Table Of ContentRev.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
[email protected].
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
[email protected]. 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
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