Behavioral and perceptual study of cat flea larvae, Ctenocephalides felis, and their responses to various stimuli

298 Pages·1997·10.5 MB·English

by  Dykstra, Thomas Matthew

ABEHAVIORALANDPERCEPTUALSTUDYOF
CATFLEALARWAE,Ctenocephalidesfelis.AND
THEIRRESPONSESTOVARIOUSSTIMULI
By
THOMASMATTHEWDYKSTRA
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1997
ThisdissertationisdedicatedtotheAngelsweknowas'Guardians'.
ACKNOWLEDGMENTS
MyprayerfulthanksmustfirstextendtoMr.RichardFox. Hissupportboth
duringandaftermydoctoraldegreeleavemethankfulthatGodhasplacedhimintothis
world.
Mycommitteemembershavebeenuncharacteristicallyhelpfulintheir
suggestions,theiradvice,andmostimportantlytheirdiscussions. Theyhavehelpedme
toreachascientificlevelofinquirythatIwouldhavebeenotherwiseunabletoreach.
AspecialnoteofthanksmustextendtoDr.PhilCallahanwhotookmeunderhis
guidanceandtoleratedmuchonmybehalf. Hehassuppliedmewithdozensofbooksto
read,aswellashundredsofreferencematerialsfromhisownextensivelibrary. Hehas
graciouslyofferedhisownlaboratorj'spaceformybenefit,andisalwayslendingmean
earformyquestions. Hisknowledgeoftheworld,especiallyphysicsandentomology,
hasbeenacontinuousfountainwherebyIaskforacupful,buthedrawsformea
bucketful. Ourweeklyluncheons,ourout-of-statetripstogether,andourmomentsof
prayerwithhiswife,Winnie,willforeverbyetchedintomysoul. Itismyhopethat
somedayImaybeworthyenoughtountiehissandalstrap.
HI
TABLEOFCONTENTS
ACKNOWLEDGMENTS
iii
ABSTRACT vi
CHAPTERS
INTRODUCTION
1 1
2 LITERATUREREVIEW1-GENERAL 6
InsectAntennae:anOverview 6
InsectAntennaeasPossibleElectromagneticReceivers 11
AntennalVariety 19
InsectSensilla:anOverview 21
AntennaeFundamentals 25
CouplingandArrays 31
DielectricWaveguides 33
InsectSensillaandRadiationDetection 36
PiezoelectricandPyroelectricPropertiesofInsectCuticle 42
DielectricAntennae:PossibleFunctioninInsects 46
ScatterSurfaces 50
Electromagnetics:anOverview 56
AnimalPerception 62
DetectionofElectromagneticFieldsbyInsects 66
ResponseofInsectstoElectromagneticFields 72
Electricalfields 78
Magneticfields 82
Termitebiofields 86
Magneticfielddetection 89
Molecularemissions 96
3 LITERATUREREVIEW2-FLEAS Ill
EcologyofFleas Ill
TheCatFlea 121
iv
1
4 MATERIALSANDMETHODS 125
FleaColony 125
ExperimentalConditions 127
DataAcquisition 129
HeightExperiments 132
ElectromagneticFieldExperiment 133
MagnetExperiments 133
FanExperiments 135
CompetingHumanStimuli 135
StatisticalAnalysis 136
ExternalMorphology 138
5 PILOTEXPERIMENTS 139
Introduction 139
TheExperiments 140
Conclusions 147
6 RESULTS 149
MiscellaneousExperiments 149
HeightExperiments 149
NumberExperiments 150
MagneticExperiments 151
Magnet1 Experiments 153
FanExperiments 154
BreakdownData 154
ElectromagneticFieldExperiment 156
CompetingHumanStimuli 158
ExternalMorphology 158
GrossAnatomy 158
ElectronMicrographs 159
7 DISCUSSION 212
TheAntennae 215
BodySetae 22
Scattering 226
MolecularEmissions 228
FleasandElectromagnetism 229
APPENDIX-ADDITIONALBREAKDOWNDATA 231
REFERENCES 264
BIOGRAPHICALSKETCH 289
AbstractofDissertationPresentedtotheGraduateSchool
oftheUniversityofFloridainPartialFulfillmentofthe
RequirementsfortheDegreeofDoctorofPhilosophy
ABEHAVIORALANDPERCEPTUALSTUDYOF
CATFLEALARVAE,Ctenocephalidesfelis,AND
THEIRRESPONSESTOVARIOUSSTIMULI
By
ThomasMatthewDykstra
December1997
Chairman:Dr.PhilipS.Callahan
MajorDepartment:EntomologyandNematology
Catflealarvae,Ctenocephalidesfelis,werefoundtoexhibitanorientation
responsetowardahumanstimulus. Thisisthefirstreportdescribingthisbehaviorinthe
catflealarva. Theresponsewasfirstobservedandtestedthroughoutthisstudyina
coveredplasticpetridish,andwasdeterminedtooccuroverrelativelyshortdistancesof
upto2metersfromahumanbeingsittinginachair. Theorientationresponsecouldbe
enhancedbyincreasingthe numbersofcatflealarvaeinanexperiment.
Catflealarvaewereadditionallyfoundtoreacttomagneticfieldsof
approximately750Gaussandelectricfieldintensitiesof4.1x10"^V/m,whichwere
discoveredtoaltertheorientationresponseiftestedinconjunctionwithahuman
stimulus. Thepresenceoftwotypesofmagnetswhenplacedbetweenthefleasandthe
humanstimulusadverselyaffectedtheorientationresponse,whichresultedinrandom
vi
movementaboutthepetridish. Thesameresultwasachievedwithwindproducedfroma
smallfanpositionedsoastopassairacrossthesurfaceofthepetridish.Random
behavior,ornon-directionalmovement,wasadditionallynotedwhentheflealarvaewere
placedaboveheadlevel. Catflealarvaecouldlocateandorienttoahumanstimulus
belowheadlevel,buttheresponsewasreducedatmuchlowerlevelssuchasground
level.
Thecauseofthisorientationresponsemaybemediatedinpartorinwholeby
electromagneticfrequenciesofunknownorigin. Thispossibilitywastheoretically
analyzedinreferencetoexternallarvalmorphology. Thecatflea'sbodyaswellastwo
ofitscomponents,theantennaandthebodysetae,arecertainlycapableofreceiving
complexelectromagneticmessages. Detectionofelectromagneticradiationmaybe
operatingindividuallyorinconcert. Thepossibleoccurrenceofelectromagneticfield
detectionforaninsectisdiscussedwithanextensiveliteraturereviewoutliningpossible
mechanisms.
vu
CHAPTER
1
INTRODUCTION
Thecatflea,Ctenocephalidesfelis,isoneofthemostimportantpestsintheurban
environment. Largevolumesofresearchhavebeendevotedtoitsmanagement,
especiallyaroundthehome. Themajorityofthisresearchfocusesoninsecticides,which
arethemostcommonmeansofmanagingadultfleapopulations. Behavioralstudieson
theadultcatfleaarerareandoftenhighlyanecdotal. Evenlesshasbeenpublishedonthe
behaviorofcatflealarvae,andvirtuallynothinghasbeenpublishedconcerningtheir
responsestonormalandartificialstimuli.
Thisdissertationinvestigatesanewlyfoundbehaviorofthecatflealarva,that
beingitsverystrongorientationresponsetowardahumanbeing. Thebehaviorwasan
unexpectedlypleasantdiscoverythatIobservedinthelaboratorybackin1994. Ibecame
intriguedwiththisbehavioranddecidedtobuildaresearchdissertationaroundit.
Pilotexperimentswereinitiatedinordertocharacterizethisbehaviorandto
ascertainwhatlimitationsitexhibited. Thesepilotexperimentsansweredsomequestions
and,asexpected,raisedsomemore. Dataacquisitionwaslimitedtobehavioral
observationsonly. AreviewofthepilotexperimentsisthesubjectofChapter5. Based
upontheresultsofthepilotexperiments,aresearchplanwasdevisedthatincludedthe
numberoflarvaetouseinanexperiment,theageofthelarvae,andthetimelimitwithin
1
whichallexperimentsshouldbeconducted. Italsobecameapparenttomethat
electromagneticfieldsmaybelinkedtothisbehavior,hence,alargepartofthe
experimentsanddiscussionaredevotedtothissubject.
Asimplelistingofmyresultsinordertodrawobviousconclusionsisaprocedure
IcarriedoutformyMaster'sdegree. Speculatingupontheimplicationsofmyresearch,
andthenprobingawidevarietyoffieldsinordertohelpexplainthem,ismore
appropriateforadoctorallevelstudent. TheresultsreportedinChapter6are
straightforwardandrelativelyeasytofollow. However,afterthescienceisreported,the
philosophyshouldbegin,afterallaPh.D.isaphilosophydegree. Probingquestionsand
theassimilationofliteraturefromallovertheworldshouldbe,andwillbe,aprimary
focusofthisdissertation. Themostimportantquestiontoaskisnot"Whatisgoingon?"
butrather"WhatdoIthinkisgoingon?".
Entomologyandelectromagneticsarenotoftenfoundtogetherintheliterature.
Forthisreason,athoroughreviewandanalysisofthepertinentliteraturenotonly
discussingthesetwoareas,butintegratingthesetwoareas,isabsolutelynecessary. The
generalliteraturereview(Chapter2)beginswithananalysisofinsectantennaeandtheir
possibleroleaselectromagneticreceivers. Thisbackgroundinformationwillhelpthe
readerunderstandwhytheantennaeofcatflealarvae,asrevealedbyscanningelectron
microscopy,couldverywellbeelectromagneticreceiverswithahighdegreeof
directionalityinherentintheirstructure.
Thegeneralliteraturereviewwillcontinuewithananalysisofinsectsensilla,
emphasizingtheirexternalmorphology. Followingthisisadiscussionofbasicantennal
propertiesincludingtheeffectsofantennalarrays,aswellasthecharacteristicsofa
specialtypeofnon-conductingantennaknownasadielectricwaveguide. Thisdiscussion
willtiebackinwithinsectsensilla,thushelpingthereadertobetterunderstandthelink
betweenelectromagneticantennaeandinsectsensilla.
Areviewdiscussingpiezoelectric/pyroelectricpropertiesoftheinsectcuticle
relatesdirectlytothedetectionofvariousenvironmentalstimuli. Thisinherentproperty :
ofinsectcuticlewillhelptoexplainhowstimulicanbereceivedandeventuallyperceived
byanorganismwithoutthebenefitofdistinctsensoryorgans.
Adiscussionoftheroleofantennaeinreceivingelectromagneticsignalswould
notbecompletewithoutaknowledgeofthe''surfaceterrain"surroundinganantenna,for
thisprofoundlyinfluencestheelectricalpropertiesoftheantennaandhowradiationis
receivedbythatantenna. Thephenomenoniscalled"scattering"andvolimiesof
literaturehavebeenwrittenaboutasubjectIonlywishtointroducetothereader. The
presenceofspinesonthebodyofflealarvae,theirmorphologicalsimilaritytodielectric
antennae,andtheoddsurfaceterrainsfoundonflealarvalcuticle,especiallythatregion
directlysurroundingthespines,allstronglysuggestanelectromagneticfunction. The
briefreviewonscatteringfoundinChapter2(entitled"ScatterSurfaces")willprovide
thenecessarybackgroundforthereadertoappreciatetheimportanceofscatteringand
howcatflealarvaemayusethisphysicalphenomenonforsensingtheirenvironment.
Themostcomprehensivesectionofthegeneralliteraturereviewwillfocuson
electromagneticenergyduetoitslargeemphasisintheexperiments. Anoverviewofthe
electromagneticspectrumisanappropriatestart,whileaconsiderationofthedetectionof