species were analyzedinthreeecologicallydifferentvillages.AmongAn.culicifacies, only sibling species A and B were found.InPuram,avillagewith22wells,speciesApredominated; species B predominated in a village withfour wells and a stream, and in a village with a streamand no wells. P. reticulata fish were introduced into allwells and streams in the villages, and after one year novectors were found in Puram, and all, or nearly all, An.culicifacieswerespeciesBintheothertwovillages.AllAn.fluviatilisbelongedtothesiblingspeciesT.Beforetheintroductionoffish,theannualparasiteincidenceformalariawashighinPuram,butmuchlowerintheothertwovillages.From1998(overoneyear after release of fish) until 2003, no malaria caseswere detected in the three villages42.4.Nothobranchiusguentheri(Pfeffer),(Commonname: Killi fish: Egg laying toothed carp)Size: 7 cm (2.5 inch), females are smaller than males.Distribution:EastAfrica:MombassatothePanganiRiver in Tanzania.Ecology:N. guentheri is a fast growing fish, growingfrom egg to spawning adult in four weeks. Female laysabout 20-100 eggs per day for the whole life which maybe until the pool dries up during the dry season.Fieldtrials:Natural habitats - Vanderplank43 brought into lightthefactthatN.guentheriwasthemostsuitableanti-malaria fish available for use when Panama Canal wasunderconstruction.5.Xenentodoncancila(Hamilton-Buchanan),1822(Common name: Fresh water gar fish)Size: 30 cm (12 inch).Distribution:Pakistan,India,Bangladesh,SriLanka,Burma (now Myanmar) and Thailand.Ecology:Thisisanelegantsurfacelivingfish,whichattains a length of 40 cm TL. In North Bengal, it occursin clear, gravelly, perennial streams and ponds of TeraiandDuars.ItisfairlycommonintheGanga-Brahmaputrasystem.Laboratorytrials:Chatterjee & Chandra44 reported the efficacy of X.cancilaasbiocontrolagentagainstfourthstagelarvalformofAn.subpictus,Cx.quinquefasciatusandAr.subalbatusunderlaboratoryconditions.Itsaverageconsumptionrateduring24hstudyperiodwasappreciable. Three specimens of X. cancila separatelyconsumedanaverageof31,28,21ofAn.subpictus,Cx.quinquefasciatus and Ar. subalbatusrespectivelyduring24 h study period.20 INDIAN J MED RES, JANUARY 20086.(i)Oreochromismossambica(Peters),1852(Common name: Mozambique cichlid, Tilapia)Size:Up to 32 cm (12-13 inch).Distribution: East Africa; an introduced species in India,Pakistan, Sri Lanka, etc.Ecology:O.mossambicagrowsfastandattainsamaximumlargesize(approx.3kg).Itisobservedinwild, but stunting is common in culture. It grows welland reproduces under salinities as high as 35 per cent.Thelowerlethaltemperatureforthisspeciesis10C.O. mossambica is a good candidate for hybridization ifsalinity tolerance is desired in the offspring generation.Fieldtrials:Man made habitats - O. mossambica were effectiveforcontrollingmosquitoesincowdungpits22whenintroduced against III and IV instar larvae and pupae ofCx. quinquefasciatus and An. culicifacies at the rate of5 fish per square meter surface area.(ii)Oreochromisniloticusniloticus(Linnaeus),(Common name: Nile Tilapia)Size: Up to 34 cm (13-14 inch).Distribution: East Africa, West Africa, River Nile.Ecology:O.niloticusniloticusisthefastestgrowingspeciesinmanycountries.Maximumsizeisabout3 kg. It does not tolerate high salinity and has poor coldtolerance.Itishighlysuitableforfarmingintropicalclimate,freshwaterandbrackishwatersystems.Thelower lethal temperature is 12C.Laboratorytrials:Ghoshetal45performedanexperimentandestablished O. n. niloticus as a strong biological agentagainst larval mosquitoes in the laboratory.Fieldtrials:Man made habitats - Under field conditions a studyrevealed a significant decrease in per dip larval densityafter one and half month from introduction of fishes45.Thelarvaldensityagainincreasedsignificantlyafterremoval of fish from mosquito breeding ground. When20 fish were introduced in field conditions, the per diplarval density reduced to 17.38 and 11.39 after 30 and45 days respectively from an initial value of 26.78. Onthecontrary,thelarvaldensityincreasedto21.2and24.37after30and45daysrespectivelyafterremovalof fish.MixedcultureoflarvivorousfishesasbiocontrolagentsIn order to obtain high production per ha of waterbody,fastgrowingcompatiblespeciesoffishofdifferentfeedinghabits,ordifferentweightclassesofthe same species are stocked together in the same pondsothatallitsecologicalnichesareoccupiedbyfish.This system of pond management is called mixed fishfarming or composite fish culture or polyculture.Predationunderco-existencerevealsthesignificance of predatory efficiency of different predatorcombinationswithreferencetopreydensityandexposureperiod.Severalexperimentalsetupswereinitiatedbydifferentresearchersusingamixtureofexoticandindigenousfishandattimesevenbacteriawere included. The main aim was to study the efficacyof such combinations as potential biocontrol agents andthereby control mosquito borne diseases.Laboratorytrials:Ambroseetal46performedapredationexperimentusing Gerris (A) spinolae, Laccotrephes griseus and G.affinis against fourth stage culicine larvae with varyingprey densities. Ranking of individual predatory efficiencyshowedthefollowingsequence:largeGambusia>mediumGambusia>smallGambusia>femaleLaccotrephes > male Laccotrephes > Gerris. Predationunder co-existence revealed the significance of predatoryefficiencyofdifferentpredatorcombinationswithreference to prey density and exposure period.Further Kim et al47 demonstrated biological controlofvectormosquitoes(An.sinensis)bytheuseoffishpredators,MorocooxycephalusandMisgurnusanguillicandatus in the laboratory. A sustained controlwas achieved during the study period. It was Hurstetal48 who first reported the predation efficacy of 7 nativeBrisbane fresh water fish on I and IV instars of the freshwater arbovirus vector Cx. annulirostris when evaluatedinaseriesof24hlaboratorytrials.Thepredatoryefficacyofnativecrimson-spottedrainbowfishMelanotaenia duboulayi (Melanotaeniidae), Australiansmelt Retropinna semoni (Retropinnadae), Pacific blue-eyePseudomugilsignifer(Atherinidae),firetailgudgeonHyposeleotrisgalii(Eleotridae),empiregudgeonHypseleotriscompressa(Eleotridae),andestuary perchlet Ambassis marianus (Ambassidae) wascompared with that of the exotic eastern mosquito fishGambusia holbrooki (Poeciliidae). This environmentallydamaging exotic fish has been disseminated worldwideCHANDRA et al: MOSQUITO CONTROL BY FISH 21andhasbeendeclarednoxiousinQueensland.M.duboulayi was found to consume the greatest numberofbothIandIVinstarsofCx.annulirostris.Thepredation efficacy of the remaining Australian nativespecieswascomparablewiththatoftheexoticG.holbrooki. Later Ghosh et al49 reported that predationexperimentsusingaquariumfishBettasplendens,Pseudotropheus tropheops, Osphronemus gorami andPtereophyllum scalarae were conducted against fourthinstarAnophelesstephensilarvaewithvaryingpreyand predator densities. Ranking of individual efficacyagainst the larval form showed the following sequence:P. tropheops > B. splendens > O. gorami > P. scalarae.The mean larval feeding rates per day of each of thedifferentfishin1literofwaterwere247,238,180and 40 respectively in descending order of predationefficacy. The corresponding feeding rates in 2 liter ofwater were 185, 185, 134 and 30 respectively and werenotstatisticallydifferentwhethertastedindividuallyorinaschoolofsix.PredationexperimentusingC.carpio(Linnaeus1758),Ctenopharyngdonidella(Valenciennes 1844), O. n. niloticus (Linnaeus 1758)andClariasgariepinus(Burchell1822)wereconducted against fourth instar An.stephensi (Liston1901) larvae at varying prey and predator densities50.TherelativeconsumptionratesofthesefourfishspeciesonAn.stephensilarvaeduring24hexperimentsunderlaboratoryconditionswereCl.gariepinus>C.idella>C.carpio>O.n.niloticus.Predatoryefficacywaspositivelyrelatedwithpreydensityandinverselyrelatedwithwatervolumei.e.searcharea.Alaboratory-basedexperimentwasconductedonlarval feeding efficacy of fish against III and IV instarlarvaeofAnopheles,CulexandAedessp.inBHELindustrialcomplex22 where,10fish[5P.reticulata(length 3.00.1 cm) and 5 G. affinis (length 3.50.1cm)]wereplacedinseparateenamelbasins.After30min of introduction of fish, 25 III and IV instar larvaewerelet in andthelarvaeswallowed by fishafter 10,20 and 30 min and every hour up to 6 h were counted.The results of the laboratory studies showed that in thefirst hour, fish were slow in devouring larvae but becamevery voracious later on. P. reticulata consumed 76 larvaein6h,withanaveragelarvivorouspotentialof2.53larvae per hour per fish. On the contrary, G. affinis wassomewhatfastininitialhoursbutsloweddownlaterand consumed only 50 larvae in 6 hrs with an averagelarvivorouscapacityof1.66larvaeperhourperfish.Chatterjee & Chandra37 studied the feeding activity ofthefish,G.affinisandLebistesreticulatusonAn.subpictus larvae in the laboratory. They observed thatthe average larval feeding rate of adult G. affinis and L.reticulatuswas48and32perdayrespectivelyinthelaboratory.Fieldtrials:Naturalhabitats-Ghoshetal50 reportedthatpredation experiment using C. carpio (Linnaeus 1758),Ctenopharyngdonidella(Valenciennes1844),O.n.niloticus(Linnaeus1758)andClariasgariepinus(Burchell1822)wereconductedagainstfourthinstarAn.stephensi(Liston1901)larvae.Asignificantdecreaseinlarvalabundanceindippersampleswasobservedat30and45dayssinceintroductionoffishunderfieldconditions.Theefficacyofthefishunderfieldconditionswasalsoestablishedbysignificantincreaseoflarvalmosquitoabundanceatthe30thandthe45thdaysinceremovaloffishfrommosquitobreedingspots.Willemsetal51reportedthepredationrate of Pseudomugil signifer and G.holbrooki againstfourlarvalinstarsofCx.annulirostris,threepreydensities,andthreevegetationdensities.Insimulatedvegetation trials, P. signifer performed marginally betterthan G. holbrooki in medium to high-density vegetation(0.3 stems/cm2 and 0.6 stems/cm2, respectively).Ricefields-Yu&Lee52studiedthebiologicalcontrolofmalariavector(An.sinensisWied)bythecombined use of larvivorous fish (Aplocheilus latipus)andherbivoroushybridfish(Tilapiamossambicusniloticus)inthericefieldsofKorea.StockingofA.latipus and T. mossambicus in weed infested rice fieldsresulted in an 80-82 per cent reduction in the immaturedensity of An. sinensis from fifth week onwards. Initiallythe reduction in the larval density was in the range of70.8 and 73.5 per cent. Later, Kramer53 tried both fish(G. affinis and Tilapia nilotica nilotica respectively) andBacillus thuringiensis together and found that both thecontrolagentswerecompatibleincontrollingAn.freeborni and An. franciscanus (for the former) and An.gambiae (for the latter) breeding in rice fields. In China,Wu et al54 found that stocking rice paddies with ediblefish(Cyprinuscarpio,Ctenopharyngodonidella,Tilapia spp.) improved rice yield, supported significantfishproduction,andgreatlyreducedthenumberofmalariacasesbyreducingpopulationofAn.sinensiswithin 150-170 days. Wee et al55 studied the advantagesofmosquitocontrolbystockingediblefishinricepaddies. In various field studies conducted in China, itwas found that stocking edible fishviz., C. carpio,C.22 INDIAN J MED RES, JANUARY 2008idellaandTilapiaspeciesattherateof60-800/0.07hectare in rice fields controlled breeding of An. sinensissignificantly,which,inturnwascorrelatedwithdecrease in malarial transmission. Cost - benefit analysisindicatedthatthisapproachprovidedconsiderableeconomicadvantagesandgaveincentivetothecommunity to participate in vector control programmes.Biological control of vector mosquitoes (An. sinensis)was demonstrated by Kimet al47 using fish predators,MorocooxycephalusandMisgurnusanguillicandatusin the semifield rice paddy. A sustained control (53.8 -55.2%)wasachievedduringthestudyperiod.Composite culture of edible fishes in rice fields, resultedin 81 per cent reduction in immature population of An.subpictusandAn.Vagus56.Bellinietal57showedefficacy of various fish species (Carassius auratus, C.carpio, G. affinis) in the control of rice field mosquitoesin northern Italy.Ponds-Chatterjee&Chandra37studiedfeedingactivity of the fish, G. affinis and Lebistes reticulatus onAn. subpictus larvae in field conditions in the Hooghlydistrict,WestBengalandobservedthatlarvaldensitydecreased from 25.7 to 0.36 and 23.7 to 0.5 per dip in thepresence of G.affinis and L. reticulatus respectively.Peridomestichabitats-Integratedcontrolofperidomestic larval habitats of Aedes sp. and Culex sp.was studied58, and mosquito abundance before and aftertreatment with P. reticulata and polystyrene beads wascomparedtotheabundanceinanuntreatedvillage.Entomological indices from human bait collections andlarval surveys indicated that mosquito populations werereducedsignificantlycomparedwithconcurrentsamplesfromtheuntreatedcontrolvillageandthatmosquito control remained effective for 6 months sincetreatment.Man made habitats:Tanks-Martinez-Ibarraetal59 conductedstudiesontheindigenousfishspeciesforthecontrolofAe. aegypti in water storage tanks in Southern Mexico.Five indigenous fish species, Lepisosteus tropicus (Gill),Astyanaxfasciatus(Cuvier),Bryconguatemalensis(Regan),Ictalurusmeridionalis(Gunther)andP.reticulata (Valenciennes) were used as mosquito controlagents.Thestudyrevealedsignificantefficacyofindigenous fish against larval mosquitoes.Ditches - Marti et al60 reported that two neotropicalfish species, Cnesterodon decemmaculatus (Poeciliidae)andJenynsiamultidentata(Anablepidae),werecollected from human made ditches, a common habitatofCx.pipiensinLaPlata,Argentina.C.decemmaculatusandJ.multidentataadultsconsumedIV instar larvae of Cx. pipiens but the consumption ratevaried with prey and predator densities.Eradication ofCx. pipiens from a ditch, where densities had averaged250 immatures per dip, was achieved 17 days after theintroduction of 1700C. decemmaculatus.Openblockeddrain,undergroundtank,effluentponds and cement tanks: A field-based experiment onlarvalfeedingefficacyoffish(P.reticulataandG. affinis) in four different habitats22. P. reticulata wereintroducedinopenblockeddrainsandfactoryunderground tanks, whereas G. affinis were released ineffluent pond and cement tanks in the township.Foursimilarhabitatswereselectedascontrol.Thelarvaldensityofeachhabitatwasmonitoredatweeklyintervals using a 250 ml dipper.Fishattherateofabout50fish/sq.meterwereintroduced. Field studies on the impact of P. reticulataonmosquitobreedingindrainsshowedthatitcancontrolheavyCx.quinquefasciatusbreedinginabout3months,thelarvaldensitybeingreducedfrom145/dipto20/dip.TheimpactofP.reticulatawashighlypronouncedinfactoryundergroundtankssupportingheavybreedingofCulexsp.Therewas100percentelimination of breeding of Culex sp. in about four weeksand no breeding was recorded in subsequent weeks. Ontheotherhand,incaseofG.affinis,breedingwascontrolled up to 90-95 per cent in effluent ponds in about3monthswhereitwasabletocontrol100percentbreeding of An. culicifacies and An. stephensi in about2 wk in cement tank inside township21.In India, uses of larvivorous fish constitute one oftheimportantcomponentsoftheUrbanMalariaSchemes(UMS)andhavebeenincorporatedasanimportant component of selective vector control strategyintheEnhancedMalariaControlProject(EMCP)launched in 1998 with World Bank support in the tribalareas of Gujarat and other parts of the country thoughUMSfacedwithoperationalconstraintsduringapplication61.Duetoemergingthreatofmalariaanddengue in urban areas, Malaria Research Centre (MRC)(nowNationalInstituteofMalariaResearch)FieldStation at Nadiad in collaboration with the AhmedabadMunicipal Corporation took up a demonstration projectonthemanagementofmalariaanddenguevectorsinAhmedabadcity62.ImpactoflarvivorousfishonmosquitobreedingwasassessedbymonitoringtheCHANDRA et al: MOSQUITO CONTROL BY FISH 23larval density before and after the application. The mostcommon mosquito breeding places such as undergroundcementtanks,groundleveltanks,fountains,elevatorchambers(liftwells),wells,millhydranttanks,cattletroughsandpondswereexclusivelymonitored.Ingeneral,asharpreductioninthelarvaldensitieswasobservedinmostofthehabitatsduringthepostapplicationperiod.Experience of the development of larvivorous fishnetworkformosquitocontrolinAhmedabadcitydemonstratedthefeasibilityofusinglarvivorousfishandprovedthatthiscanplayanimportantroleinmosquito control in urban areas provided a systematicandplannedapproachisapplied.Thisstrategywouldbehelpfulincontrollingthere-emergenceofcertainvector-bornediseases,particularlyinurbanareasandwill reduce the dependence on insecticides62.Discussion&ConclusionMosquitoes are and will be the major concerns tocome.Biologicalcontrolisexpectedtoplayanincreasing role in vector management strategies of thefuture. The technology is challenging as well as difficult.Unlikethechemicalpesticides,theresultsareoftenunpredictablewithbiologicalagents.Thiscallsforabetter understanding of the biological interactions withtheenvironment.Developingandacquiringthenecessary skills assume paramount importance. Anotherimportantconsiderationistherecognitionofthefactthat, in developing countries like India, success of suchstrategiesdependsondevelopingsimpletechnologybacked by a campaign of public education. Interventionstargetingvectorsofdiseasesareessentiallythemosteffectivestrategiestocontrolvector-bornediseases.Much of the current efforts directed at the developmentofnewmosquitocontroltoolsareconfinedtothelaboratoryscale63.Onlybiologicalagentscarrythepotential for overcoming such obstacles, and the mostlikelyagentsarethoserepresentedbycloselyrelatedorganisms. Towards this end, we require a programmeof biological research aimed towards understanding thefactors that limit the number of mosquitoes. The searchefficiency of the introduced predator and prey selectivitypatterns of larvivorous organisms need to be exploredby offering mosquito larvae in combination with otheralternatenaturalprey.Thesuccessinmeasuringtheefficacy of the candidate agents depends on a multitudeoffactors:(i)characterizationofnaturalenemycandidatesincludingecological,morphological,taxonomical,orgeneticmarkers;(ii)selectionofclimaticallymatchingcandidates;(iii)evaluationofsemi-field or field cage conditions following quarantineevaluations prior to proceeding with natural release; (iv)assessment of unintended impacts; and (v) the potentialefficacyofexistingindigenousagentsagainstlarvalpopulations.Thetwomainfactorsdeterminingtheefficacyofthe fish are the suitability of the fish species to the waterbodieswherethevectorspeciesbreedandtheabilityofthefishtoeatenoughlarvaeofvectorspeciestoreduce the number of infective bites. The first factor isbestaddressedbyfindinganativefishspeciesthatthrives under the conditions prevalent in breeding sitesratherthantochangebreedingsitestoaccustomthefish, although Wu et al54 have recommended a ditch ridgesystem for rice fields to better accommodate the fish. Ithastobekeptinmindthattheuseofpesticidesandfertilizerscannegativelyinfluencefishstockedinirrigatedfields64.Thesecondfactormaybestronglyinfluencedbyaquaticvegetation,whichinturn,caninterfere with fish feeding and can also provide refugefor the mosquito larvae. The effectiveness of larvivorousfishtocontrolmosquitoesmayvaryduetoenvironmentalcomplexity.Itneedstoevaluatetheefficacyofseveralindigenouslarvivorousfishinseasonal wetlands and larger water bodies and their rolein the trophic cascade from the community view point65.Thereareseveraldisadvantagesofusinglarvivorousfish.Gambusiawhenstockedinwatersoutside their native range, often causes serious negativeecologicalimpacts.Gambusiaisanopportunisticpredator with a highly variable diet that includes algae,zooplankton, aquatic insects, as well as eggs and youngoffishandamphibians.Gracia-Berthou66documenteda diet shift from diatoms to cladocerans to adult insectwith the maturation ofGambusia. They are voraciousand highly aggressive fish that compete with the nativefishverysuccessfullyforviablefoodandspace.Gambusiaessentiallydepletesalllargezooplanktonwhile rotifers and phytoplankton densities increase67,68.Gambusiaalsoconsumesahighpercentageofthephytoplanktongrazers.Theyindirectlycauseadverseecological changes including increased phytoplanktonabundance, higher water temperatures, more dissolvedorganicphosphorousanddecreasedwaterclarity69.Periodicremovalofvegetationmaybeneededtofacilitatetheactivityofthefish70.Intemporaryorephemeralmosquitohabitats,otherformsofcontrolmustbedevelopedasevokingactivecommunityparticipation will be a more difficult task.24 INDIAN J MED RES, JANUARY 2008References1. CollinsLE,BlackwellA.ThebiologyofToxorhynchitesmosquitoes and their potential as biocontrol agents. BiocontrolNews Information 2000;21: 105-16.2. Milam CD, Farris JL, Wilhide JD. Evaluating mosquito controlpesticides for effect on target and non-target organisms. ArchEnviron Contam Toxicol 2000; 39 : 324-8.3. Service MW. Biological control of mosquitoes has it a future?Mosq News 1983; 43 : 113.4. Service MW. Importance of ecology in Aedes aegypti control.Southeast Asian J Trop Med Public Health 1992; 23 : 681-8.5. GratzNG,PalR.Malariavectorcontrol:larviciding.In:WernsdorferWH,McGregorI,editors.Malaria:Principlesandpracticeofmalariology.Edinburgh,UK:ChurchillLivingstone;1988.p.1213-26.6. Mulla MS. Mosquito control investigations with emphasis onintegrationofchemicalandbiologicalcontrolinmosquitoabatement.29thProcPapAnnConCalifMosquitoContrAssoc 1961. p. 1-4.7. RaghavendraK,SubbaraoSK.Chemicalinsecticidesinmalaria vector control in India. ICMR Bull 2002; 32 : 1-7.8. GerberichJB.Updateofannotatedbibliographyofpapersrelatingtocontrolofmosquitoesbytheuseoffishfortheyears1965.Geneva,WorldHealthOrganization,1985(unpublisheddocumentVBC/85.917.9. Waage JK, DJ Greathead. Biological control: challenges andopportunities.Phil Trans R Soc Lond 1988; 318 : 111-28.10. Marten GG, Bordes ES, Nguyen M. Use of cyclopoid copepoidformosquitocontrol.Hydrobiologia1994;292/293:491-6.11. Arthington AH, Lloyd LN. Introduced Poecillidae in AustraliaandNewZealand.In:MeffeGK,SnelsonFF,editors.Evolutionandecologyoflivebearingfishes(Poecillidae),New York: Prentice-Hall; 1989. p. 333-48.12. Arthington AH, Marshall CJ. Diet of the exotic mosquito fishGambusiaholbrookiinanAustralianlakeandpotentialforcompetition with indigenous fish species. Asian Fish Sci 1999;12 : 1-16.13. DenothM,FridL,MyersJH.Multipleagentsinbiologicalcontrol: improving the odds? Biol Control 2002; 24 : 20-30.14. CarlsonJ,KeatingJ,MbogoCM,KahindiS,BeierJC.Ecologicallimitationsonaquaticmosquitopredatorcolonizationintheurbanenvironment.JVectorEcol2004;29 : 331-9.15. Job TJ. An investigation of the nutrition of the perches of theMadras coast. Rec Mind Mus 1940; 42 : 289-364.16. HoraSL,MukherjeeDD.Theabsenceofmillions,Lebistesreticulates(Peters)inIndia.MalariaBureauNo.4,HealthBulletin No.12, Delhi 1938. p. 1-49.17. Ataur-Rahim M. Observations on Aphanius dispar (Ruppell,1828),amosquitolarvivorousfishinRiyadh,SaudiArabia.Ann Trop Med Parasit 1981; 75 : 359-62.18. Manualofentomologicalsurveillanceofvector-bornediseases. Delhi: National Institute of Communicable Diseases;1988.19. LouisJP,AlbertJP.MalariaintheRepublicofDjibouti.Strategyforcontrolusingabiologicalantilarvalcampaign:indigenouslarvivorousfish(Aphaniusdispar)andbacterialtoxins. Med Trop 1988; 48 : 127-31.20. Fletcher M, Teklehaimanot A, Yemane G. Control of mosquitolarvae in the port city of Assam by an indigenous larvivorousfish, Aphanius dispar. Acta Tropica 1992; 52 : 155-66.21. KumarA,SharmaVP,SumodanPK,ThavaselvamD.FieldtrialsofbiolarvicideBacillusthuringiensisvar.israelensisstrain 164 and the larvivorous fish Aplocheilus blocki againstAnopheles stephensiformalariacontrolinGoa,India.J AmMos Control Assoc 1998; 14 : 457-62.22. SharmaVP,GhoshA,editors.LarvivorousFishesofInlandEcosystems. In: Proceedings of the MRC-CICFRI Workshop;1989 Sep 27-28; New Delhi. Malaria Research Centre (ICMR):Delhi;1989.23. MathavanS,MuthukrishnanJ,HeleenalGA.Studiesonpredation on mosquito larvae by the fish Macropodus cupanus.Hydrobiologia1980;75:255-8.24. ChatterjeeSN,DasS,ChandraG.Goldfish(Carrasiusauratus) as a strong larval predator of mosquito. Trans ZoolSoc India 1997; 1 : 112-4.25. ChatterjeeSN,ChandraG.LaboratorytrialsonthefeedingpatternofAnophelessubpictus,CulexquinquefasciatusandArmigeressubalbatuslarvaebyGambusiaaffinis.SciCult1997; 63 : 51-2.26. Hackett LW. Malaria in Europe. An ecological study. London:Oxford University Press; 1937.27. Menon PKB, Rajagopalan PK. Control of mosquito breedingin wells by using Gambusia affinis and Aplocheilus blochii inPondicherry town. Indian J Med Res 1978; 68 : 927-33.28. SingaraveluG,MahalingamS,JayaBharatiK.Predatoryefficiency of larvivorous fish Gambusia affinis on the mosquitolarvaeofAedesaegyptiandAnophelesstephensi.CurrSci1997; 72 : 512-4.29. Tabibzadeh GB, Nakhai R. 1970. Use of Gambusia fish in themalaria eradication programme of Iran. Geneva, World HealthOrganization,(unpublisheddocumentWHO/VBC/70.198).30. SitaramanNL,KarimMA,ReddyGV.ObservationsontheuseofGambusiaaffinisholbrookitocontrolAnophelesstephensibreedinginwells.ResultsoftwoyearsstudyinGreaterHyderabadcity,India.IndianJMedRes1975;63:1509-16.31. RaoBUS,KrishnamoorthyK,ReddyCBS,PanickerKN.Feasibility of mosquito larval control in casuarina pits usingGambusia affinis. Indian J Med Res 1982; 76 : 684-8.32. Rajnikant, Pandey SD, Sharma SK. Role of biological agentsforthecontrolofmosquitobreedinginricefields.IndianJMalariol 1996;33: 209-15.33. Rafatjah HA, Arata AA. 1975. The use of larvivorous fish inantimalaria programmes. Geneva, World Health Organization,(unpublisheddocumentMAL/WP/75.6Rev.1).34. Tabibzadeh I, Behbehani G, Nakhai R. Use of Gambusia affinisasabiologicalagentagainstCulextarsalisandAnophelesfreeborni in Sacramento valley rice fields. Mosq News 1971;32 : 146-52.35. Das MK, Prasad RN. Evaluation of mosquito fish Gambusiaaffinis in the control of mosquito breeding in rice fields. IndianJ Med Res 1991; 72 : 214-7.CHANDRA et al: MOSQUITO CONTROL BY FISH 2536. PrasadH,PrasadRN,HaqS.RoleofbiologicalagentsforthecontrolofmosquitobreedingthroughGambusiaaffinisin rice fields. Indian J Malariol 1993; 30 : 57-65.37. ChatterjeeSN,ChandraG.FeedingpatternofGambusiaaffinis and Lebistes reticulates on Anopheles subpictus larvaein the laboratory and field conditions. J Appl Zool Res 1997;8 : 152-3.38. Nalim S, Tribuwono D. Control demonstration of the rice fieldbreeding mosquito Anopheles aconitus Donitz in central Java,usingPoeciliareticulatathroughcommunityparticipation:2.Culturing,distributionanduseoffishinthefield.BullPenet Kesehatan 1987; 15 : 1-7.39. SabatinelliG,BlanchyS,MajoriG,PapakayM.ImpactdelutilisationsdupoissonlarvivorePoeciliareticulatasurlatransmission du paludisme en RFI des Comores. Ann ParasitolHum Comp 1991; 66 : 84-8.40. GuptaDK,BhattRM,SharmaRC,GautamAS,Rajnikant.Intradomesticmosquitobreedingsourcesandtheirmanagement. Indian J Malariol 1992; 29 : 41-6.41. Saha D, Biswas D, Chatterjee KK, Chandra G, BhattacharyaA,BhattacharyaS,etal.Guppy(Poeceliareticulata)asanaturalpredatorofCulexquinquefasciatuslarvae.BullCalSch Med 1986; 34 : 1-4.42. GhoshSK,TiwariSN,SathyanarayanTS,SampathTR,Sharma VP, Nanda N,et al. Larvivorous fish in wells targetthe malaria vector sibling species of the Anopheles culicifaciescomplexinvillagesinKarnataka,India.TransRSocTropMed Hyg 2005; 99 : 101-5.43. Vanderplank FL. Nothobranchius and Barbus sp: Indigenousantimalarial fish in East Africa. E Afr Med J 1941; 17 : 431-6.44. ChatterjeeSN,ChandraG.LaboratorytrialsonthefeedingpatternofAnophelessubpictus,CulexquinquefasciatusandArmigeressubalbatusbyXenentodoncancilafry.EnvEcol1996; 14 : 173-4.45. Ghosh A, Bhattacharjee I, Chandra G. Biocontrol efficacy byOreochromis niloticus niloticus. J Appl Zool Res2006; 17 :114-6.46. Ambrose T, Mani T, Vincent S, Cyril L, Kumar A, MathewsKT. Biocontrol efficacy of Gerris (A) spinolae, Laccotrephesgriseus and Gambusia affinis on larval mosquitoes.Indian JMalariol 1993;30: 187-92.47. KimHC,KimMS,YuHS.Biologicalcontrolofvectormosquitoes by the use of fish predators, Moroco oxycephalusandMisgurnusanguillicandatusinthelaboratoryandsemifield rive paddy. Korean J Entomol 1994; 24 : 269-84.48. Hurst TP, Brown MD, Kay BH. Laboratory evaluation of thepredationefficacyofnativeAustralianfishonCulexannulirostris (Diptera: Culicidae). Am J Mosq Control Assoc2004; 20: 286-91.49. Ghosh A, Bhattacharjee I, Ganguly M, Mondal S, Chandra G.Efficacy of some common aquarium fishes as biocontrol agentof preadult mosquitoes. Bull Pen Kesh 2004; 32 : 144-9.50. Ghosh A, Mondal S, Bhattacharjee I, Chandra G. Biologicalcontrolofvectormosquitoesbysomecommonexoticfishpredators. Turk J Biol 2005; 29 : 167-71.51. WillemsKJ,CameronEW,RussellRC.Acomparisonofmosquito predation by the fish Pseudomugil signifer Kner andGambusia holbrooki (Girard) in laboratory trials. J Vect Ecol2005; 30 : 87-90.52. YuHS,LeeJH.Biologicalcontrolofmalariavector(AnophelessinensisWied.)bycombineduseoflarvivorousfish(Aplocheiluslatipus)andherbivoroushybrid(Tilapiamossambicusniloticus)inricepaddiesofKorea.KoreanJAppl Entomol 1989; 28 : 229-36.53. Kramer VL. The ecology and biological control of mosquitoes[Culextarsalis,AnophelesfreeborniandAnophelesfranciscanus(Anophelespseudopunctipennisfranciscanus)]inCaliforniawildandwhitericefields(usingBacillusthuringiensisandlarvivorousfish).DissertationAbstractsInternational. Bull Sci Engin 1989; 49 : 4670-B.54. WuN,LiaoG,LiD,LuoY,ZhongG.Theadvantagesofmosquitobiocontrolbystockingediblefishinricepaddies.SoutheastAsianJTropMedPublicHealth1991;22:436-42.55. Wee N, Liao GH, Li DF, Luo YL, Zhong GM.The advantageof mosquito biocontrol by stocking edible fish in rice paddies.Southeast Asian J Trop Med Public Health 1991; 22 : 436-42.56. VictorTJ,ChandrasekaranB,ReubenR.CompositefishcultureformosquitocontrolinricefieldinSouthernIndia.Southeast Asian J Trop Med Public Health 1994; 25 : 522-7.57. BelliniR,VeronesiR,RizzoliM.EfficacyofvariousfishspeciesCarassiusauratus(L.),Cyprinuscarpio(L.),Gambusia affinis (Baird and Girard) in the control of rice fieldmosquitoes in Northern Italy. Bull Soc Vector Ecol 1994; 19 :87-99.58. Lardeux F, Sechan Y, Loncke S, Deparis X, Cheffort J, FaaruiaM. Integrated control of peridomestic larval habitats of AedesandCulexmosquitoes(Diptera:Culicidae)inAtollvillagesof French Polynesia. J Med Entomol 2002; 39 : 493-8.59. Martinez-IbarraJA,GuillenYG,Arredondo-JimenezJI,Rodrigu-LopezMH.Indigenousfishspeciesforthecontrolof Aedes aegypti in water storage tanks in Southern Mexico.BioControl 2002;47: 481-6.60. Marti GA, Azpelicueta MM,Tranchida MC,Pelizza SA, GarciaJJ. Predation efficiency of indigenous larvivorousfish speciesonCulexpipiiensL.larvae(Diptera:Culicidae)indrainageditches in Argentina. J Vect Ecol 2006; 31 : 102-6.61. PattanayakS,SharmaVP,KalraNL,OrlovVS,SharmaRS.Malaria paradigms in India and control strategies.IndianJ Malariol 1994; 31 : 141-99.62. HaqS,YadavRS.Developinglarvivorousfishnetworkformosquitocontrolinurbanareas:Acasestudy.ICMRBull2003; 33 : 69-73.63. SpielmanA,KitronU,PollackRJ.Timelimitationandtherole of research in the worldwide attempt to eradicate malaria.J Med Entomol 1993; 30 : 6-19.64. LaceyLA,LaceyCM.Themedicalimportanceorricelandmosquitoesandtheircontrolusingalternativestochemicalinsecticides. J Am Mos Control Assoc 1990; 6 (Suppl) : 1-93.65. Blaustein L, Chase JM. Interactions between mosquito larvaeand species that share the same trophic level. Ann Rev Entomol2007;52: 489-507.26 INDIAN J MED RES, JANUARY 200866. Garcia-BerthouE.Foodofintroducedmosquitofish:ontogenetic diet shift and prey selection. J Fish Biol 1999; 55:135-47.67. Hurlbert SH, Mulla MS. Impacts of mosquitofish (Gambusiaaffinis)predationonplanktoncommunities.Hydrobiologia1981; 83: 125-51.68. Bence JR. Indirect effects and biological control of mosquitoesby mosquitofish. J Appl Ecol 1988; 25 : 505-21.Reprintrequests: DrGoutamChandra,Professor&FormerHead,DepartmentofZoology,MosquitoResearchUnitParasitologyResearchLaboratory,UniversityofBurdwan,Burdwan713104,Indiae-mail:goutamchandra63@yahoo.co.in69. Hurlbert SH, Zedler J, Fairbanks D. Ecosystem alteration bymosquitofish(Gambusiaaffinis)predation.Science1972;175 : 639-41.70. Dua VK, Sharma SK. Use of guppy and gambusia fishes forcontrolofmosquitobreedingatBHELindustrialcomplex,Hardwar (U.P.). In: Sharma VP, Ghosh A, editors, Larvivorousfishes of inland ecosystems. Delhi: Malaria Research Centre;1994.p.35-42.CHANDRA et al: MOSQUITO CONTROL BY FISH 27