POLISH JOURNAL OF ECOLOGY 47 1 29--47 1999 (Pol. J. Ecol.) W em er ULRICH Nicholas Copemicus University in Torun Department of Animal Ecology 87-100 Torun. Gagarina 9: Poland e-mail: ulrichw @ cc.uni.torun.pl 'I'HE HYMENOPTERA OF A DRY MEADOW ON LIMESTONE: SPECIES COMPOSITION, ABUNDANCE AND BIOMASS ABSTRACT: In 1986 and 1988 the hymenopterous fauna of a semixerophytic meadow on lime­ stone near Gottingen (FRG) was studied using ground-photo-eclectors. A total of 4982 specimens be­ longing to 475 different species \vere collected. Extrapolations from double-log functions revealed that there may be as many as 1330 parasitoid species present per year. 455 of the 475 species were parasito­ ids. 155 of them attack dipterans. 48 lepidopterans. 36 beetles. 23 wasps, 22 plant hoppers and 13 ap­ hids. 47 of the species are egg-parasitoids and parasitoids of miners. ectophytophages count for 44 of 2 the \V asp species. The abundance of the wasp fauna was rather high ( 1120 ± 53 in d. m- a- I ( 1986) and 2 1 335 ± 42 ind. m - a- ( 1988). Most abundant were the parasitoids of miners, gall-makers and the egg­ parasitoids. Compared \vith the high abundance the biomass was low. In 1986 the wasps weighed a total 2 1 2 1 of 194 ± 24 n1gDW m- a- and in 1988 only 69 ± 20 mgDW m- a- . The parasitoids of ectophytopha­ gous lepidopterans and coleopterans counted for n1ore than half of the whole biomass. KEY WORDS: Hymenoptera. parasitoids. faunal composition, density, biomass. species numbers, local extinction. 1. INTRODUCTION The insect order Hymenoptera is the species is very limited. Most studies on order with the largest nun1ber of species the community structure and faunal com­ in the tetnperate regions (Gas ton et al. position only dealt with parts (norrnally 1996). In Europe tnany n1ore than 10,000 families) of the Hymenoptera and used species occur (Townes 1969, Kas­ sweeping samples, and color or light p a rj an et al. 1981, T r j a pit z in et al. traps, that have a great bias towards ac­ 1978, Krombein et al. 1979, To bias tive and relatively large species (We i­ 1986) of which over 85o/o are parasitoids. demann 1965, Konig 1969, However, our knowledge about the Abraham 1969, Horstmann 1970, biology, hosts and habitats of 1nost the Owen and Svensson 1974, Janzen 30 Werner Ulrich and P o n d 1975, C o p 1 a n d and est near Freiburg (southern FRG). These Askew 1977, Garb arc z y k 1981, studies showed that in temperate habitats saw 0 n i e w i c z 1981' s t er z y n ski the parasitoids not only have the highest 1981 ). Quantitative samples with species diversity of all insect groups but ground-photo-ec1ectors, which should also account for a large part of the insect minimize the bias, have only seldom abundance and biomass. been undertaken: T h i e de ( 197 5) stud­ ied the fauna of a spruce forest in the The aim of this study together with Soiling (FRG), Ulrich (1987, 1998) some forthcoming ones is to analyze the described the results about the fauna of a community structure of the parasitic Hy­ beech forest on limestone near Gottingen menoptera of a dry grassland on species and Hi 1pert ( 1989) presented data on level and to present data on the species the hymenopterous fauna of a mixed for- number, abundance, and biomass. 2. STUDY AREA AND METHODS The studies were undertaken at the Campanula rotundifolia, Achillea Drakenberg in the vicinity of Gottingen millefolium, Agrimonia eupatoria, and (FRG). The plateau of the hill (= 350 m Rhinanthus minor. Frequent are also Bro­ altitude) is formed by huge layers of mus erectus and Carexflacca. which is covered by LoB-layers chalk, During 1986 and 1988 samples were soil is ( T h o 1e & Me ye r 1979). The taken using ground-photo-eclectors. De­ characterized by a thin rendzina (T h o 1 e tailed descriptions of the sampling & Me ye r 1979), with pH ranging from method provided Ulrich (1987, 1988, 6.2 to 7.6. The summers are (normally) 1998). In 1986, 12 eclectors, which cov- relatively cool (around 16 °C) with low ered 0.25 m .. each, were placed. From precipitation (B or n k a m m 1960). The April to July groups of 4 were transposed mean annual temperature is 8.5 °C, the every 2 weeks; from July to December mean annual precipitation is 685 mm. half of them were transposed every The samplings were done on a dry 4 weeks. In 1988 8 eclectors were placed. meadow on the plateau of the hill. This From April to mid July they were trans­ 1neadow is roughly 1 ha large and is sur­ posed every 4 weeks in groups of 4. rounded by mixed beech I hazel hedges. Fro1n July to the end of November the Normally, the meadow is cut in June. traps remained in place. Picric-acid was A detailed account on the flora of the used as killing liquid. Drakenberg is provided by N a u en - The sampling boxes were checked bur g (1980). He describes the dry weekly but only the boxes of those eclec­ meadows of the plateau as fortns of the tors were analyzed that stood for more Gentiano-Koelerietum association. than 2 weeks in place. Due to this proce­ Dominating plant species are Cirsium dure only those insects were counted that acaule, Poa pratensis, Brachypodium had probably emerged under the trap. In­ pinnatum, Plantago media, P. lanceola- sects that were trapped during the instal­ tum, Pimpinella saxifraga, Galium al­ lation of the eclector should mostly have bum, Lotus corniculatus, Viola hirta, been captured the week after installation Medicago falcata, Linum carthaticum, (U 1r i c h 1 9 85). The Hymenoptera of a dry meadow 31 All the specimens were sorted into spe­ The biomass was assessed by the cies and at least identified to genus level. The formula developed by Ulrich (1998): literature used is given in U 1rich ( 1987, dry-weight (mg) = thorax volume 3 3 1988). The ichneumonids were kindly deter­ (mm ) 0.52493 (mg mm- ); r = 0.97; p mined by K. Horstmann, R. Hinz, E. Diller < 0.001. Both, data on biomass and on and W. Schwenke. The determination of the density refer to individuals or dry­ diapriids were checked by H. Hilpert. A list weight per square meters and year - 2 - I) of all species is provided in the appendix. ( m a . 3. RESULTS 3.1. NUMBER OF SPECIES Tables 1 and 2 (see also the appen­ specimen each of Olesicampe patellana dix) give an overview over the species and 0. subcallosa were found, and the found at the Drakenberg up to now. The large group of sawfly parasitoids whole material comprises 4982 speci­ Ctenopelmatinae was represented only by mens. In the two study years I was able one species of Synomelix (1 specimen). to identify 475 different species of Hy­ 96% (455 species) of the Hymenop­ menoptera. tera are parasitoids (Table 1, 2). 155 of Only 20 species are nonparasitic. them attack dipterans, 48 parasitize lepi­ Out of the 5 ant species detected, Myr­ dopterans, 36 coleopterans and 23 other mica rubra (387 specimens), Lasius ni­ wasps. The high number of parasitoids of ger ( 13 7) and Lasius flavus (82) were the Diptera coincides with the respective most abundant. Formica rufa and Lasius high number of their potential hosts: ruginodis reached only minor densities. mainly Cecidomyiidae, Phoridae, Only 8 solitary nest building Aculeata Sphaeroceridae and Fanniidae (Hove­ were caught (Anoplius viaticus, Priocne­ me ye r 1996). When the parasitoids are mis perturbator and P. femora/is, Spilo­ sorted according to host guild it appears mena troglodytes, Oxybelus uniglu1nis, that the egg-parasitoids and the parasi­ Osmia sp., Andrena spp.); however, this toid of miners are the dominant group (4 7 number is much to low due to the sam­ species each), followed by the parasitoids pling method. The two species of Prioc­ of ectophytophages (44 species) (Ta­ nemis (Pompilidae)) were the most ble 2). abundant solitary aculeate Hymenoptera It should be kept in mind that the (21 specimen). parasitoid guilds have different spe­ The number of sawflies was surpris­ cies-area-relationships (U 1 r i c h 1998). ingly low. Only 30 adults out of 5 species Therefore, the ranking of the guilds does (Rhogogaster viridis, Pristiphora not reflect the real dominance order of monogyniae, Pachyprotasis rapae, Mac­ the whole meadow but instead the rank­ rophya quadrimaculata, Allantus trunca­ ing of every respective small part (11 m2 tus, all Tenthredinidae) and 98 larvae area sampled by the traps). In the Gottin­ were caught. Correspondingly low was gen beech forest which was studied over the number of sawfly parasitoids: only 1 a period of 8 years (U 1 ri c h 1998) only Table 1. Number of parasitoid species of certain host taxa detected at the dry meadow Drakenberg ( 11 m2 sampled) and in the Gottingen beech forest (based on 12m2 sampled area, data from Ul rich 1998). The numbers of expected species are computed by formulas derived from collector's curves which are given in U I rich ( 1998). Parasitoids of Drakenberg: Expected No. of Ratio expected Gottingen forest Number of species in I I tn2 No. versus 1982: Detected species in 1 I m2 area detected No. No. of species in area sampled I 2m2 area samE led Arachnida 6 2 Blattaria I 0 Heteroptera 2 1 Aphidina 13 4 0.31 7 Cicadina 22 5 0.23 6 Coccina 7 3 Aleyrodina 0 3 Psocoptera 0 1 Thysanoptera 1 1 Planipennta 3 6 Coleoptera 36 23 0.64 21 Symphyta 3 4 Apocnta 23 9 0.39 8 Diptera 155 79 0.51 75 Lepidoptera 48 30 0.63 34 Host unknown 135 33 0.24 32 Sum 455 201 0.44 204 Other Hymenoptera Nest-building species 8 Phytophagous species 7 Social species 5 Total number 475 Table 2.