SERIES EDITORS KARL MARAMOROSCH Rutgers University, New Brunswick, New Jersey, USA THOMAS C. METTENLEITER Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Greifswald – Insel Riems, Germany FREDERICK A. MURPHY University of Texas Medical Branch, Galveston, Texas, USA ADVISORY BOARD DAVID BALTIMORE PETER C. DOHERTY HANS J. GROSS BRYAN D. HARRISON BERNARD MOSS ERLING NORRBY PETER PALUKAITIS JOHN J. SKEHEL MARC H.V. VAN REGENMORTEL AcademicPressisanimprintofElsevier 225WymanStreet,Waltham,MA02451,USA 525BStreet,Suite1800,SanDiego,CA92101-4495,USA 32JamestownRoad,LondonNW17BY,UK TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UK Firstedition2014 Copyright©2014,ElsevierInc.AllRightsReserved. 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ISBN:978-0-12-801246-8 ISSN:0065-3527 ForinformationonallAcademicPresspublications visitourwebsiteatstore.elsevier.com CONTRIBUTORS YehezkelAntignus PlantPathologyandWeedResearchDepartment,ARO,TheVolcaniCenter,BetDagan, Israel FabrizioCillo IstitutodiVirologiaVegetale,CNR,Bari,Italy MasarapuHema DepartmentofVirology,SriVenkateswaraUniversity,Tirupati,India JohnH.Hill DepartmentofPlantPathologyandMicrobiology,IowaStateUniversity,Ames,Iowa,USA Jacquelined’A.Hughes AVRDC—TheWorldVegetableCenter,Shanhua,Tainan,Taiwan,P.R.China RogerA.C.Jones SchoolofPlantBiologyandInstituteofAgriculture,UniversityofWesternAustralia, Nedlands,andDepartmentofAgricultureandFood,SouthPerth,WesternAustralia, Australia NikolaosKatis FacultyofAgriculture,ForestryandNaturalEnvironment,SchoolofAgriculture,Plant PathologyLab,AristotleUniversityofThessaloniki,Thessaloniki,Greece LawrenceKenyon AVRDC—TheWorldVegetableCenter,Shanhua,Tainan,Taiwan,P.R.China SanjeetKumar AVRDC—TheWorldVegetableCenter,Shanhua,Tainan,Taiwan,P.R.China SafaaG.Kumari InternationalCentreforAgriculturalResearchintheDryAreas(ICARDA),Tunis,Tunisia MosheLapidot InstituteofPlantSciences,VolcaniCenter,ARO,BetDagan,Israel P.LavaKumar InternationalInstituteofTropicalAgriculture,Ibadan,Nigeria Herve´ Lecoq INRA,UR407,StationdePathologieVe´ge´tale,MontfavetCedex,France JamesP.Legg InternationalInstituteofTropicalAgriculture,DaresSalaam,Tanzania KhaledM.Makkouk NationalCouncilforScientificResearch,Beirut,Lebanon PeterPalukaitis DepartmentofHorticulturalSciences,SeoulWomen’sUniversity,Seoul,RepublicofKorea ix x Contributors BasavaprabhuL.Patil NationalResearchCentreonPlantBiotechnology,IARI,PusaCampus,NewDelhi,India JaneE.Polston DepartmentofPlantPathology,UniversityofFlorida,Gainesville,Florida,USA DodlaV.R.Reddy FormerlyPrincipalVirologist,ICRISAT,Patancheru,Hyderabad,India MargaretG.Redinbaugh USDA,AgriculturalResearchService,Corn,SoybeanandWheatQualityResearchUnit andDepartmentofPlantPathology,OhioStateUniversity-OARDC,Wooster,Ohio,USA PothurSreenivasulu FormerlyProfessorofVirology,SriVenkateswaraUniversity,Tirupati,India Wen-ShiTsai AVRDC—TheWorldVegetableCenter,Shanhua,Tainan,Taiwan,P.R.China JoopA.G.vanLeur NSWDepartmentofPrimaryIndustries,TamworthAgriculturalInstitute,NewSouth Wales,Australia StevenA.Whitham DepartmentofPlantPathologyandMicrobiology,IowaStateUniversity,Ames,Iowa,USA WilliamM.Wintermantel USDA-ARS,Salinas,California,USA Jose´ L.Zambrano InstitutoNacionalAuto´nomodeInvestigacionesAgropecuarias(INIAP),Programa NacionaldelMa´ız,Quito,Ecuador PREFACE Cropplantssufferfromanumberofabioticandbioticdiseaseswithsomeof themcausinghigh-yieldlosses.Itisgenerallyacceptedthatviraldiseasesrank second after fungal plant diseases in terms of economic losses they cause globally. So far, morea thousand viral diseaseshave been describedworld- wide and currently new viruses are characterized due to the new technol- ogies. Viruses are intercellular parasites which depend on the host plant cell machinery for their replication. Therefore, they cannot (at present) be controlled by chemical pesticides as is practiced for fungal or bacterial plant diseases. Management of viral diseases relies on the prevention measures.Thecurrentmethodsformanyimportantcrops,boththoseprop- agatedbyseedandthosepropagatedvegetatively,willbeoutlined,describ- ing the most up-to-date state of knowledge. The chapters were written by experts who have been working for years with the respective crop(s). Eachchapterdealingwithaspecificoranumberofrelatedcrops(e.g.,Cit- rus) summarizes the most important viruses infecting the crop, their epide- miology and ecology, and finally measures for their control. Also, chapters dealingwithnovelstrategiesconcerningcontrolofair-bornevirusesinthe fieldandingreenhouseswillbeoutlined.Transgenicresistanceanoveland promisingapproachwillhelptoincreasefoodproduction,oncesomepublic phobia will diminish. The information on the control of plant viruses in the various crops necessitates splitting it into two volumes. The present volume contains two general chapters and chapters on control of crops propagated by seed, such as cucurbits, legumes, maize, and pepper. The following one will be centeredoncontrolinvegetativepropagatedcrops,suchasberrycrops,cas- sava, citrus, grapevine, and pome and stone fruits. WewouldliketoexpressourgratitudetoProf.KarlMaramoroschwho encouraged us to proceed with the subject and Ms. Helene Kabes and her staff who helped us with the technical details. Finally, we hope that this book will be of interest to plant virologists, horticulturists, and practitioners and will further contribute to the control of viral diseases and minimize the losses they cause to the crops. GAD LOEBENSTEIN AND NIKOLAOS KATIS August 2014 xi CHAPTER ONE Management of Air-Borne Viruses “ ” by Optical Barriers in Protected Agriculture and Open-Field Crops Yehezkel Antignus*,1 *PlantPathologyandWeedResearchDepartment,ARO,TheVolcaniCenter,BetDagan,Israel 1Correspondingauthor:e-mailaddress:[email protected] Contents 1. Introduction 2 2. TheInsectsVisionApparatus 2 2.1 UVvisionandinsectsbehavior 3 3. UseofUV-AbsorbingCladdingMaterialsforGreenhouseProtectionAgainst theSpreadofInsectPestsandVirusDiseases 7 3.1 SpectraltransmissionpropertiesofUV-absorbingcladdingmaterials 7 3.2 EffectofUV-absorbingfilmsontheimmigrationofinsectpestsinto greenhouses 9 3.3 EffectofUVfiltrationonthespreadofinsect-vectoredvirusdiseases 11 3.4 EffectofUVfiltrationoncropplants 12 3.5 EffectofUVfiltrationonpollinators 14 3.6 EffectofUVfiltrationoninsectnaturalenemies 16 3.7 EffectofUV-absorbingscreensontheimmigrationofinsectpestsinto greenhouses 17 3.8 ModeofactionofUV-absorbinggreenhousecladdingmaterials 18 4. StickyTrapsforMonitoringandInsectsMassTrapping 19 5. SoilMulches 20 6. ReflectiveandColoredShadingNets 23 7. ReflectiveFilmsFormedbyWhitewashes 24 8. ProspectsandOutlooks 26 References 26 Abstract Theincurablenatureofviraldiseasesandthepublicawarenesstotheharmfuleffectsof chemicalpestcontroltotheenvironmentandhumanhealthledtotheriseoftheinte- gratedpestmanagement(IPM)concept.Culturalcontrolmethodsservetodayasacen- tral pivot in the implementation of IPM. This group of methods is based on the understandingofthecomplexinteractionsbetweendiseaseagentsandtheirvectors aswellastheinteractionsbetweenthevectorsandtheirhabitat.Thischapterdescribes AdvancesinVirusResearch,Volume90 #2014ElsevierInc. 1 ISSN0065-3527 Allrightsreserved. http://dx.doi.org/10.1016/B978-0-12-801246-8.00001-9 2 YehezkelAntignus asetofculturalcontrolmethodsthatarebasedonsolarlightmanipulationinawaythat interferes with vision behavior of insects, resulting in a significant crop protection againstinsectpestsandtheirvectoredviruses. 1. INTRODUCTION Insect-borneplantvirusesmaycauseseverelossestomanyannualand perennialcropsofahigheconomicvalue.Insectvectorsofplantvirusesare foundin7ofthe32ordersoftheclassInsectaandarethereforeresponsible for severe epidemics that form a threat to the world’s agricultural industry. Insect vectors transmit plant viruses by four major transmission modes that are supported by a number of viral and insect proteins (Raccah & Fereres, 2009).Theobligatoryparasitismofplantvirusesandtheirintimateintegra- tionwithintheplantcellrequiresanindirectapproachfortheircontrol.This chapter will focus on the use of light manipulation to affect insects vision behaviorinawaythatinterfereswiththeirflightorientation,theirprimary landing on thecrop,and thesecondarydispersalwithin thecrop.Manipu- lationoflightsignalssimultaneouslydiminishestheinsectimmigrationinto thecropandreducesfeedingcontactsbetweentheinsectvectorandthehost plant, thus lowering significantly virus disease incidence. 2. THE INSECTS VISION APPARATUS Insects perceive light through a single pair of compound eyes which facilitate a widefield of vision. The basicunit of the compound eyes is the ommatidiumwhichrestsonabasementmembrane.Thecorneagencellsare locatedatopalongretinulaformedbylongneuronsandsecondarypigment cells.Acrystallineconelieswithinthecorneagencells.Thedorsalsurfaceof theommatidiumiscoveredwiththecorneallenswhichisaspecializedpart of insect cuticle. Part of each retinula cell is a specialized area known as a rhabdomere.Anerveaxonfromeachretinulacellprojectsthroughthebase- ment membrane into the optic nerve. Ommatidia are functionally isolated because the retinula cells are surrounded by the secondary pigment cells (Diaz & Fereres, 2007). Vision involves the transduction of light energy into a bioelectric signal within the nervous system. The first events in this process take place in the retinula cells. The fine structure of rhabdomeres consists of thousands of closelypackedtubules(microvilli).Thevisualpigmentsoccurmainlyinthese ManagementofAir-BorneViruses 3 rhabdomericmicrovilli.Ithasbeensuggestedthatthesmalldiameterofeach microvillusinhibitsfreerotationofvisualpigments.Thisspecificorientation may be the molecularbasis ofinsects’sensitivity to polarized light.Photobi- ologicalprocessesintheinsecteyeoccurinanarrowbandoftheelectromag- netic spectrum between 300 and 700nm. Visual pigments initiate vision by absorbing light in this spectral region. These pigments are a class of membrane-boundproteinsknownasopsinsthatareconjugatedwithachro- mophore. Visual pigments whose chromophoreis retinalarecalled rhodop- sins. The visual pigments of all invertebrates, including insects, crustaceans, and squids, are all rhodopsins. According to which parameter of the light is being used or what information is extracted from the primary sensory data, visionisoftendividedintosubcategorieslikepolarizationvision(Wehner& Labhart, 2006), color vision, depth perception, and motion vision (Borst, 2009).Polarizationarisesfromthescatteringofsunlightwithintheatmosphere enablingtheinsecttoinferthelocationofthesuninthesky.Thepolarization planeisdetectedbyanarrayofspecializedphotoreceptors(Heinze&Homberg, 2007). Many insects can discriminate between light wavelength (color) (Fukushi,1990)itscontrastandintensity.Motionsignalsarealsopartofvision cuesthatserveasarichinformationsourceontheenvironmentinwhichthe insectisacting(Borst,2009;Diaz&Fereres,2007). 2.1. UV vision and insects behavior Ininsects,thedifferentvisualpigments(opsins)aresegregatedintodifferent subsetsofcellsthatform theommatidium.In thefruitfly Drosophila,seven genesencodingdifferentopsinshavebeenidentifiedandsequenced(Hunt, Wilkie, Bowmaker, & Poopalasundaram, 2001). The ability of insects and mites(McEnrone&Dronka,1966)toperceivelightsignalsintheUVrange (300–400nm) is associated with the presence of specific photoreceptors within their compound eye. UV receptors of the greenhouse whitefly Trialeurodesvaporariorum(Westwood)asinotherherbivorousinsectsarepre- sent in the dorsal eye region (Mellor, Bellingham, & Anderson, 1997; Vernon & Gillespie, 1990). Many insects have two rhodopsins, one with maximum absorption in ultraviolet wavelengths (365nm) and one with maximum absorption in the green part of the spectrum (540nm) (Borst, 2009; Matteson, Terry, Ascoli, & Gilbert, 1992). UV component of the lightspectrumplaysanimportantroleinaspectsofinsectbehavior,includ- ing orientation, navigation, feeding, and interaction between the sexes (Mazokhin-Porshnykov, 1969; Nguyen, Borgemeister, Max, & Poehling, 4 YehezkelAntignus 2009; Seliger, Lall, & Biggley, 1994). The involvement of UV rays in the flightbehaviorofsomeeconomicallyimportantinsectpestshasbeenstudied by several workers (Coombe, 1982; Issacs, Willis, & Byrne, 1999; Kring, 1972; Matteson et al., 1992; Moericke, 1955; Mound, 1962; Vaishampayan, Kogan, Waldbauer, & Wooley, 1975; Vaishampayan, Waldbauer, & Kogan, 1975). 2.1.1 Effect of UV on insects dispersal and propagation Whiteflies [Bemisia tabaci (Gennadius)] dispersal pattern under UV-absorbing films was examined using a release-recapture experiment. In “walk-in” tunnels covered with a UV-absorbing film and an ordinary film, a grid of yellow-sticky traps was established forming two concentric circles: an inner and an external. Under UV-absorbing films, significantly higher numbers of whiteflies were captured on the internal circle of traps thanthatontheexternalcircle.Thenumberofwhitefliesthatwerecaptured on the external circle was much higher under regular covers, when com- paredwithUV-absorbingcovers,suggestingthatfiltrationofUVlighthin- dered the ability of whiteflies to disperse in a UV-deficient environment (Antignus, Nestel, Cohen, & Lapidot, 2001). Following artificial infestation of pepper plants with the peach aphid [Myzus persicae (Sulzer)] in commercial tunnels, covered with a UV-absorbing film, aphid population growth and spread were significantly lower compared to tunnels covered with an ordinary film. In laboratory experiments, no differences in development time (larvae to adult) were observed when aphids were maintained in a UV-deficient environment. However, propagation was faster in cages covered with the regular film. Thenumbersofaphidswas1.5–2timesgreaterincagesorcommercialtunnels coveredwithanordinaryfilm.Inallexperiments,thenumberoftrappedwin- gedaphidswassignificantlylowerunderUV-absorbingfilms.Itwassuggested thateliminationofUVfromthelightspectrumreducesflightactivityanddis- persal of the alate aphids (Chyzik, Dobrinin, & Antignus, 2003). Mazza, Izaguirre, Zavala, Scopel, and Ballare´ (2002) reported that in choice situations Caliothrips phaseoli (Hood) (Thysanoptera: Thripidae), favored areas with ambient UV-A (320–400nm) radiation compared with areaswherethispartofthelightspectrumwasblocked.Thistypeofbehav- iorwasexplainedbytherelativelybroadgapbetweenthepeaksensitivities ofthephotoreceptorsthatareresponsibleforsensingtheUVrange(365nm) and the visible light (540nm). It was assumed that under UV-deficient environment formed by the photoselective film, UV receptors are not ManagementofAir-BorneViruses 5 stimulated by the ambient light, lacking the short wavelength (<400nm) and thus did not trigger the dispersal flight of thrips. Moreover, it was hypothesized that if only the 540-nm receptor is activated, thrips should be unable to discriminate colors but only light brightness because at least stimulation of two receptors is essential for color vision, and blue and UV are of special importance regarding color opponency mechanism (Doring & Chittka, 2007). In large-scale dispersal experiments with Frankliniellaoccidentalis[westernflowerthrips(WFTs)],plantsorbluesticky cardswerearrangedinconcentriccirclesaroundasourceplantattherelease point.DispersaloftheWFTtendedtoexhibitreduceddispersalfromsource plants under UV-deficient conditions (Kigathi & Poehling, 2012). 2.1.2 UV stimulated phototaxis of insects The UV range (360–400nm) forms a strong stimulus for whiteflies to fly; e.g., the greenhouse whitefly, T. vaporariorum, took off more readily and walked faster when exposed to light of wavelengths under 400nm than when exposed to that between 400 and 500nm (Coombe, 1981). Similar photosystems and effects of UV light were suggested for aphids and thrips (Kring,1972;Mattesonetal.,1992).MonochromaticUVlampsinaflight chamberservedtostudytheattractionofB.tabacitodistinctwavelengthsin theUV-AandUV-Cpartsofthespectrum.Whiteflieswereattractedsimilar to light source emitting at 366 and 254nm (Antignus, Mor, Ben Joseph, Lapidot,&Cohen,1996).PreferenceforricherUVenvironmentshasbeen shown for the whiteflies B. argentifolii (Bellows & Perring) and T. vaporariorum, when tested in choice situations (Costa & Robb, 1999; Costa, Robb, & Wilen, 2002; Doukas & Payne, 2007b; Mutwiwa et al., 2005). A striking demonstration of the effect of UV phototaxis on aphids andwhitefliesoccursingreenhouseswithroofarchesthatarecoveredalter- nately,withaUV-transmittingfilmandaUV-absorbingfilm.Incaseswhere suchgreenhousesareinvadedbyvirusborninsects,alltheplantsunderthe UV-transmitting film become infected, while plants under the UV-absorbing film remain totally virus free (Y. Antignus, unpublished) (Fig. 1.1). This dramatic scenario is a consequence of the fact that when an insect is in a choice situation, it will be attracted always to a UV-rich environment. Inchoicesituations,Ceratothripoidesclaratris(Shumsher)thripsexhibiteda clearpreferencetoflytowardroomsenlightenedwithhigherUVintensities, whileitavoidsgreenhouseconstructionswithlowinternalUVradiation,as initially shown by Kumar and Poehling (2006). Costa and Robb (1999)