Dispersal and population dynamics of Frankliniella thrips and progress of tomato spotted wilt virus in tomatoes

86 Pages·1991·1.5 MB·English

by  Puche Erlich, Helena

DISPERSALANDPOPULATIONDYNAMICSOFFRANKLINIELLATHRIPS
ANDPROGRESSOFTOMATOSPOTTEDWILTVIRUSINTOMATOES
By
HELENAjPUCHEERLICH
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREE
OFDOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1991
ACKNOWLEDGEMENTS
iwishtoexpressmysinceregratitudetoDr.JosephE.
Funderburk,Dr.DonaldC.Herzog,Dr.J.HowardFrank,Dr.RichardD.
Berger, andDr.SteveM.Olsonforservingontheadvisorycommittee
andforgivingtheirtimeandexperiencetoimprovemyprofessional
developmentinentomologyandplantpathology.Theirconstructive
criticismswereinvaluableinthecourseofthisresearchandinthe
preparation ofthis manuscript.
SpecialthanksgotoMyrnaLitchfield,SheilaEldrige,Tracey
Austin,JanSmith,ConnieRudd,ElizabethLewis,AndrewBrown,
LeslieSmithfromtheDepartmentofEntomologyandNematologyin
GainesvilleandtheNorthFloridaResearchandEducationCenterin
Quincyfortheirassistanceduringthedevelopmentofthisstudy.
Theirpatienceandwillingnesstohelpandsuggestionsofideasare
greatly appreciated.
ThanksareextendedtoWayneWilliamsforallhishelpin
managing properlythemeteorologicalfieldStation inQuincy,;to
DavidW.Hallforidentificationofthewildplanthosts,toAnn
Fosterforsuggestionsinstatistics,andto Dr. LarryBrownfor
developingtheELISAtests.
Specialthanksgotomyhusband,Alejandro,forhispatience,
friendship,support,andloveintimesofhardwork,andforhis
commentsonearlydraftsofthismanuscript.
TABLEOFCONTENTS
Page
ACKNOWLEDGEMENTS
jj
LISTOFTABLES v
LISTOFFIGURES vi
ABSTRACT vii
CHAPTERS
1 INTRODUCTION 1
VirusCharacteristics 2
VirusInfectivity 2
ThripsandtheepidemiologyandcontrolofTSWV.. 4
2 CAPTURESOFFrankliniellaspp.(THYSANOPTERA:
THRIPIDAE)INTOMATOESBASEDONWEATHER,
SURROUNDINGVEGETATION,ANDORIENTATIONOF
STICKY-CARDS 6
Introduction 6
MaterialsandMethods 8
Results 11
Discussion 14
3 ANANALYSISOFDISPERSALOFFRANKLINIELLASPP.
(THYSANOPTERATHRIPIDAE)INGREENHOUSE
TOMATOES 21
Introduction 21
MaterialsandMethods 23
Results 28
Discussion 31
in
4 POPULATIONDYNAMICSOFTHRIPSAND
PROGRESSOFTOMATOSPOTTEDWILT
INFIELDTOMATOES 40
Introduction 40
MaterialsandMethods 42
Results 46
Discussion 48
5 CONCLUSIONS 54
REFERENCES 60
BIOGRAPHICALSKETCH 74
IV
LISTOFTABLES
Table Page
2.1. MeanNo.(±S.E.M.)ofthripscapturedper
trapperweekonstickycardslocatedatthe
north,south,east,west,andcenteroftomato
fieldsin1989and1990.GadsdenCounty,FL.
19
2.2. MeanNo.(±S.E.M)ofthripscapturedpertrap
perweekonstickycardsintomatofields
accordingto surrounding vegetation habitat,
in1989and1990,GadsdenCounty,
Fla 20
3.1. Characteristicsofthedispersal and
movementofadultsofFrankliniellaspp.
markedwithafluorescentdyeandreleased
ongreenhousetomatoesin1989and1990.
Diffusioncoefficientinonedimension (D);
diffusion coefficient between rows (Di),
diffusion coefficient within rows (D2), and
disappearancerate(u)determinedbythe
equationofDempster(1957) 36
3.2. Kurtosisofthespatial distribution (Ku) at
fourtimesofthedayofadultsof
Frankliniella spp. markedwith fluorescent
dyeandreleasedingreenhousetomatoesin
1989and1990.Heterogeneityofmovement
indicatedbyasignificant(£,<0.05(*))
departure from the normal distribution with
respecttothedistancefromthepointof
releaseaccordingto at-test.
37
LISTOFFIGURES
Figure Page
2.1. Weeklycapturesofthripsonstickycardsin
threetomatofieldsin 1989andtwotomato
fieldsin1990,GadsdenCounty,FL 18
3.1. Diagrammatic representation ofthe four3x3
latticesquaresevaluatedtodeterminethe
coefficients ofdiffusion (D) in two
directionsandthedisappearancerate(|i)of
Frankliniellathrips, ingreenhousetomatoes.
38
3.2. Timevariationsofthevarianceofdispersal
ofFrankliniellathrips;thetotal numberof
individualsreleasedrangedbetween700to
1300. Variabilityofthedatawasexplained
byalogarithmicmodel:y-=-7729.4+0.0002
*Log(x),R2-
0.905 39
4.1. Meanweeklycapturesofthripsonsticky
cards,TSWVdiseaseincidenceaveragedover
twotomatofields,andthecorresponding
dailyrainfallin1989(A)and 1990(B),
GadsdenCounty,FL. Notethatscalesare
differentbetweenyears 53
AbstractofDissertation PresentedtotheGraduateSchool
ofthe University of Florida in Partial Fulfillment
oftheRequirementsfortheDegreeofDoctorofPhilosophy
DISPERSALANDPOPULATIONDYNAMICSOFFrankliniellaTHRIPSAND
PROGRESSOFTOMATOSPOTTEDWILTVIRUSINTOMATOES
By
HelenaPucheErlich
August 1991
Chairman: D.C.Herzog
Cochairman: J.E.Funderburk
MajorDepartment: EntomologyandNematology
ThripsofFrankliniellaspp.cancauseinjurytotomatofruits,
andvectorthetomatospottedwiltvirus(TSWV). Population
dynamicsofthripsandepidemicsofTSWVweremonitoredintwo
commercialtomatofieldsduring 1989and 1990. Timeanddirection
ofmovementofthripswereexaminedusingblueandyellowsticky
trapsatdifferentorientations. Morethripswerecapturedonblue
cards. Capturesofthripswerenotdifferentoneithercardside,
indicating similarimmigration and emigration. Morethripswere
capturedontrapsatthecenterandeastpositions. Fewerthrips
werecapturedontrapsalongroads.
PopulationdynamicsofthripswerefittedtotheWeibull
model. Thripsratesofincreaseweresimilarinbothyears,anda
smallpopulationofthripswasalreadyinthefieldwhentrapping
hadbegun.TheWeibullfunctionwasfittedtothecumulative
numbersofthripscapturedovertimeandthisincreasewas
sigmoidal. Anasymptoteof1850and4000thripswasprojectedin
1989and 1990withtheWeibullfunction.
Diseaseincidencewaslessthan10%inbothyears, and
attributed to low transmission efficiency or low proportion of
viruliferousthripsinthefield. Polynomialand linearmodels
describedprogressofTSWVin1989and1990,withlowepidemic
rates. Diseasedplantsweredistributedatrandom,although40%of
therowshadanaggregateddistribution. SpreadofTSWVoriginated
from populationsofthrips bothwithin andoutsidetomatofields.
Secondaryinfectionoccurredlateintheseason.
Movementratesofthripsbetweenandwithin rowswere
estimatedintomatoplotsinthegreenhouse. Rateofthrips
recapturewas12%. Meanratesofmovementbetweenandwithin
rowswere0.501 and0.403cm2/h, respectively. Movementrate
withinrowswasgreateratdawnanddusk,accountingforswarming
behaviorofthrips. Thekurtosisandvarianceofdisplacementof
thripsrevealedanhomogeneousandnonrandomthripsmovement.
ThespeedandmovementofFrankliniellathripsmayhelpto
understandTSWVdiseasespatialtransmission. Therefore,
monitoringTSWVanditsthripsvectorsmayhelptoforecastan
impendingepidemicandtoprovideanearlyalertofTSWVin
tomatoes.
CHAPTER1
INTRODUCTION
Epidemicsoftomatospottedwiltvirus(TSWV)havebeen
observedsince1986inmajorvegetableproductionareasinnorth
Floridaincludingtomatoes,peanuts,andothercrops(Kucharek
1986).Tomatospottedwiltvirusalsohasbeenreportedonmany
plants including cultivated malvaceous plants (Halliwell 1988);
watermelon (IwakiMai- 1984),papaya(Gonsalves&Trujillo 1986),
peppers(Zitter1989), flowersandvegetables (Haliwell &Barnes
1987,Schuster&Price1987,Wilson&Moran1983),artichokes
(Gracia&Feldman1978),peanuts(Costaelal.1977,Culbreathelal.
1990a,Toddelal.1990),andtobacco(Bertrand elal.1990,
Culbreathelal-1990b).Sixspeciesofthrips(Thysanoptera:
Thripidae)havebeenreportedasvectorsoftheTSWV(Aminelal-
1981,Ghanekarelal-1979,Raoelal-1980,Sakimura1969).
Intomatoes,diseasedfruitsshowyellowconcentricringsand
chlorotic spots thatgreatly diminish its value forthe profitable
freshmarket.TomatoisaveryimportantvegetablecropinFlorida
representingalmost42.7%ofFlorida'sfresh marketsales
(Pohronezkyelal.1986).TherapidincreaseofTSWVamongtomato
andothercropsisthreateningthe$603millionrevenuethatthe
tomatocropgeneratesinFlorida.
Virus Characteristics
ThetomatospottedwiltvirusisasphericalssRNAvirus.
Particlesfixedwithglutaraldehydehaveacorrecteddiameterof85
nm, asedimentationcoefficientof530andanelectrophoretic
mobilityatpH7of-19.8x10"5cm2V"1 (Joubertelal. 1974).One
minorprotein(ofMW220,000d),andthreemajorstructural
proteins(ofMW84,000, 50,000, and 29,000d)havebeenfoundas
partoftheTSWV.Thesethreemajorproteinsareglycoproteinsand
constituteabout98%ofthetotalviralprotein.Oneofthemajor
proteinsandtheminorproteinareassociatedwithsubviral
particles(Mohamedfilai.1973).
Virus Infectivity
TSWVinfectionproducesdiffusemassescontainingdenser
striatedspotsofabout5nm.Thesemassesareintimately
surroundedbyribosomesandoccurfreelyinthecytoplasmofplant
cells.Thecisternaeoftheendoplasmicreticulumsystemalso
presentdiffuse massesaloneorincombinationwith characteristic
clustersofvirusparticles(le 1971).Asaresult, symptomsofthe
diseasearecharacterized by marginalwilting, yellowing, brown
spotting,andgeneralstuntingofthevegetativeportionsofthe
infectedplant(Chofilal. 1987a,1989,Paliwal1974).The
incubationperiodofthevirusintomatoplantsunderfield
conditionshasbeenreportedbetween8to10days(Bald1937).
TSWVisapersistentvirusandmayreplicateinthesalivary
glandsofthrips. Later, thevirus istransmittedduring salivation at
thefeedingsite(Sakimura1962).Thripsfeedbypiercing leafcells