Biological control of citrus leafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae) in Southwest Florida

112 Pages·1999·3.8 MB·English

by  Pomerinke, Mark Allen

BIOLOGICALCONTROLOFCITRUSLEAFMINER,
PHYLLOCNISTISCITRELLA(LEPIDOPTERA:GRACILLARIIDAE)
INSOUTHWESTFLORIDA
By
MARKALLENPOMERINKE
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1999
Idedicatemydissertationtomywife,Tracy,andmyparents,DaveandBetty
Pomerinke. Withouttheirencouragementandsupportthisstudywouldnothavebeen
completed.
ACKNOWLEDGMENTS
Iwouldliketoacknowledgetheassistanceprovidedtomebythecitrusgrowersin
southwestFlorida. Theyprovidedmeaccesstotheirgroves,helpandequipmentto
conductmyresearch. Withouttheircooperationthisstudycouldnothavebeen
accomplished. 1thankalltheemployeesoftheEntomologysectionatSouthwestFlorida
ResearchandEducationCenterinImmokalee. Theyprovidedmewithassistanceand
supportforthisstudywhenasked,eventhoughtheyhadotherduties. IthankDr.Carmen
ArteagaofFloridaGulfCoastUniversityforhelpingmewiththestatistics. Iacknowledge
thesupportandassistanceofmycommittee. Theiradviceandsuggestionsgiventome
duringthisstudywhereinvaluable. PhilipRucksprovidedthecitrustreesusedinthis
study. Finally,Ithankmyadviser.Dr.PhilipStansly. Hespentmanyhoursreadingand
re-readingdraftsofthisdissertation,eachtimegivingsuggestionstoimprovemythinking
andwriting. Withouthishelpandguidancethefinalversionofthisdissertationwouldnot
havebeenpossible.
iii
TABLEOFCONTENTS
ACKNOWLEDGMENTS
iii
ABSTRACT vi
CHAPTERS
INTRODUCTION
1 1
2 RELEASEANDESTABLISHMENTOFAGENIASPISCITRICOLA
(HYMENOPTERA:ENCYRTIDAE) 4
Introduction 4
MaterialsandMethods 5
EstablishmentandApparentParasitism 6
Dispersal 7
OrchardStructure 8
Weather 8
Results 8
Weather 8
Establishment 9
ApparentParasitism 10
OrchardStructure 11
Dispersal 12
Discussion 12
3 IDENTIFICATIONANDEFFECTOFMORTALITYFACTORSON
PHYLLOCNISTISCITRELLA(LEPIDOPTERA:GRACILLARIIDAE) 25
Introduction 25
MaterialsandMethods 28
1994Cohorts 28
1996and1997Cohorts 29
CohortPreparation 29
iv
MortalityTypes 31
SurvivorshipCurves 33
Results 34
1994PreliminaryCohortStudy 34
1996and1997Cohorts 35
MoralityTypeandOccurrence 36
SurvivorshipCurves 42
Discussion 43
4 INCIDENCEOFNATURALENEMYCOMPONENTSAND
THEEFFECTOFGROVESTRUCTURE 64
Introduction 64
MaterialsandMethods 67
Results 70
ExclusionStudy 70
LocationComparisons 70
BlockHeightComparisons 71
Discussion 72
5 CONCLUDINGREMARKS 81
Summary 81
StudyModifications 82
FutureStudies 83
APPENDIXLIFEEXPECTANCYTABLESFOROBSERVEDCOHORTSIN1994,
1996AND1997 86
REFERENCESCITED 95
BIOGRAPHICALSKETCH 103
V
AbstractofDissertationPresentedtotheGraduateSchool
oftheUniversityofFloridainPartialFulfillmentofthe
RequirementsfortheDegreeofDoctorofPhilosophy
BIOLOGICALCONTROLOFCITRUSLEAFMINER,
PHYLLOCNISTISCITRELLA(LEPIDOPTERA:GRACILLARIIDAE)
INSOUTHWESTFLORIDA
By
MarkAllenPomerinke
May1999
Chairperson:Dr.PhilipA.Stansly
MajorDepartment:EntomologyandNematology
Citrusleafminer(CLM){PhyllocnistiscitrellaStainton)wasfirstdetectedin
FloridainMay1993. InMay1994,theparasitoidy4gert/a5/?wd/nco/a(Hymenoptera:
Encyrtidae)wasintroducedintosouthwestFloridaasaclassicalbiologicalcontrolagent
forcontrolofCLM.
A.citricolawasreleasedat52sitesinsouthwestFloridafromMay1994to
September1995. Fourreleasesitesweremonitoredmonthlyfrom1994to1996to
confirmestablishment. Dispersalwasdocumentedbysurveyingsurroundingcitrus
orchardsaroundthesefoursitesforthepresenceofA.citricola. Mortalityfactorsof
CLMweredeterminedbyexaminingcohortsplacedatthreedifferentorchardsin1996
vi
and1997. Cohortswereobserveddaily,andthedevelopmentalstageofeachCLM
determined. DeadCLMwereclassifiedashavingdiedfromparasitism,predationor
abioticfactors. Survivorshipcurvesweredevelopedtobetterunderstandwhichformof
mortalitywasprevalentandwhen. In1997,theeffectofgroveheightonmortalityfactors
ofCLMwasexamined. Oneorchardofshort,mediumandtallheighttreesdividedinto3
blockseachwasused. Fourpottedplants,twocagedandtwouncaged,wereplacedin
eachorchardmonthly. Numberofdead,alongwithcauseofdeath,andsurvivingCLM
werecataloged. SiteswerecomparedtodetermineiftreeheightinfluencedCLM
survivorshipormortalityfactors.
Establishmentwasconfirmedinspring,1995. Parasitismfrom^^.citricola
increasedfrom2%inMay1994to86%inOctober1995,whileparasitismbyindigenous
parasitoidsfellfrom18%to2%duringthesameperiod. A.citricoladispersedinall
directionswithamaximumrecordeddispersaldistanceof48km. Fiveparasitoidspecies
werecollectedduringthestudy,theintroducedparasitoid,A.citricola,andfour
indigenousparasitoids. A.citricolawasthemostabundantparasitoidcollectedin1996
and1997. Pnigaliominio(Hymenoptera:Eulophidae)wasthemostabundantindigenous
parasitoidcollected. PredationhadthegreatestimpactonCLMsurvival. Antswerethe
mostprevalentpredatorobservedduringthestudy. Undefinedmortality("heatstress")
occurredinfirstandsecondinstarsandwasthoughttobetheresultofhightemperatures.
SurvivorshipcurvesshowedthatA.citricola'sgreatestcontributiontoCLMmortality
occurredinOctoberandNovember. CLMsurvivalwashigherinshorttrees,whileA.
viii
citricolarecoverywasgreatestintalltrees. Treeheightdidnotinfluencerecoveriesof
indigenousparasitoidsorpredators.
CHAPTER
1
INTRODUCTION
Citrusspp.(familyRutaceae)wereprobablyintroducedintoFloridabySpaniards
atSt.Augustinein1565(Jackson1991). Citrusplantingsoriginallywerelimitedtothe
eastcoast,anditwasnotuntilFloridawascededtoEnglandin1763thatcommercein
orangesincreased. AccordingtoJackson(1991)thefirstbigexpansionincitrus
productionoccurredinthe1870sasgrowersrealizedthesizeofthepotentialcitrus
marketforFlorida. Since1894freezeshavecausedthecitrusindustrytomovesouth.
Today,southwestFloridahasapproximately179,093acresofcitrus,20%ofthestate's
totalacreage(CommercialCitrusInventory1996).
ThefirstdamagingcitruspesttoarriveinFloridawasthelongscale,Insulaspis
(Lepidosaphes)gloverii(Pack.)in1838,andfrom1840to1870,itcausedseriousdecline
incitrusproduction. SincethenaseriesofpestsinvadedFlorida. Thecottony-cushion
scale,IceryapurchasiMask.,wasintroducedintoFloridainthe1800s. Damagetocitrus
treesfromcottony-cushionscalewasfinallybroughtundercontrolbyintroductionofthe
vedalialadybeetle,Rodoliacardinalis(Muls.)(Browning1994). Priorto1960themost
damaginginsectpestofcitruswasthepurplescaleLepidosaphesbeckii(Newman). In
1958aparasiticwaspAphytislepidosaphes(Compere),wasdiscoverednearFt.Pierce,
Florida. Today,thepurplescaleisunderexcellentbiologicalcontrol,andisnolonger
1
2
consideredaseriouspest(Knapp1991). ThestoryofFloridaredscaleChrysomphalus
aonidum(L.)issimilartothatofpurplescale,aseriouspestofcitrusuntilthe1960s,
whentheparasiticwaspAphytisholoxanthus(DeBach)wasintroducedforbiological
control. Floridaredscaleisnowconsideredaninfrequentpest(Knapp1991). Other
pestsofcitrusincludedCaribbeanblackscale,Saissetianeglecta(DeLotta),thegreen
citrusaphid,Aphiscitricola(VanderGoot),blackcitrusaphid,Toxopteraaurantii
(Pons.),citruswhitefly.Dialeurodescitri(Ashmead),andcitrusblackfly,Aleurocanthus
woglumi(Ashby). Mostofthesepestscauselittledamagetocitrusduetointroductionof
naturalenemiesinclassicalbiologicalcontrolprograms. Withinthelastfiveyears,three
morepestsofcitrushavebeenfoundinFlorida. Theyincludetherecentlyarrivedcitrus
psylla,DiaphorinacitriKuwayama,thebrowncitrusaphid,Toxopteracitricida(Kirk.),
andthecitrusleafminer.PhyllocnistiscitrellaStainton. Itwasthediscoveryofcitrus
leafminerinFloridathatinitiatedthisstudy.
ThecitrusleafminerarrivedinFloridainMay1993(Heppner1993). Itquickly
spreadacrossthestateandwithinsixmonthswasfoundinallcitrus-growingregions.
Threestepsweretakentoreducedamagefromcitrusleafmmer. Thefirstwasan
economicassessmentofthedamage. Thesecondwasacombinationofculturaland
chemicalcontrolsforshorttermcontrolandclassicalbiologicalcontrolwouldbe
attemptedasaneconomicalandenvironmentally-soundlongtermsolution(Knappetal.
1995). Atthetimeitwasalsoconcludedthatrelyingsolelyonchemicalcontrolwouldbe
ineffective,costlyandcouldresultindisruptionofexistingintegratedpestmanagement
programs(Knappetal.1995). Itwasdecidedthatanintroducednaturalenemywouldbe