Insect Diversity in Agricultural Grasslands the Effects of Management and Landscape Structure

Research Collection

Doctoral Thesis

Insect diversity in agricultural grasslands the effects of management and landscape structure

Author(s): Di Giulio Müller, Manuela

Publication Date: 2000

Permanent Link: https://doi.org/10.3929/ethz-a-004056948

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ETH Library Diss. ETI! No. 13698

Insect diversity in agricultural grasslands:

The effects of management and landscape structure

A dissertation submitted to the

Swiss Federal Institute of Technology Zurich

for the degree of

Doctor of Natural Sciences

presented by

Manuela Di Giulio Müller

Dipl. zool. University of Zurich bora L7 July 1970

from Bettlach SO

accepted on the recommendation of

Prof. Peter J. Edwards, examiner

Dr. Erhard Meister, coexaminer

Dr. Bernhard Merz, coexaminer

2000 Table of contents

Summary 1

3 Zusammenfassung

5 General introduction

Chapter i. Enhancing insect diversity in agricultural grasslands: The roles of management and landscape structure

23 Chapter 2, Insect and plant diversity patterns in agricultural grasslands

36 Chapter 3. The bug fauna (Heteroptera) of agricultural grasslands in the Schaffhauser Randen (SH) and Rottal (LU). Switzerland, with updated checklists of Heteroptera of the Cantons Luzern and Schaffhausen

62 Chapter 4. The influence of host plant diversity and food quality on larval survival of plant feeding heteropteran bugs (Heteroptera: Stenodemini)

Conclusions

79 Curriculum vitae 1

Summary

This study investigates the influence of management and landscape structure on insect diversity of hay meadows. The aim of the thesis is to examine what are the most important environmental factors affecting the insect fauna of meadows and how insect chosen as the diversity can be enhanced m agricultural landscapes. Meadows have been study system because m Switzerland they cover a large part of the agriculturally used The four area, and they therefore represent an important structure of cultural landscapes. chapters of the thesis deal with the following questions: l) How does management affect the insect diversity of grasslands? Do different grassland types have characteristic insect communities? 2) How important are the various grassland types for species the insect diversity on a landscape level? How does the surrounding landscape affect community of single meadows? 3) How valuable arc the meadows of the research area for the bug fauna of Switzerland? 4) How does plant diversity influence the insect diversity of grasslands'? Does host plant di\crsity affect the larval development of oligophagous insects?

The true bugs (Heteroptera) were chosen as an indicator group for insect diversity, because they are ecologically very diverse and because meadows represent a typical in habitat for this insect group. The research area is located in the Schaffhauser Randen Northern Switzerland and belongs to the Jura formation. It is an extensive forested area with a number of more or less isolated enclaves of agricultural land. Four such enclaves with varying mixtures of arable and grassland habitats were selected for the study. We chose a nested block design with two levels. The block level (landscape type) was represented by the four enclaves (area), and within each block we investigated two grassland management types (officially referred to as medium intensive and extensive), and for each management type we selected three replicate sites.

The data presented m chapter 1 indicate that management greatly affects the heteroptcran bug diversity of grasslands. Extensive meadows are richer in species than medium intensive ones. Further, species differ m their response to management, and thus species composition is also affected. Two species appear to benefit from intensive management and are most abundant in medium intensive meadows. Both of these species develop two generations per year and are relatively mobile; it is argued that these characteristics enable them to survive in highly disturbed habitats. Six species, however, arc adversely affected by intensive management and arc most abundant m extensively managed meadows. Most of these overwinter as eggs and larval development takes place in spring. Frequent and early cutting, therefore, may damage the larval stages and prevent the insects from developing and reproducing. Ground living species which need a warm and dry microclimate are also adversely affected by intensive management. Medium intensive meadows are characterised by a dense and closed vegetation and therefore do not represent suitable habitats for these species.

The bug fauna of extensne meadows differs greatly between the areas investigated. The medium intensive sites, however, show a rather small variation in respect to their species richness and composition. Many bug species occur only in individual areas and appear to have restricted ranges. Most of the rare species can reach locally high densities but are often restricted to one or a lew sites. It is therefore crucial to preserve many different sites m order to maintain species dnersity at the landscape level. Chapter 2 examines whether the differences between areas in species composition can be explained by the structure of the surrounding landscape. The results indicate that the 2

proportion of arable land in the surrounding might affect the bug fauna of a meadow and that some species apparently benefit from the presence of this habitat type. However, it is concluded that the spatial scale used in this study was too coarse to understand in detail how insects are affected by their surrounding habitats.

Chapter 3 investigates the importance of the meadows in the research area for the bug fauna of Switzerland. Based on my own findings and on data from a similar study conducted in the Randen an updated species list of Heteroptera for the Canton Schaffhausen is given. To evaluate the value of the sites investigated from a conservation point of view, the species list is compared to data from other regions of Switzerland (based on literature and on a comparable study which has been conducted in the Canton Luzern). The results indicate that the extensively managed meadows of the Schaffhauser Randen are relatively very species rich habitats for the heteropteran fauna of Switzerland.

Chapter 4 explores how host plant diversity and food quality affect the larval development of two bug species (Stenodemmi) which arc strictly phytophagous and capable of feeding on a wide range of different grass species, but arc normally found on and it has been only a few species. They change their host plants during ontogenesis suggested that this represents a response to the changing protein content of the hosts. In a laboratory experiment the development of insects reared on grass monocultures was compared with that when they were reared on mixtures of four species. In addition the is the host grasses were grown under two nitrogen regimes to test if protein content key factor determining host plant switching. The results indicate that host plant diversity significantly increases larval survival and that crude protein content is not the main factor responsible for the effect. Other important factors might be the form and availability of nitrogen, the balance of amino acids, the water content of the host and the content of mineral and trace elements. Furthermore, secondary compounds and mechanical or chemical plant defences may also play an important role. A highly diverse meadow might therefore enhance insect diversity by increasing larval survival of herbivores and, indeed, the field data indicates that host plant diversity is positively correlated with the species richness of Stcnodemini. 3

Zusammenfassung

Diese Arbeit untersucht den Einfluss von Nutzungsintensität und Landschafts¬ struktur auf die Insektenvielfalt von Mähwiesen. Das Ziel der Dissertation ist aufzuzei¬ gen, welche Umweltfaktorcn die Tnsektenfauna von Mähwiesen bestimmen und wie die Tnscktenvielfalt in Agrarlandschaften gefördert werden kann. Als Untersuchungsobjekt sind Wiesen gewählt worden, weil sie in der Schweiz einen grossen Teil der landwirt¬ schaftlich genutzten Fläche ausmachen und ein wichtiges Element der Kulturlandschaft darstellen. Die vier Kapitel der Arbeit behandeln folgende Fragestellungen: 1) Welchen Einfluss hat die Bewirtschaftungsintensität auf die Tnscktenvielfalt? Können für die ver¬ schiedenen Wiesentypen spezifische Lebensgemeinschaften definiert und charakterisiert werden? 2) Wie viel tragen die verschiedenen Wiesentypen zur Artenvielfalt auf Land¬ schaftsebene bei? Wie beeinflusst die umgebende Landschaft die Tnsektenvielfalt einer Wiese? 3) Wie wertvoll sind die Wiesen des Untersuchungsgebietes für die Wanzen¬ fauna der Schweiz? 4) Welchen Einfluss hat die Pflanzcnvielfalt auf die Insektenvielfalt einer Wiese? Hat die Wirtspflanzenvielfalt einen Einfluss auf die Entwicklung oligo- pbagerInsekten?

Als Indikatorgruppe für die lokale Wanzenvielfalt wurden Wanzen (Heteroptera) gewählt, weil sie ökologisch sehr vielfältig sind und weil Wiesen typische Habitate die¬ ser Tnsektenordnung darstellen. Die Untersuchungen wurden im Schaffhauser Randen durchgeführt, dem östlichsten Ausläufer des Tafeljuras. Die landwirtschaftlich genutz¬ ten Gebiete auf den Hochflächen sind durch ausgedehnte Wälder voneinander getrennt. Vier solche Gebiete wurden ausgewählt, die sich in ihren Anteilen an Gras- und Acker¬ land unterscheiden. Als Versuchsanordnung wurde ein Blockdesign gewählt, mit zwei Nutzungsintensitäten (extensiv und mittel intensiv) pro Gebiet und drei Wiederholungen pro Gebiet und Nutzungsintensität. Insgesamt wurden 24 Flächen erfasst.

Im Kapitel 1 wird gezeigt, dass die Bewirtschaftung die Wanzenvi elfalt einer Wiese stark beeinflusst. Extensive Wiesen sind diverser als mittel intensive und weil die Wan¬ zenarten unterschiedlich auf die Nutzung reagieren, wird auch die Zusammensetzung der Lebensgemeinschaften durch die Nutzung verändert. Die Reaktionen der häufigsten Arten werden mit Hilfe von Varianzanalysen geprüft. Zwei Alten reagieren positiv auf die intensivere Bewirtschaftung und sind in mittel intensiven Wiesen häufiger als in extensiven. Beide Arten entwickeln mehrere Generationen pro Jahr und sind relativ mo¬ bil, was ihnen das Überleben in stark gestörten Habitaten zu ermöglichen scheint. Sechs Wanzenarten hingegen werden durch die Bewirtschaftung klar beeinträchtigt und sind in extensiven Wiesen häufiger als in mittel intensiven. Viele dieser Arten überwintern im Eistadium und beginnen ihre Entwicklung erst im Spätfrühling. In früh und häufig geschnittenen Wiesen können sie ihre Entwicklung deshalb nicht abschhessen und ver¬ schwinden längerfristig aus diesen ITabitaten. Wanzenarten die am Boden leben und für ihre Entwicklung auf ein warmes und trockenes Mikroklima angewiesen sind, werden ebenfalls durch eine intensive Nutzung beeinträchtigt. Mittel intensive Wiesen zeichnen sich durch eine dichte und geschlossene Vegetation aus und sind deshalb für diese Tiere ungeeignete Habitate.

Die Wanzenfauna der extensiven Wiesen unterscheidet sich stark zwischen den vier Gebieten. Die mittel intensiven Flächen hingegen gleichen sich stärker in ihrer Arten- zahl und -Zusammensetzung. Viele Wanzenarten kommen nur in einzelnen Gebieten vor und scheinen eine kleinräumige Verbreitung zu haben. Die meisten der seltenen Arten können zwar lokal häufig auftreten, sind aber auf einzelne Flächen beschränkt. Es 4

braucht deshalb viele verschiedene Wiesen um das ganze Spektrum an Arten in einer Region zu erhalten. Im Kapitel 2 wird untersucht, ob die Gebietsunterschiede durch die unterschiedliche Strukturierung der Landschaft erklärt werden kann. Die Resultate wei¬ sen daraufhin, class der Anteil an Ackerland in der umgebenden Landschaft die Wan¬ zenfauna einer Wiese beeinflussen kann und dass gewisse Arten durch diesen Habitat¬ typ gefördert werden. Es hat sich aber auch gezeigt, dass die gewählte räumliche Skala zu grob ist, um verstehen zu können, wie Insekten durch die umgebende Landschaft beeinflusst werden.

In Kapitel 3 wird aufgrund dieser Arbeit eine aktualisierte Artenliste für den Kanton Schaffhausen vorgestellt. Dafür werden Daten einer Studie einbezogen, die ähnliche Fragestellungen bearbeitet und im gleichen Untersuchungsgebiet durchgeführt wurde. Um den Wert der untersuchten Wiesen für den Artenschutz abschätzen zu können, wird die Artenlistc mit Daten aus anderen Regionen der Schweiz verglichen. Dafür werden Literaturdaten und Resultate einer Arbeit verwendet, die extensive Wiesen im Kanton Luzern untersucht hat. Der Vergleich zeigt, dass die extensiven Wiesen des Schaffhau- ser Randens wertvolle Flabitate für die Wanzenfauna der Schweiz darstellen.

In Kapitel 4 wird untersucht, ob die Vielfalt von Wirtspflanzen die larvale Ent¬ wicklung phytophager Wanzen (Heteroptera: Stcnodemini) beeinflusst und ob der Roh¬ proteingehalt der Nahrung dabei eine entscheidende Rolle spielt. Die Larvcncntwick- lung von Tieren, die mit Mischungen aus vier verschiedenen Pflanzcnarten gefüttert worden sind, wird mit derjenigen von Insekten verglichen, denen reine Monokulturen gefüttert worden sind. Die Resultate zeigen, dass eine Vielfalt an Wirtspflanzen die lar¬ vale Mortalität senken und dass der Proteingchalt der Pflanzen nicht alleinc dafür ver¬ antwortlich sind. Die vorteilhafte Wirkung eines vielfältigen Pflanzenangebots für her¬ bivore Insekten scheint demnach durch verschiedene Faktoren verursacht zu werden, wie zum Beispiel sekundäre Pflanzenstoffc, chemische oder mechanische Abwehrstoffe oder die unterschiedliche Zusammensetzung und Verfügbarkeit von Stickstoff. Ein viel¬ fältiger Pflanzcnbestand kann daher die Tnscktenvielfalt fördern, indem er die larvale Entwicklung der Insekten positiv beeinflusst und die Mortalität senkt. Felddaten unter¬ stützen diese Resultate und /eigen, dass die Artenzahl oligophagcr Herbivoren mit der Artenzahl ihrer Wirtspflanzen zunimmt. 5

General Introduction

The heterogenous and species rich landscapes of Central Europe were generated during the Middle Ages by traditional small scale and extensive management (Mühleberg & Slowik 1997). They are characterised by both temporal and spatial heterogeneity (Macdonald & Smith 1990). In the last fifty years, however, agricultural practices have changed and strongly altered agricultural landscapes. The mechanisation of cultivation and the use of artificial fertiliser and pesticides have greatly increased agricultural production but at the same time led to an impoverishment of the landscape and to environmental pollution. The decrease m habitat heterogeneity and the use of pesticides resulted in a major decrease m species diversity (lsler-Htibscher 1980; Mühlcbcrg & Slowik 1997). These negative effects have led to growing public concern about the environmental problems caused by modern agricultural practices, and to an increasing demand for food produced in an ecologically sensitive way. Further, the Convention of Rio in the 1990's resulted m greater awareness about the issue of biodiversity and the negative consequences of species loss. In parallel major changes have occurred in world economics which have greatly altered the rural economies of most countries of Europe. In many countries the time had come for major changes m agriculture policy. For example, the Swiss government introduced subsidies for extensive management and ecological compensation areas; these were intended partly to enhance species diversity m agricultural landscapes and partly to support Swiss agriculture without causing damaging effects. The new policy led to a great interest in management techniques to enhance biodiversit> m agricultural landscapes and they were therefore investigated in the Priority Programme Environment (SPPE) of the Swiss National Science Foundation. This thesis is part of that programme and has the objectives, firstly, to examine how management and landscape structure affect insect diversity of agricultural grasslands and, secondly, to evaluate management techniques to enhance species diversity m agricultural landscapes.

Several studies have investigated the influence of different grassland management types on the species diversity of insects (for an overview see Curry (1994) and Gerstmeier & Lang (1996)). Although landscape structure may influence the effect of management on species diversity, most studies have focused on individual sites, without taking into account the surrounding landscape (Saunders, Hobbs & Margules 1991). However, landscape structure can be important: m a mosaic of different grassland types insects have a better chance to find suitable habitats, shelter or food over the season. Furthermore, the destructive effect of mowing may be mitigated when different grassland types are present, since insects may escape to adjacent meadows. This thesis, which investigates the influence of management and landscape structure on insect diversity of grasslands, is concerned with both the local system and with the influence of the surrounding landscape. A survey was made of insect diversity in grasslands under extensive and medium intensive management m the North of Switzerland. As an indicator group for insect diversity the true bugs (Heteroptera) were chosen because they are an ecologically very diverse group, including phytophagous, saprophagous and predatory species (Dollmg 1991). Furthermore, some species arc generahsts while other are specialists. Both larval stages and adult individuals live m the same habitat and respond sensitively to environmental changes (Morns 1969, 1979; Achtziger 1995; Otto 1996). Previous studies have shown that the richness of the bug fauna correlates strongly with total insect diversity (Duelh & Obnst 1998). Finally, it is a manageable group in terms of numbers of species. 6

Only few studies have investigated the dispersal and dispersion of arthropods in agricultural landscapes, though dispersal ability is a key factor determining how species Forman are affected by management and the surrounding landscape (Samways 1994; 1995; Mortimer, Hoi her & Brown 1998). The sink-source model (Pulliam 1988; Howe & Davis 1991; Watkinson & Sutherland 1995) and the mctapopulation concept (Harrison 1993; Reich & Grimm 1996; Han ski 1997) are theoretical concepts which recognise the essential role of dispersal for long term persistence of organisms in patchy habitats. Apart from Southwood (I960), few authors have examined the dispersal ability of heteropteran bugs. A few pest species have been thoroughly investigated, but otherwise only little is known about the ecology of species in this insect order (Brown 1965; Dingle 1968; Dmglc & Arora 1973). We designed a field experiment to investigate how rapidly new habitat patches are colonised by bugs and which species disperse most readily.

Although, the relationship between species richness of insects and plants has been investigated in several studies, the results are contradictory and the underlying mechanisms are not yet entirely understood (Strong, Lawton & Southwood 1984). The relationship is dependent on various factors, including the age of a habitat and the stage of succession. Early in a succession there may be a positive correlation between insect and plant diversity, but later the structure of the vegetation may become a more important factor than plant species numbers influencing the species richness of insects (Southwood, Brown & Reader 1979). Tn this thesis the relationship between species richness of plants and heteropteran bugs was investigated using the insect data from the field study and in close collaboration with Sibylle Studer (2000) who studied the vegetation of the same sites. In the laboratory the influence of plant diversity on a guild of plant feeding bugs (Heteroptera: Stenodemini) was investigated experimentally. The effect of host plant diversity and food quality in terms of crude protein content on larval development and survival of two bug species {Leptopterna dolobrata L. and Notostira crratica L.) was studied.

Outline of this thesis

Chapter 1 examines the influence of grassland management on the heteropteran fauna. Chapter 2 explores the species patterns on the landscape level and compares them with those of plants and butterflies, which were investigated by Studer (2000) and Widmer (2000). In addition, the influences of the surrounding landscape on heteropteran bug diversity of grasslands are discussed. Chapter 3 analyses the faunistic data gained in the field study in terms of the abundance and ecological affinity of the various species and discusses the biogeography of rare species in respect to data from Germany. Chapter 4 presents the results of the laboratory experiment on the effect of host plant diversity on larval survival of two phytophagous bug species.

References

Achtziger, R. 1995. Die Stiuktui von Insckteiiqeinemschaften an Gehölzen: Die Hemipteren-Fauna als Beispiel fur che Biodiversitat \on Heiken- und Waldiandökosystemen. Bayreuther Forum Oekologie 20.

Brown, E.S. L965. Notes on the migration and direction of flight of Eurygastci and Aelia species (Hemiptcra, Pentatomidae) and then possible bearing on invasions ol cereal crops. Journal of Animal Ecology 34-93-107. Curry, J P. 1994. Grassland inveitebrates Chapman & Hall. London

Dingle, H. 1968. The influence of envnonment and heredity on flight activity in the milkweed bug 7

Oncopeltus. Journal of Experimental Biology 48:175-184. Dingle, TT. & Arora, G. L973. Experimental studies of migration in bugs of the Genus Dysdercus. Oecologia 12:119-140. Dolling, W.R. 1991. The Hemiptera. Oxford University Press. Oxford. Duelli. P. & Obrist, M. 1998. In search of the best correlates for local organismal biodiversity in cultivated areas. Biodiversity and Conservation 7:297-309.

Gerstmeier, R. & Lang, C 1996. Beilrag zu Auswirkungen der Mahd auf Arthropoden. Zeitschrift für Oekologie und Naturschutz 5: LI 4. Hanski, I. 1997. Habitat destruction and metapopulaüon dynamics. In: Picket), S.T.A, Ostfeld, R.S., Shachak, M. & Likens, G.E. The ecological basis of conservation, pp. 217-227. Chapman & Hall, New York. Harrison, S.P. 1993. Melapopulations and conservation. In: Edwards, P.E. May, R.M. & Webb, N.R. Large-scale ecology and conservation biology, pp. 11-127. Blackwell Scientific Publications, Oxford.

Howe, R.W. & Davis, G..T. 1991. The demographic significance of 'sink' populations. Biological Conservation 57:239-255.

Tslcr-Hübscher, K. 1980. Beiträge 1976 zu Georg Kummers "Flora des Kantons Schaffhausen" mit Berücksichtigung der Grenzgebtete. Mitteilungen der Natitrforscheiiden Gesellschaft Schaffhausen 31:7-121. Macdonald, D.W. & Smith, H. 1990. Dispersal, dispersion and conservation in the agriculture ecosystems. In: Bunce, R.G.G. & Howard, D.C Species dispersal in agricultural habitats, pp. 18-64. Belhaven Press, London. Morris, M.G. 1969. Differences between the invertebrate faunas of grazed and ungrazed chalk grasslands. III. The heteropterous fauna. Journal of Applied Ecology 6:475-487. Morris, M.G. 1979. Responses of grassland invertebrates to management by cutting. TT. Heteroptera. Journal ofApplied Ecology 16:417-432. Mortimer, S.R.. Hollicr, J. A. & Brown, V.K. 1998. Interactions between plant and insect diversity in the restoration of lowland calcareous grasslands in southern Britain. Applied Vegetation Science 1:101-114.

Mühleberg, M. & Slowik, J. 1997. Kulturlandschaft ah Lebensraum. Quelle & Meyer Verlag, Wiesbaden.

Otto, A. L996. Die Wanzenfauna montaner Magerwiesen und Grünbrachen im Kanton Tessin (Insecta: Heteroptera). Dissertation ETH Zürich. Pulliam. R.EI. L988. Sources, sinks, and population regulation. The American Naturalist 132(5):652-661. Reich, M. & Grimm, V. 1996. Das Metapopulalionskonzept in Oekologie und Naturschutz: Eine kritische Bestandesaufnahme. Zeitschrift fur Ockologie und Natui schütz 5:123-139. Samways, MJ. 1994. Insect Conservation Biology. Chapman and Hall, London.

Saunders, D.A., TTobbs, R.J. & Margules, CR. 1991. Biological consequences of ecosystem fragmentation: a review. Conservation Biology 5:18-32. Southwood, T.R.E. 1960. The flight activity of Heteroptera. Transactions of the Royal Entomological Society of London 112(8): 173-220. Southwood, T.R.E. Brown, V.K. & Reader, P.M. 1979. The relationship of plant and insect diversities in succession. Biological Journal of the Linnean Society 12:327-348.

Strong, D.R., Lawton, J.H. & Southwood. T.R.E. 1984. bisects on plants. Blackwell Scientific Publications, Oxford.

Studer, S. 2000. The influence of management on the floristic composition of hay meadows. Dissertation ETH Zürich.

Watkinson, A.R. & Sutherland, W.J. 1995. Sources, sinks and pseudo-sinks. Journal of Animal Ecology 64:126-130.

Widmer, L. 2000. Lepidoptcra in differently managed grasslands: assessing the impact of habitat variability. Diploma thesis Ihmersity of Zurich. Chapter 1. Enhancing insect diversity in agricultural grasslands: The roles of management and landscape structure

Manuela Di Giulio, Peter J. Edwards & Erhard Meister

Accepted by Journal of Applied Ecology

Summary

in Switzerland 1. During the last few years a variety of methods have been applied The to preserve and enhance biological diversity in agricultural systems. purpose of this study is to evaluate grassland management techniques in respect to their effectiveness within the managed area itself and to examine how these areas con¬ tribute to species diversity at a landscape scale.

2. In a heterogenous landscape in part of the Swiss Jura we examined insect diver¬ sity in grasslands subject to different management. Four study areas with varying landscape structure were selected and in each area, meadows of two grassland management types were investigated.

3. The true bugs (Heteroptera) have been chosen as an indicator group for insect di¬ versity on the basis of previous work which had shown that the richness of the bug fauna correlates strongly with total insect diversity. 4. The variance of the heteropteran species data is partitioned into spatial (area) and management components. Area accounts for 35.4%, management for 29.7% and the interaction management x area for 7.2% of the species variance. The species diversity is greater m extensively managed meadows than in medium intensive

ones; extensive sites have more individuals and show a more even rank abun¬ dance distribution.

5. Individual species differ in their responses to management. Two species benefited from intensification whereas six species were affected negatively by intensive management. The influence of management on individual species is discussed in detail. Two main groups of species do not appear to respond to management; these are mostly widespread species which occur in various types of habitats, and polyphagous species which live in a wide range of grasslands but which show a certain affinity to managed meadows.

6. Our study indicates that extensive management of grasslands can enhance both local and regional insect diversity in agricultural landscapes. Extensively man¬ aged meadows are species rich habitats which support some rare and specialised species. In contrast the bug community of medium intensive meadows is domi¬ nated by more widespread and less specialist species. Key-words: grassland management, Heteroptera, landscape structure, species diversity, Switzerland

INTRODUCTION

Agricultural landscapes are characterised by a very high spatial and temporal het¬ erogeneity which is determined largely by human activities. Little is known about how species are affected by such heterogeneity and how they persist in agricultural systems (Macdonald & Smith 1990). For example, few studies have investigated the dispersal 9

and dispersion of arthropods in agricultural landscapes (Samways 1994; Forman 1995; Mortimer, Hollier & Brown 1998), though there is information on some groups, notably butterflies (Fry 1994; Sutcliffe & Thomas 1996), spiders (Bishop & Riechert 1990; Thomas, Hoi & Everts 1990; Thomas 1996), carabid beetles (Thomas, Wratten & Sotherton 1991; Kinnunen & Tiainen 1994; Forman 1995) and wild bees (Steffan- Dewentcr 1998).

In contrast, there have been several studies of the influence of grassland manage¬ & ment on insect diversity; for an overview sec Curry (1994) and Gerstmeicr Lang (1996). Some management operations, for example mowing, have a direct effect on in¬ and sects by damaging or killing individuals or removing them from the site. Immobile relatively immobile species or stages are specially affected, and in the long term the also occur whole population may be threatened (Volkl et al. 1993). Indirect effects may mainly through changing the habitat; for example, if management alters the plant spe¬ cies composition and the structure of the vegetation, it is also likely to affect the micro¬ climate and other aspects of the microhabitat. Since many arthropods respond very sen¬ sitively to the microclimatic conditions such indirect effects can strongly influence community composition (Franz 1931; Fewkes 1961: Curry 1994; Gerstmeicr & Lang 1996). Lcafhoppers (Auchenorrhyncha) arc strongly affected by indirect effects of grassland management. They are closely associated with particular plant species and reach their greatest diversity in species-rich, highly structured meadows. Many species the sward the occupy definite layers in a grassland and move vertically within during season. Changes in the species composition and in the structure of the plant community due to management therefore affect the community of lcafhoppers greatly (Andrzcjew- ska 1965; Curry 1994). Although it is recognised that landscape structure also affects the species composi¬ tion at a particular site, most studies of management have focused on the site alone, without taking into account the surrounding landscape (Saunders, Flobbs & Margulcs 1991). However, insects have a better chance to find suitable habitats, shelter or food over the course of a season in a mosaic of different grassland types. Furthermore, the destructive effect of mowing may be mitigated when different grassland types arc pres¬ ent, since insects can escape to adjacent meadows where they find new habitats. Indeed the sink-source model (Pulliam 1988; Howe & Davis 1991; Watkinson & Sutherland 1995) and the metapopulation concept (Harrison 1993; Reich & Grimm 1996; Hanski 1997) are theoretical concepts which recognise the essential role of dispersal for long term persistence of organisms m patchy habitats. Moreover, since species differ in their responses to management, it is important to support a high diversity of management types in order to maintain and enhance species diversity at a regional level (Morris & Rispin 1993; Dietl 1995).

This paper is part of a study on the effects of both management and landscape structure on species diversity of agricultural grasslands in Switzerland. We chose the true bugs (Heteroptera) as an indicator group for insect diversity in general for various reasons. Firstly, the bugs are an ecologically very diverse group, including phytopha¬ gous, saprophagous and predatory species (Dollmg 1991). Furthermore, some species are generalists while other are specialists. Secondly, both larval stages and adults live in the same habitat and respond sensitively to environmental changes (Morris 1969, 1979; Achtziger 1995; Otto 1996). Thirdly, previous studies have shown that the richness of the bug fauna correlates strongly with total insect diversity (Duelli & Obrist 1998). Fi- 10

nally, and despite their ecological diversity, the Heteroptera is a manageable group in terms of the numbers of species occurring in grasslands. In Switzerland different schemes have been developed to enhance biological diver¬ sity in agricultural systems. The aim of our study is to evaluate how contrasting grass¬ land management techniques influence insect diversity in agricultural landscapes and to In assess to what extent insect diversity of grasslands is affected by landscape structure. of the het¬ this paper we focus on the effect of management on the species composition eropteran fauna. The effects of landscape structure on the relative abundance and com¬ position of heteropteran communities will be presented in a separate paper (Manuela Di Giulio, in preparation).

Material and methods

Research area and study sites

The research area is located in the Schaffhauser Randen (northern Switzerland, Ta¬ ble 1) and forms part of the hills of the Swiss Jura. The soils are nutrient poor is limestones. The average yearly precipitation in Schaffhausen (437 m a.s.l.) 866 mm, and the highest mean monthly are m summer and lowest in late winter. The mean tem¬ perature is 7.8 °C, with a maximum mean monthly temperature in July (23.2 °C) and a minimum in January (-3.9 °C) (SMA 1998). The study site is an extensive forested re¬ gion with several more or less isolated enclaves of agricultural land. Local agricultural policy encourages farmers to maintain extensive meadows by offering subsidies if they follow specified forms of grassland management.

Table l.The four areas are situated in different municipalities of the Canton Schaffhausen. The altitude is

based on given in meters above sea level. The area of the mdn idual enclaves has been estimated 1:5000 maps.

Area Community ALTITUDE Area op COORDINATES Enclave

Zeigli/Mösli Hemmental 800 30 ha 8° 34'E/47° 45'N

Hinterranden Hemmental/ 830 40 ha 8° 34'E/47° 44'N Siblinçen

Klosterfcld Hemmental 670 100 ha 8° 36'E/47° 44'N

Merishauscr Randen Merishausen 780-830 240 ha 8° 36'E/47° 46'N

For our study we chose a nested block design with two levels. At the block level (landscape type) we selected four enclaves (= areas) ranging in size from 30 to 240 ha (area) with varying proportions of arable and grassland habitat. Within each block (area) we investigated two grassland management types (officially referred to as medium in¬ tensive and extensive), and for each management type wc selected three replicate sites. The management types are defined by two main factors: the number of cuts per year, and the type and amount of fertiliser used, Medium intensive meadows are regularly fertilised with slurry and are cut 2-3 times per year. The time of the first cut is approxi¬ mately the end of May. The extensive meadows are not fertilised and arc cut once or twice per year. The time of the first cut is July. We selected the grassland types on the basis of the plant species composition and later we interviewed the farmers about the amount and type of fertiliser used, the number of cuts, the time of cutting and the previ- 11

the se¬ ous management. In these interviews we learned that in the area of Hinterrandcn lected medium intensive grasslands had only been managed in a less intensive way for than in the last few years. The management contrast in this area was therefore smaller the other areas.

The plant species composition was assessed in summer 1997 using six randomly lo¬ the 24 cated Ixlm2 quadrats per site. A total of 110 plant species were recorded in sites, with the number of species sampled per site ranging from 21 to 48. The extensive and medium intensive meadows showed clear differences in plant species richness and in species composition. The community of the extensive meadows was dominated by Bromus erectus and there was a mean species number of 42 in the sample of 6 quadrats. The medium intensive sites were dominated by Arrh en ath enun elatius and Trisetum flavescens and the mean species number was 30 (Studer 2000).

Sampling Methods

The heteropteran bugs were sampled during the summer of 1997 using a standard¬ ised sweep-net method (Remane 1958; Bornholdt 1991; Otto 1996). The sweep-net had a diameter of 40 cm and was fitted with a heavy cloth suitable for sampling insects in the vegetation. Samples were collected every two weeks by making 100 sweeps with the net over a distance of about 100 m. The net was emptied after every twentieth sweep, re¬ sulting in five subsamples per site at each sampling date. Sampling was only carried out when the weather conditions were good, ie a minimum of 17°C and sunshine. Sampling was also restricted to the period between 10.00 a.m. and 17.30 p.m.; the sampling order of the fields was varied between weeks. Every site was sampled between 7 and 9 times from May to September.

The adult insects were determined with the aid of entomological handbooks (Wag¬ ner 1952; Wagner & Weber 1964; Wagner 1966. 1967, 1970-1971, 1975). The nomen¬ clature followed Günther & Schuster (1990). All species determinations were checked by R. Heckmann (Germany) and Ch. Rieger (Germany).

Statistical Analysis

For the analysis of the data, all samples were pooled over time, resulting in one sample per meadow. Rank abundance distributions are a useful method to describe and compare communities (Magurran 1988) because they take into account both species number and their abundance. We used rank abundance distributions to compare the bug communities of the two management types. Canonical Correspondence Analysis (CANOCO, version 3.1 by ter Braak 1987-1992) was used to study the influence on bug communities of management factors and spatial effects. The variance of the bug species data was partitioned into spatial (area) and management components (Borcard, Legendre & Drapeau 1992). Number of cuts, time of the first cut, and number of plant species sampled per meadow were included in the model as management variables. The four ar¬ eas investigated (enclaves) were included as a spatial factor. The apparent species com¬ position of communities is strongly influenced by sample size and rare species tend to be recorded only in large samples. To minimise sampling effects we omitted both rare species (< 3 individuals) and sites that were sampled fewer than eight times. The latter concerns three sites in the area Merishausen and one in the area Hinterranden. For the

24 most common species (> 14 individuals) analyses of variance were conducted to ex¬ amine how individual species respond to management. 12

Results

Influences of grassland management on insect diversity A total of 5608 adult bugs comprising 93 species characteristic of meadows were recorded in the 24 sites (occasional vagrants from wooded habitats were excluded). A full species list will be presented elsewhere (Di Giulio, Beckmann & Schwab 2000).

In three of the four areas the bug communities of the extensive meadows demon¬ strate clearly a more even rank abundance distribution than those of the medium inten¬ sive meadows (Figs la to lc), while in the fourth area (Hintcrranden) the community structures are similar (Fig. Id). The overall pattern in the intensive sites is for a few spe¬ in exten¬ cies to have a very high abundance while the majority arc less abundant than sive meadows. This contrast is clearest within areas, as the communities vary strongly

from area to area.

1000

1000 r b)

c 100

Xs 10 extensive <

~U—

0 10 20 30 40 50 60 10 20 30 40

Rank Rank

1000 1000 n c) d) O O Ö 100 S 100 d cd

Ö O 3 extensive 10 10 extensive < < intensive

10 20 30 40 10 20 30

Rank Rank

Fig. I. Rank abundance distributions of hctciopteran communities of extensively and medium intensively managed meadows m different areas: a) Klosteifeid, b) Zelgli/Mösli, c) Mcnshauser Randen, d) Hinterranden. Three sites per management type and area have been pooled for this analysis.

The ordination model explains 72.3% of the total variance (total inertia: 1.578, sum of all canonical eigenvalues: 1.141, Monte Carlo permutation test: P = 0.01; Fig. 2). Of this, area accounts for 35.4% (eigenvalue 0.559, P = 0.01) of the species variance, man¬ agement for 29.7% (eigenvalue 0.468, P = 0.01), and the interaction management x area for 7.2%. The plant species number was included into the variable 'management' and we therefore cannot say how much variation if explains. 13

1UU 10

27 7 D unexplained

O il area 2 50% u 35 4! cd D \ iummmttl management > 7.2 area H management

A(V„ L ^^NW,\\NNy.W'

Fig 2. Paititioning of the species vanance by en\i- lonmcntal vatiables (see tevt foi specifications)

The first and second axes (eigenvalues 0.554 and 0.191 respectively) of the ordina¬ tion analysis (Table 2, Fig. 3) account for 47.2% of the species variance, while the third and fourth axes (eigenvalues 0.158 and 0.077 respectively) for 14.9%. The ordination diagrams show that the axes one and two separate the area Klosterfeld from Hinterran- den, and also the extensively managed meadows (July cut and one cut) from the more intensively managed ones (Fig. 3a). The extensive meadows are grouped in the upper part of the diagram of axes one and two, while the medium intensive ones are found m the lower part. The medium intensne sites are closely gioupecl, indicating that their het¬ eropteran communities are very similar. Further, the extensive sites of Klosterfeld are separated from those of the other areas by the first axis. Hmterranden is clearly sepa¬ rated from the other areas by axes one and three, indicating that these sites have a mark¬ edly different species compositions (Figs 3a and b). The plant species number is the only non nommai variable m the model and is correlated with the first and second axes, though the correlation is not very strong (Table 2). 14

rpi M N x b) O 4-

Z* z. «z number of plant species

K1 Km

H 2 cuts c ^ *,'Klosterfeld # i)t Merishausen Hjfi,K . Juy axis 1 »M j^Zelgli axis3i , Hinterr.randeTr ff .Zelgji u »M 40 7 -0 7 1 C ,tv' M* 7 -0.7 +0 • Z Hinterranden# 2 cuts Klosterfeld-,1 Z» h»»H •H »June » Z

K* K«w 3 cuts Mayj,i • k a 1 cut -,.»Z June »K Z* » 2 cuts »Z ï3 cuts # 3 cuts

\<- cnvhonmcnlal vaiiablcs 9 -«K

Fig. 3. Ordination diagrams based on a Canonical Correspondence Analysis (CCA). Nominal variables arc represented as points (centroids), non nominal variables as vectors in the diagram. Different symbols are, given for the number of cuts per year. The capital letters indicate the areas: Z: Zelgli/Mösli, K: Klosterfeld. M: Merishauser Randen. H: ITinterranden. Sites with similar species compositions and community structures are represented by points close to each other in the diagrams. Total inertia: 1.578, eigenvalue first axis: 0.554, eigenvalue second axis: 0.191, eigenvalue third axis: 0.158, eigen¬ value fourth axis: 0.077. The model was tested using a Monte Carlo permutation lest: P = 0.01. For this analysis four sites (three in Merishauser Randen and one in ITinterranden) were omitted because they were sampled less frequently than the other ones (see text for specifications).

Table 2. The correlation matrix is based on a Canonical Correspondence Analysis and shows the values of

the first four environmental axes.

Variables Env. AX.l Env. ax. 2 Env. ax. 3 Env. ax. 4

Area 1 : Klosterfeld 0.8807 0.2660 -0.2635 -0.2660

Area 2: Zelgli/Mösli -0.1488 0.0289 0.7723 0.0133

Area 3: Hjnerranden -0.6090 -0.3265 -0.7059 0.1146

Area 4: Merishauser Randen -0.0983 0.0814 0.3996 0.1649

1 CUT -0.2656 0.6369 0.2167 -0.0080

2 CUTS -0.0469 -0.3609 -0.2097 0.3909

3 CUTS 0.5121 -0.4222 0.0022 -0.6430

May cut 0.3777 -0.4323 0.2351 0.1534

June cut 0.4391 -0.4653 0.1505 -0.2255

July cut -0.6070 0.666 -0.2832 0.0646

Number of plant species -0.4240 0.4058 -0.001 0.0170 15

There is no significant correlation between the species number of plants and heter¬ opteran bugs (t2i = 0.96, P = 0.35, R2 = 0.04; Fig. 4).

38 r

(1)

O • en 30 P- w

on ?fi - ci X> 4-1 22 o

*-< (1> x> 1« H s !z; 14 -

10 L ' 18 22 26 30 34 38 42 46 50 Number of plant species

Fig. 4. The species number of plants and heteropteran bugs are not correlated. Each point is for a different grassland site and is based on 6 Ixl m2 quadrats tot the vegetation and the recorded data for the bugs.

Species response to management

At the species level, eight out of 24 species are significantly influenced by manage¬ ment. Because the timing of the first cut and the number of cuts arc not independent variables we cannot be certain which factor is more important for the bug community. However, one or the other factor usually correlated more strongly with the occurrence of species.

Only two species appear to benefit more from medium intensive management: these are Nabis pseudoferus (Fijo = 3.55, P < 0.05) and Notoslira erratica (F?.,2o = 4.57, P < 0.05) which are most abundant m intensive, frequently cut meadows (Fig. 5). There is evidence that N. pseudoferus is reduced by cutting in July (7*2,20 = 9.2, P < 0.01; Fig. 6).

Six species arc adversely affected by intensive management. Of these, Mégalo- ceraea recticornis (F2,io = 5.39, P < 0.05), Peritrechus gracilicornis, (F?„20 = 13.36, P < 0.001) and Adomerus biguttatus (F220 = 3.96, P < 0.05) are apparently reduced by fre¬ quency of cut but not by the timing of the cutting. These species occur most abundantly in extensive meadows (Fig. 5). The abundances of Adelphocoris seticornis (Fo,2o = 5.0, P < 0.05; F220 = 8.19, P < 0.0 L), Hadrodemus m~jlavum (F2ao = 13.29, P < 0.001; F2,2o

= 4.6, P < 0.05) and Leptopterna dolobrata (F7 2o = 9.26, P < 0.01; F220 = 13.95, P < 0.001) appear to be reduced by both frequency of cutting and by early cuts (Figs 5 and 6). 16

N. pseudoferus r Af. erratica A. seticornis

a a

- b b fi ab ab t rf-i i

m u _ — —- S

1 2 3 1 2 3 1 2 3

/F m-flavum F. dolobrata M. recticornis ii

0) ri a O fi b cd Ä b It? -u- fi 1 2 3 1 2 3 i

P. gracilicornis A. biguttatus

b 21 b b 5.1 -1

Number of cuts

Fig. 5. Responses of individual species to the number of cuts (mean ± sd). The pairwise comparison was conducted with a Tukey test. Significant differences between the number of cuts are marked with dif¬

ferent letters (a/b). N. pseudoferus (F220 = 3.55. P < 0.05) and V. erratica (F2,20 = 4.57, P < 0.05) are most abundant in frequently cut sites. In contrast the abundances of A. seticornis (F2.2o = 5.0, P < 0.05), H. m-flavum (7A20 =13.29, P < 0.001), L dolobrata (F2,20 = 9.26, P < 0.01), M. recticornis (F2io = 5.39, P < 0.05). P. gracilicornis (F220 = 13.36. P < 0.001) and A. biguttatus (F2,20 = 3.96, P < 0.05) are reduced by frequent cutting.

A. pseudoferus A. seticornis 6 a 4 a a X A 4- 2 b

0 LXl ! ii DJ

-2 May June July May June July o G

ö H. m-flavum L, dolobrata

^t x LI

May June July May June July

Time of the first cut

Fig. 6. Responses of individual species to the time of the first cut (mean ± sd). The pairwise comparison was conducted with a Tuke) test. Significant differences between the, time of cut are marked with dif¬

ferent letters (a/b). July cut reduces the abundance of N. pseudoferus (F220 = 9.20, P < 0.01). May and June cut reduces the abundances of A. seticornis (F12Q = 8.11, P < 0.01). H. m-flavum (F2.20 ~ 4.6, P <

0.05) and L. dolobrata (F ,n = 13.95, P < 0.001 ). 17

Sixteen species show no response to management intensity. These are: Lygus pra¬ tensis, Lygus ntgulipennis, Dolycoris baccarum, Eurygasler maura, Carpocoris fuscispinus, Berytinus minor, Polymerus unifasciatus, Sirongylocoris steganoides, Pia- giognathus chrvsemthemi, Stenodema laevigatum, Trigonotylus caelestialum, Adelpho- coris lineolatus, Catoplatus fabricii, Nabis brevis, Chiamydolus pulicarius and Haïtiens apterus.

Discussion

Responses of the bug community The data presented here show that management effects are clearly important (Figs 2 and 3) for the species composition of the heteropteran bug community. They account for 30% of species variance and the ordination diagrams indicate that the extensive and me¬ dium intensive meadows have differing species compositions (Figs 3a and b). The ex¬ tensively managed meadows show a high variation in species composition, especially factors like between areas, indicating that apart from management several other aspect, medium light conditions or isolation affect the species composition of these sites. The is intensive sites, however, have very similar communities, suggesting that management the most important factor influencing the species composition of these meadows. Fur¬ ther, species diversity tends to be greater in extensively managed meadows than in me¬

dium intensive ones. Tn three areas the extensive sites have more individuals and show a

more even rank abundance distribution (Figs la to 1c). One area (Hinterranden), how¬

ever, is different. The rank abundance distributions (Fig. Id) and the ordination dia¬

grams (Figs 3a and b) for Hinterranden show that the bug communities are very similar in both management types. As already mentioned, the medium intensive grasslands have been managed less intensively in the last few years. Interestingly, the vegetation does not reflect the recent changes in management so clearly and the species composition re¬ mains typical of medium intensive and extensive sites elsewhere (Sibylle Studer, un¬ published data); this suggests that the bug communities react more quickly than plants to management changes (Mortimer, Hollier & Brown 1998). The environmental variables included in the CCA model explain most of the species variance (72.3%). The interaction term is very small (7.2%) indicating that the spatial and management variables are clearly separable in their effects (Borcard, Legendre & Drapeau 1992). Spatial effects account for an important part of the total variation (35.4 %) and have a strong effect on the structure and assemblage of bug communities (Figs 2 and 3). It is not yet clear whether this is due to historical factors (eg differences in for¬ mer land use) or to present day differences in landscape structure. However the obser¬ vation is consistent with various studies which show that geographic distributions of ter¬ restrial invertebrates tend to be patchier, with more species having restricted ranges than is the case for terrestrial vertebrates and plants (Colwell & Cocldington 1994; Otto 1996). The possibility that the structure of the landscape surrounding a site interacts with management effects on the insect community will be addressed in a more detailed spatial analysis of the data using G1S,

Interestingly, there is no correlation between the species number of plants and het¬ eropteran bugs (Fig. 4) and only a weak relationship between plant species number and the species composition of the bug fauna as represented m the CCA (Table 2, Figs 3a and b). Our findings are supported by the study of Otto (1996) who showed that the het¬ eropteran fauna is significantly correlated with the structure of the plant community but 18

not with the species richness. Apparently the bug fauna is affected more strongly by the structure and the microclimatic conditions in the grasslands than by plant species rich¬ herbivores the ness per se. As many bug species are zoophagous or polyphagous pant species richness might play a less important role than the structural diversity of the habitat.

Responses of individual species Although the trends associated with management are clear, species do differ in their N. erratica is responses to management, and not all arc adversely affected. For example, most abundant in medium intensive meadows (Fig. 5). This mirid bug has at least two in cut generations per year. It feeds on grass leaves and can find its food even freshly meadows. It is not yet clear how this species survives the frequent disturbances by cut¬ Morris ting. It may be that it rccolomses meadows soon after the cut (Remane 1958; 1969, 1979; Gibson 1980; Otto 1996). Bockwinkel (1990) has shown that at least a pro¬ portion of the adults take shelter m adjacent meadows. If this is the case, then it is rather surprising since the females are very weak fliers due to their reduced flight muscles. The males, in contrast, are good fliers and seem to be quite mobile (Kullenberg 1944; Doll¬ ing 1991).

N. pseudoferus is a macropterous nabid with two to three generations per year which lives in various habitats eg grasslands, cereals fields and field margins (Remane 1958; Southwood & Leston 1959; Pen cart 1987). It is a predatory species that feeds mostly on smaller insects (Péricart 1987). Little is known about its biology, though it appears to benefit from intensive management and is more abundant in the medium intensive grassland site (Figs 5 and 6). Macropterous nabids are often associated with ephemeral habitats and seem to be fast and strong fliers (Southwood I960). In general, insect spe¬ cies with several generations per year have a better chance of persisting in highly dis¬ turbed habitats than those with only one (Southwood 1960; Morris 1979). This appears to be the case for both N. erratica and N. pseudoferus. In contrast to these species, M. recticornis is severely reduced by cutting and is more abundant in extensive meadows (Fig. 5) or fallow land with a high proportion of grasses (Morris 1979; Otto 1996). Lar¬ val development takes place in spring when the intensively managed grasslands are cut for the first time. This phase is the most sensitive of the whole life-cycle and therefore susceptible to disturbances. The life-cycle may therefore explain the sensitivity of the species to intensive management. Moreover this species is a poor flier and therefore may be slow to colonise new habitats (Southwood I960).

It is known that L. dolobrata does not occur on very poor soils (Kullenberg 1944) and that nitrogen is a factor which limits its larval development (McNeill 1973; McNeill & Southwood 1978). We might expect that intensively managed meadows with a high nitrogen availability would be a favourable habitat for this species. However, frequent and early cutting reduces this species severely (Figs 5 and 6) and the life-cycle may be the critical factor. Since the females lay their eggs on the bottom part of grass-stems (Kullenberg 1944), damage to the eggs is probably not the reason that it is restricted to extensive sites. Larval development, however, may be the critical phase since this takes place in June when the medium intensive meadows are cut (Kullenberg 1944; Wagner 1952; Southwood & Leston 1959).

P. gracilicomis is restricted to extensively managed meadows (Fig. 5). It is a lygaeid bug that occurs in warm, dry places (Wagner 1966), though little more is known 19

about its biology. The heterogeneous and open vegetation of extensive sites provides a for xero- warm and dry microclimate on the ground and therefore ideal conditions thermophilic species (Otto 1996).

A. biguliatus is also a xero-tiiermophilic species and therefore favoured by extensive management (Fig. 5). Moreover it lives on Mclampyrum spp. where it feeds mostly on the roots (Southwood & Leston 1959; Wagner 1966). It is therefore restricted to the habitats of its hostplant which is found in extensive but not in intensive meadows (Lau- ber & Wagner f 996).

H. m-flavum is a monophagous species that Ihes on Salvia pratensis (Wagner 1952; Southwood & Leston 1959). Like its host plant, it is restricted to extensively managed meadows (Figs 5 and 6). This species, too, overwinters as an egg and develops in early the larval summer (Southwood & Leston 1959), therefore early cutting may damage stages.

A. seticornis lives on Vicia species and is reduced by frequent and early cutting (Figs 5 and 6). The females lay their eggs in the upper part of the hostplants stem and larval development begins in spring (Kullenberg 1944; Wagner 1952; Southwood & Leston 1959). Cutting in May or June therefore may destroy its eggs or damage the lar¬ val stages.

For the species that do not appear to respond to management, two main groups can be identified:

1) Widespread species which occur in various types of habitats: F. pratensis, L. rugulipennis (Southwood & Leston 1959; Morris 1979), C. fuscispinus (Wagner 1966), D. baccanun (Wagner 1966), T. caelestialum (Remane 1958; Otto 1996), A. lineolatus (Kullenberg 1944; Southwood & Leston 1959), S. laevigatum (Wagner 1952; Remane 1958; Otto 1996), P. imifasciatus (Kullenberg 1944; Wagner 1952), E. maura (South- wood I960) andN. brevis (Southwood 1960; Péricart 1987).

2) Polyphagous species, which live in a wide range of grasslands and which show a certain affinity to managed meadows: Ch. pulicarius (Otto f996), H. aplerus (Kullen¬ berg 1944; Otto 1996), P. chrvsanthemi (Kullenberg 1944; Morris 1979; Otto 1996), C. fabricii (Péricart 1983; Otto 1996) and 5. minor (Péricart 1984; Otto 1996).

In conclusion, this study shows that extensively managed meadows can be species rich habitats and valuable for specialised insect species. In contrast, the bug community of medium intensive meadows is dominated by more widespread and less specialist spe¬ cies. Frequent and early cutting reduces the abundance of many species, and especially certain specialised or rare species like the xero-thei-mophilic clement of the Swiss bug fauna. The more widespread species, however, do not show a consistent response to management and some may even benefit from medium intensive management. Our re¬ sults indicate that the extensne management of grasslands, as supported by agricultural schemes in Switzerland, is effective m maintaining insect diversity in agricultural land¬ scapes. Tn our study we have mainly investigated only management techniques which are used in practice, and we can therefore not say whether there are management tech¬ niques which would support even more species. Moreover, our study reveals that the extensively managed meadows can vary greatly in respect to their species composition, suggesting that to maintain species richness on a landscape level it is crucial to preserve a range of sites in various locations of a region. Acknowledgements

We are greatful to Bernhard Merz, Andrea Schwab, Sibylle Studer and Karin Ull¬ rich for their critical reading of the manuscript, to Philippe Jeanneret for statistical as- sistence, to Robyn Siin/i for her help in the field and in the laboratory, to Bruno Koch for his help in finding an excellent research area and suitable study sites, to Sibylle Studer for permission to use unpublished data and to the farmers of Hemmental, Siblin- thank two gen and Merishausen for permission to work on their sites. Further we anonymous reviewers for their useful comments on an earlier version of the manuscript.

This work was funded by the Swiss National Science Foundation (5001-044634/1) and the Canton Schaffhausen (Kantonales Plantings- und Naturschutzamt).

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Saunders, D.A, FTobbs, R.J. & Margules, C.R. (1991) Biological consequences of ecosystem fragmentati¬ on: a review. Conservation Biology, 5, 18-32. SMA (1998) Annalcn der Schweizerischen Meterologischcn Anstalt 1997, SMA, Zürich. Southwood, T.R.E. (1960) The flight activity of Heteroptera. Transactions of the Royal Entomological Society of London, 112(8), 173-220.

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Studer, S. (2000) The influence of management on the floristic composition of hay meadows. PhD thesis, ETH Zürich.

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Thomas, C.F.G., Hoi, E.FI.A. & Everts, J.W. (1990) Modelling the diffusion component of dispersal du¬ ring recovery of a population of linyphiid spielers from exposure to an insecticide. Functional Ecology, 4, 357-368.

Thomas, M.B., Wralten, S.D. & Sotherton, N.W. (1991) Creation of habitats in farmland to manipulate populations of beneficial arthropods: predator densities and emigration. Journal of Applied Ecology, 28,906-917.

Völkl, W., Zwölfer, FL, Romstöck-Völkl, M. & Schmelzer, C. (1993) Habitat management in calcareous grasslands: Effects on the insect community developing in flower heads of Cynarea. Journal of Applied Ecology, 30. 307-315.

Wagner, E. & Weber, H.FI. (1964) Hétéropteres Miridae Faune de France, 67. Fédération Française des Sociélés de Sciences Naturelles, Pans.

Wagner, E. (1952) Blindwanzen oder Miriden. Die Tierwelt Deutschlands und der angrenzenden Meere¬ steile. 41. Gustav Fischer Verlag. Jena. Wagner, E. (1966) I. Pentatomorpha. Die Tierwelt Deutschlands und der angrenzenden Meeresteile, 54. Gustav Fischer Verlag, Jena. Wagner. E. (1967) //. Cimiconiorpha. Die Tierwelt Deutschlands und der angrenzenden Meeresteile, 55. Gustav Fischer Verlag, Jena. Wagner, E. (1970-1971) Die Miridae des Mittelmeerraumes und der Makaronesischen Inseln (Hemip- tera, Heteroptera), Teil 1. Entomologischc Abhandlungen, 37. Akademische Verlagsgesellschaft Geest & Portig KG. Leipzig. Wagner, E. (1975) Die Miridae des Mittelmeerraumes und der Makaronesischen Inseln (Hemiptera, He¬ teroptera), Teil 3. Entomologische Abhandlungen, 40. Akademische Verlagsgesellschaft Geest & Por¬ tig KG. Leipzig. Watkinson, A.R. & Sutherland. W.I. (1995) Sources, sinks and pseudo-sinks. Journal ofAnimal Ecology, 64, 126-130. 23

Chapter 2. Insect and plant diversity patterns in agricultural grasslands

Manuela Di Giulio, Sibylle Studer, Luzia Widmer & Peter I. Edwards

Summary

and J. The purpose of this study is to investigate the effects of management landscape In this we structure on plant and insect diversity of agricultural grasslands. paper to the focus on the local diversity of different meadow types and their contribution regional diversity of the research area. Further, we investigate whether variation in between sites is related to the species number and abundance of individual species surrounding land use.

and 2. lire research area (Schaffhauser Randen) is located in the North of Switzerland belongs to the Swiss Jura. Four study areas with varying landscape structure were selected and meadows of two grassland management types were investigated in each

area.

3. The true bugs (Heteroptera) and the butterflies (Lepidoptcra: Rhopaloccra, Hesperiidae, Zygaenidae) were chosen as indicator groups for local insect diversity because they differ ecologically m various ways and can be expected 1o respond to their environment differently.

4. Extensive meadows are more species rich than medium intensive sites and contain contribute more more rare and specialised insect and plant species. They therefore and the strongly to the regional species diversity. In contrast to the flowering plants butterfly fauna, the heteropteran communities differ greatly between the areas investigated. It is argued that the heteropteran bugs appear to be more limited by dispersal than the plant and butterfly species. These findings are supported by a field experiment which investigated how rapidly new habitat patches arc colonised and by which bug species.

5. The differences m the heteropteran bug communities of meadows in different areas can partly be explained by the surrounding land use. Multiple regression analyses indicate that several bug species do respond to the structure of the landscape surrounding a site.

Key words: grassland management, Heteroptera. landscape structure, Lepidoptcra, local diversity, regional diversity, Vegetation

INTRODUCTION

From an aeroplane, agricultural landscapes appear as a mosaic of various forms, structures and colours. The heterogeneity of the substrate, and the various types of natural disturbance and human activities all contribute to the development of this mosaic structure. A landscape is composed of local ecosystems, which are relatively homogenous and more or less clearly limited (Forman 1986. 1995). Our study is concerned with both the ecosystem and the landscape levels. If investigates the effects of management and landscape structure on plant and insect diversity of agricultural grasslands. In this paper we describe the local diversity of different meadow types and their contribution to the regional diversity, or as suggested by Whittaker (1972), we investigate the alpha diversity of differently managed meadows and discuss their contribution to the gamma diversity of the research area. Our study was carried out in an 24

extensive forested region in the north of Switzerland, known as the Schaffhauser Randen, which has several more or less isolated enclaves of agricultural land. These enclaves arc situated on a plateau of 650 to 850 m a.s.l. and have different mixtures of arable and grassland habitats with varying proportions of shrubs and woods. Four such enclaves were selected to investigate the influence of landscape structure on plant and insect diversity. In each enclave (area), differently managed meadows were chosen to assess the influence of management on species diversity. We chose the true bugs (Heteroptera) and the butterflies (Lepidoptcra: Rhopalocera, Hcsperiidae, Zygaenidae) as indicator groups for local insect diversity because they differ ecologically in various ways and therefore perceive and respond to their environment differently. A first difference is that the bugs are an ecologically very diverse group, including phytophagous, saprophagous and predatory species (Dolling 1991), while butterflies are strictly phytophagous and therefore closely bound to the vegetation. Secondly, the larval stages and adult individuals of bugs live in the same habitat, while the different stages of butterflies can live in contrasting habitats. Thirdly, butterflies are a highly mobile group and most species are strong fliers, while bugs have a wide range of dispersal abilities, with flightless species but also very mobile ones. Finally, from a practical point of view, both groups arc manageable in terms of numbers of species. To understand how species survive in agricultural landscapes it is important to know how they move and how they perceive their environment (Macdonald & Smith 1990; Samways 1994). Rather little information is available for bugs and we therefore designed an experiment to assess dispersal ability of bugs. The main goal of this cxpcritnent was to investigate how rapidly new habilat patches are colonised and by which species. The present pattern of species diversity has been influenced by the history and the development of the landscape. We therefore describe briefly how the Schaffhauser Randen developed and what were the most important factors determining the spatial structure of this landscape. During the Middle Ages the area was cleared of forest to gain charcoal for the smelting of iron ore. Only later were the clear-cut areas used agriculturally. The fields on the plateau have been used for several hundred years to cultivate cereals and hay for livestock. For most of this period the agriculture was very extensive and was organised in a special system called 'Dreizelgenwirtschaft'. The land belonging to a community was divided into three sectors which were cultivated differently. A communal plan defined which crop was to be cultivated annually in each sector respectively on which piece of land, and the farmers had to keep strictly to this plan. There was a system of crop rotation on every field which included a fallow period when the land was used to produce hay for the livestock or as grazing (Bronhofer 1956; Russenberger 1984).

The forest was mtenshely used but the management had little in common with that practised today in the forests of Central Europe. The trees were regularly cut for wood and never reached the height they do nowadays. Moreover, the forest was grazed regularly as a kind of wood pasture so that it remained open. Thus, these forests represented a totally different habitat type from the dense production forest which occurs in Switzerland today. Moreover, the transition between forest and agricultural land was less sharply defined and the transitional areas provided very species rich habitats (Schiess-Buhlcr & Schiess 1997). In the mid 191'1 century, as a result of both political and economic upheavals, the population of the Randen communities decreased 25

and most of the arable land on the plateau was abandoned. The higher areas of the Randen were rcafforested and the remaining agricultural area was converted to grassland which was managed extensively. Thus most of the Randen was covered with either forest or extensively managed meadows for a period of about fOO to 150 years until the mechanisation and intensification of the agricultural production commenced in the 196()'s. Subsequently a large part of the grassland was turned into arable land and most of the remaining grasslands were intensified through increased use of fertiliser and machinery (Schiess-Btihler & Schiess 1997; Zehnder 1998). These developments led to a decline in the species richness of the region, which has been documented for both the vegetation (Isler-Hiibscher 1980) and the butterfly fauna. A comparison of the butterfly fauna recorded in the 1920's with new data from the 1990's showed that during this period about half of the species had declined in their abundance while 20% had disappeared altogether (Schiess-Btihler & Schiess 1997).

Material and Methods

Research area and sampling design

The research area is located in the Schaffhauser Randen (northern Switzerland) and is part of a chain of limestone hills which forms the Swiss Jura. The soils are derived from nutrient poor limestones. The average yearly precipitation in Schaffhausen (437 m a.s.l.) is 866 mm. The average mean annual temperature is 7.8 °C, with a maximum mean monthly temperature in July (23.2 °C) and a minimum in January (-3.9 °C) (SMA 1998).

For our study we chose a design with two levels, the landscape and the site level. At the landscape level we selected four enclaves (areas) with varying proportions of arable and grassland habitats (Fig. 1). Within each area we investigated two grassland management types (officially referred to as 'medium intensive' and 'extensive'), and for each management type we selected three replicate sites. The butterfly community was investigated in only three areas (without Hinterranden). The management types are defined by two main factors: the number of cuts per year, and the type and amount of fertiliser used. Medium intensive meadows are regularly fertilised with slurry and cut 2- 3 times per year. The time of the first cut is around the end of May. The extensive meadows are not fertilised and arc cut once or twice per year. The time of the first cut is July. 26

0 3 6 Kilometer

Fig. 1. The agricultural used ai cas resemble enclaves in a sea of forest and have different mixtures of arable and grassland habitats. Zelgli/Mosli has onh grasslands; more than half are extensively managed meadows, the test compuse both medium and little intensive meadows. Hmterrandcn has only little arable land, the rest aie giasslands with a high propoition of extensively used meadows.

The areas of Chlosterfcld and Merishauser Randen consist of a mixture of arable land and grassland habitats.

The heteropteran bugs were sampled using a standardised sweep-net method (Remane 1958; Bornholdt 1991; Otto 1996). The sweep-net had a diameter of 40 cm and samples were collected ever\ two weeks by making one hundred sweeps with the net over a distance of about 100 m, Sampling was only carried out when the weather conditions were good, ie a minimum of 17°C and sunshine. Sampling was also restricted to the period between 10.00 a.m. and 17.30 p.m.; the sampling order of the fields was varied between weeks. Every site was sampled between 7 and 9 times from May to September. The nomenclature of the bugs follows Günther & Schuster (1990). The butterflies were counted using a transect method. Sampling was carried out between 10 a.m. and 4 p.m., on days when temperatures were over 17°C, wind speed was below a maximum of 3 Beaufort and there was at least 60% sunshine. Every site was sampled eight times from May to August. A transect of 200 m was walked at every site and the butterflies were recorded within a 5 m corridor. The average time spent for one transect was about 15 minutes per site (Widmer 2000). To assess plant species 27

composition, six Im quadrats were randomly located witbm each site. Percentage cover of all species (top cover; summing up to 100%) was estimated in each quadrat just before the first cut. For statistical analysis the six subsamples were pooled.

For both management types a hierarchical analyses was conducted to estimate species diversity at the level of the site, the area and the entire region (Lande 1996). For each level the average species number was calculated. Two-way ANOVAs were conducted to assess how management and area affect the species numbers of insects and plants. The landscape elements of the four areas investigated were mapped in summer 97 and entered into a GIS. Partial regression models were used to analyse whether variation in species number and abundance of individual species between sites was related to the surrounding land use. For this purpose the proportions of different land use types were measured in the GIS for zones of 10m, 30m, 50m and 100m surrounding each site. The regression models were developed m several steps. We first analysed which variables were intcrcorrelated and excluded those which were most strongly correlated with all others. The remaining variables were used to define partial regression models. Finally we recalculated the models with only the significant variables.

Dispersal experiment We enhanced plant diversity in five intensively managed sites by planting 50 individuals of each of nine different flowering plant species in plots of 5m x 5m. Subsequently these plots are referred to as 'flower patches'. As control plots we selected five comparable sites (in terms of topography and management intensity) and plots within the treated meadow (outside of the flower-patch plot). The following plant species, none of which occur in medium intensive meadows, were introduced: Lathyrus pratensis, Sctnguisorba minor, Salvia pratensis, Onobrychis viciifolia, Thymus pulegioides, Leontodon hispidus, Daucus carota, Cenlaurea jacea and Knautia arvensis. The experiment was set up at the beginning of June 1998. Sampling started one month later and was continued at three weeks intervals until the end of September. On each occasion 20 subsamples of 0.02 m" (total area 0.4 m2) were taken with an insect suction sampler of the type 'Vortis' (Arnold 1994). The results showed, that the suction sampler collected mostly species which live on the ground and not those living in (he vegetation layer. We therefore changed the sampling method in the second year and used a standardised sweep net method with 50 sweeps per plot (Remane 1958; Bornholdt 1991; Otto 1996). In the second year sampling started in April and finished in June, when the control meadows were cut for the first lime. Sampling was only carried out when the weather conditions were good, ie a minimum of 17°C and sunshine. Sampling was also restricted to the period between 10.00 a.m. and 17.30 p.m. We varied the sampling order of the fields between weeks.

One-way ANOVAs were conducted to test the influence of the flower patches on bug species number. We compared the flower patch with the control plots within the treated site and outside. We also analysed the data qualitatively by investigating whether the bug species found exclusively in the flower patches were specialised on one of the introduced plant species.

Results

Spatial effects on species numbers

There were fewer butterfly species in the medium intensive sites than in the extensive, though the partitioning of species within and between areas was similar for 28

the two management types (Fig. 2). For the extensive sites, the mean number of species per area was 28 while the total number in all three areas was 43. Species number increased by 35% from the area level to the regional level. For the medium intensive sites, the mean number of species per area was 20.33 and increased by 41% up to 34. For plants in extensive sites the mean number of plants per area was 62.75 and increased by 33% up to 93 for the three areas. The mean number of plants in the medium intensive sites was 44 per area and increased by 41% up to 74. Plant species number of extensive sites varied little particularly between areas, while the species number of the medium intensive sites showed a higher variation. The mean number of bug species in the extensive sites was 36.25 and increased by 50% up to 72. In medium intensive sites the mean species number was 28.75, while the total was 62. Species number increased by 54%. Moreover, the mean bug species number is significantly higher in the Chlosterfeld (Table 1; Tukey post-hoc test).

Extensive sites

100r

Medium intensive sites

100 r

Level

Fig. 2. Mean species number of butterflies, heteropteran bugs and plants per site, area and in total (me + min./max.). 29

Table t shows that plant and butterfly species number is influenced significantly by both management but not by area, while bug species number is affected significantly by management and area.

Table 1. Two-way ANOVAs of the effect of management and area on the species numbers of plants, bugs and butterflies. The species numbers of the insects wcie log-transformed, the plant species numbers wcic square-root transformed.

source of variation df MS F-ratio p-value

Plants Management I 6.011 30.045 0 0001 Area 3 0 121 0 607 0 621

Interaction 3 0.886 4.426 0.02 Residual 15 0.200 Total

Bugs Management 1 0.055 7 25 0.017 Area 3 0.056 7.12 0.003 Interaction 3 0.016 2 01 0 156 Residual 15 0.008 Total 22

Butterflies Management 1 0.J29 8.04 0 015 Area 2 0.052 3.23 0.076 Interaction 2 0.001 0 07 0 933 Residual 12 0.016 Total 17

Species response to the surrounding landscape structure of The land use in a zone up to 10m surrounding a site has no effect on the number bugs, butterflies or plant species (multiple regression analyses). Furthermore, the number of plant and butterfly species do not differ significantly between areas and we therefore did not carry out any further analyses (Table J). The bug species numbers, however, differ strongly between the four areas and we therefore investigated how the present landscape structure affects the bug fauna. We computed multiple regressions to analyse how single species respond to the surrounding landscape considering zones of varying widths around the site. In total we analysed 13 species with more than 25 individuals.

Seven species seem not to respond to the surrounding landscape structure (Adelphocoris seticornis, Carpocons fuscispinus, Leptopterna dolobrata, Lygus pratensis, Nabis pseudoferus and Plagiognathus chrvsanthemi). Six species, however, are significantly affected by the structure of the surrounding landscape (Table 2). The abundance of Adelphocoris lineolatus, Notostira erratica, Lygus rugulipennis and Trigonotylus caelestialium increases with the proportion of arable land. For N. erratica this is the case only up to 50 m, but all others arc independent of the distance. In addition, T. caelestialium correlates positively with the proportion of roads in the with the surrounding up to 30 m. The abundance of Polymerus unifascialus increases proportion of grassland in the surrounding (Table 2). Chlamydatus pulicarius, N. erratica and Stenodema laevigatum are affected differently by site area (Tables 2 and 30

3), C puhtanus is most abundant m large meadows, while S laevigatum and N erratica aie moie stiongly associated with small ones.

Table 2 Regiession analysis shows the icsponses of single bug species lo landscape stmctuie The p value îcpiesent the coetficients of thepaitial conelation

Specie s I Butter distance 10 m 30 ni 50 m î 00 m

B p value B p value B p value B p value

Adelphotons lineolatus R2 = 0 37 R1 = 0 54 R" =-0 6 R2 - 0 68

ai able land 3 63 0 001 4 2 «.0 0001 4 47 ^.0 0001 4 71 -.0 0001

Lygus lugidipen/iis R2 =-0 17 R° - 0 "U R2 = 0 42 R2 = 0 57

ai able land 2 8^ 0 03 3 7 0 002 4 13 0 0005 4 68 <0 000l

- Tiiqonotdns cackstiahum R" = 0 36 R7 - 0 4 R2 0 39 R2 = 0 46

ai able land 196 0 04 2 "s 0 004 2 89 0 004 3 62 0 0003 loads 4 69 0 009 5^6 0 0^ 4 7 Ol 118 0 71

Notostaaeiiatiea R2 = 0 5 R' = 0 4^ R; = 0 4t R2 = 0 37 .nable land 124 0 008 101 0 03 3 0 95 0 05 0 78 0 13

site ai ea 0 74 0 001 0 6S 0 004 0 64 0 007 0 63 0 012

Pohmeiusunifasctatus R2 = 0 13 R° = 0 24 R2 = 0 25 R2 -= 0 26 gtassland 153 0 05 2 19 0 01 2 55 0 01 3 33 0 008

fable 3 J wo bug species aie onl\ aliected by the site aiea

Species B P value

Chlamvdatus pulicaiiiis R =0 17

site ai ea 105 0 03

Stenodema laeMgatum R =0 18 siteaica 0 95 0 03

Dispersal experiment

The first summet aftei v\e set up the di speis al expeiiment was veiy dry and hot m the Schaffhausei Randen, and many of the mtioduced plants died in the first month of the expenment Few plants achieved any new giowth oi floweied However, despite these difficulties, tout plant species not otheiwise piesenl in the sunoundmg vegetation did become established and two of them floweied, at least m the peiiod of the study We weie thetefoie able to achieve a local mciease in plant species richness In the llowei and contiol patches a total of 27 bug species and 114 individuals weie recoided There is no significant difleience (one-way ANOVAs) between the mean numbeis of bug species in the flowei patches (6 ± 2 65) and m the control patches withm (2 6 ± 2 07) and outside the tieated sites (4 2 ± 2 17) The qualitative analysis showed that none of the iccoided species is specialised on the mtioduced plants species In general, the bug fauna iccoided is typical foi medium intensively managed meadows (M Di Giuho, m piep) 31

DISCUSSION

Spatial effects The meadows of the Schaffhauser Randen plateau are highly fragmented habitats 20th and represent a only small fraction of the former grassland. Until the mid century studies the plateau was covered with extensive, continuous grassland and various suggest that the species diversity was considerably higher than at present (Zoller 1954; Isler-Hübscher 1980; Schiess-Bühlcr & Schiess 1997). The extensively managed meadows are about 100 to 150 years old and arc remnants of formerly much larger areas of continuous grasslands (Bronhofer 1956). In contrast the medium intensive sites were there created by intensification over the last few decades and are of varying age. Since with the has been a longer period for the extensive grasslands to reach an equilibrium habitat conditions and management, it is not suiprising that, in contrast to the medium intensive grasslands, the extensive grasslands only show little variation in plant species richness (Fig. 2) and plant species composition. Moreover, the management of the medium intensive meadows is more variable in respect to the amount and type of fertiliser used than the extensive ones, which arc not fertilised at all. Insects, however, in show a different pattern of variation. The extensive sites investigated vary greatly both their bug species number (Fig. 2 ) and the composition of the bug fauna (M. Di Giulio. in prep.), indicating that the bug fauna is determined by various environmental factors besides management, for example aspect, isolation and previous management. The species number of butterflies varies much less between sites within an area (Fig. 2), probably because adult insects are mobile and unsuitable habitats between the grassland

sites are not much of a barrier for them.

Given the history of land use change and the fact that most, if not all, of these sites were at one time arable land, most of the plant and animal species which presently occur there must have recolonised these areas at one stage. The present species composition of sites, and in particular the differences between sites, will reflect at least in part the differing dispersal abilities of different taxa. For plants, no regional differences in species composition and species richness were detected between the four areas. Rare for species with a scattered distribution, which often are responsible regional patterns, I9lh when these are missing. After the period of arable land use until the mid century, grasslands developed, there were probably only few grasslands that could have served short as seed sources. Since a dense vegetation cover can establish within a relatively time (Zoller 1954). slowly dispersing species probably were clearly at a disadvantage. Therefore the plant species which occur arc mainly those which arc common and apparently readily dispersed. This hypothesis is supported by a separate study conducted in the same study area (Studer 2000) where exactly the same set of species War was found in 50 years old grasslands that were ploughed during the Second World and in older grasslands that were not ploughed for about 150 years. However, species that do not disperse or establish easily are now rare in the Randen and are confined to sites which have not been ploughed. Additionally the intensification of the land use in the region led to a fragmentation of the grasslands, especially of the extensively used ones and, as a consequence, to a reduction m rare species. The butterflies are obviously strong fliers and therefore the distances between suitable habitats within and between areas might not be a barrier for them. This is supported by the our findings that we found only small differences in species number (Table 1) and species composition (Widmer 2000) between the areas suggesting that most species which occur are not limited by dispersal. The bugs show the strongest differences between areas, both in 32

species number (Table 1) and species composition (M. Di Giulio, in prep.). Of the regional diversity only 50% of the species occur in individual areas (Fig. 2), indicating that many bug species occur only locally and have very restricted ranges. Many bug species seem not to be very mobile and therefore habitat fragmentation represents a problem for their populations.

The bug fauna of the Chlostcrfeld is richer in species than the other areas, though the reasons are not obvious. In general, the management history has been similar in all four areas. In fact, Chlosterfeld, due to its vicinity to the village of Hemmental, has been used mainly as arable land and may have been managed more intensively in the past few decades (Bronhofer 1956; Keel 1993). We think it likely that climatic conditions are chiefly responsible for the greater species richness. Most bug species that occur exclusively in the Chlosterfeld are associated with very warm and dry habitats and are typical for chalk grasslands (R. Heckmann, pers. comm.). The Chlosterfeld is located about 100 m lower, is more open and less shady than the other areas and the snow melts sooner (pers. obs.). The climatic conditions therefore differ from those of the other areas and may favour species which prefer warm and dry habitats. Nevertheless, we also have an indication that the spatial structure of the surrounding landscape influences the bug community. We could show that at least some species, like the quite common species L. rugulipennis, A. lineolatus, T. caelestialium and N. erratic prefer a mixture of arable and grassland (Table 3). Plowever, we also found several less frequent species, like Eurydema oleraceum. Aelia acuminata, Eurygaster maura or Aptus mirniicoides (Wagner L966; Péricart 1987) which occur exclusively in mixed enclaves. Areas with a mixture of arable land and grassland habitats provide more niches and habitats for insects and are therefore more heterogenous.

Dispersal experiment and bug species response to landscape structure

The results of the dispersal experiment were negative. Although we achieved a modest increase of the local plant species diversity, there was no apparent effect on bug species directly, and no 'new' species appeared in the community. In view of the rather poor growth of the introduced plants, it would be a mistake to read too much into these findings. However, they do support the general conclusion that many grassland bugs are relatively immobile and their distribution is limited by habitat fragmentation. There is an interesting contrast in this respect to species found on flower strips planted in arable land, which appear to be more mobile. Ullrich & Edwards (1999) found that some of the bug species occurring in the flower strips can colonise newly created patches of host plants within a few weeks. Distances of over 100 m do not seem to present a significant barrier to these species.

The management of the adjacent fields appears to have no significant effect on the species diversity of plants and insects. However, several bug species do respond to the structure of the landscape surrounding a site. A. lineolatus, L. rugulipennis, T. caelestialium and N. erratica are most abundant m grasslands that arc surrounded by arable land (Table 2). They are widespread species which feed also on crops and occur frequently in arable land (Kullenberg 1944; Wagner 1952, 1970-1971, 1975; Afscharpour 1960; Vans 1972; Hattwig 1997; Fasterbrook 1997). For these species arable land might represent an additional habitat or one they can switch to under unfavourable conditions and therefore enhance their local abundance. AU but N. erratica are very mobile and have a high flight activity (Southwood I960; Morris 1969, 1979; Gibson 1980). Previous studies have shown thai /Y. erratica flies only over short distances and that the females are very weak fliers because of their reduced flight 33

muscles (Kullenberg 1944; Dolling 1991; Bockwinkel 1990). The restricted dispersal fields to 50 m. T. ability may explain why this species is influenced by crop only up caelestialium is positively influenced by the roads to a distance of up to 30 m. In the We research area, the roads arc mostly un metalled tracks with wide grassy margins. therefore suggest that the abundance of T. caelestialium is positively correlated with the road margins rather than the roads themselves. This miricl bug is specialised on various with a amount of grasses (Southwood & Leston 1959). Undisturbed road margins high their local abundance. grasses may represent an additional habitat and therefore enhance it is a flier Only field margins in the vicinity seem to be important even though strong (Southwood 1960). the of Only one species, P. unifasciatus. is significantly influenced by proportion grassland in the surroundings (Table 2). This ohgophagous species feeds on Galium sp (Kullenberg 1944; Wagner 1952). Galium spp. occur in a wide range of meadow types and are very common in the research area. The proportion of grassland probably correlates strongly with the abundance of this plant species, ie the bugs host plant. P. unifasciatus is therefore positively affected b) the abundance of its host plant. in the Interestingly no other species were influenced by the proportion of grassland surrounding. Many common species which are frequently found in meadows, like A. seticornis, L. dolobrata, L. pratensis, N. pseudoferus and P. chrysanthemi (Kullenberg 1944; Southwood and Leston 1959; Wagner 1970-1971. 1975) seem not to be affected the by the presence of grassland in the surroundings. The bug fauna responds to structure, the species composition and the management of meadows and therefore from a bug's perspective not all meadows are suitable habitats (Remane 1958; Curry 1994; Otto 1996). Our scale might therefore be too coarse to detect differences from a bugs

view and we would have to work on a much finer scale to analyse specific spatial effects on bugs (Wiens 1989; Kotliar & Wiens 1990).

Site area affects three species (Tables 2 and 3), The abundance of C. pulicarius increases with the habitat size, a relationship that has already been found in previous studies (Simbcrloff 1974. 1976). The opposite is the case for S. laevigatum and N. erratica, both species that are most abundant in small meadows. the We used a quantitative approach to investigate how landscape structure affects communities of plants and insects and how individual species respond to the spatial structure of their surrounding. One problem with this approach is that only very abundant species can be investigated. Species which occur only locally or less frequently cannot be analysed properly for want of data, although these species would be particularly interesting from a conservation point of view. Moreover, the scale turned out to be too coarse and therefore only very rough pattern could be detected. Nevertheless, the study has yielded valuable insights into what are the most important factors affecting the regional plant and insect diversity in the Schaffhauser Randen.

References

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Arnold. A..I. 1994. Tnsect suction sampling without nets, bags oi hlteis. Ci op protection 13(1): 73 76. Bockwmkel, G. 1990. Unsere Kultui Landschaft als Lebensiaum fur Graswanzen (Stenodemini. Miridae, Heteropteia). Veihandliingen des Westdeutschen Entomologen Tag 1989: 265-283. Bornholdt, G. 1991. Auswiikungen der Pflegemassnahmen Mahd, Mulchcn, Beweidung und Gcholzruckschnitt aul die Insektenoidnungen Orthopteia, Fieletopteia, Auchenorrhyncha und Coleoptera der ITalbtrockemascn im Raum Schlüchtern Maibwgei Entomologische 34

Publikationen 2(6): 1-330. Bronhofer, M. 1956. Die ausgehende Dreizelgenwirtschaft in der Nordost-Schweiz. Dissertation Universität Zürich.

Curry, J.P. 1994. Grassland invertebrates. Chapman & Hall, London. Dolling, W.R. 1991. The Hemiptera. Oxford University Press, Oxford. Easterbrook, M.A. 1997. The phenology of Lygus rugulipennis, the European tarnished plant bug, on late-

season strawberries, and control with insecticides. Annales ofApplied Biology 131: 1-10.

Forman, R.T.T. 1986. Innelscape Ecologv. John Wiley & Sons. New York.

Forman, R.T.T. 1995. Land mosaics - The ecology of landscapes and regions. Cambridge University Press, Cambridge. limestone Gibson, C.W.D. 1980. Niche use patterns among some Stenociemini (Heteroptera: Miridae) of Notostira grasslands, and an investigation of the possibility of interspecific competition between clongata Geoffroy and Megaloceraea recticornis Gloii-ro-i. Oecologia 47: 352-364. Günther, FI. & Schuster, G. 1990. Verzeichnis der Wanzen Mitteleuropas. Deutsche Entomologische Zeitschrift NF 37(4-5): 361-396. TIattwig, F. 1997. Wanzen (Heteroptera) in Getreidekulturen unterschiedlicher Bewirtschaftung bei Braunschweig. Braunschweig Naturkundliche Schriften 5(2): 353-358. mit Isler-Hübscher, K. 1980. Beiträge 1976 zu Georg Kummers "Flora des Kantons Schaffhausen" Berücksichtigung der Grenzgebiete. Mitteilungen der Naturforschenden Gesellschaft Schaffhaiisen 3i: 7-121. Keel, A. 1993, Vegetatioriskundlich-ökologische Untersuchungen und Bewirtschaftlingexperimente in Halbtrockenwiesen (Mcsobromion) auf dem Schaffhauser Randen. Dissertation ETH Zürich. Kotliar, N.B. & Wiens. J.A.. 1990, Multiple scales of patchmess and patch structure: a hierarchical framework for the study of heterogeneity. Oikos 59: 253-260. Kullenberg, B. 1944. Studien über che Biologie der Capsulen. Dissertation University of Uppsala. Lande. R. 1996. Statistics and partitioning of species diversity, and similarity among multiple communities. Oikos 76 (1): 5-13. Macdonald, D.W. & Smith, H. 1990. Dispersal, dispersion and conservation in the agriculture ecosystems. In: Bunce, R.G.G & Floward, D.C. (eds) Species dispersal in agricultural habitats, pp. 18-64, Bcihavcn Press. London. Morris, M.G. 1969. Differences between the invertebrate faunas of grazed and ungrazed chalk grasslands. III. The heteropterous fauna. Journal of Applied Ecology 6: 475-487. Morris, M.G. 1979. Responses of grassland invertebrates to management by cutting. II. Heteroptera. Journal ofApplied Ecology 16: 417-432.

Otto, A. 1996. Die Wanzenfauna montaner Magerwiesen und Grünbrachen im Kanton Tessin (Insecta: Heteroptera). Dissertation ETH Zürich. Péricart, I. 1987. Flémiptères Nabidae d'europe occidentale et du Maghreb. Faune de France Volume 71. Fédération Française des Sociétés de Sciences Naturelles. Paris.

Remane, R. 1958. Die Besiedlung von Grünlandflächen verschiedener Flerkunft durch Wanzen und Zikaden im Wcser-Ems-Gebiet. Zeitschrift fur Angewandte Entomologie 42(4): 353-400.

Russenberger, H. 1984. Der Randen. Werden und Wandel einer Berglandschaft. Ncujahrsblatt der Natur-forschende Gesellschaft Schaffhausen 36. Samways. M.J. 1994. Insect Conservation Biology. Chapman & Hall, London. Schiess-Biihler, C. & Schiess. Fl. 1997. Die Tagfalterfauna des Schaffhauser Randens und ihr Wandel im 20. Jahrhundert. Mitteilungen der Naiurforschenden Gesellschaft Schaffhaiisen 42: 35-106. Simberloff, D. 1974. Equilibrium theory of island biogeography and ecology. Annual Review of Ecology and Svstcmatics 5: 161-182.

Simberloff, D. 1976. Experimental zoogeography of islands: Effects of island size. Ecology 57(4): 629- 642.

SMA (1998). Annalen der Schweizerischen Meterologischen Anstalt 1997. SMA, Zürich.

Southwood, T.R.E. & Lesion. D. 1959. Land and water bugs of the British isles. Frederick Warne & Co. Ltd., London. 35

Southwood, T.R.E. 1960. The (light activity of Heteroptera. Transactions of the Royal Entomological Society of London f 12(8): 173-220.

Studer, S. 2000. The influence of management on the floristic composition of hay meadows. PhD thesis. ETFI Zürich.

Ullrich, K. & Edwards, P..I. 1999. The colonisation of wild flower strips by insects (Fleteroptera). In: Maudsley, M. &l Marshall, J. (eds) Heterogeneity in landscape ecology: Pattern and Scale, pp. 131-138. Bristol.

Varis, A-L. 1972. The biology of Lygus rugulipennis POPP. (Het.. Miridae) and the damage caused by this species to sugar beet. Annales Agi icitlturae Fenniae 11(56): 1-56. Wagner, E. 1952. Blindwanzen oder Miriden. Die Tierwelt Deutschlands und der angrenzenden Meeresteile 41. Gustav Fischer. Jena.

Wagner. E. 1966 I. Pentatomorpha. Die Tierwelt Deutschlands und der angrenzenden Meeresteile 54. Gustav Fischer Veilag. Jena. Wagner, E. 1970-1971. Die Miridae des Mittelmeerraumes und der Makaronesischen Inseln (Hemiplera, Heteroptera). Teil 1. Entomologische Abhand hingen 37 Supplement. Akademische Verlagsgcsellschaft Geest & Portig KG, Leipzig. Wagner, E. 1975. Die Miridae des Mittelmeerraumes und der Makaronesischen Inseln (LIemiptera, Heteroptera). 'Teil 3. Entomologische Abhandlungen 40 Supplement. Akademische Vcrlagsgesellschaft Geest & Portig KG, Leipzig,

Whittaker, R.H. f 972. Evolution and measurements of species diversity. Taxon 21: 213-25 L Widmer, L. 2000. Lepidoptcra in differently managed grasslands: assessing the impact of habitat variability. Diploma thesis University of Zurich.

Wiens, .I.A. & Milne, B.T. 1989. Scaling of landscapes' in landscape ecology, or, landscape ecology from a beetle's perspective. Landscape Ecology 3(2): 87-96. Zehnder, A. 1998. Die Schaffhauser Landwirtschaft im Wandel. Neiijahrsblatt der Naturforscltenden Gesellschaft Scliafftiauscn 50. Zoller, IT. 1954. Die T_\pen der Bromus erectus-Wiesen des Schweizer Juras. Beiträge zur geobotanischen Landesaufnahme der Schweiz 33: 1-309 36

Chapter 3. The bug fauna (Heteroptera) of agricultural grasslands in the Schaffhauser Randen (SH) and Rottal (LU), Switzerland, with updated checklists of Heteroptera of the Cantons Luzern and Schaffhausen

Manuela Di Giuho, Ralf Heckmann & Andrea Schwab

Submitted to the Mitteilungen der Schweizerischen Entomologischen Gesellschaft

Abstract

We investigated 45 meadows of three different management types in the Schaffhauser Randen (Canton Schaffhausen) and 31 extensively managed meadows in Rottal (Canton Luzern). Wc recorded 140 species of bugs in the Canton

Schaffhausen and 78 in the Canton Luzern. Based on the literature and our own

findings we give specics-hsts for the Cantons of Schaffhausen and Luzern: From the Canton Schaffhausen 207 bug species are known and 201 from the Canton Luzern The biogeography of some species ol special interest is discussed in detail. Three species from the Schaffhauser Randen are new records for Switzerland: Physalocheila harwoodi CHINA, 1936, Polymerus microphlhalmus (WAGNER, 1951) and Strongylocoris steganoides (J. SAHl BERG, 1875). The previous records of Strongylocoris leucocephalus should be revised. Keywords: grassland, Heteroptera. Canton Luzern, Canton Schaffhausen, Switzerland

Introduction

True bugs (Heteroptera) arc an ecologically very diverse group, including phytophagous, saprophagous and predatory species (Dolling, 1991). Furthermore, some species are generahsts while others are specialists. The larval stages and adult individuals live m the same habitat and respond sensitively to environmental changes (Morris, 1969, 1979; Achtziger, 1995; Otto, 1996). Previous studies have shown that the richness of the bug fauna correlates strongly with total mscct diversity (Duelli & Obrist, 1998). These properties and the fact that despite their diversity, they are a manageable group in terms of numbers of species, make the heteropteran bugs an attractive insect group for ecological studies m agricultural systems. Unfortunately, little is known about the distribution and biology of these insects. In Switzerland, the number of publications concerning Heteroptera is Jess than half the corresponding number for Baden-Württemberg m Germany (Otto, 1994; Reeger, 1996). According to the literature, 758 species of Heteropteia are known m Switzerland (Otto, pers. comm., 1997) and 724 m Baden-Württemberg, Germany (REEGER, 1996).

The aim of this paper is to contribute to the knowledge of the true bugs of Switzerland, with a focus on the regions of Schaffhausen and Rottal (Luzern). The faumstic records presented here come from various studies at the Federal Research Station for Agriculture and Agroecology Zürich-Reckenholz about the influence of management techniques on biodiversity in rural landscapes (financial support by the Swiss National Science Foundation is acknowledged). The ecological results will be presented m separate papers (DiGtutto, m prep.; Schwab, m prep.).

Material and Mimons

One research area is located m the Schaffhauser Randen (Canton Schaffhausen, Tab. 1 and Fig. 1) and is pint of the Swiss Jura. The soils arc nutrient-poor limestone. 37

Matertal and Methods

One research area is located in the Schaffhauser Randen (Canton Schaiihausen, Tab. 1 and Fig. 1) and is part of the Swiss Jura. The soils are nutrient-poor limestone.

is 866 the The average yeaily precipitation m Schaffliauscn (437 m a.s.l.) mm, highest annual rainfall occurring m summer and the lowest m late winter. The average mean temperature is 7.8 °C, with maximum in July (23 2 °C) and minimum in January (-3.9 °C) (SMA, 1998). From 1997 to 1999, we imesltgated 45 meadows of three grassland management types (medium intensive, moderately intensive and extensive) in four different locations of the Schaffhauser Randen (Tab. I and Fig. 1). In all four locations all three grassland types were investigated. The medium intensive meadows are regulaily fertilised with slurry and cut 2-3 times per year. The vegetation is dominated by Arrhenatherum elatuis and Triselum flavescens. The moderately intensive meadows are fertilised occasionally with manure and cut twice per year. No single plant species is dominant but Trifolium pratensis and Tnsetum flavescens reach the highest mean cover values. The extensive meadows are not fertilised and are cut once or twice per year. The

All sites were community is dominated by Bromus credits (Stlder, unpublished data). sampled during at least one summer by sweep-netting, but frequency and number of of sweeps per site varied. Besides, 10 meadows weie sampled with a suction sampler the Vorüs' 1994) and 18 with Barber 1980). type , (ARNOin, pitfall traps (CURTIS,

* i

Fig 1 The leseaich aieas aie located m the Noith of Sw itzeiland (Canton Schaffhausen) and the Cenüal patt of Switzei land (Canton Luzein)

Tab I The five investigated aieas situated m the Canton Schaffhausen and Canton Luzein.

Klosteifeld (SH) Hemmental Menshausen (Sil) 780-830 Menshausen 683T)00/291'500- 8°36'E/46°44-N 6S'7'500/29F000 Rottal heights (LU) 750-830 RuswilBultisholz 650 000/220'000 8° 08'F / 47° 07'N

The other study sites are located m the eastern hills of Rotlal (Canton Luzern, Tab. 1 and Fig. 1). The area is composed of hilly Molasse and a few moraines. The soils tend 38

maximum mean monthly temperature in July (17.4 °C) and the minimum in January (- 0.7 °C) (SMA, 1998). The whole area is used very intensively for agriculture. During 1999. 31 extensively managed meadows were investigated in an area of approximately 8 km2 in the communities of Ruswil and Buttisholz. The vegetation is very heterogeneous, in some sites beinç dominated b\ crass and in others by forbs. Overall,

Trifolium repens, Poa trivialis and Ranunculus repens arc the most abundant plants, all of them typical of intensively used meadow s w Inch are heavily fertilised and cut early and frequently. Also common arc Lolium multiflorum and Dactylis glomerata, both of them characteristic species of intensive management and wet soils. All sites were sampled monthly from May to August with a standardised sweep net method and with Barber pitfall traps during 10 weeks. Tf not specified in the text, the keys of Wagner (1952, 1966, 1967, 1971, 1973, 1975) and Péricart (1972, 1990) were used for the determination of species. R. HECKMANN discussed the faunistic records.

Results

In total, 167 species have been recorded in both regions, which amounts to 22 % of the 758 (Otto, pers. comm.) known species of Switzerland. Most species were collected with a sweep net (156) and only 11 species were caught only in pitfall traps or suction samplers (Tab. 2). As there is no Red List of endangered species for Switzerland, those of Baden-Württemberg (RlEGTR, 1986), Bayern (ACHTZIGER et al., 1992) and Germany (Günther et al., 1998) have been taken as a basis for assessing the conservation values of the investigated sites. In the Schaffhauser Randen, we recorded 140 species (12'080 specimens). 29 species (21 %) arc listed in the Red Lists for Germany. In Rottal, 78 bug species (1' 129 specimens) were recorded. Ten species account for more than 80 r/c of all specimens recorded and only 10 species (13 %) arc listed in at least one of the Red Lists for Germany (Tab. 2).

"*" Altogether 3 I species have been found that do not belong to grassy habitats (see in Tab. 2). Fourteen of them were found in Schaffhausen and 22 in Luzern. Most of these species probably drifted by wind from trees and shrubs in the nearby woodlands and the forest edge. That species characteristic of the herbal layer of the forest edge can also live in moist meadows is confirmed by a much higher rate of vagrants in the Luzern than in the Schaffhauser meadows (Judex, 1999). 39

Tab. 2. Species list of the investigated meadows in the Schaffhauser Randen (Canton Schaffhausen) and the Rottal heights (Canton Luzern). Columns: M: Merishausen. IT: Hinterranden. K: Klosterfeld, Z: Zelgli. SIT and LU.: Total number of individuals recorded in the two Cantons. Met.: Sampling method used; n: Sweep net, s: Suction sampler, p: Pit fall traps. R.L.: f: Baden- Württemberg (D), 2: Bayern (D). 3: Germany. "*": Species specialised on plants not normally occurring in meadows (trees, shrubs, ferns) and which probably have been drifted by the wind. The nomenclature of the species list from Ceralocombidae to Miridae (excluding the arrangement in the subfamily Mirinae) follows the Catalogue of the Heteroptera of the Palaearctic Region (Aukcma & Ricger, 1995, 1996. 1999). The subfamily Mirinae (changed names adapted from the above catalogue) of Miridae and the Pentatomorpha follow the Verzeichnis der Wanzen Mitteleuropas (Günther & Schuster, 1990).

Species M II K Z SH LU Met. R.L.

Ceratocombidae Ceratocombus coleoptralus (Zctlcrsledt, 1819) + 6 s 2

Salmdae

Saldula c-allntm (Fieber, 1859) 3 P 1 Saldiila orthochila (Fieber. 1859) + 1 n Saldula saltatoria (Linnaeus, 1758) + + 2 11 n/p

TlNGIDVE

Acalypia carinaia ('Panzer. 1806) + 4 1 P 1,2 Aealvpla marginale! (Wolff, 1S04) + + 90 3 n/p 2 Campylosteira venia (Fallen. 1826) + + 18 n/s/p 2.3 Catoplatus jabricii (Stâl, 1868) + + + 71 n/p 2,3 Kaiama iricomis (Schrank, 1801) + + + + 22 9 n/s/p 2 %Physaiochcüa harwoodi China, 1936 + 1 n 2,3 Tingis reticulata Hcrrich-Schaffcr, 1835 5 n/p

Nabidae

Himacerus major i.A. Costa, 1842) 1 P 2 Iliinacerus ininnicoides (O. Costa, 1834) + + 7 20 n/p "Himacerus apterus (Fabricuis, 1798) 3 n Nabis flavomarginalus (Scholtz, 1847) + 3 n Nabis brevis brevis Scholl/.. 1847 + + 34 4 n/p Nabis jenes (Lmnacus, 1758) + + + + 5 18 n/p Nabis pseudoferus pseudoferus Romano, 1949 + 4- + + 131 2 n/s/p Nabis punetatus punelatiis A. Costa, 1847 + + + 18 n 1.2 Nabis nigosii.s (Linnaeus, 1~5S1 + + 10 11 n/s/p

Antiiocoridak

"'Acoinpocoris alpinus Reuter. 1875 + 1 1 n 2

Anlhocoris neinonun i Linnaeus. 1761) + + 2 40 n

'''Temnostclluis pusilliis (Herrich-Schàffer, 1 1 P 1835) Onus majuseulus (Reuter, 1879) + 9 n

Orias minimis (Linnaeus. 1"dX) + + 3 6 n 40

Species M II K z SIT LU Met.

Miridae ^Rrvocoris pleridis (Fallen, 1807) 1 n Campyloneiira virgiila (Herrich-Schäffer. 1835) 4 f 1 n Dicyphus anntdalus (Wolff, 1804) + to n Dicvphus globulifer (Fallen, 1829) + 2 n

1 n Dicyphus errans (Wolff, 1 S04) i *Dicyphus pal/icltis (Hcinch-Schäffcr. 1836) 6 n/p ^Dicyphus slaehydis slachxdis J. Sahlberg, 18"8 1 n

Deraeocoris inorio (Boheman, 1852) -r i + 9 n Deraeocoris ruber (Linnaeus, 1758) + 4 2 to n Pithanus maerkelii (Herrich-Schäffer, 1838) 15 n/p Leplopterna dolobrata (Linnaeus, 1758) + + + t- 4152 n/p Stenodema ealcarata (Fallen, 1807) 40 n Stenodema holsala (Fabricius, 1787) + + 7 78 n/p Stenodema laevigata (Linnaeus. 1758) + + + + 164 8 n/pi

Stenodema vi reus (Linnaeus, 1767) 3 n Megaloceraea recticornis (Geoffroy, 1785) + ; + + 222 n/p Nolo.stira + 1 1 n clongata (Geoffroy, 1785) i Noloslira erratica (Linnaeus. 1758) + + + + 1065 177 n/s/p Trigonotxlus caelestialium (Kirkaldy, 1902) + i + + + 157 1 n/s Phytocoris longipcnnis Flor. 1860 + | 1 n Adelphocoris lineolatus (Goeze, 1778) + ! + + 473 4 n Adelphocoris seticornis (Fabricius. 1775) + 1 + + + 696 n/p

Brachvcoleus (Panzer. , + 1 n ' pilieomis pilicornis 1805) ; Calocoris a)finis (Herrich-Schäffer, 1835) + 1 2 3 n ""Calocoris alpeslris (Meyer-Dùr, 1843) 8 n Closlerolinus bielavatus (Herrich-Schäffer, 1835) + 1 n Closlerolflinus norvégiens (Gmelin, 1790) + + 12 322 n/p *Giypocoris sexgiillalus (Fabncius, 1777) + 1 n '*Rhabdomiris slrialcllus strialellus (Fabricius, 1 n 1794) Hadrodemus in-fhivuin (Goc/e, 1778) + + + 4- 239 n Slenolus binolatus (Fabricius, 1794) + I 1 n

""Dichrooscxliis intermedins Reiner, 1885 ~f + 2 n

Apolvgus liieorum (Meyer-Dui. 1843) 4 1 n Apolygus spinolae (Me_\ci-Diir. 1841) 4- 2 n L.ygocoris pabutinus (Linnaeus, 1761) + 4 35 n '-l.vgocorn viridis (Fallen, 18Ü7) 3 n Lygus pratensis (Linnaeus. P5S! + + + + 677 1 n/s Lygus rugulipennis Poppius. l^ll + + 4- + 371 161 n/s/p Lygus wagneri Remane. 1955 + + 4 n Orlhops basalts (A. Costa, 1853) + + + 6 4 n Orlhops campestris (Linnaeus, P58) + f 2 n Orlhops kalmii (Linnaeus. 1758) + + to n "Pinalitus alomarius (Me)er-Dür, 1843) 1 n

"''Pinalilus visicola (Puten. 1888) 1 n Charagochilus gxllenltalii (Fallen IS071 + + + 19 i n/s/p Polxmerus nigrila (Fallen. 1S29) + ' + + 13 n 41

Species M II K Z SU LU Met. R.L.

Polyments lnicwphtulinus i Wagner. 1951) + 1 n Polvmenis unifasciatus (Fabricius. 1794) 4- f 4- + 745 2 n/s/p Capsodes gotlucus gothicus (Linnaeus, 1758) + 2 n

Capsus aler (Linnaeus. 1758) -r + + + 11 n Haïtiens aplerus apterus (Linnaeus. 1758) + + + 44 1 n/s Orl/iocephalus coriaceus (Fabiicius, 1777) 4- 2 3 n Orthocephalus saltator (Hahn, 1835) + 3 n Strongylocoris steganoidcs (J. Sahlberg, 1875) + + + 39 n/p

1 t n ^Blepharidoptcrus angiilalus (Fallen. 807) | 1 Globiceps flavomaculaius (Fabricius, 1794) 4- | 2 2 n ' Globiceps fulvicollis Jakovlev. 1877 4- + 23 n/p ^Heterocordylus tiunidieornis (Herrich-Schäffer. i + 1 n 1835) Heterotoma planicornis (Pallas, 1772) 1 n '^Malacocoris chlonzans (Panzer, 1794) + 1 n *Cremnocephalus alpestris Wagner, 1941 1 n 0 + n Hallodapus ntfescens (Burmcislcr. 1835) i 1,2,3 Ainbylvlus nasutus (Kirschbaum. 4- 2 2 n 1856) i i *Alractoiomits inagnicornis (Fallen, 1807) + + 1 8 n '*Alraclotomtis parvuhis Renier, 1878 + 3 n Campylonuna verbasei tMe>er-Diir. 1843) 4- l n Chlamydalus pulicarius (Fallen. 1807) + 4, l 4" + 215 1 n/s/p Chlamydalus pulltis (Reuici, 1870) + + 2 n Criocoris crassieornis (Hahn, 1834) + 1 11 *Harpoeera thoracica (Fallen. 1807) 2 11 Macrotyhis herrichi (Reutei. 1873) + + + 11 n 2 Megalocolcus inolliculiis (Fallen, 1807) + + 2 1 n ^Phoenicocoris obscurellus (Fallen, 1829) + 1 n Plagiognalhiis arbuslonun arbiistorum + ; + 4 10 n/p (Fabricius. 1794) Plagiognalhiis chrysantheini (Wolff, 1804) 4- + + + 1274 n/p '"Plesiodema pinclella (Zetlcisledt, 1828) 4- 1 n "Psallus perrisi (Mulsanut Rev, 1852) 3 n "Psallus piceae Reutei. 1878 2 n Psallus haemalodes (Gmelin, 1790) 3 n

^Psallus varians varians (Herrich-Schäffer. 1841) 4 n

ARADIDAE 1 1 "'Aradiis cinnainoineus (Panzer, 1794) + î 4 2 P

Piesmatidae

Piesma maculaluin (Lapone. 1832) 4- + 2 n

Berytidae Berylinus clavipes (Fabricius. 1775) + ! + to n/p Bervlinus minor (Hcrrich-Sehaffcr, 1835) + + 4- 4- 43 9 n/s/p Berylinus crassipes iHernch-Schhft'cr. 1835) + 1 n 2 Bervlinus monlivaspts (\le\ei-Diir. 1841) + .i + 16 n/p 1,2 Berylinus signoreti (Fieber. I 859") + 1 n 2 Campsocoris pimetipes iGcrmar,lS22) + l n 42

Species M II k Z se LU Met. R.L.

Lygaeidaf

Nysius encae (Schilling 1829) + i 2 n >Kleidoeens it\edae (Pan/ci, 179/) 1 n Cymus inelanoLcplialus Fiebei, 1861 1 n o Isclinodemiis sabulcii (Fallen 1829) 11 2 Plalxplaxsahnu (Schilling 18291 b 19 n Plmlhistis biei ipenms (Latiulle 1S07) 4 + 14 n/p 3 Piopislelhus holosaiLCiis (Scholl/, 1845) r t n Di vmus latus Douglas iV. Scolt. 1871 + 2 P 1,2 3

Di vmus i veil Dou.il is & Scolt 1865 + 2 n/s

Dnimts s\hattcus (Fibuuus 1775) -r 8 n/p 1 Gasliodes abtelwn Beigioth. 1914 4 1 2 n Scoloposlethus aftinis (Schilling, 1829) + 1 P Seolopostethus thomsoni Reutei 1874 + f 1 n Stygnocons milieus (Fallen, 1807) + 2 s/p Slxgnocoiis sabulosus (Schilling 1829) 1 2 s Giaplopellus lynccus (Fabnuus 1775) + + 53 n/p Rlnpaiochiomus pun (Linnaeus 1758) 46 P Peiitiechiis qiaahcoinis Pulon 1877 + 1 1 57 n/p 1,2 Meçalonotits cluia^ni ihiiagia (Fabnuus, 1 97 2 n/s/p 1794) Fmbletlus \eibasn (Fibiuius 1803) 1 l n 1

Pyrriiocoridve

Pyiihoeons aplerus (Ï innaetis 1758) + 1 n

CoRrio VL

Svminastus ihoinbciis (Linnaeus 1767) 4 2 n i Coieus inaiguialus (Linnaeus. 1738) 4 1 n Conciliais dtnliculalus (Scopoli 1763) i + 4 11 n

Alydidae

Alydus calcul alio, (Linnaeus 1758) + 1 6 n

_- --

Riiop vi in vi

Coiizus Inoscvami (Linnaeus, 1758) + + 3 n Rhopalus panimpunclaUc Schilhn» 1829 1 -t- 2 n Rhopahis subnipc (Gniclin 1790) 3 n Sliclopleiiius abutiloii abutiloii (Rossi, 1790) 1 3 n Sliclopleiiiuspiinclaloneivosus (Goczc, 1778) 4- 1 n

Plaiaspidvi i

Coptosoma saiiellatum (Gioihoj 1785) f 16 n

Cydnid \e

Sehinis lueliiosus MulsanuV. Rt\ 1866 1 + + 17 n/p ' Caullwphoius uupii s>u\ llomtli 1 b>S1 F b 2 n 1 Xdomeius bcpitkwis (1 innaius '"^5) I <- e + 90 n'p 1 Legnolu s pu ipi M Fallen ISO? | 4 r 3 n 2

_ Thyreocoridvi

ThvHOcons Haiabaeoidcs (Linnia,s 1758) 4 1 n 43

Species: M IT K Z SH LU Met. R.L.

Scutelleridae

Eurygaster maura (Linnaeus. 1758) + + 22 1 n Eurygaster testiidinaria (Geoffroy, 1758) 2 n

Pent.vtomidae Sciocoris lnacrocephahis Fieber, 185 1 4- 3 n 1.3 Sciocoris niicropluhalrnus Flor, 1860 50 n 2 Aelia acuminata (Linnaeus. 1758) + 8 n > Neolliglossa ptisilla (Gmelin. 1789) + n Rubicoiiia intermedium (Wolff, 1811) I n 2,3 Paloinena prasina (Linnaeus, 1761) + + ? 6 n

Paloinena viridissima (Poda, 1761) + 3 4 n

Drvocoris vernal is (Wolff, 1804) + 1 n Carpocoris fiiscispimis (Boheman, 1849) 4- + + + 97 8 n/s/p Carpocoris piirpiireipennis (Dc Gccr, 1773) 4- 4- + 4- 23 3 n Dolycoris baccanun (Linnaeus. 1758) + + + 135 n/s/p Eurvdema oleraceum (Linnaeus. 1758) + 4- + 8 n/p *PenlaIoma rufipes (Linnaeus. 1758) 4- 2 n Troilus luridiis (Fabricius, 17"75) + 1 n/p "''Anna cuslos (Fabneius. P94) 1 n Zicrona caerulea (Linnaeus, 1758) 4- + 4- + IS n/p 2

Total number of species 167 112 41 70 46 140 78 44

Discussion

General discussion Recent faunistic publications concerning the heteropteran fauna of Switzerland mostly deal with the cntomologically more interesting southern part of the country, especially the Canton Ticmo where till now 395 species have been found (PÉRICART, L984; GöLLNER-SaiHiDiNG & Rezbanyai-Rksfr, 1992; Otto, L992, 1994, 1995, 1996; Otto & Burki, 1996; Otto & Rezbanyai-Rlsfr, 1996; Rampazzi & Detiiier, 1997; Rezbanyai-Reser, 1993, 1997). The other Cantons are not well investigated and the fauna is much less well known than that of various regions of Baden-Württemberg. Tab. 3 gives a survey of the faunistic knowledge in the various Cantons of Switzerland m relation to data available from Middle-Europe (Günther & Schuster, 1990), Switzerland (Otto, unpublished list), Baden-Württemberg (RiEGER, 1996) and the Landkreis Konstanz m Baden-Württemberg (Hlckmann, 1989, L990, 1993, 1996, 1999; Heckmann & Rteger, m prep.).

One way to assess the ecological differences between regions of a country is to look at differences in species number of families known to be indicators for varying climate types. The numbers of species of families like the Tingidae, Reduviidac, Lygaeidae, Rhopalidae, Coreidae Bcrytidae and the Pentatomidae increase from boreal and alpine areas to mediterranean and tropical habitats. These taxa can therefore be used as indicator families of xero-thermophily. On the other hand species numbers of Miridae and Anthocoridae decrease m the same direction, being indicators for more temperate climates (Gollner-Scheiding, 1989a). Although the data are not complete it is interesting to note that there is a good fit of the data from SH, KN and even TG which are located close together (Tab. 3). Moreover, there are big differences between these areas and the Canton Luzern which has the highest proportions of Miridae and the lowest proportions of xero-thermophihe Tingidae. Reduviidae, Berytidae, Lygaeidae, Coreidae and Rhopalidae.

We found more than one fifth of all known species of Switzerland in the meadows oi" the Schaffhauser Randen and the Rottal. The sites in the region of Schaffhausen, however, arc much more diverse than those in Luzern and we found nearly twice as many species and a much higher proportion oï rare or endangered species. Most of the latter are xero-thermophilic species, which are restricted to dry and extensively managed meadows (Di GiULiO. m prep.). The climatic conditions in the Schaffhauser Randen not only favour these species directly, but in combination with the soil conditions, have limited the intensification of agricultural production. It is known for other taxa (eg butterflies and flowering plants) that many species could persist here which have disappeared from the other regions of Switzerland (Isler-Hubsciier, 1980; Schtess-Buiiler & Schiess. 1997). 45

Tab. 3. List of absolute and relative numbers of ecologicallymost important families caugbt in different regions.Columns: EU: Middle-Europe (Günther & Schuster, 1990). CH: Switzerland (Otto, unpublished list & pers. comm.. 1997: uncontrolled literature data).BW: Baden-Württemberg (Rieger. 1996: literature data) KN- Landh-eis Konstanz (Heckmann. 1989. 1990, 1993. 1996. 1999; Heckmann & Rieger. in prep., unpublished verified records).TI: Canton Ticino (Péricart,1984: Rezbanyai-Reser.1993: Olio. 1994. 1995, 1996: Otto & Bürki. 1996; Rezbanyai-Reser.1997: the 12 unpublished records of Dethier excluded). SIT: Canton Schaffhausen (Tab. 5). LU: Canton Luzern (Tab. 4). TG: Canton Thurgau (Blöchlinger.verified records of unpublished list & pers. coram., 1999 partlybased on Hofmânner. 1928). Other families: Hydrocorisae.Amphibiocorisae and the "rest"'of Geocorisae.

Absolute Numbers Percentage Numbers

CII TI Sil Ti si i EU j ; ; BW KN ; LU TG EU jCH BW KN LU TG

! : Tingidae i 74 49 4^ 22 ! 20 10 4 10 7,0 6.5 6 2 5,4 5.2 4,8 2,3 3,8

! Nabidac IS 16 14 11 ! 7 8 8 7 1,7 : 2.1 1,9 2.7 1.8 3,9 4,5 2,7

Anthocoiiddc 52 36 33 23 18 7 9 12 4,9 4,7 4.6 5.6 4,7 j 3,4 ! 5,1 4,6

jj. Rcduvndae IS 14 13 7 7 1 6 1,7 1.8 1,8 1.7 1,8 2,4 0,6 2,3

Miridae 401 271 284 164 156 76 100 95 37,8 35,8 39,0 39.9 40.8 36,7 56.5 36,1

Beiytidae 14 10 10 7 i 2 7 1 4 1.3 J,3 1,4 1.7 0.5 3,4 0,6 1.5

1 ! ! Lygaeidae 155 116 110 62 58 25 19 30 14 6 15.3 15.2 15.1 15,2 | 12.1 10 7 11,4

i 1 Coreidae 27 23 17 7 10 5 5 2.5 [joy 23 1.7 2.6 j 2.4 0,6 1.9

I 17 15 10 10 5 8 1.6 ! 2.0 1.9 2.4 1,1 Rhopalidae ; 14 2 2.6 2.4 __3.0_

1~k Pentatomidae 70 52 43 26 28 18 Î2 6,6 6,9 5,9 6.3 7,3 8,7 j 6,8 8,7 j

! I Other families 251 157 141 72 67 31 44 63 23.7 20.1 19,5 17.5 17.5 !15,0 121 9 24,0

Species \ *

! t««t 758 724 411 383 207 201 263 100 71,4 68,2 38,7 36,0 !19,5 18.9 24,8 number | 46

Canton Luzern

Faumstic data are available from the Canton Luzern for the upland moor Baimoos near ïlasle (Rezbanyai, 1980; Gollner-Schtiding, 1981) and for the surroundings of the Vogelwarte Sempach (Gollner-Scheiding. 1982). Later the Vogelmoos near Neudorf (Gollner-Schftding, 1990) was investigated and occasional records for different places in the Canton of Luzern were published (Gollner-Schetding, 1989b). The record of Panaoriis adspersus Muls. & Rey was added from the Museum of Natural History in Pans (Péricart, 1998) and 35 species by an investigation near Rottal (Judex, 1999). Tlnrty species of water and seniiaquatic bugs (Nepomorpha and Gerromorpha) were found m the Wauwiler Ebene and 18 in the Mösliwciher near Schötz (Wipraciitiger, 1999 a, b). We found 78 species for Rottal, 26 of them being

'""" new records for this Canton (see m Tab. 4). Altogether 201 species have been recorded in the Canton Luzern.

In the publications of GöLLNER-ScnETDiNG (1981, 1982) Orlhops basalis A.C. was published as Ortliops kahnii L. The misidentification of these two species was apparently due to a mistake in the key of Wagnfr (1967, 1971) which later was revised (RlEGER, 1985). 47

Tab. 4. Check list of Heteroptera for the Canton Luzern. The nomenclature of the species list from Ceratocombidae to Miridae (excluding the subfamily Mirinae) follows the Catalogue of the Heteroptera of the Palaearcric Region (Aukcma & Riegcr, 1995, 1996, 1999). The subfamily Mirinae (the names were adapted from the above catalogue) of Miridae and the Pentatomorpha follow the Verzeichnis der Wanzen Mitteleuropas (Günther & Schuster, 1990). For complete names sec Tab. 2. The number of species in the different families are noted. The asterisks indicate the 26 new species for the Canton.

Check list ok Heteroptera for the Canton Luzern 201

Nepidae 2 Gerridae 6 Nepa cinerea L. Aquarius pallidum F. Ranalra linearis L. Gerris argenlatus Sebum.

CORIXIDAE 12 Gerris gibbifer Schum. Micronecla scliollzi Ficb. Gerris lacustris L. Gerris Zeit. Callicorixa praeusla Ficb. odontogasler Gerris thoracicus Schum. Con.\a punctata 111. Hesperocoma linnaei Ficb. Saldidae 4 Hesperocorixa sahlbergi Ficb. Charloscirla cincla II.-S.

Paraeorixa conanna Ficb. Macrosaldida variabilis 14.-S. Sigara nigrolineata Ficb. '''Saldula c-album Fieb, Sigara semisiriata Ficb. Saldula sallatoria L.

Sigara striata L. TlNGlDAF. 4 distincte Fieb. Sigara "Acalypla carinata Pz. Fieb, Sigara falleni *Acalvpla marginale WIT.

Sigara lateralis Lch . ''Kalama iricornis Schrank Natjcoridae 1 "Tingis reticulata II.-S. Ilvocoris cimicoides L. Nabidae 8 NOTONECTIDAE 1 "Hiniacerus major A. C. Noloiiecta glauca L. Himacents minnicoides 0. C. Noloiiecta maculate F. '"Hiniacerus apterus F. Noloiiecta viridis Dele. Nabis limbalus Dhlbm. "'Nabis brevis Sz. Pleidae 1 Nabis 1,. Plea minulissima Lch. ferns Nabis pseudoferus Rem. Mesoveliidae 1 Nabis rugosus L. Mesovelia furcata Muls. & Rey Anthocoridae 9 Hydrometridae 2 Acompocoris alpinus Reut. Hydromctra gracilenta Horv. Anlhocoris confiisus Reut. Hydromel in slagnorum L. Anlhocoris limbalus Ficb. Veliidak 4 Anlhocoris neinonim L Microvelia Dut", pygmaea Teimiostellius pusillus U.S. Micmvelia reticulata Burin. Orius lalicollis Reut. Veiia Tarn. caprai Oriiis majusculus Rent. Velia sciulii Tarn. GVws miiiulus L. GV/hs victims Rib. 48

CïMICTOAE 1 Lygus punctalus Zell. Cimex lectularius L. Za ç»i pratensis L. Lyells rugulipennis Popp. Reduvhdae 1 Lygus wagneri Rem. Reduvius P£_rsonahj.sL. Orlhops basalis A. C. Miridae 100 "'Orthops catnpestris L. ''''Bryocoris pleridis Fall. Orthops monlanus Schill. Monalocoris L. jilicis "Pinalitus alomarius Mey.-D. 1-1.-S. "'Campyloneiira virgule Pinalitus cervinus U.S. Rcut. Dicyphus epilobii Pinalitus rubricalus Fall. Wff. Dicyphus errans ''Pinalitus visicola Put. Burin. Dicyphus hyalinipennis Agnocoris rubieundus Fall. H.-S. *Dicxphus pallidas Liocoris iripusiiilaiiis F. I. Dicyphus slachydis Shlbg. Camplozyguni aeqnale Vill. Alloeotomiis E. germaniciis Wgn. Charagochilus gyllenhalii Fall. Alloeotomus Fall. golhicus Polymerus holosericeus Hahn Deraeocoris ruber L. ''Polymeries unifasciatus F. Deraeocoris lulescens Schill. Capsus aler L. Pilhanus inaerkelii IL-S. "Haïtiens apterus L. dolobrata L. Leplopterria "Orlhocephalus coriaceus F. Teralocoris J, pallidum Shlbg. B/epharidoptenis angulatiis Fall. Stenodema calearata Fall. Blep/iaridoplerus diaphanus Kb. Stenodema holsata F. Drxophilocoris /lavoqiiadriiiiaciilaliis De G. Stenodema laevigata L, ""Globiceps flavomaciilatus F. Stenodema virais L. ""Helerotoma planicornis Pali. Megaloceraea recticornis Gcolïr. Mecomma ambulans Fall. Noloslira el ongala Gcolïr. Orlhotyliis marginalis Rcut. Noloslira erratica L. Orlholyliis nassalus F. Trigonolvlus caelestialium Kirk. I Orlhotyliis prasinus Fall. Phvlocoris dimidiatus Kb. [ Pseiidoloxops coccineus Mey.-D. Phylocoris intricaïus Flor Crcinnoccphalus alpestris E. Wgn. Phvlocoris longipennis Flor Pilophorus clavatus L. Phylocoris liliac nliac F. Pilophorus confusiis Kb. Phylocoris pini Kb. Pilophorus perplexus Doug. & Sc. Pant il ins lunicatus F. "Ambvlvlus nasillas Kb. ^Adelphocoris lineolatus Gz, Alraclolomus kolenalii Flor Adelphocoris seticornis F. Atraclotomus magiiicornis Fall. Calocoris ajjinis U.S. Compsidolon salicellum U.S. Calocoris alpestris Mey.-D. '"Clilamydalus pulicariiis Fall. Calocoris roseomaculalus De G. Harpoccra thoracica Fall. Closlerolinus biclavanis U.S. "'Megalocoleus inollicuhis Fall. Closlerotonnis norvégiens Gm. Orthonotus nififrons Fall. Grypocoris sexguitaius F. Phoenicocoris obscurellus Fall. Rhabdomiris striate!Iw. F, Phyllis coryli L. Slenolus binolaliis F. Phyllis inelanocephalus L. Apolvgus lucoruin Mey.-D. Placochiliis seladonicus Fall. tcygocoris pabulums L, Plagiognalhiis arbustoriiiii F. Lygocoris nigicollis Fall. Psallus belitleli Fall. Lvgocoris contaminai us Fall. Psallus ambiguus Fall. Lygocoris viridis Fall, ; "'Psallus perrisi Muls. & Rey 49

Miridae CONT. Coreidae

''Psallus piccae Rcut, Coreus marginatus L.

Psallus fallen/ Rcut. Rhopalidae _ Psallus haemalodcs Gm. i Rhopalus siibrufus Gill. Psallus lepidus Fieb S7z< lopleurus crassicornis L. Psallus mollis Muk & Rc> Scltelleridae 2 Psallus varians varians II -S Eurygaster maura L. Aradidae Eurygaster lesludinaria Geo ffr. vAradus cinnamoineus Pz Pextatomidae 12 Berytidae Eysarcoris fabricii Kiik. II -S. Berytinus minor | Paloinena prasina L. Lygaeidae 19 I Paloinena viridissima Pd. Spilostethus scnatilis Scop. Carpocoris fiiscispimis Boh. Nysuis cvirioidcs Spin. 1 Carpocoris piirpiireipennis De G. '•Nysius ericae Schill. Dolycons baccanun L. Kleidocerys icsedae Pz. Eurvdema dominuhiin Scop. Cymes glandicolor Hahn Rhaplugasler nebulosa Pd.

1 Cvmus auicsccns Dist. Penlatoma rufipes L.

' Cyinus inelanoicphalus Fieb Picromenis bidens L.

Ischnodemus sabuleti Fall 1,1»»« oustos F.

Gaslrodes abiclum Bgtth Z(c; o»a caerulea L. De G. Gaslrodes grossipe.s ACANTIIOSOMATIDAE 4 , SCHILL. Scolopostelhiis iifjmis 1 Acaiilhosoma haemonhoidale L.

1 Scoloposlelhus thomsoniRruT. Elasinosletlius minor FTorv.

Stygnocons rusticiis F\ll, Elastnostetliiis interstinetiis L. , Pachvbrachius Schill. jiacticollis Elasinucha grisea L. Panaoriis adspersus Ml'LS, & REY Rhvparochromus pini L Peiitrechus penicillatus PI \H\

Pentrechus nubilus F \i I Meçalonolus chiraçra F. 50

Canlon Schaffhausen The earliest records for the Canton Schaffhausen include 23 species of Miridae collected by S. Sfttfr (Mfyer-Dur, 1843). A list of 76 species was published by Frey-Gessner (1864-1866), most of them also collected by S. Setler in the midst of the 19th century. In his list, he included a revised list of the Mirids recorded by MEYER- Dur (1843). Much later the occurrence of two Saldid species was reported (Dethtfr & Péricart, 1990). Together with our results, wc present here a list of 207 species of Heteroptera for the Canton Schaffhausen, 1 18 of them being new records for the Canton (see ai-" in Tab. 5).

We were not able to check the determinations of" Frey-Gessner because his collection, which was probably deposited m the Natural History Museum of Schaffhaiisen, was destroyed by bombing of Schaffhausen during world-war II (A. MÜLLER, pers. comm.). Therefore, we have only updated the names (AuKEMA & RffiGER, 1995, 1996, 1999; HEISS & PÉRICART. 1983; PÉRICART, 1984, J998; STICHEL, 1955-1962). However, the following four records are problematic:

1. Velia currens F. was published in the lists for the Canton of FREY-GESSNER (1864-1866). Much later, Velia caprai Tam. and Velia saulii Tam. were separated from that species as distinct species (Tamanini, 1947), It is therefore not clear which of the three species was actually found. Probably it was Velia caprai TAM., which is also very common in the southern part of Baden-Württemberg, while Velia currens F. occurs only in Ticino (DETHIER & MATTHEY. 1977).

2. Aconipocoris alpinus REUT, was described in 1875 and separated from Aconipocoris pygmaeus Fall, so that we do not know which of the two species was found.

3. Taphropeltus hamulatus Thoms. was described in 1870. After being considered as a synonym of Taphropeltus contractus H.-S. it was later separated again; we do not know which of the two species was really collected.

4. Sehirus morio L. was published in the lists for the Canton of FREY-GESSNER (1864-1866). At that time Sehirus luctuosus MULSANT & Rey had not been described as a separate species front S. morio. We assume that the record probably deals with S. luctuosus Muls. & Rey which is found frequently, while S. morio L, is seldom found in Middle-Europe. 51

lab 5 Check list ol Hcteiopteia foi the Cmton Schaffhausen The nomcnclatuic of the species list fiom Ceiatocombidac to Mnidae (excluding (he subfamily Mumae) follows the Catalogue of the Ileteioptu i oi the Palaeatctic Region (Aukema & Riegei 199s 1996 1999) The subtamih Mumae (the names weie adapted fiom the above catalogue) of Miiidae and the Puititomoipha follow the Veizeichms det '"?" Wanzen Alittdeuiopas (Gunthei

On c k i is i or Hi i lrop ii ra i or i m C \nt on Sciiatthausen 207

ClRVlOCOMHIDVL 1 \abis nnosus L Ceiatoeombus colcoptiatus Zelt Vmiiocoridal 7

Nr pro vi 1 \( ompocons alpnuis Reut ' lai« Tall ' Ranali a luit ai is L pocons pyginacus

"• bithocons nanoium I CORIXID VI 7annoslclhuspusillusll S Hi spaocoiixa inoesta Ficb Onus majuscules Reut Siçaia slilata L Onus minimis L Strata fallait Ficb f\< aeons campeslnsT Sigai a Jossen um Lch RlDLMIDU 5 Vn iid vr / De G Micio\clia icliculala Buim mpicons culicifoimis / I ' mpiLOiis vagabundus f Vcha capiat copiai 1 am Pin mata aassipcs 1 Gerrid u P\ qolampis bidentala Gz tienlatus Schum Ganyai RIiMiot ons iiacundus Pd S\iDm\r Miridvi 76 Saldula e album Fieb Lampxloneuia MiqulaU S 'saldula oithodula Ficb Du \phus iiniuilatiis Wii Saldula sallatona L Du \phus qlobiilifa Fall

IING1D \1 10 Di i cu oloi is moi w Boh Pz Aeahpta cannula Di nu i ons nibci I

"- \calypta marqinata WI1 Dciacocoiis lulescens Schill \( 1 all ahptapaisula /1 plop le nut dolobiala I [z-iamina hutiim Fill Steno lema holsala I ''Campx/ostcua \eina Fill Stenodema lae\i%ata 1 *("aloplalus/abncii Stil Meçaloceiciea leclicoims Gcolli Diet]la celui Schi ink \otostua elongate Gcolh Dicnla lupu/iU S Vi/i si n a eiiatica L kalama tnioinis Still ink Tnjonolylus caelestialium Kuk Pin satoi lu da han\ oodi Chin i Plniocoits longipenms Floi

"- Nvbidw [delphocons lineolatus Gz Pioslemma aillitla I \di Iphoeons seticoims F

'~Ilunac

Nabis bu i is Sz Caleçons loseomaculalus De G

Nobis je ins I Closleiolomus biclcnalus H S %Nabispsaidofaus Rem ( loste lolomits fuhomaeulatiis De G Closte "~Nabis piuu latus \ C lotonius nonegicus Gm 52

Miridae cont. i ""Plagiognalhiis arbitsionini F.

1 Grypocoris sexyuitaltis F. "Plagiognalhiis chrvsanlheiniWfii.

' Rhabdomins striatedliis F, "•Ples'wdcina pinetella Zelt. *Hcidrodemus m-llavum Gz Psallus ambiguiis Fall.

' Slenotus binotatus F. Psallus variabilis Falk

*Dichrooscvtus intermedins Reut. Aradidae 3 Apolygus Iiicorum Mey.-D. "'Aradits ciimamoineus Pz. *Apolygus spinoleie Mey.-D. | Aradits conspiciuis U.S. bid inns L. "'Lygocoris pa I Aradits depressus F. ""Lygus pratensis L. ! Piesmatidae 2 *Lygus rugulipennis Popp. Piesma capilatum WIT ^Lygtis wagneri Rem. 1 "Piesma maciilatuiu Lap. "'Orlhops basales A. C. Berytidae 7 "'Orlhops campesti is L. 1 F. "Orlhops kabnii L. Berylinus clavipes minor U.S. Pinalitus rubricalus Fall. Berylinus U.S. Charagochilus gylleiihalii Fall. , "'Berylinus crassipes Polymerus holosericeus Hahn j "'Berylinus monlivagus Mey.-D. J "'Berxlinus Fieb. "'Pedvmerus nigrila Fall. signoreli ! Germ. ''"Polymerus unifasciatus V. "'Gampsocoris punclipes Neides L. ""Polymerus mierophlalmiis F. Wgn. tipiilarius *Capsodes golhicus gotlucits L. Lygaeidae 25 I "'Capsus aler „ "'Nysius ericcte Schill. "'Haïtiens aptcnis aplerus L, ""Isclmodemus sahuleti Fall. 'Orlhocephalus coriaccus F. Macropiaxpreysslcri Fieb. "Orlhocephaltts solictor Halm Hclerogasler urticae F, Strongylocoris luridus Fall, '"Plalyplax salviae Schill.

' *Slrongylocoris slcganoides I. Shlbg. Plinilusiis brevipennis Latr. Cvllccons histrionius L. Propistethus holosericeus Sz. Globiceps sphaegiformis Rossi 'Drvmus leans Doug. & Sc. ^Globiceps jlavomaculatus V. "Dryinus rycii Doug. & Sc. * "'Globiceps fuivieollis Jak. Drym us sylvalicus F. Hclerocordxlus lumidicornis U.S. "fGastrodes abielmn Bgrlll. ''Malacocoris clilonzans Pz. '"Scoloposlelhus afjinis Schill. Orlhotyliis nassatus F. ''"Scolopostethus thoiusoni Rent. Orlhotyliis viridinervis Kb, IPaphropellus contractus U.S. ? '-'"Hallodapus rufeseens Bui'ill. "'Stygnocoris nislicus Fall. '"Ambylyitis nasiitus Kb. i Stygnocoris sabiilosus Schill. -'"Alraclolomus magnicornis Fall. 1 Piiclnbrachius fracticollis Schill. '''Alraclotomus pervitins Rent. Aellopus atrcUus Gz. Campylomma vcrbasci Mey.-D. "Graptopeltus lynccus F. *Chlamydaius pulicarius Fall, ""Rhxparochromuspini L. "'Chlainydatus pullus Rcut. Xanlhochiliis qiiadralus F. Criocoris crassicornis Ilahn '*Peritrechiis gracdiconiis Put. Hoploinaclius thiinbergii Fall. ""Megalonolus chiragra F. "'Macrolxlus herrichi Reut, Emblelhis verbasci F

*Megalocoleiis molHad us Fall. Plerolmetiis staphilinijormis Schill. bohananni Fall. Monosynainma Pyrriiocoridae 1 Oiicolylus viridiflavus Gz. I "-Pyrrhocoris aplerus L. ""Phoenicocoris obseurelhi.s Fall. 53

Coreidae Acantiiosomatidae Goiiocerus eicuteeingiikitus Gz, Elasinuclia ferrugeita F. Syromaslus rlwmbeus L. [ Cvphostethus trisirialus F, Enoplops scapha F. ''•'Coreus inarginattis L. '!'Coriotneris denticulatiis Scop^ Alydidae 1 Alxdus ceilcareitus L.

Rhopalidae 5 ^Corizus hvoscvami L. "•Rhopaliis pariirnpunctalus Schill. "''Rhopaliis siibnifus Gm. ""Sticlopleurus abutiloii Rossi ""Slicioplcnnis piinctatonervosns Gz._ _ Plataspidae 1 Coptosoma seutellatum Geo ffr. Cydnidae Sehirus luctuosus Mills. & Rey Trilomegas bicolor L. '•'Canlhophorus iinpressus Ilorv. ""Adomcnis bigullatus L. *Legncjiui2icipc.s Fall. Thyreocoridae "'1'hvreocoris scarabaeoidcs L.

Scutelleridae Odonloscelis fuliginosa L. "•'Eurygaster maura L. ^Eurygaster testiidinaria Geo ffr. Pentatomidae 18 "'Sciocoris macrocephaliis Fieb. ''Sciocoris microphthalmia, Flor Sciocoris umbrmus WIT.

*Aelia acuminata L. 'Neolliglossa pusilla dm. *Rubiconia intermedium Wff. "'Paloinena prasina L. ^Paloinena viridissiina Pd. Dryocoris venudis Wff. Chlorochroa juniperina I.. ""Carpocoris fuseispinus Boh. '"Carpocorispiirpiireipennis De G. "'Dolycoris baccanun L, '•'Eurydema oleraceum L. "Penlaloma rujipes L. *Troilus luridus F.

Anna cuslos F. '"Zicrona caerulea L. 54

Biogeographv of rare species

In the following, we discuss our own findings in detail with a critical focus on species on the Red list and those rarely found m Switzerland. Some species on the Red lists of Germany are very common and widespread in both Baden-Württemberg and Switzerland and will not be discussed here. These arc Saldula c-album FlEB., Saldula orthochila FlFB., Acalvpta marqinata Wff., Catoplatus fabricii S TAL, Kalama tricornis SCHR., Aconipocoris alpinus Retjt., Calocoris alpestris Mey.-D., Grypocoris sexguttatus F., Macrotydus hernchi REUT., Bentinus signoreli FlEB., Ischnodemus sabuleti FALL., Adomerus biguttatus L., Legnolus picipes FALL., Rubiconia intermedium Wff. and Zicrona caerulea L.

Canton Schaffhaiisen - We compared our results for Schaffliauscn (Tab. 5) with those ol Baden-Württemberg and the dry habitats of the Hegau (Landkreis Konstanz). For the Landkreis Konstanz 411 bug species have been recorded (Heckmann, 1989, 1990, 1993, 1996, 1999; Heckmann & Reeger, m prep.; Heckmann, unpublished data). In total 21 species of the Schaffhausen bug fauna have not been found in the

Landkreis Konstanz so far.

Light of our recently recorded species ha\c not been found in the Landkreis Konstanz, though it is a well investigated region. All species except Campylosteira venia FALL., Phvsatocheila harwoodi CHINA and Sciocoris tnicrophlhalmus FLOR, are \ero-thermophihc species and most are on the Red List of Germany: Saldula orthochila FlEB., Campylosteira venia F Ml.. Phvsatocheila harwoodi China, Brachycoleus pilicornis Pz., Hallodapus rufescens Burm., Sxromastus rhombeus L., Sciocoris niacrocephalus FlFB. and Sciocoris microphthalmus FLOR.

Thirteen species are mentioned m the early records but were neither found by us nor in the Landkreis Konstanz. Llesperocorixa moesta FlEB., Sigara fossarum LCH., Dictyla lupuli II.-S., Calocoris roseomaculatus De G.. Strongylocoris luridus FALL., Globiceps sphaegifornns Rossi, Neides tipularhis L., Aellopits a trahis F., Xanthochilus quadratus F., Sxromastus rhombeus L., Sciocoris timbrants Wff., Chlorochroa juniperina L. and Elasmucha F Also Neides L atratus fcmiqata tipitlanus , Aellopits F., Xanthochilus quadratus F. Sxromastus rhombeus L. and Chlorochroa juniperina L. are xero- thermophilic and are mostly Red List species in Germany. Strongylocoris luridus Fall, is found in the Black Forest (Rieger & STRAUSS. 1992) and lives on Jasionc montana. Elasmucha ferrugata F. also is known from the nearby Wutachschlucht in the Black Forest (Kifss, 1961) and lives on Vaccinium mxrtillus. The distribution of the other eleven species in Baden-Württemberg corresponds with hot and dry habitats along the Rhine Valley north of Basel (Heckmann, 1996).

The species of special interest found by us are-

1. Ceratocomhus coleoptratus (ZhTTFRSTEDi, 1819); In Switzerland this species has been found only recentl) from the Canton Ttcmo (OiTO, 1994). It was found several times in Baden-Württemberg and is common m the Landkreis Konstanz (Heckmann & RiEGER, m prep.). It is rarely collected because of its small size and the fact that it occurs hidden m moss. Mostly it is recorded by pitfall traps. In Bayern it has been put on the Red list.

2. Acalypta carmaia (Panzfr, 1806) is often found m the same habitats as Ceratocomhus coleoptratus Zftt and can be caught easily with pitfall-traps. Records arc known fot Vaud, Bern, Zurich and Wallis (Pfric VRT. 1983). It is on the Red list for 55

Baden-Württemberg and Bayern but seems to be common m the south of Baden- Württemberg (Rieger, 1981) and the Landkreis Konstanz (Heckmann, 1990).

3. Campy]osteva venta (Fallen, 1826) lives hidden between mosses and lichens. In Switzerland H is known from Bern and Graubunden (PÉRICART, 1983) but few record aie known for Baden-Württemberg (HÜEBER, 1891; Meess, 1907; FISCHER, 1961; Reeger, 1981). It is on the Red list of Bayern and Germany and should be also for Switzerland.

4. ThysatocheUa harwoodi China. 1936 (Fig. 2); New record for Switzerland! The known from species lives on Acer pseudoplatanus and is recorded very seldom. It is seveial places (Heiss, 1978) m fyrol (Austria), from Baden-Württemberg (RTEGER. 1981; Voigt, 1983) and from Bayern (Singer, 1952). This new record corresponds with the known distribution area.

Fig 2 Physatocheila hatwoodi The anow shows thenanow black aica of the clytna which is much wider m the othci species of the genus. The body length is about 3 5 mm. (Photo: M. Di Giulio)

5. Deraeocoris morio (BotiEMAN. 1852): This xero-therinophilic species lives on Thymus and is known only from the Ticino (Gollner-Schfiding & Rezbanyai- RESER, 1992) and several places m Baden-Württemberg and in the Landkreis Konstanz (ITECKMANN& RlFGER, in pi'Cp.).

6. Brachycoleus pilicornis pilicornis (PANZER, 1805): This thermophilic species lives on Euphorbia verrucosa. It is knov\n from the Cantons of Basel, Zürich. Aargau (Frey- Gi ssner, 1864-1866) and Thurgau (Blociilinger, pers. comm.). In Baden- Württemberg it is known from se\eral places and also from warm places in the nearby Wutachschlucht m the Black Forest (Kt fss. 1961). 7. Polymerus nticrophtlialmus (Wagnfr. 1951): New record for Switzerland! This species lives on Galium, often together with P. unifasciatus F.. and is common in the Llegau and sparsely found m other parts of Baden-Württemberg. Probably there is no Swiss record because it has been confused with P. unifasciatus F.

8. Strongylocoris steganoidcs (J. Sahlberg, 1875) was synonymised with S. leucocephalus by Reuter (1888). Kritshenko (1951) revised the genus and separated these two species. Wagner (1973) treats it as a subspecies, and it might therefore have been misidentified (RiEGFR, 1997). In Baden-Württemberg S. steganoidcs is widespread and very common whereas S. leucocephalus is a rare species. In the Landkreis Konstanz 56

only S. steganoidcs has been found (HECKMANN & RffiGER, in prep.).We assume that the same is true for Switzerland and the records of S. leucocephalus should be checked.

9. Hallodapus rufescens (BURMEISTER, 1835) is known in Switzerland only from the Cantons Vaud, Bern (FREY-GESSNER, 1864-1866), Wallis (CERUTTI, 1937a) and Graubünden (Valbella; Dl GlULlO, unpublished data). In Baden-Württemberg it is only known from the Suebian Alb (Rieger, 1976) and from the Kniebis in the northern Black Forest (RiFGER, pers. comm.).

10. Berylinus crassipes (Herrich-Schäffer, 1835) lives on Cerastium. Records arc known from Aargau and Vaud in Switzerland (PÉRICART, 1984), the Wollmatinger Ried in the Landkreis Konstanz (LIeckmann, 1990) and a few other places m Baden- Württemberg (Kless, L961: Rieger, 1976; Heckmann, 1996). 11. Berylinus montivagus (Meyer-Dur, 1841): This xero-thermophilic species is known m Switzerland only from Graubünden (Frey-Gessner, 1871) Aargau (Péricart, 1984) and Neuchâtel (Barbalaf, 1991) but is probably more widespread. It is known from the Hohentwiel in the Landkreis Konstanz and from other places in Baden-Württemberg (Sciimtd, 1967; Heckmann & Rifger, in prep.). 12. Drymus latus DOUGLAS & SCOTT, 1871: This is the second record for Switzerland. The species has only been recorded in the Canton Basel (Péricart, 1998). There are few records in the Landkreis Konstanz (Heckmann, 1990; Heckmann & Rteger, in prep.) and from few other places in Baden-Württemberg (Rieger & Strauss, 1992). 13. Peritrechus gracilicornis PUTON, 1877: This xerophilic species is known in Switzerland from Wallis and Ticino (Péricart, 1998). In Baden-Württemberg it is mostly found along the valleys of the Rhine and the Neckar and also in the Llegau (Heckmann, 1996). 14. Canthophorus impressus HORVATH, 1881: This is the third reliable record of this species for Switzerland. It has been found previously in (he Cantons Obwalden (Gollner-Schtiding, 1989b) and Ticino (Göllner-Sceteiding & Rezbanyat-Reser, 1992). The species lives on Thesium and is widespread m Baden-Württemberg (RiEGER & STRAUSS, 1992) and has been found in the Wollmatinger Ricd in the Landkreis Konstanz (Heckmann, 1999). Before Reeger (1997) the determination of the females was unsure and therefore the records of C. dubius Scop, in Frey-Gessner (1864-1866) were probably C. impressus as this is the more common species in Baden-Württemberg. 15. Sciocoris microphthalmia FLOR, 1860 (Fig. 3): This species is known from Ticino (Rampazzt & Dfthier, 1997) and Tyrol (Heiss, 1977); however, in Baden- Württemberg it is common (RfLGER, pers. comm) 16. Sciocoris macrocephalus Fieber, 1851 (Fig. 3): Reliable records exist only from Graubünden (Voellmy & Sauter, 1983), Neuchâtel (Barbalat, 1991), Ticino (Göllner-Scheiding & Rezbanyai-Reser. 1992) and Thurgau (Coll. Blociilinger, Miillheim). There are no checked records from Baden-Württemberg (RiEGER, 1996) and the Fürstentum Liechtenstein (Bernhardt, 1992), but the species is found frequently in Tyrol (Heiss, 1977). Reports also exist from Vaud, Wallis, Aargau, Zürich and Graubünden (Frey-Gessner, 1864-1866). However, if remains uncertain whether these reports differentiate between S. macrocephalus and S. microphlhahnus. 57

Fig 3 Sciocoiis maciocephalus Fieb (uppet pait) can be distinguished fiom Sciocons miciophthalmus rioi flowei pait) bv the smuated latcnil mai gins ol the head (auows) and by the longei eye stalks The body length is about 6 mm (Photos R ETcekinann and M Di Giuho)

Canton Luzei n -1 out inteiestmg species w ei e found m the Canton Luzern-

f Acalypla cannata (P \NZER, 1806) see discussion of Canton Schaff hausen

2 Hunaceius mcifoi (A COSTA, 1842). In Suitzciland theie aie only two lecoids of this species, fiom the Cantons Wallis and Basel A imfhei îecoid (Ptrtcart, 1987, Deihier & Ptrtcart, 1988) is attnbuted to a mistake of the name Kaiseistuhl The species was actually found m Baden-Wuittcmbcig (Kaiseistuhl in Baden) and not m the Canton Aaigau Several îecoids come fiom Baden-Wuittcmbeig along the Rhine Vallev (Heckmann 1996) and fiom the Landkreis Konstanz This is the fust tecoid foi Ccntial Switzeiland

s Pinalitus atomanus (Meyer-Dur, 1843) In Switzeiland this alpme-boieal species which lives on Picea is known fiom Bern, Basel and Aatgau (FrfY-Gessner, 1864 1866) and tcccntly fiom Ticino (RAMPA7ZI & DriHTFR, 1997) The distnbution in Badcn-Wuittembeig is îestiicted to the Black Foicst (Rieger & Strauss, 1992, Heckmann, 1996) and to the Suebian Alb (Rieger peis comm )

4 Pinalitus visicola (Puton, 1888) This species lives on Viscum album and has been lecoided m Switzeiland onl> m the Canton Wallis (Ceruttt, 1937b) In the Landkreis Konstanz, the distnbution conesponds with that of Viscum Its distnbution foi Baden- Win ttembei g has been desciibed m Heckmann & RiEGFR (in pi ep ) The spai se iecoids icflcct the dependence of the species on Viscum and the fact that its habitat mostly in the canopy, is îaicly sampled

Conci usions

The Red list of Badcn-Wuittembeig is veiy helpful m înteipieting the îaie species of Switzeiland Some \cio-theimophihc species iccoided moie oi less fiequently m the south of Baden-Wuittembcig especially m the valley ot the Rhine and Hegau also occui m the Canton Schaffhausen I he same species aie iccoided in the southern pait of Switzeiland and m the Cantons Basel and Aaigau, but not in the Inneischweiz and Mittelland These species which ate good candidates foi a Red list of Switzeiland

include Deuicocous mono BOEl em Burm Bervtmus Hallodapus infest , cuissipes II S Me\ -D Bentinus I ifb latus Doug & , Berytinus monlnaçus , signoreti , Dtymus Sc, Pentrechus giacihconus Pui Embletlus }eibasci F, Sciocons macrocephalus FrhB and Sciocons miciophthalmus FlOR Fiom oui findings m luzein Hunacerus majoi A C and Pinalitus \isicola PUT should be added to the list 58

Many species found in the ancient records of Meess (1900, 1907) and Frey- Gessner ( 1864-1866) appear to have decreased in abundance during the last century, eg Neides tipitlarius L., Aellopus atralus F.. Xanthochilus quadratus F., Sciocoris umb rinus WFF., Chlorochroa juniperina L. and Elasmucha ferrugata F. However, the sparse data available on the distribution of heteropteran bugs do not allow a thorough analysis of the situation in Switzerland, The data of Baden-Württemberg, however, support the conclusion that these species decreased in the last century (LIeckmann, 1996). We assume that this declines were a consequence of increasing intensification of agriculture production in both Germany and Switzerland.

Acknoledgments We thank B. Merz for general assistance, H. BLÖCEfLlNGER, Cil. RiEGER and S. Studer for permission to use unpublished data, to P.J. Edwards, Ch. Rieger and L. Reser for their critical reading of the manuscript, to A. Müller for the permission to use the material of the entomological collection of the Swiss Federal Institute of Technology (ETIIZ).

This work was funded by the Swiss National Science Foundation (5001-044634/1 and 5001-44636) and the Canton Schaffhausen (Kantonales Plantings- und Naturschutzamt).

Zusammenfassung

Im Schaffhausei Randen (Kanton Schaffhausen) wurden zwischen 1997 und 1999 drei verschiedene Wiesentypen untersucht. Dabei wurden drei verschiedene Sammelmethoden angewendet, nämlich Kescherfang, Bodenfallen und ein Sauggerät. Insgesamt wurden 45 Wiesen untersucht und 140 Wanzenarten gefunden. Auf dem Gemeindegebict Ruswil/Rutlisholz (Kanton Luzern) wurden 31 extensiv bewirtschaftete Wiesen untersucht und dabei 78 Arten festgestellt. In unseren Untersuchungen fanden wir 118 neue Arten fur den Kanton Schaffliauscn und 26 für den Kanton Luzern. Anhand der

Literatur und aufgrund eigener Funde stellten wir fur beide Kantone Artenlisten zusammen: Aus dem

Kanton Schaffhaiisen sind bisher 207 Wanzenarten bekannt, aus dem Kanton Luzern 20t Arten. Die Biogeographie ausgewählter Arten wird diskutiert.

Drei Arten aus dem Schaffhauser Randen sind Neunachweise für die Schweiz: Physatocheila harwoodi CHINA, 1936, Polymeius tniciophtlialmus (WAGNER, 1951) und Strongylocoris steganoides (.1. Sahlberg, 1875). Die bisherigen Funde von Strongylocoris leucocephalus sollten überarbeitet werden.

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Chapter 4. The influence of host plant diversity and food quality on larval survival of plant feeding heteropteran bugs (Heteroptera: Stenodemini)

Manuela Di Giuho & Peter J. Edwards

Abstract

In a laboratory experiment we investigated the influence of host plant diversity and food quality, m terms of nitrogen content, on larval survival of two plant feeding bug species (Heteroptera, Minclac: Leptopterna dolobrata L., Notostira erratica L.). of Both species are strictly phytophagous and capable of feeding on a wide range different grass species, but are normally found on only a few ones. They typically change their host plants during ontogenesis and it has been suggested that this represents a response to the changing protein content of the hosts. We compared the development of animals reared on grass monocultures with that when they were reared on mixtures o\ four species. In addition the host grasses were grown under two different nitrogen regimes to test whether nitrogen content is the key factor determmtng host plant switching.

Both species had a significantly higher survival rate when feeding on several host plants, but only L. dolobrata showed a significant response to food nitrogen content. Furthermore, there was no correlation between the nitrogen content of the host plants and the survival rate of N. erratica larvae. Moreover, there is strong evidence that our results cannot be explained by a sampling effect, in which the mixtures have a better chance than the monocultures of containing a good food plant. Our results suggest that the level of host plant nitrogen is not the main factor responsible for the diversity effect and that at least some Stenodemini need a variety of host plants during larval development. In a field survey we found a positive correlation between the number of Stenodemini species and the number of grasses, indicating that diverse meadows can support more grass bug species. Our study indicates that plant diversity can enhance insect diversity by increasing the larval survival of phytophagous insects.

Key-words: food quality, herbtvory. Heteroptera, host plant diversity, insect diversity

Introduction

Herbivory presents major difficulties to insects, partly because the chemical composition of their tissues are very different from those of plants. In particular, the protein content of insects is much higher than that of plants and the proportions of the various ammo acids differ between animal and plant proteins (Southwood 1973; Mattson 1980; White 1993). Various studies show that nitrogen content can be a crucial factor for the development and repioduction ol heibivores (Strong, Lawton and Southwood 1984). In addition, the allocation of nutrients to structures like stems, fruits and flowers changes considerably both seasonally and during the course of plant development. Thus, the protein content of plants is not only generally low but also varies during the season. Ohgophagous and polyphagous insects may respond to changes m nutrient availability by switching from a plant with a low protein level to one with a higher protein concentration (McNeill and Southwood 1978).

The Stenodemini (Heteroptera: Miridae) are strictly phytophagous and capable of feeding on a wide range ol different grass species, but are normally found on a restricted 63

set of species. They change their host plants during ontogenesis and it has been suggested that this represents a response to the changing protein content of their hosts (Braune 1971; McNeill 1971,1973; Gibson 1976, 1980). However, there are other possible advantages of changing host plant. Gibson (1976) has observed that Leplopterna dolobrata L. and Stenodema laevigatum L. switch to unusual host plants in not been affected a year of extreme drought, and in particular to grass species that have by the drought. This suggests that host plant change may also compensate for unfavourable climatic conditions. Indeed, the species richness of a pfant community insects which can may be an important factor affecting the performance of plant feeding switch their host plants in this way.

Although, the relationship between species richness of insects and plants has been investigated in several studies, the results are contradictory and the underlying mechanisms are not yet entirely understood (Strong, Lawton and Southwood 1984). In how recent years several diversity experiments have been designed to investigate species diversity influences ecosystem function, but the conclusion remain controversial and insects have rarely been included in these experiments (Huston 1997; Hector and al. 1999). Our study investigates the effect of plant diversity on the development and larval survival of phytophagous bug species and contributes to the debate about the role of species diversity in ecosystems. In a laboratory experiment we examine how host plant species diversity affects the growth and survival rate of Stenodemini. We compare the larval survival of insects reared on grass monocultures with that of insects reared on mixtures of four species. To test whether total nitrogen content is the key factor responsible for host plant switching, the plants have been cultivated under two different nitrogen regimes. It is known that total nitrogen content of grasses tends to increase with nitrogen fertilisation, though the reaction of individual grass species is variable (Meister and Lehmann 1990). The experiment was conducted with the Stenodemini species L. dolobrata and Notostira erratica L. which are common in Swiss meadows. The two species have different feeding habits; N. erratica feeds only on leaves, whereas L. dolobrata is both leaf and seed feeding. They can easily be found in a sufficiently high number for laboratory experiments and they both have been reared successfully in the laboratory (Braune 1971, 1983; Dolling 1973). If grass diversity increases the survival rate of Stenodemini then wc might expect diverse meadows with several grass species to support a higher number of Stenodemini than species-poor meadows. We test this hypothesis with data from a field survey carried out in the north of Switzerland (Canton Schaffhausen, Switzerland) in which the bug fauna and the plant species of 24 meadows of two different management types were recorded.

Material and Methods

Field survey

In summer 1997 we investigated 24 meadows representing two administratively recognised grassland management types - medium intensive (regular use of slurry; 2-3 cuts per year) and extensive (no fertiliser; one or two cuts per year). Twelve replicate sites of each management type were selected. A description of the research area and a detailed analysis of the effect of management on species diversity are presented in a separate paper (Di Giulio, m preparation). The plant species composition was assessed using six quadrats of one square meter per site. The extensive meadows were dominated by Bromus erectus, while the medium intensive sites were dominated by Arrhenatherum elatius and Trisetum flavescens (Studer 2000). 64

The heteropteran bugs were sampled using a standardised sweep-net method (Remane 1958; Born hol dt 1991; Otto 1996). The sweep-net had a diameter of 40 cm with the and samples were collected every two weeks by making one hundred sweeps the weather net over a distance of about 100 m. Sampling was only carried out when also conditions were good, îe a minimum of J7°C and sunshine. Sampling was restricted to the period between 10.00 a.m. and 17.30 p.m.; the sampling order of the from fields was varied between weeks. Every site was sampled between 7 and 9 times May to September.

Experimental design

The aim of the experiment was to investigate the effect of plant species diversity number of se upon larval survival. The important variable was therefore the species per rather than which species were present in the mixture; replicates were therefore represented by several different combinations of the same number of species (Tilman et al. 1996). Total nitrogen content was included in the experimental design as a second factor m order to separate the nitrogen effect from the diversity effect (Huston 1997). We chose a fully factorial design with the two factors: plant diversity and nitrogen content. Both factors had two levels; thus insects were offered either one or four plant species which had been raised on either high or low nitrogen. For each treatment there to the were five replicates. The low nitrogen level was selected to correspond about typical nutrient input in an extensive meadow (with no fertiliser input), and the high level to one of a medium intensive meadow (40-60 mJ slurry per ha and year). The species in both the monocultures and the mixtures were chosen randomly out of a host species pool comprising eight grass species which were cited in the literature as the plants and were very common in the study area (Table 1). To compare single monocultures with the mixtures and to exclude the sampling effect (Wardle 1999) we also examined the three monocultures which were not m the sampling design (P. trivialis, F. ovina and F. pratensis). These treatments could only be carried out with N. erratica as we had not enough larvae of L. dolobrata. The insects were reared on high nitrogen treatment plants. 65

Table L The table shows the full list of the grass species selected for the experiment and the randomly chosen monocultures (column: Mono) and mixtures. All species are quoted in the literature as host plants of N. erratica and L. dolobrata.

Species Mono Mixtures References

I 2 3 4 5

Arrhcnateritm clatius X X x X X Kullenberg 1944; Gibson i976

Dactylis glotnerata X X x Osborn 1918; Kullenberg 1944; Southwood & Leston 1959; Braune 1971; Gibson 1976

Festuca ovin a x X Osborn 1918; Kullenberg 1944; Gibson 1976

Festuca pratensis X X Kullenberg 1944; Osborn 1918; Gibson 1976

1976 Holen s lanaliis X X X Kullenberg 1944; Braune 1971; Gibson

Loliiini perenne X X X X x Kullenberg 1944

Leston 1959 Phleuin praten sc X X x Kullenberg 1944; Southwood &

Poa trivialis X x ' Kullenberg L944

Cultivation and chemical analysis of'the food plants

The grass seeds were of local provenance and had been provided by the Swiss Federal Research Station of Agroccology and Agriculture. The cultivation method is a standardised procedure used at the research station to study the effects of different nutrient inputs on the growth and development of various grass and leguminous species (U. Walthcr, pers. comm.). The plants were grown out-of-doors under a mobile roof. They were uncovered in dry weather but remained covered when it was raining so that rainfall and nutrient input could be controlled, while temperature, humidity and light regime corresponded closely to natural conditions. Each species was cultivated separately in double-walled pots of 23.5 cm diameter which were filled with 9 kg of loamy soil. The soil was fertilised with 6 g KMFPOa before sowing. The nitrogen fertiliser was prepared as a solution (2,5 g F1 of CaNcGô x 4LI20), and 100 ml was added to a pot at any one time. The pots were regularly watered and the surplus water drained through the pots and was collected in separate containers, from where it was refilled into the pots so that no nutrients were washed out. The grasses grown at a low nitrogen level were fertilised only once, ten weeks after germination. The pots of the high nitrogen treatment were fertilised monthly and thus received five times as much nitrogen over the whole experimental period. The food grasses were cultivated from the end of March to the end of August. Food plants for both bug species came from the same batches of material over the whole experimental period.

The total nitrogen content of the plant material was determined by a modification of the Kjeldahl method (Novozarasky et al. 1983; Houba et al. 1989). Plant material for these analyses was collected every two to three weeks from the beginning of May to Mid August.

Rearing of the insects

The insect rearing cages, made from acrylic plexiglass, measured 25x25 cm and had a circular opening in the front with a gauze tube for handling the insects. Each cage was equipped with a small pot for the food plants and a water dispenser which was filled daily. Freshly cut grass leaves and stems served as food and were provided every second day. We fed only stems and leaves to both bug species, although under natural conditions L. dolobrata feeds on leaves, flowers and seeds. To provide food in equal 66

quantities all animals were fed a total of eight stems and leaves. For the mixtures we combined two stems of each grass species. The specimens were reared under a constant photoperiod of 16 h light/8 h dark at a constant temperature of 20°C. The humidity in the climate chamber varied between 60 and 90 %, but it was lower in the cages. Low humidity in climate chambers can be responsible for a high mortality at moult when rearing nymphs of L. dolobrata m the laboratory (McNeill 1973). We therefore sprayed water into the cages daily m order to increase the humidity, though this did not completely prevent larval death. Every day dead individuals were removed and the number and larval stage of the larvae determined. The adult insects were killed the day after the final moult.

The experimental material for L. dolobrata comprised first instar larvae which were collected m the field at the beginning of June from three populations in the Safienial (Canton Graubiinden, Switzerland). In each cage we put eight larvae. The state of development of the larvae was recorded daily. The duration from moult to moult and the total duration (20-22 d) corresponded closely with the values given by McNeill (1971).

Larvae of N. erratica were reared from adult females which were collected at the beginning of July in the Schaffhauser Randen m the North of Switzerland. These females were kept in the climate chamber and pro\ided with freshly cut grass material. In the first few days we observed several females laying eggs on the upper part of the stems. The stems were replaced every second day and those with eggs were placed on humid tissues and kept in transparent plastic boxes in the climate chamber. After about 12 to 14 days the first larvae hatched and they were immediately placed in the cages (20 per cage). The first adult males hatched after about 22 days and the first females after 25 days; after 35 days all insects had hatched.

Statislical analysis

Least squares regression was conducted to analyse the influence of food species diversity on the species number of Stenodemini. We used one-way ANOVA to test how nitrogen fertilisation affected the total nitrogen content of the grasses during the season. Two-way ANOVA was conducted to analyse the influence of crude prolem content and host plant diversity on larval survival of A. erratica and L. dolobrata. As a measure for larval survival we calculated the proportion of the larvae which emerged as adults. Larvae killed during handling (in total 12 out of 620 individuals) were subtracted from the total number of larvae put info the cages at the beginning. We tested two models for the N. erratica data. The first model comprised all monocultures tested, while the second one included just the five monocultures actually used in the experimental design. We also tested two models for the data of L dolobrata. The first model included only fully hatched adults. In the second one we also included insects which had died during the final moult, because the total number used was rather small and the mortality high at the final moult.

Results

Influence of grass diversity on the species number of Stenodemini

The number of grass species in the field samples ranged from 6 to 13, while the number of Stenodemini species sampled per site ranged from 2 to 4. Despite the small numbers of bug species the species number of Stenodemini increased significantly (P < 0.05) with the number of grass species (Fig. 1, Table 2). 67

Table 2. Regression model of the influence of grass species number on the species number of Stenodemini. The

values were In-transformed before the anahsis

REGRESSION MODE1 Variable SE p(0

R2 = 0.162 Constant -0 088 0 535 -1.64 0 87

Grass species number 0 554 0.242 2.291 0 03

-a 4 o c £

3 Î5

^ ZJ

en CD

° 1 ' CD Q. 00 6 7 8 9 10 11 12 13 14

Species number of grasses

with the Fig.l The species number of Stenodemini correlates positively a different species number of glasses (P < 0 05). Each point is lor grassland site and is based on 6 Ixf m? quadrats for the grass species and the recorded data for the buss.

Food quality

In the experiment the use of nitrogen fertiliser increased the nitrogen content of the

= there were also grasses significantly (ANOVA: Fi,7s 24.89, P < 0.00001) and differences in the temporal variation in nitrogen content between the two nitrogen treatments (Fig. 2). There was much more variation in nitrogen content between species in the low nitrogen plants than m the high nitrogen treatment. However, in the high nitrogen plants nitrogen content dropped sharply between June and July in all species. The two bug species used in the experiment do not develop at the same time of year and therefore they experienced differing nitrogen levels. L. dolobrata was reared in May and June, while N. erratica developed m Jul)' and August. During May and June the nitrogen content was on average higher and varied more than m July and August; food quality for L. dolobrata was therefore better but varied more than for N. erratica (Fig. 2). 68

jC CD 40 "(1)

T3 30 CD high nitrogen input c 8,20 o

.05. 20.5. 14.6. 27.7. 12.8.

CD * 40 "CD

CD 10

4.05. 20.5. 14.6, 27.7. 12.3.

Date

• A. elatius D. glomerata F. ovina F. pratensis H. lanatus L. perenne P. trivialis Ph. pratense

Fig. 2. The development of the nitrogen content is shown ovei the expeinnental period. The grasses with high nitrogen input (uppei part) were teitthscd legularly, while the ones with low nitrogen input (lower part) weie feitihsed once in Ma\ (see text loi specification). The grey boxes show appioxtmately the period during which the two bug species developed. The dark grey box indicates the development time of L. dololvata. the light grey box the one of N. erratica. The piotcm level was high, but \anecl strongly in late spimg when L. dolobrata developed (May/June), while it was low and \aned less in summer, when N. erratica developed (July/August).

Influence of host plant diversity and food quality on larval survival ofL. dolobrata

Host plant diversity (Pi l6 = 22.86. P < 0.001) and food qualify (Model I: PL16 = 13.91, P < 0.002) drastically increased larval survival of L. dolobrata (Fig. 3, Table 3). Moreover, there was a significant interaction between the two factors (Model I: Fus = 13.91, P < 0.002). Both the effect of nitrogen level and the interaction term tended to 69

increase the larval survival when excluding the insects which died at the final moult (Model II: P1J6 = 0,059, P = 0.066).

Table 3. Two-way ANOVA of the influence of nitrogen level and diversity on the survival of I. dolobrata. In Model I all adults were included which reached the adult stage, while in Model II insects which died at the final moult were excluded (specifications see text). The proportion of

hatched adults was taken as a measure for larval survival. The values were arcsine (square)- transformed for the analysis.

Modt;1I Model 11

Source of variation d.f. MS F-ratio p-value d.f. MS F-ratio p-valuc

N-Level 1 0.125 13.91 0,002 1 0.059 3.91 0.066 Diversity I 0.206 22.86 0.0002 1 0.117 7.8 0.013

Interaction term I 0.125 13.91 0.002 t 0.059 3.91 0.066 Residual 16 0.009 16 0.015

Total 19 0.025 19 0.013

0.5 r

w 0.4

TJ CO ~a 0.3 CD

o 05 0.2

O 0.1 .2

o Q. O 0.0 v., Q_ monoculture -0.1 low high mixture N-level

Fig. 3. Interaction plot of the two-way ANOVA of the effect of food quality and plant diversity on larval sun ival of L. dolobrata. For this analysis the insects which died at the final moult were included (Model I). The nitrogen level represents the two nitrogen regimes high and low fertiliser input. Mean

values of the two treatments are shown.

No larvae of L. dolobrata survived on monocultures on either the low or high nitrogen plants, whereas survival on mixtures ranged from 0 to 75% (Fig. 4). Larval survival on mixtures of high nitrogen plants ranged from 12.5 to 75%, while that on mixtures of low nitrogen plants ranged from 0 to 25%. There was a significant interaction between nitrogen level and plant species number. 70

1.0

0.8

T3 CO

"O CD 0.6 SI O 03 0.4 Ci

2 "c o 0.2 Q. 1 case O 1. Q. id CclSGS 0.0 4 cases

1 4 10 cases

Number of plant species

Fig. 4. The larval survival of L. dolobrata increased with the species number of host plants. Larval survival of insects reared on monocultures was compared to that of insects reared on mixtures of four species. The dots indicate the replicates of different species combinations at each level of species richness. The size of the dots represents the number of cases.

Larval mortality of insects reared on monocultures differed from that of insects reared on mixtures (Fig. 5). The majority of animals reared on monocultures died before they had reached the fifth larval stage, while insects reared on mixtures showed not only lower mortality overall but a more equally distributed mortality between the larval stages.

\zzz3 Mixtures

— Monocultures

2 3 4 5

Larval stage

Fig. 5. 'The frequency distribution shows the mortality of L. dolobrata during larval development. Insects reared on monocultures died earlier than those reared on mixtures of four species.

Influence of host plant diversity andfood quality on larval survival qf'N. erratica Table 4 and Fig. 6 indicate that host plant diversity increased the survival rate of N. erratica very greatly (Fp16 = 22.66, P < 0.001), while food quality had no effect (PU6 71

= 0.21, P = 0.65). There was no interaction between food quality and diversity (PU6

0.27, P = 0.61). The same effects were found when including all monocultures into the model (diversity: FU6 = 16.28, P < 0.001; nitrogen level: FU6 = 0.55, P = 0.47; interaction term: P].i6 = 0.63, P = 0.44).

Table 4. Two-way ANOVA of the influence of nitrogen level and diversity on the survival of N. erratica. The design was fully factorial, with five monocultures and five mixtures for both nitrogen levels. The proportion of hatched adults was taken

as a measure for larval survival. The values were arcsme (square)-transformed for the analysis.

Source of variation d.f. MS F-ratio p-value

N-EEVEL 1 0.007 0,21 0.65 Diversity I 0.748 22.66 0 0002 interaction term 1 0.009 0.27 0 61 Residual 16 0.033

Total 19 0.042

I.U

0.9 tn .+_* U 0 8 "O CO

T5 0.7 CD SZ o OR CO sz 0.5 o c 0.4 o r o O.M CI. o

CL U.2 monoculture 0.1 low high mixture

N-level

Fig. 6. Interaction plot of the two-way ANOVA of the effect of food quality and plant diversity on larval sur\i\al of As eriatica. For this analysis the fully factorial design was chosen with li\e monocultures and five mixtures for both nitrogen levels, The nitrogen level represents the two nitrogen regimes high and low fertiliser input. Mean values of the two treatments are shown.

On monocultures survival ranged from 0 to 88%, while on mixtures it ranged from 50 to 100% (Fig. 7). On four monocultures survival was higher than on mixtures; these were the monocultures of P. ovina (88%,), F. pratensis (82%) and L. perenne (67 and 71%)). One or more of these grass species were also included in the mixtures with the lowest survival rates, which ranged from 50 to 82%. The monoculture with the highest survival rate (P. ovina: 88%) was also included in the mixtures with the two lowest survival rates (50 and 67%). 72

1 case

9 2 cases

• 1 4 5 cases

Number of plant species

Fig. 7 .The larval survival of N. erratica increased with the species number of the host plants. Larval survival of insects reared on monocultures was compared to that of insects reared on mixtures of four species. All monocultures tested in the experiment are included in this analysis, that are five monocultures of low nitrogen plants and eight of high nitrogen plants. The dots indicate the replicates of different species combinations ai each level of species richness. The size of the dots represents the number of cases.

Larval mortality occurred mainly in the first and second larval stage and was much higher for insects reared on monocultures than for insects reared on mixtures (Fig. 8).

90 r

>, 60 o I 5° °" 40 ^ 30 - i~n Mixtures

«a Monocultures 20

0 _ 2 3 4 5

Larval stage

Fig. 8. The frequency distribution shows the mortality of A', erratica during larval development. The larval mortality of insects reared on monocultures was very high m the first and second larval stage, but stayed low in the later stages. The mortality of larvae reared on mixtures was generally low. For this analysis the fully factorial design was chosen with five monocultures and five mixtures. 73

The mean nitrogen content was calculated as the average nitrogen content of plant material collected at the beginning of the experiment (27.7.) and after two weeks (12.8.). There was no significant correlation between the larval survival of TV. erratica

= = All and the mean nitrogen content of the food plants (Fig. 9; t <; -0.88, P 0 41). monocultures of the high nitrogen treatment were included in this analysis.

175

§155-

0.00 0.25 0.50 0.75 1.00

Proportion of hatched adults

Fig. 9 Lai val suivival of \ cuatiea was not con elated with the mean nitrogen content of the food plants To calculate the mean nitiogen content, we used plant matenal collected at two diffeient dates (27 7 and 12 8) That was at the beginning of the evpeitmenf and aftei two weeks Foi this analysis we included all eight monocultuics of the high nitiogen tiealmcnt

Discussion

Both Stenodemini species have a significantly higher survival rate when feeding on several host plants, but only m the case of L. dolobrata is there evidence that survival is affected by nitrogen content (Figs 3, 4, 6, 7 and 9, Tables 3 and 4). These results suggest that neither variation nor level oi host plant nitrogen is the main factor responsible for the observed host plant changes as has been hypothesised (Gibson 1976. 1980; McNeill 1971, 1973), We suggest that other factors may also be responsible for the positive effect of host plant diversity on the survival of the two bug species. Previous studies indicate that insects respond to several components of the diet and not only to total nitrogen content. Other important 1 actors can be the form and availability of nitrogen, the balance of ammo acids, the water content of the host and the content of minerals and trace elements. Furthermore, secondary compounds and mechanical or chemical plant defences may also pla\ an important role (McNeill and Southwood 1978; Strong, Lawton and Southwood 1984). N. erratica larvae reared on monocultures showed the highest mortality in the first larval stage, while it was much lower later m development (Fig. 8). Mortality of insects reared 011 monocultures of A. elatius (100%), IL lanatus (100%) and D glome rata (77.5%) was extremely high, although these plants are usual hosts of older larvae and adults. The fust instar larvae died very soon after they were put into the cages, indicating that they could not feed on these grasses and starved. We suggest that chemical or mechanical plant defences may have prevented the young larvae from feeding on these plants. How ever, larvae reared on mixtures could avoid the negative effects ol the plants by choosing between various species and 74

therefore had a better chance of survival. Our findings are supported by Gibson (1976) who observed that certain grass species are avoided particularly by very young Stenodemini larvae. Larval mortality of L. dolobrata showed a different pattern (Fig. 5). The majority of larvae reared on monocultures died between the second and fourth larval stage while, when reared on mixtures, larval mortality was more evenly distributed over development time. This indicates that the second to the fourth larval instar are sensitive stages, during food quality and a variety of host plants play an important role. A problem inherent in all diversity experiments is the so-called sampling effect; in this experiment a positive effect of mixtures could result simply because there is a higher probability that mixtures of several species contain a good quality plant, in terms results of a high nitrogen content, than monocultures (Huston 1997). However, the indicate that the diversity effect cannot entirely be explained in this way. No larvae of L.

dolobrata survived on monocultures, while most of the larvae reared on mixtures of high nitrogen plants did reach the adult stage (Fig. 4). The effect is less clear for N. erratica, though in most cases survival on mixtures was greater than on any of the monocultures (Fig. 7). However, the values of the four mixtures lie below those of the best monocultures, indicating that some monocultures are better than some mixtures. It in the is interesting that the grass species of the best four monocultures are also included mixtures with the lowest survival rates, indicating that larval survival on mixtures is not determined by the best plant species in the mixture. The benefit of the mixtures therefore results from the various plant species in the mixture and not exclusively from the best species.

The nitrogen content of the grasses drops towards mid-summer and remains low until autumn (Fig. 2), trends winch occur in natural populations of grasses (Gibson 1980). Bug species which develop m spring therefore have generally better food than those emerging in summer or autumn (Gibson 1976), which is also the case for the two species used m the experiment. The food plants of N. erratica had much lower nitrogen contents than those of P. dolobrata (Fig. 2). In fact, N. erratica can produce two generations per year. The first generation develops during spring while the second one emerges in late summer, indicating that this species can cope with a wide range of nitrogen levels (Gibson 1976). Further, Gibson (1980) showed that TV. erratica does not fully exploit the nitrogen available in a sward and apparently does not select within a sward for plants with an above average nitrogen content. Our results support these findings. Larval survival of TV. erratica seems not to be affected by the nitrogen treatment and the nitrogen content of the host plants (Table 4, Figs 6 and 9). L. dolobrata. however, does seem to need both host plant diversity and good food quality (Table 3, Figs 3 and 4), Our observation that this species only occurs in diverse but not excessively nutrient-poor meadows supports these findings. Several studies show that L. dolobrata has a high nitrogen demand during its development. McNeill (1971, 1973) demonstrates that it changes from leaf to seed feeding at a time when protein content of the leaves drops drastically and plant nutrients are increasingly allocated to the development of stems and seeds. Furthermore, it fully exploits the available nitrogen in a sward by feeding on hosts with an above-average nitrogen content (Gibson 1980). Some noticeable features of its hfe-history may be responsible for this high nitrogen demand. Under natural conditions this species develops and reproduces within a period of about two and a half months (Braune 1971; McNeill 197L, 1973). Two morphological forms of females occur in this species: the brachypterous or short winged morphs produce many more eggs than the long winged macropterous morphs which 75

have a dispersal function. Because of their high egg production the brachypterous female morphs need a higher amount of nitrogen and, indeed, nitrogen seems to be the crucial factor for the trade-off between dispersal and reproduction. A shortage of nutrient rich seeds and flowers induces the development of macropterous females. These disperse but postpone the development of eggs and produce on average fewer offspring (Osborn 1918; Braune 1983). To summarise, the experiments show that at least some Stenodemini species arc The dependent on a variety of host plants for their larval development and survival. nitrogen content of the host plants appears not to be the crucial factor for host plant switching during ontogenesis. The survey study supports these results (Fig. I, Table 2), indicating that there is a positive correlation between the numbers of grass and Stenodemini species. Species rich meadows therefore may support more Stenodemini species by offering better conditions for larval development.

Acknowledgements

We thank Josef Lehmann, Andreas Rtiegger and Hansueli Briner for the grass seeds, Josef Lehmann, Ueli Walther, Ernst Brack and Robert Richli for their assistance and tips on cultivating the food grasses and Stefan Bosshard for his help at rearing the bugs in the climate chamber. We are grateful to Sibylle Studer for permission to use unpublished data, to Franz Schubiger and the technical staff of the Swiss Federal Research Station for Agroeeology and Agriculture for the chemical analysis of the plant material, to Josef Lehmann and Walter Dietl for their comments on the reaction of

grasses to fertilisation and to Bernhard Mer/, Sibylle Studer and Erhard Meister for their critical reading of the manuscript. Finally, we thank Bernhard Schmid for his assistance with the experimental design.

This work was funded by the Swiss National Science Foundation (5001-044634/L) and the Canton Schaffhausen (Kantonales Plantings- und Naturschutzamt).

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Conclusions

Grassland management affects both species richness and species composition of

insect communities. Extensive meadows arc more diverse than medium intensive

meadows; they contain a number of rare and specialised insect species while the medium intensive sites are characterised by common and widespread bug species. Our study supports the findings of previous studies and further indicates that even a slight intensification of management reduces bug species diversity in grasslands (Chapter I). The extensive meadows of the Schaffhauser Randen are particularly valuable habitats for some rare xcro-thermophilic bug species The climatic and soil conditions m this region apparently favour these species and have also limited the intensification of agricultural production. This is also the reason why many species of other taxa (eg butterflies and flowering plants) persist m this area but have disappeared from other regions of Switzerland. As few data are available on the distribution of individual bug species m Switzerland, we cannot say how the heteropteran fauna changed m the last decades, but we think that the situation is similar to that for other taxa (Chapter I & 3). The bug fauna vanes both within and between grassland management types. The extensive sites arc specially variable m species nchness and composition. These lmdmgs suggest that apart fiom management, lactois like structure of the surrounding landscape, aspect and location strongly influence the communities. The medium intensive meadows, however, show only little variation, indicating that management is the most impoitant factor determining the heteropteran fauna of these sites (Chapter I).

We found no correlation between the species numbers of bugs and plants at a site (Chapter 1). However, the number of ohgophagous bug species (eg Stenodemini) increases significantly with the species number of their host plants, suggesting one reason why flonstically diverse meadows can support more herbivorous insect species. Previous studies have shown that Stenodemini change their host plants during ontogenesis and it has been suggested that this repiesents a response to the changing piotcm content of the hosts. In a laboratoiv expenment we examined how host plant diversity and food quality affect larval survival. The results suggest that host plant diversity significantly increases the larval survival but that the crude protein content is not the mam factor responsible for this effect. At least some herbivorous bugs seem to depend on a variety of host plants for their development, and there is evidence that plant diversity can increase insect diversity by enhancing the larval performance (Chapter 4). In contrast to the flowering plants and the butterfly fauna, the heteropteran communities differ greatly between the four areas investigated (Chapter 1 & 2). Many bug species occui only m one or two areas and seem to have restricted ranges, suggesting that their distribution is limited bv then dispersal abilities. Fragmentation of the habitat therefore represents a major problem for their populations. In general plant and butterfly species associated with grassland seem to have colonised the areas more equally, perhaps because they aie less limited by dispersal. We had expected insect diversity to be greater in the area containing only grasslands (Zelgli/Mösli) than in areas with a mixture of grassland and arable land habitats. Interestingly this was not the case, and there is even an indication that species richness is greater in areas of mixed land because these use, perhaps areas are more heterogenous and present a wider range of niches We found several bug species which occur only m areas of mixed land use and tor some common species we could show that then abundance increases significantly with the proportion of arable land in the surrounding landscape (Chapter 2). Another reason for the difference may be that the grassland area is dominated by extensively 78

managed meadows. According to the regulations for subsidies, extensive meadows are not to be cut before the first of July. Most farmers therefore cut the meadows as soon as both the weather conditions and regulations allow, and most sites are cut almost simultaneously. Moreover, the machinery used makes the cutting very fast and many insect, particularly species and stages with very limited mobility have no chance to escape to alternative habitats. A rotational management of grasslands is therefore recommended to enhance insect diversity at a landscape level. 79

Curriculum vitae

Name Di Giuho Müller

Vorname Manuela

Geburtsdatum 17. Juli 1970

S t aats an geh öri gkei t Italien, Schweiz Bürgerort Bettlach (SO)

Matura Wirtschaftsgymnasium in Solothurn Mafuritätsabschluss; September 1989

Studium Studium der Zoologie und der Umweltwissenschaften an der Univer¬ sität Zürich, 1990-1996

Abschluss 1996 am Institut für Umweltwissenschaften und am Zoo¬ logischen Museum der Universität Zürich Diplomarbeit: Die phytophage Insektengemeinschaft des Teufelsab- biss (Succisa pratensis)

Dissertation Dissertation am Geobotani sehen Institut der ETHZ und der Eidg. Forschungsanstalt für Agraröko logic und Landbau (FAL), 1997-2000 Insect diversity in agricultural grasslands: The effects of management and landscape structure Leitung: Prof. P.J. Edwards

Aktuelle Anstellunt Wissenschaftliche Mitarbeiterin ETHZ