Dipterous Guilds of Small-Sized Feeding Sources in Forests of Hungary

Acta Zoologica Academiae Scientiarum Hungaricae 48 (Suppl. 1), pp. 197–213, 2002 DIPTEROUS GUILDS OF SMALL-SIZED FEEDING SOURCES IN FORESTS OF HUNGARY L. PAPP Department of Zoology, Hungarian Natural History Museum H-1431 Budapest, Pf. 137, Hungary, E-mail: [email protected] Insect guilds (of Diptera and Coleoptera) on “very small-sized feeding sources” (droppings of forest animals, dead snails, tinder fungi, decaying fungi, sap of deciduous woods, Vespa nests, etc.) in low mountain forests in Hungary were studied from 1995 to 1998 (504 positive samples for flies, more than 20500 dipterous individuals). A small but significant fraction (about 20%) of these sources is not exploitedby flies at all. The high species diversityof those that are colonizedrepresents a majority of forest Diptera diversityin Hungary (with numerous species andgenera new to Hungary andeven new to science). The quality, size, persistency andplace of renewal of the sources, the potential size of each dipterous population, the flies’ ability to findnew sources andcomposition of the local fauna are all important factors in determining the actual frequencies of species found on extant sources. Although the primary texture of the forest community structure is formedby the more abun- dant forest species populations, those species in guilds on small-sized food sources put a colourful pattern on that texture. They are mostly rare andare probably insignificant for the main energy flow processes, but knowledgeof their presence andlife histories wouldseem to be indispensable for a complete understanding of ecosystem structures and diversity mainte- nance. Biomonitoring of these species, however, is a challenge because of their poorly under- stoodecology andfluctuating abundance.The relationships of rarity andthe species coloniz- ing these sources are discussed and the development of raritology (study of rare species) as an individual branch of ecology is predicted. Key words: small-sized feeding sources, Diptera, species composition, diversity, raritology, Hungary INTRODUCTION The insect guilds found in small-sized food sources have attracted very little attention in ecology, particularly so for those sources consisting of dead organic matter. In ecology textbooks, even in the best ones, only a small portion is devoted to animals developing in droppings, carrion, etc. (cf. KREBS 1985, PRICE 1984, THOMPSON 1984). Even SZELÉNYI (1953) left them out of consideration. The most comprehensive analysis was foundin B ALOGH’s (1953) book which, although qualitative, summarisedthe important literature of the time andassignedthese guilds their proper importance by including them as a category in forest ecosystems. (Note that I use the term “guilds” in the sense of HAWKINS andM ACMAHON (1989) rather than in its original meaning (ROOT 1967)). Acta zool. hung. 48 (Suppl. 1), 2002 Hungarian Natural History Museum, Budapest 198 L. PAPP Despite their importance to the understanding of the diversity of many ecosystems, comparatively few papers have dealt with insects from small-sized food sources. This is probably because: (a) Their role in the material andenergy turn - over of the communities is negligible; (b) Their study is difficult from a method- ological point of view, andthe classical methodsandconsiderationsare not usable for their study without modification (cf. SOUTHWOOD 1978); and(c) The results of previous studies reported that the species composition and frequencies of these insect populations appearedto be highly variable, almost accidental;hence entomol - ogists – like any other natural scientists tunedto look for invariance – didnotfind pleasure in their long-term study. Most of the studies resulted in the publication of a list of the collected species and usually not much more. In view of these problems, we developed new collection techniques to more effectively obtain critical data on composition and frequencies of species that com- prise the guildson small-sizedfoodsources. We usedregular sampling andsimple but reliable methods (i.e., counting rather than making estimations on abundance of flies on the small-sized sources in natural conditions). With the voluminous data thus obtainedwe hope to answer the following questions: (a) How repeatable is the species composition of the guilds on a given type of small-sized source? (b) Based on the abundance of the dominant and subdominant species we found, may we at- tribute any structural characteristics (i.e., less than a true structure) to those assem- blies/assemblages (there is no reason to call them communities)? (c) Is there enough commonality in the organisation of the guilds of the various small-sized sources to give them a unifying name? Our goal for this research is to be able to estimate the contribution of these guilds to the species richness of the forest ecosystems. In additon, we also hope to increase the scientific community’s awareness of the forms of rarity among insects. MATERIAL AND METHODS The sampling sites were selectedin low mountain forests in Hungary: 1) Börzsöny Mts (central North Hungary): Verőce-Magyarkút: Keskenybükki-patak valley andthe Les-völgyi-patak valley; forests along the roadfrom Diósjenő to Kemence; two forested brook valleys (Vasfazék valley andSzénpatak valley) accessible from Királyrét; 2) Visegrádi Mts (central North Hungary): Apátkúti valley near Visegrád, on the other side of Danube; 3) Vértes Mts (NW Hungary, Transdanubia): Fáni valley. Supplementary collections were made also in other parts of Hungary (Kőszegi Mts, Bükk Mts, Zempléni Mts). Insects were collectedon or near various small organic sources as listedin Table 1. Tech - niques were developed to determine the abundance of each species on a given source sample by Acta zool. hung. 48 (Suppl. 1), 2002 DIPTEROUS GUILDS OF SMALL-SIZED FEEDING SOURCES IN FORESTS OF HUNGARY 199 counting andnot by estimation. Therefore isolators were usedto capture flies andother insects actu - ally present on these sources. The isolators are large aluminium funnels usedin wine cellars anda glass aspirator usedto catch mosquitoes boundwith sections of bike tires (see P APP 1985). Using a strong aspirator, I capturedthe smallest flies which might crawl out from underthe rim of the funnel. We constructedspecial traps (in a way similar to some pitfall-traps) to collect all the flies in - cluding phorids on dead snails; we then reared them to adulthood to determine the quantities and species from each source. A new type of soil bait trap was constructed to collect adult Diptera on dead Helix snails (PAPP &TÓTHMÉRÉSZ in prep.). These special traps were necessary because of the special properties of the Phoridae species (the photo-eclector type traps we used at first were ineffective, since the phorids – unlike other Diptera – do quite well in complete darkness). Some kinds of substrates were collected and taken into the laboratory where Diptera adults were reared from them. This way one can collect data on the actual quantity of the individuals and species composition developing in small-sized feeding sources such as dead Helix snails exposedfor 48 hours and Vespa crabro nests (PAPP 2000). Rearing was done largely by MIHÁLYI’s (1967) method. Where the distance of the sampling points were reliably measurable, we used a Data Disto de- vice to obtain distance data, and a map was drawn by the aid of the “Profly” software. To findsmall-sizedsources in a native forest is mostly a matter of goodluck. One can finda good piece of tinder fungi comparatively easily, whereas one may seek all the day in vain for deer dung. In the past we have collectedextensive dataon flies from wildfruits (P APP 1992, apple bait collections) andhuman faeces in the same forest brook valleys (P APP 1993), as well as on flies developing in fruiting bodies of mushrooms (ÁGNES DELY-DRASKOVITS reared50 thousandadultDiptera of 128 species in 24 families; see DELY-DRASKOVITS 1976), but these data were not included in this project. Statistical analysis of species richness data was done using the non-parametric analysis (Chao2 and Jack1, the first order jackknife method). The structure of our other data does not allow us to use more sophisticatedmethodsformerly used(I ZSÁK &PAPP 1994, PAPP et al. 1997, PAPP & IZSÁK 1999). RESULTS Ecological results From April 1995 to November 1998 insects (flies andbeetles) were collected on more than 500 small source samples; more than twenty thousandadultflies were captured or reared. Number of species, individuals and samples collected from 1995 to 1998 are summarisedin Table 1. A separate paper was published about the flies reared from Vespa crabro nests (PAPP 2000). Table 2 shows a part of our results obtainedin a creek valley of the Börzsöny Mts where we appliedspecial traps to collect flies on deadsnails( Helix pomatia). Twenty traps were set up for 24 and48 hours on the identicalplaces on the same days of July and August in three consecutive years (1995–1997); flies were also Acta zool. hung. 48 (Suppl. 1), 2002 200 L. PAPP rearedfrom the deadsnailsleft out two days.The number andspecies composition of the flies on a dead snail likely depend much more on whether a snail died in the close vicinity of a fresh corpse some time earlier than on the physical or environ- mental factors of the micro-site. The species numbers foundon four types of sources is summarisedin Table 3 andcomparedwith species number estimation madeby the Chao 2 andthe first or - der jackknife method. When analysing data shown in Table 1, all the sources sam- pledare taken into consideration.The species richness calculations summarisedin Table 4, however, only include the number of the adult flies captured on tinder fungi, on fox faeces, on deer faeces and on rotten or mouldy fungi. Some faunistic results A by-product of our studies is that dozens of species and genera were found as new for the fauna of Hungary (numerous species even new to science have been foundhitherto). P APP (1999) recorded eight genera and 15 species as new for the Hungarian fauna (Elephantomyia edwardsi (MEIGEN, 1818), the genera Phalacro- Table 1.

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