O Society fbr Tropical Ecologv DIVERSITYOF ORTHOPTERA FROM BORNEAN LOWLAND RAINFORESTTREES Andreas Florenl, Klaus Riede2& Sigfrid Ingrisch2 lTheodor-Boveri-lnstitute,Department of AnimalEcology and TropicalBiology, Biozentrum, Am Hubland,D-97074 Wuerzburg, Germany 2Alexander Koenig Zoological Research lnstitute and Museumof Zoology,Adenauerallee 160, 53113Bonn, Germany Absnact.The composition and colonization dynamics of arboreal Orthopteran communities were studied in a SE-Asian mixed dipterocarp lowland rain forest by insecticidal fogging, re-fogging after different periods oftime, and by srem eclecrors during different times of the year. In total, 2324 Orthoptera were collected by fogging, of which 87 .3o/o were nymphs. Imagines were sorted to 49 morphospecies, ofwhich 47 (96ok) were new to science.Almost 500/owere singlerons, and only three species, all belonging to the omnivorous subfamily Mogoplistinae (gents Ornebius), occurred with more than I 0 adult individuals. Orthoptera seemedto be randomly distributed in the canopy without showing any host-tree-specific adaptation. This is also indicated by the re-foggings, in which Orthoptera colonized the trees, according to the relative proportions ofsubfamilies and feeding guilds occurring in the canopy. No pioneer or climu speciescould be distinguished. ln the stem eclectors787 specimenswere caught, ofwhich 98.20lowere nymphs, mostly first and second instar, indicating migration into the canopy after egg development in the soil or lower forest strata. In contrast to the numerous nymphs of hemimetabolous taxa, lessmobile arthropods, mainly larvaeof holometabolous groups, were almost completely lacking in the canopy. This is probably due to the high predation pressureof the ants which influence communiry composirion. Arepted 9 July 2001. Kry words: Ant predation, canopy fogging, colonization dynamics, diuersity, hemimetaboly, stem eclectors. INTRODUCTION distinguished: the Caelifera ("grasshoppers")which are diurnal and herbivorous, showing all varietiesof the The existenceofan extremely diverse arthropod fauna specialist-generalistcontinuum (Rowell 1978), and in the canopy oftropical lowland rain forest, as first "karydids" "crickets") the Ensilera(mainly and which suggestedby Roberts (1973) and Erwin (1982), has are nocturnal and comprise a wider range of feeding sincebeen confirmed by various investigations(refer- habits, including herbivores, predators, and omni- ences,e.g., in Stork et dl. 1997, Linsenmair et al., in vores. To date, most studies have locused Neo- press),raising the question ofhow such high diver- on siry is maintained (e.g., Beaver 1979, Huston 1994, tropical Caelifera, which were collected either by (Roberts Linsenmair 1995, Pianka 1996, Price et al. 1995, Fogging I 973) or tree-felling,and netting of (Descamps Rosenzweig1995). This is the locus of our project in grasshoppersat ground level 1978, 1981). SE Asia that aims at understanding the mechanisms Those studies revealeda species-richcanopy fauna and structuring arboreal arthropod communities. In this gaverhe firsr insighrsinto communiry strucrure.re- paper we consider the Orthoptera, which usually source partitioning (Amdddgnato 1997), and ethology account for berween I and 3 o/ooF the specimens in (Riede 1987). Although the Ensiferan launa oftrees tree communities (Stork 1991, Floren & Linsenmair is generally much more diverse than the Caeliferan 1997,'S7agner1997). In contrast to previously ana- launa, the arboreal Ensilera remain largely unstudied. lJzed insect orders from the canopy, Orthoptera are Here we present for the first time an analysis of hemimetabolous. Their nymphs are usually highly complete Orthopteran communities from trees in a mobile and basicallybelong to the sameleeding guild SE-Asianlowland rain lorest,which were sampledby as the adults. Two major groups ofC)rthoptera can be fogging, re-fogging, and stem eclectors. \7e describe the Orthoptera launa associatedwith three tree spe- e-mail: fl oren@biozentrum. uni-wuerzburs.de cies, in terms of their diversiry and re-colonization 33 dynamics (of the primary fogged rrees) and ask how one A. lagenocdrpatree was re-fogged on Four conse- c important tree trunks are as pathways [or canopy cutive mornings. colonization. Furthermore we investigate whether Stem photo-eclectors(emergence traps) were in- ( differencesin life history featuresof holometabolous stalled on 47 tree trunks at 4 m height in order to I and hemimetabolous taxa have an effecr on the struc- quanti$/ arthropod immigration into the canopy c ture oFtree-dwelling communities. along tree stems lrom the ground (these were 35 t A. lagenocarpa, 4 A. subcaudata, 4 Depressaneruosa c MATERIALS AND METHODS (Guttiferaceae),and 4 unidentified trees.Their bark T was only slightly structured and not covered with Study site and samplingprocedures.Investigations were S thalloid epiphytes.For the operational method ofthe c conducted in Kinabalu National Park, substation Por- eclector-traps see Bassetet al. (1997). The traps were c ing Hot Spring, Sabah, Malaysia, Borneo (6"5'N, filled with 4o/o formalin solution and emptied every l 11633' E), in a floristically rich mixed dipterocarp fwo weeks.A total of 171 sampleswas evaluared. l, lowland Forest(500 to 700 m a.s.l.).The region is t characterized by a rypical tropical climate with at Arthropod sorting and data anallsh. Orthoptera were I least2000 ml precipitation per year (Kitayama 1992, separatedand sorted to morphospeciesby one o[ us t Pfeiffer 1997). All investigations were done after the (SI). However, most of the nymphs could be identi- c rainy seasons(which last from February ro May and fied only to subfamily level, therefore evaluation is i August to end of November) during lour field stays only based on adults. Classification lollowed the c between 1992 and 1993. Orthoptera SpeciesFile (One & Naskrecki 1997). An improved method of canopy logging was used Specimensfrom the studies have been deposited in to sample arthropod communities associatedwith the Museum Koenig, Bonn or in the institutions men- c individual trees.Since methodical details have been tioned in the resulting taxonomic publications. In published elsewherewe give only basic information addition, various persons kindly provided data from € € here (Floren & Linsenmair 1997,2000). The trees hand collecting and light-traps which were conrrasred C were fogged For ten minutes with natural with the fogging material. pyrerhrum f Shinozaki curves were calculated to comDare com- used as insecticide early in the morning and all ar- t thropods that had dropped into the funnels after rwo munitiesar rhe bera-diversitylevel (Shinozaki 1963, C hours lollowing fogging were used in the analysis. Achtziger et al. 1992). These are expected species Nineteen medium-sized trees of the canopy un- accumulation curves and their steepnessprovides derstory, representing three speciesfrom nvo lamilies, inlormation about the overall complerenessof the (a were fogged. These were ren Aporusa lagenocarpa,fle sampling effort more comprehensivediscussion is I A. subcaudzta(both Euphorbiaceae),and foturXan- given in Floren & Linsenmair 2000). In addition, s toph/lum afine (Polygalaceae) (we recognized only Soerensentindex was used to measuresimilariry in (Magur- T during the investigations that the Euphorbiaceae trees speciescomposition berween communities ran : belonged to two species).A. lagenocarpawas rhe on- 1988). For a benveen comparison, the fogging data were ly speciesthat occurred in larger numbers in our re- standardized lor a crown projection of I m2 and a leafcover 1 search area of which sufficient available individuals oF 00o/o.Bonferroni's correction was used to adiust the level of significance for multiple were lound that were not covered with lianas. All trees pairwise comparisons (Lehmacher et al. 1991). were smaller than 30 meters in height and similar with respectto insecthabitat conditions, for examplecon- cerning the existenceofstem cavities, dead wood, and RESULTS detritus accumulations, etc.; epiphytes were almost A total of 2324 individuals of Orthoptera was ob- completely lacking (Floren & Linsenmair 1998a). tainedby fogging.The numberof specimenscollected Only one l. lagenocarpaflowered during one samp- on treesfogged for the first time variedconsiderably ling period, however,without a noticeable elfect on berween7 and,238,representing beween0.72o/o and the speciesabundance patterns. All trees showed con- 3.4o/oof all foggedarthropods. The proportionof tinuous leaf flushes of low intensity. Ten trees (five nymphs within primary fogging samplesfluctuated A- lagenocarpa, three ,4. subcaudata, and wo X. ffi- berweenB0 and 100o/o(nean 82.94t 19.59).This nde) were re-fogged at least after six months, nvo l. patternwas independent ofthe monthoflogging and subcaudata trees were fogged again alter a week, and showedno seasonaliry.In the stemeclectors, 787 spe- 34 DIV!,RSI'fY OF ORTHOPTEM FROM I]ORNEAN LO\flLANt) RAIN FORIST TREES cimens were collected, and the proportion of nymphs All other taxa were represented by only a lew indivi- was significantly higher than in the fogging samples duals or singletonsin each sample.A remarkablege- (mean 96.9 + 5.28, Mann \Whitney U-test, P< 0.001). neral leature was the low percentage ofshort-horned Table I comparesthe higher taxonomic composirion grasshoppers (Caelifera) which were represented by o[fogged Orthoptera versus those caught by eclector only 32 nymphs in the fogging samples. They oc- traps, ranked by the number of nymphs.