Rev.ChilenaEnt. 2000,26:93-95 DO HOSTPLANTTRAITS AND GALLINGINSECTS AFFECTTHEABUNDANCEOF ISSUSSP. ON COLLIGUAJA ODORÍFERA MOL. ALONGANALTITUDINAL GRADIENT?^ WlLFREDOL.GONZÁLES^ AnDRoSARIOFERNÁNDEZ^ ABSTRACT The association between the abundance ofthejumping Hemiptera Issus sp. and host plant traits (fruits, flowers,buds,plantsizeandcover)andgallinginsectsinColliguajaodoríferaMol.alongaltitudinalgradient, wasevaluated.Twocontrastingsiteswerestudied:low(850m.a.s.l.)andhigh(1150m.a.s.l.)-Atthelowsite, thenumberoffruitsandbuds,coverandplantsizewerelarger(t-test,P<0.05,foreachtrait)thaninthehigh site. The numberofgallinginsectsand isids was higherinthe low site. Theratioofisids to galls was not significantlydifferentinlowandhighsites.Theratiooffruitstoisidswassignificantlylargerinthelowsite (t-test,P<0.05)thaninthehighsite. Usingmultivariateapproachesineachsite,inthelowsiteplantcover wassignificantly(¥^^^=4,^9,P<0.01)andpositivelyassociatedwithisidabundance.Whilstatthehighsite thenumberoffruitswassignificantly(F,,^=3.18,P<0.05)andpositivelyassociatedwithisidabundance. Keywords: Colliguaja odorífera, Issidaeabundance,gallinginsects, altitudinalgradient. RESUMEN SeevaluólaasociaciónentrelaabundanciadeIssussp.yelnúmerodeinsectosagalladoresylosatributosde laplantahospederaColliguajaodoríferaMol.(frutos,flores,yemas,coberturaydimensionesdelaplanta), alo largo de ungradientealtitudinal. Seestudió dos zonas contrastantes: unabaja(850msnm) y otraalta (1150msnm).Enlazonabaja,elnúmerodefrutosyyemas,ylacoberturaydimensionesdelaplantafueron mayores(t-test,P<0.05paracadacarácter)queenlazonaalta.Elnúmerodeinsectosagalladoreseísidosfue mayorenlazonabaja.Laproporciónísidos/agallasnofuesignificativamentediferenteentreamboslugares. Laproporción frutos/ísidos fue significantemente mayoren la zonabaja(t-test, P<0.05) con respecto ala alta. Utilizandoregresionesmúltiplesencadaárea,seobservóqueenlazonabajalacoberturadelaplanta estuvoasociadasignificativa(F,^,.^=4,89,f<0.01)ypositivamenteconlaabundanciadeísidos.Porotrolado, enlazonaaltaelnúmerodefrutosestuvoasociadosignificativa(Fj,^=3.18,P<0.05)ypositivamenteconla abundanciade ísidos. Palabras claves: Colliguaja odorífera, abundancia de Issidae, insectos formadores de agallas, gradiente altitudinal. INTRODUCTION time and space by environmental conditions (Crawley, 1986;Thompson, 1988; Price, 1997). In Herbivore-plantinteractionsmaybeaffectedin particular, altitudinal range can affect the pattem of hostplantdistribution andconsequently thatof its closely related herbivores (Boecklen & Cour'sTehiosnwIonrsekctw-aPlsanptroIdntuecreadctidounrsinhgeltdheatInRteesrenravtiaonNaalciFoinealld Spellenberg, 1990;Aguilar&Boecklen, 1992).The Río Clarillo andLaboratoriodeQuímicaEcológica, Departa- common shrub Colliguaja odorífera Mol. shows mentodeCienciasEcológicas,FacultaddeCiencias,Universi- an altitudinal distribution range between 600 to daddeChile, from November28 to December 14, 1999. The 1200 meters above sea level, is scarcely attacked resultspresentedarebasedon6daysoffieldwork. ^LaboratoriodeQuímicaEcológica,DepartamentodeCien- byfolivorousinsects(Montenegroetai, 1980),but cias Ecológicas, Facultad de Ciencias, Universidad de strongly attacked by gall makers (Martínez etai, Chile, Casilla 653, Santiago, Chile, email: 1992).Workinthissystemhasfocusedondifferent willy@abulafia.ciencias.uchile.cl. aspects of the galling insect-C. odorífera 'LaboratoriodeEcofisiología,ÁreadeBiodiversidadAni- mal,FacultaddeCienciasNaturalesyMatemáticas, Universi- relationship, emphasizing the relevance of plant dad Nacional Federico Villareal, Lima-Perú, email: traitssuchasspecificityofattackedorgansorplant rosariofi@hotmail.com. phenology(Núñez&Sáiz, 1994; Sáizetai, 1999; (Recibido: 3 de diciembrede 1999. Aceptado: 5 deenero de 2000) 94 Rev.ChilenaEnt.26,2000 Martínez et al.,1992), and the influence of beating trap (0.5m x 0.8 m) was placed under the altitudinalgradient(Fuentes-Contrerasetal., 1999). representativeplantvolumechosenandthecanopy Acommoninsectfoundassociatedto C. odorífera wasshakentocollectanddeterminethenumberof is the jumping Hemiptera, Issus sp. isidsfallen. (Fulgoromorpha: Issidae), but it has been poorly Porcomparisons between low and high sites, a studied. In this work, the pattern ofabundance of í-testwasusedforplanttraits,herbivoreabundance Issus sp. on C. odorífera growing at two sites of (gallinginsectsandisids),andtheratiosoffruitsto differentaltitudewasevaluatedinrelationtoplant isids andisidstogalls.Múltipleregressionanalyses traitsandgalHnginsectabundance. consideringplanttraitsandgallinginsectsasvaria- bles affecting isid abundance, were used for both METHODS ANDMATERIALS samplingáreas. C. odorífera occursattheRíoClarilloNational RESULTS Reserve (33°51'S- 70°29'W, 45 km southeastof Santiago,Chile)mostlyonequatorialfacingslopes. At the low site, the number offruits and buds, Two sites of different altitude (850 and 1150 m and the cover and dimensión of the plants were above sea level) were chosen. Modular plants significantly (t-test, P< 0.005, for each plañí trait m separatedbyatleast5 wereselectedateachsite evaluated)greaterthanatthehighsite.Thenumber (n = 100 in low site, and n = 40 in high site). The offlowerswasnotsignificantlydifferent(í-tesí,P> size of each plant (breath and length) and 0.1)between low andhighsites (Figure 1). approximate áreacovered by it were recorded. A Atthelowsite,thenumberofgallinginsectsand representative volume (40cm x 40cm x 40cm) of isidsweresignificandyhigher(t-test,P<0.005,for each plant was chosen and the number of fruits, each herbivore evaluated) than at the high site. flowers,buds andgallspresentin thisvolumewas Múltipleregressionsshowedthatatthelowsiteonly determined.Onlythegallscorrespondingtothelast thecoveroftheplantwaspositivelyassociated(Fj^, seasonwereconsidered,i.e.gallswhichwereeither =4.899, P<0.01)withisidabundance.Atthehigh completely green or atleastgreen attheirbase. A site,thenumberoffruitswaspositivelyassociated 70 ^•^^.j^.1 lowsite 60 ^^B highsite 50 40 30 20 10 fruits flowers buds cover dimensión Figura 1. Comparison ofplant traits in Colliguaja odorífera growing at low and high altitudes. Different letters mean significant differences (t-test, P<0.05). Fruits, flowers and buds are represented as number; coveras porcentage oftotal plant área, and total dimensiónassquaremeters. GonzálesandFernández: Planttraits,gallinginsectsandabundanceofIssussp 95 (F„, = 3.18, P< 0.05) with isid abundance. The On the other hand, the abundance of galling 3,36 ratioofisidstogallswasnotsignificantlydifferent insects was not relevant to explain the pattem of (t-test,P>0.2)between thelowandhighsites.The isidabundance(lowandhighsite).Possibly,galling ratio of fruits to isids was significantly larger (t- insectsandisidshavedifferentpatternsofhostplant test, F<0.05) atthe low site than atthehigh site. use, thus avoiding possible negative interactions. However, athighdensity ofisidsthepatterncould DISCUSSION change. Environmentalconditionsmayaffectsomehost ACKNOWLEDGEMENTS plant traits and act directly or indirectly on herbivores. Plant traits showed significant Wethank all participants tothecoursefortheir differences between sites of different altitudes: enthusiasticandhelpfulcriticismofthemanuscript, number of fruits and buds, and plant cover and specially ChristerBjorkman, Mattias Jonsson, Er- dimensión were greateratlow altitude (Figure 1). nesto Gianoli, RichardJ. Hopkins, andClaudioC. These traits suggest that C. odorífera represents a Ramírez.Wegratefully acknowledgethefinancial resource ofpoorer quality at the high site than at supportofMISTRA/IFSforourparticipationinthe the low site. Henee, fewer herbivores (galling course,andthehelpandadvicereceivedfromstaff insectsandisids)wereexpectedatthehighsitethan atCONAF. at the low one. The multivariate approach which considered bothplanttraits and numberofgalling REFERENCES insects at each site (low and high) as independent Aguilar,J.M.&BoECKLEN,W.J. 1992.Patternsofherbivoryin variables,showedthatthesevariableswererelevant the Quercus grísea x Quercus gambeUi species complex. toexplainisidabundance. Oikos 64: 498-504. Atthelowsite, coveroftheplantexplainedthe BoECKLEN,W.J.&Spellenberg,R. 1990.Structureofherbivore number ofisids at this site. This suggests that for communities in two oak {Quercus spp.) hybrid zones. thisjumpinginsect,thehostplantwithlargercover Oecologia«5:92-100. Crawley,M.J. 1986.PlantEcology.Secondedition.Blackwell, willbeabetterhabitat(microclimaticadvantageor Oxford. refuge zone, etc.) thanthatwith smallercover. Fuentes-Contreras, E. Gianoli, E., Caballero, P.P. & Ontheotherhand,atthehighsitethenumberof Niemeyer, H.M. 1999. Influenceofaltitudeandhost-plant fruits showed a positive association with isid species on gall distribution in Colliguaja spp. abundance,butcoverwasnotrelevant.Atthissite, (Euphorbiaceae)inCentralChile. RevistaChilenadeHis- toriaNatural 72: 305-313. someplanttraitsweresignificantly smallerthanat Martínez, E., Montenegro, G. & Elgueta, M. 1992. thelow site, in particularthe number offruits (Fi- Distribution and abundance of two gallmakers on the gure 1). Giventhelowerhostplantquality andthe euphorbiaceous shrub Colliguaja odorífera. Revista Chi- lower fruits to isids ratio, the resource could well lenadeHistoriaNatural65: 75-82. be limiting, and henee the number of fruits is a Montenegro,G.,Jordán,M.&Alfaro,M.E. 1980.Interactions betweenchileanmatorralshrubsandphytophagousinsects. relevant plant trait affecting isid abundance. The Oecologia45: 346-349. lack of significance of number of fruits in the Núñez, C. &Sáiz,F. 1994. Cecidios en vegetación autóctona múltipleregressionforthelowsitewherethefruits deChiledeclimamediterráneo.AnalesdelMuseodeHis- to isidsratio ishigher, may beexplainedby atime toriaNaturaldeValparaiso22: 57-80. lagbetweentheinsectpopulationdynamicsandthe Price, PW. 1997. Insect Ecology . Third edition.Wiley, New York availability of the resource. Interestingly, most Sáiz,F.,Morales,A.&Olivares,M.(inpress).Sobreelcom- females in the low site were gravid; henee, it is plejo de cecidios de Colliguaja odorífera Mol. expectedthatlaterontheseasontheisidpopulation (Euphorbiaceae). AnalesdelMuseodeHistoriaNaturalde would increase, and the number of fruits would Valparaíso. explainisidabundance. Thompson, J. N. 1988. Variation in interspecific interactions. AnnualReviewofEcologyandSystematics19:65-87.

Do host plant traits and galling insects affect the abundance of Issus sp. (Hemiptera: Issidae) on Colliguaja odorifera Mol. along an altitudinal gradient?

Similar Do host plant traits and galling insects affect the abundance of Issus sp. (Hemiptera: Issidae) on Colliguaja odorifera Mol. along an altitudinal gradient?