BC cover final:Layout 1 2/1/08 11:02 AM Page I A3842 Biological control of insects and mites An introduction to beneficial natural enemies and their use in pest management DanielL.Mahr PaulWhitaker NinoRidgway BC cover final:Layout 1 2/1/08 11:02 AM Page II BC 1-5:Layout 1 1/31/08 5:07 PM Page I Biological control of insects and mites An introduction to beneficial natural enemies and their use in pest management BC 1-5:Layout 1 1/31/08 5:07 PM Page II preface Why use biological control? Biologicalcontrolrepresentsonealterna- S tivetotheuseofinsecticides.Biological incethelate1940s,insectcontrolhas controlistheconscioususeoflivingbenefi- reliedheavilyonsyntheticchemical cialorganisms,callednaturalenemies,for insecticides.Insecticidesarerelatively thecontrolofpests.Virtuallyallpestshave easytouseandhavegenerallyprovided naturalenemiesandappropriatemanage- safeandeffectivepestcontrol.Theywill mentofnaturalenemiescaneffectively certainlycontinuetobeacomponentof controlmanypests.Althoughbiological mostpestmanagementprograms.Many controlwillnotcontrolallpestsallofthe newerpesticidesmadeavailableinthe time,itshouldbethefoundationofanap- pastdecadeorsoaremoreselectiveand proachcalledintegratedpestmanagement, lesshazardousthanmostoftheoldercom- whichcombinesavarietyofpestcontrol pounds.Nevertheless,mostinsecticides methods.Biologicalcontrolcanbeeffective, haveatleastsomeoftheseundesirableat- economical,andsafe,anditshouldbemore tributes:theyusuallypresentsomedegree widelyusedthanitistoday. ofhazardtotheapplicatorandotherpeo- plewhomaycomeincontactwiththem; Why this publication? theycanleaveresiduesthatsomefindun- Biologicalcontrolreliesonlivingorganisms acceptable;theycancontaminatesoiland thatmusthavefoodandshelterandthatin- waterandaffectwildlife,aquaticlife,and teractwiththepests,thecrop,andotheren- othernontargetorganisms;theycaninter- vironmentalfactors.Thepestmanager(a ferewithbeneficialorganisms,suchaspol- farmer,cropconsultant,orgardener)should linatinginsectsandthenaturalenemiesof beabletorecognizeimportantnaturalene- pests;andinsectscandevelopresistanceto mies,understandtheirneeds,andknow insecticides,effectivelyeliminatingthose howtomaximizetheireffectiveness.Thisre- materialsaspestmanagementoptions.In quiresdifferentknowledgeandskillsthan addition,organicstandardspreventthe areneededforchemicalcontrol.Agoodun- smallbutrapidlygrowingnumberofor- derstandingoftherelationshipsbetween ganicgrowersandprocessorsfromusing pests,theirnaturalenemies,andtheenvi- syntheticchemicals.Forthesereasons, ronmentisessentialforsuccessinbiological manyfarmersandgardenersareexploring control.Theneedforthistypeofknowledge andadoptingmethodsthatreducepesti- istherationaleforthispublication. cideuse. II BC 1-5:Layout 1 1/31/08 5:07 PM Page III Thispublicationprovidesanintroduction Theremainderofthepublicationdiscusses Thefirsteditionofthispublication,now tothebiologicalcontrolofpestinsectsand thethreebroadapproachestobiological outofprint,wasprintedin1993.Inthein- mites.Becausesuccessfulbiologicalcontrol controlofinsects:findingnewusefulnatu- terveningyearstherehavebeenmanynew reliesonknowledgeofpestsandtheirnat- ralenemies,enhancingtheeffectivenessof developmentsinbiologicalcontrol,includ- uralenemies,weincludebasicbiological naturalenemiesbyprotectingthemfrom ingthearrivalofnewpestssuchassoy- informationoninsectsanddiscusshowin- harmandprovidingthemwithnecessary beanaphid,thedevelopmentofnew sectsbecomepests.Wealsodiscussbiolog- habitatandotherresources,andreleasing classesofinsecticidesthatarelessharmful icalcontrolinthecontextofotherformsof additionalnaturalenemieswhenthose tobeneficialnaturalenemies,andthepro- pestcontrol,examiningtheroleoftheen- naturallypresentarenotadequate. ductionofnewresourcematerialsavailable vironmentinsuppressingpests(natural tofarmers,foresters,andgardeners.The Numerousbooksandthousandsofscien- control),aswellasthevariousgeneral originalauthors(MahrandRidgway)thank tificandnontechnicalarticleshavebeen methodsforcontrollinginsects. MichelleMiller,CenterforIntegrated writtenonthissubject.Thispublicationis AgriculturalSystems,Collegeof Amajorportionofthepublicationisde- notanencyclopedicsummaryofallthisin- AgriculturalandLifeSciences,Universityof votedtoasurveyofnaturalenemies.There formation.Instead,wehopethisoverview Wisconsin–Madison,forherdedicationto arehundredsofimportantnaturalenemies stimulatesyoutoseekadditionalinforma- theproductionofthisrevisededition,and intheNorthCentralUnitedStates,anditis tionontheuseofnaturalenemiesforyour Dr.PaulWhitaker,DepartmentofBiological impracticaltocoveralloftheminthispub- specificpestcontrolneeds.Additional Sciences,UniversityofWisconsin– lication.Instead,weprovideexamplesfrom ExtensionresourcesrelevanttotheNorth MarathonCounty,forresearchingandwrit- themorecommongroupsofinsectpreda- Centralstatesincludebiologicalcontrol ingthenewmaterial. tors,parasiticinsects,insect-parasiticne- publicationsonpestsofcabbageandre- matodes,andinsectpathogens.Weinclude latedcrops(NCR471)andgreenhousecrops Ihopethispublicationhelpsyouplanand numerousphotographstohelpyourecog- (NCR531)producedbytheUniversityof conductsuccessfulbiologicalcontrol. nizethesebeneficialorganismsandsug- Wisconsin,andpestsoffieldcrops(E-2721), DanielL.Mahr,Coordinator gestseveralsourcesoffurtherinformation forests(E-2679),andhomegardens(E-2719) ExtensionBiologicalControlPrograms andimages. producedbyMichiganStateUniversity. DepartmentofEntomology UniversityofWisconsin-Madison January2008 III BC 1-5:Layout 1 1/31/08 5:07 PM Page IV B I O L O G I C A L C O N T R O L O F I N S E C T S A N D M I T E S acknowledgements Thispublicationwasfunded,inpart,by tion.Wealsothanktheseveralpeoplewho UniversityofWisconsin-Extension,the suppliedexcellentphotographsthatwewere WisconsinInstituteofSustainableAgriculture unabletouse.Additionally,wewouldliketo oftheUniversityofWisconsin–Madison,the thankKerryKatovich,SusanMahr,Steve UniversityofWisconsin–MarathonCounty, Mroczkiewicz,KenRaffa,KammySchell,Mike andtheNorthCentralRegionSustainable Strand,DaveHogg,andMerrittSingleton,all AgricultureResearchandEducation(SARE) oftheDepartmentofEntomology,University programoftheUnitedStatesDepartmentof ofWisconsin–Madison,forprovidinglivingin- Agriculture,CooperativeExtensionService. sectsforphotographicpurposes.Weappreci- Thefirsteditionofthispublicationwassub- atetheloanofmuseumspecimensbySteven stantiallyfundedbyagrantfromthe KrauthfromtheInsectResearchCollection, PesticideImpactAssessmentProgramofthe DepartmentofEntomology,Universityof UnitedStatesDepartmentofAgriculture’s Wisconsin–Madison,forillustrationpurposes. CooperativeExtensionService(nowthe Commercialnaturalenemieswerekindlypro- CooperativeStateResearch,Education,and videdforphotographicpurposesbyApplied ExtensionService). BionomicsLtd.,Sidney,BC;GardensAlive!, Lawrenceburg,IN;IPMLaboratories,Inc., Wethank11reviewersfortheirinsightful Locke,NY;andBiotactics,Romoland,CA. commentsandsuggestionsonthissecond edition.TheyarefarmersDanSpecht,Harry WearegratefultoDianaBuddeoftheart Hoch,LindaGrice,LindaHalley,KevinShelley, departmentattheUniversityofWisconsin– andSandraWhitney;andresearchersDoug MarathonCountyandartstudentAbigail Landis,MichiganStateUniversity;Mike Guzinskiforcreatingallofthelinedrawings Hogan,OhioStateUniversity–Extension;Rick inthispublicationonrelativelyshortnotice. Weinzierl,UniversityofIllinoisatChampaign- A N O T E A B O U T Weacknowledgewithgratitudethesupport, Urbana;BobWright,UniversityofNebraska– S C I E N T I F I C N A M E S encouragement,andpatienceofcolleagues Mostnaturalenemiesdonothave Lincoln;andCliffSadof,PurdueUniversity.We withintheDepartmentofEntomologyand commonnames.Therefore,weuse alsothankMimiBroeske,NutrientandPest theWisconsinInstituteofSustainable ManagementProgram,Universityof scientificnamesthroughoutthe AgricultureattheUniversityofWisconsin– Wisconsin–Madison,forsuggestionsoncon- publication.Thesectionentitled Madison,andmembersoftheNorthCentral tent.AndwethankTomKalb,KenoshaCounty “Classification”onpage8provides RegionalCommitteeontheBiologicalControl CooperativeExtensionOffice,Kenosha, anexplanationofthenatureand ofPestArthropods(NCR125),fortheirworkto Wisconsin;SusanMahr,Universityof useofscientificnames. bringthefirstandsecondeditionstofruition. Wisconsin–Madison;andRickWeinzierland Theauthorsofthefirsteditionacknowledge BobWrightforreviewingandprovidingcom- T E R M S I N B O L D F A C E theencouragementandsupportofMichelle mentsonthefirstversionofthemanuscript. Importanttermsareprintedin Millerforthisrevisededition,andtheauthor- TheanonymousreviewsofNorthCentral boldfacewheretheyfirstappearin shipofPaulWhitakerfortheexpandedand StatesExtensionentomologistswerealso thetextandaredefinedinthe updatedtext. appreciated. Glossary(pages103–105). Thecreativity,hardwork,andgoodhumorof Thispublicationwouldbemuchlessuseful theCooperativeExtensionPublicationsUnit withoutthemanyexcellentphotographsof MM 10 20 30 40 oftheUniversityofWisconsin-Extension,es- naturalenemiesthatweresuppliedbyseveral peciallyLindaDeithandSusanAnderson,is people.Thecontributorsforeachphotograph deeplyappreciated. INCH 1 areacknowledgedattheendofthepublica- IV BC 1-5:Layout 1 1/31/08 5:07 PM Page V contents 1 Whatisbiologicalcontrol? . . . . 1 5 Otherapproaches ORDER DIPTERA: Overview . . . . . . . . . . . . . . . 1 toinsectpestcontrol. . . . . . 21 Flies,gnats,midges,andothers. . . 38 Typesofnaturalenemies . . . . . . . 2 Culturalcontrols . . . . . . . . . . . 21 (cid:1) FamilyCecidomyiidae: Gallmidges . . . . . . . . . . 38 Host-plantresistance. . . . . . . . . 22 2 Thebiologyofinsects. . . . . . . 4 (cid:1) FamilySyrphidae:Hoverflies . 39 Physicalcontrols . . . . . . . . . . . 22 Insectgrowthanddevelopment. . . . 4 (cid:1) FamilyTachinidae: Mechanicalcontrols . . . . . . . . . 22 Tachinidflies. . . . . . . . . . 40 Reproduction . . . . . . . . . . . . . 6 Chemicalcontrols . . . . . . . . . . 22 (cid:1) Additionalfamiliesofflies . . 41 Theinsectbody . . . . . . . . . . . . 7 Integratedpestmanagement(IPM) . 24 ORDER HYMENOPTERA: Behavior. . . . . . . . . . . . . . . . 8 Wasps,ants,andbees . . . . . . . 42 6 Thenaturalenemiesof Insectecology . . . . . . . . . . . . . 8 (cid:1) FamilyBraconidae: insectpests . . . . . . . . . . 25 Classification . . . . . . . . . . . . . 8 Braconidwasps . . . . . . . . 43 Predatoryandparasiticinsectsand 3 Insectsaspests . . . . . . . . . 10 arachnids. . . . . . . . . . . . . . . 25 (cid:1) FIcahmneiluymIcohnnideuwmasopnsid.ae.:. . . . 44 Typesofcroppests. . . . . . . . . . 10 ORDER MANTODEA: (cid:1) SuperfamilyChalcidoidea: Prayingmantids . . . . . . . . . . 26 Methodoffeeding. . . . . . . . . 10 Chalcidoidwasps . . . . . . . 45 ORDER HEMIPTERA:Truebugs . 26 Feedinglocation. . . . . . . . . . 11 (cid:1) Additionalfamilies Directversusindirectdamage . . . 11 (cid:1) FamilyAnthocoridae: ofparasiticwasps . . . . . . . 47 Minutepiratebugs. . . . . . . 27 Severityandregularityofdamage . 12 (cid:1) FamiliesVespidaeand (cid:1) FamilyMiridae:Plantbugs . . 27 Sphecidae:Stingingwasps . . 48 Plantdiseasetransmission . . . . . 13 (cid:1) FamilyReduviidae:Assassin (cid:1) FamilyFormicidae:Ants . . . 48 Othertypesofpests . . . . . . . . . 13 bugsandambushbugs . . . . 28 CLASS ARACHNIDA:Arachnids . 48 Howinsectsbecomepests . . . . . . 13 (cid:1) FamilyLygaeidae:Seedbugs (cid:1) OrderAraneida:Spiders. . . . 49 Non-nativepests. . . . . . . . . . 13 andbigeyedbugs . . . . . . . 28 (cid:1) OrderOpiliones:Harvestmen . 51 Non-nativecrops . . . . . . . . . 15 (cid:1) FamilyNabidae:Damselbugs. 29 (cid:1) OrderAcari:Mites. . . . . . . 51 Monocultures . . . . . . . . . . . 15 (cid:1) FamilyPentatomidae: Insect-parasiticnematodes. . . . . . 52 Stinkbugs. . . . . . . . . . . 29 Interferencewithnaturalenemy Insectpathogens. . . . . . . . . . . 53 activity . . . . . . . . . . . . . . 15 ORDER COLEOPTERA:Beetles. . 30 Insect-pathogenicviruses . . . . . 54 Pesticideresistance . . . . . . . . 16 (cid:1) FamilyCarabidae: Groundbeetles . . . . . . . . 30 Insect-pathogenicbacteria. . . . . 55 Howtotellifaninsectisapest. . . . 16 Economicsofpestmanagement . . . 17 (cid:1) FamilyCoccinellidae:Lady Insect-pathogenicfungi . . . . . . 56 beetlesorladybirdbeetles. . . 31 Insect-pathogenicprotists . . . . . 57 4 Naturalcontrolofpestinsects . . 18 (cid:1) FamilyStaphylinidae: Vertebratepredators. . . . . . . . . 58 Rovebeetles. . . . . . . . . . 34 Abioticnaturalcontrols . . . . . . . 18 (cid:1) FamilyHisteridae: 7 Implementingbiologicalcontrol: Weather. . . . . . . . . . . . . . 18 Histerbeetles . . . . . . . . . 34 Theintroductionofnon-native Topographyandgeography . . . . 19 (cid:1) Additionalfamiliesofbeetles. 35 naturalenemies. . . . . . . . . 59 Soilconditions. . . . . . . . . . . 19 ORDER NEUROPTERA: Optimumenvironmentalrange Bioticnaturalcontrols . . . . . . . . 19 Lacewings,antlions,andothers. . . 36 ofnaturalenemies . . . . . . . . . . 60 Predators . . . . . . . . . . . . . 19 (cid:1) FamilyChrysopidae: Controlofminorandlocalizedpests. 60 Parasiticinsects . . . . . . . . . . 19 Greenorcommonlacewings. . 36 Increasingthebenefitsof Insect-parasiticnematodes. . . . . 20 (cid:1) FamilyHemerobiidae: non-nativenaturalenemies . . . . . 60 Brownlacewings. . . . . . . . 37 Insectpathogens . . . . . . . . . 20 Generalistsandspecialists . . . . . 20 V BC 1-5:Layout 1 1/31/08 5:07 PM Page VI B I O L O G I C A L C O N T R O L O F I N S E C T S A N D M I T E S — C O N T E N T S 8 Implementingbiologicalcontrol: (cid:1) Minutepiratebugs. . . . . . . 74 10 Implementingbiologicalcontrol: Protectingnaturalenemies . . . 63 (cid:1) Predatoryflies . . . . . . . . . 75 Puttingitalltogether . . . . . . 86 Cropmanagementpractices . . . . . 64 (cid:1) Prayingmantids . . . . . . . . 75 Howdoesbiologicalcontrolfitintoan overallpestmanagementprogram?. 86 Intercropping . . . . . . . . . . . 64 Parasiticinsects . . . . . . . . . . 75 Factorstoconsiderwhenplanning Alternateharvesting. . . . . . . . 64 (cid:1) Trichogramma . . . . . . . . . 75 abiologicalcontrolprogram. . . . . 87 Residuemanagement . . . . . . . 64 (cid:1) Encarsia . . . . . . . . . . . . 76 Effectivenessofthe Providingnaturalenemy (cid:1) Parasitesofcabbagecaterpillars. 76 naturalenemies . . . . . . . . . . 87 requirements. . . . . . . . . . . . . 64 (cid:1) Parasitesofleafminers . . . . . 76 Sustainability . . . . . . . . . . . 87 Habitatprovisionandmanagement 64 (cid:1) Parasitesofstored-grainpests . 76 Safety . . . . . . . . . . . . . . . 87 Hostprovision. . . . . . . . . . . 65 (cid:1) Parasitesoffilthflies . . . . . . 77 Cost. . . . . . . . . . . . . . . . 87 Supplyingnonhostfoods . . . . . 65 Insect-parasiticnematodes. . . . . 77 Environmentalconstraints Reducinginterferencewith Insectpathogensand tosuccess . . . . . . . . . . . . . 88 naturalenemies . . . . . . . . . . . 67 microbialcontrol. . . . . . . . . . 78 Regionaldifferences. . . . . . . . 88 Naturalenemieshavetheirown (cid:1) Bacteria . . . . . . . . . . . . 78 Assessingthesuccessofa naturalenemies . . . . . . . . . . 67 Bacillusthuringiensis . . . . . . 78 biologicalcontrolprogram. . . . . . 89 Culturalpracticescanhinder Bacillussphaericus . . . . . . . 79 Visualfieldcounts . . . . . . . . . 89 naturalenemies . . . . . . . . . . 67 MilkydiseaseofJapanesebeetle 79 Sweeping . . . . . . . . . . . . . 89 Hostplantcharacteristicscan hindernaturalenemies . . . . . . 67 (cid:1) Viruses. . . . . . . . . . . . . 80 Pitfalltraps . . . . . . . . . . . . 89 Pesticidesaffectnaturalenemies (cid:1) Fungi . . . . . . . . . . . . . 80 Yellowstickytraps. . . . . . . . . 90 aswellaspests . . . . . . . . . . 67 (cid:1) Protists . . . . . . . . . . . . 81 Assessingparasitismofplantpests. 90 (cid:1) Summaryofeffectsofmajor Assessingthequalityof Assessingfilthflyparasitism . . . . 90 insecticidegroupsonnatural purchasednaturalenemies . . . . . 81 Thebestadvice:Startsmalland enemies. . . . . . . . . . . . 68 Survival . . . . . . . . . . . . . . 81 learnasyougrow. . . . . . . . . . . 91 (cid:1) Reducingimpactsofpesticides. 69 Vigor . . . . . . . . . . . . . . . 82 Additionalreading . . . . . . . . . . 92 9 Implementingbiologicalcontrol: Quantity. . . . . . . . . . . . . . 82 Theperiodicreleaseofnatural Sexratio. . . . . . . . . . . . . . 82 Appendix1 enemies. . . . . . . . . . . . . 70 Properspecies. . . . . . . . . . . 82 Commonnaturalenemiesofmajor Commonusesofaugmentation . . . 71 Generalconsiderations. . . . . . . 82 insectpestsofimportantcropsin Greenhouses . . . . . . . . . . . 71 Costanalysisofnaturalenemy theNorthCentralUnitedStates . . . 93 Filthflies. . . . . . . . . . . . . . 71 releases. . . . . . . . . . . . . . . . 83 Appendix2 Orchardsandvineyards . . . . . . 71 Approachestodeveloping augmentationprograms. . . . . . . 84 Asimplifiedkeyforidentifying Vegetablesandsmallfruits. . . . . 71 commonnaturalenemies . . . . . . 96 Buyingdirectlyfromasupplier. . . 84 Fieldcrops. . . . . . . . . . . . . 72 Homegardens. . . . . . . . . . . 72 Contractingwithapest Glossary . . . . . . . . . . . . . . . 103 managementconsultant. . . . . . 84 Commerciallyavailable Grower-cooperativesproducing Photographycredits . . . . . . . . . 106 naturalenemies . . . . . . . . . . . 72 naturalenemies . . . . . . . . . . 84 Predatoryinsectsandmites . . . . 73 Augmentationbygovernmental Index . . . . . . . . . . . . . . . . 107 (cid:1) Ladybeetles. . . . . . . . . . 73 agencies. . . . . . . . . . . . . . 84 (cid:1) Lacewings. . . . . . . . . . . 74 Thefutureofaugmentation (cid:1) Predatorymites . . . . . . . . 74 intheUnitedStates . . . . . . . . . 85 (cid:1) Predatorystinkbugs. . . . . . 74 VI BC 1-5:Layout 1 1/31/08 5:07 PM Page 1 1 R E T P A What is biological control? H C Overview are not adequately controlled by exist- ing natural enemies may also be the B iologicalcontrolistheintentional target of classical biological control. manipulationofpopulationsofliving These activities are tightly regulated beneficialorganismsinordertolimit and are conducted solely by federal populationsofpests.Althoughbiological and state agencies, unlike the following controlcanbeusedtocontrolweeds,the two approaches, which can be used by microorganismsthatcauseplantdiseases, anyone. andevensomevertebrates,thispublica- tionfocusesonthebiologicalcontrolofin- (cid:1)(cid:1) Augmentative biological control(or augmentation of natural enemies) typi- sectsandmites.Inthispublication,werefer cally involves the purchase and release tothebeneficialorganismsthatattack of natural enemies that are already pestsasnaturalenemies,thoughyoumay present in the United States but may alsoknowthemas“goodbugs,”beneficial not be numerous enough to ade- insects,orbeneficials.Thenaturalenemies quately control pests in a particular lo- ofinsectsareadiversegroupoforganisms cation. The goal of augmentative thatincludespredators,parasiticinsects, biological control is to temporarily in- nematodes,andvariousmicroorganisms. crease the number of natural enemies Theintentofbiologicalcontrolisnotto and, therefore, the level of biological eradicatepests,buttokeepthemattolera- control of the target pest. blelevelsatwhichtheycausenoapprecia- bleharm.Infact,becausenaturalenemies (cid:1)(cid:1) Conservation biological control(or requiretheirpreyorhostsforsurvival,bio- conservation of natural enemies) im- logicalcontrolworksbestwhenthereisal- proves the effectiveness of natural ene- waysasmallpopulationofpeststosustain mies through farming and gardening theirnaturalenemies.Thisisamajordiffer- practices that provide necessary re- encebetweenbiologicalcontrolandthe sources for their survival and protect useofpesticides. them from toxins and other adverse conditions. These conservation prac- Therearethreebroadapproachestobio- tices will benefit all natural enemies, logicalcontrol: whether they are native, successfully (cid:1)(cid:1) Classicalbiological control(also established through classical biological called importation of natural control, or released for augmentative enemies) involves the importation, biological control. screening, and release of natural ene- These three approaches are discussed in mies to permanently establish effective greater detail in chapters 7–9, but a few natural enemies in new areas. Classical historical examples may help clarify the biological control usually targets intro- three approaches to using natural enemies duced (non-native) pests, most of in biological control. which arrive here without the natural enemies that control their populations in their native lands. Native pests that 1 BC 1-5:Layout 1 1/31/08 5:07 PM Page 2 B I O L O G I C A L C O N T R O L O F I N S E C T S A N D M I T E S — C H A P T E R 1 Many centuries ago, Chinese farmers ob- In the mid-1880s, southern California’s de- Types of natural served that ants were helping to control in- veloping citrus industry experienced devas- enemies sect pests in their citrus orchards by feeding tating losses from an introduced pest called on caterpillars, beetles, and leaf-feeding cottony cushion scale. Growers tried every N atural enemies of insects include bugs. The farmers discovered that collect- available chemical control, even fumigation predators, parasitic insects, nema- ing the papery nests of these ants from with hydrogen cyanide, but nothing pro- todes, and pathogens. Successful ap- trees in the countryside and moving them vided sufficient control; many growers re- plication of all forms of biological control into their orchards improved control of moved their citrus groves because the requires familiarity with these natural ene- some orchard pests. They also provided aer- damage was so serious. After determining mies and their benefits and understanding ial bamboo runways among the citrus trees that the scale insect was native to Australia how they fit into an overall pest manage- to help the ants move easily from tree to and New Zealand, the United States ment program. Although the types of natu- tree. These efforts to increase the numbers Department of Agriculture sent an ento- ral enemies are discussed in more detail in of ants in orchards and to heighten their ef- mologist to that area to look for effective chapters 4 and 6, a brief introduction is ficiency as predators are the first recorded natural enemies. The entomologist found a necessary here. occurrence of biological control of insects. small lady beetle, the vedalia beetle, which Specifically, the movement of ants from the he sent to California. It reproduced rapidly Predatorsmay be insects or other insectiv- countryside into the orchards is an example in infested citrus groves and brought the orous animals, each of which consumes of augmentative biological control. The use cottony cushion scale under complete and many insect preyduring its lifetime. of runways between trees increased the lasting control. This was the first highly Predators are often large, active, and/or ants’ access to prey while keeping them successfulcase of controlling a non-native conspicuous in their behavior, and they are away from potential harm on the orchard pest by introducing its natural enemies therefore more readily recognized than are floor, so this is also an example of conserva- from their native land, a technique now parasites and pathogens. Familiar preda- tion biological control. known as classical or importation biological tors of insects include lady beetles, praying control. mantids, spiders, birds, and bats. Parasitesof insects (also called para- sitoids) are insects that lay their eggs in or Figure 1. The generalized life cycle of a parasitic wasp, as exemplified by an on a hostinsect. When the parasite egg aphid parasite. (A) Wasp lays egg in a host, in this case a young aphid. hatches, the young parasite larva feeds on (B) As host feeds and grows, parasite larva feeds on host and also grows. the host (the pest) and kills it (figure 1). (C) When parasite larva is full grown, it pupates within the host, which is now Usually that one host is sufficient to feed dead. (D) The parasite pupa transforms into an adult wasp, which emerges the immature parasite until it becomes an from the host. After mating, the young wasp seeks new hosts to parasitize. adult. Many parasites are host-specific, meaning they attack only one or at most a few closely related speciesof host. No in- B sect parasites are harmful to humans or other vertebrates. Although very common, they are not well known because of their small size. One of the smallest, Trichogramma, is only about the size of the A period at the end of this sentence. C D 2