35392 Gießen ·FrankfurterStr V e-mail: [email protected] ·Homepage: http://www erlag: Deutsche V eterinärmedizinische GesellschaftService GmbH ISBN 978-3-939902-34-8 . 89·T el. 0641/24466 ·Fax:0641/25375 .dvg.net

Determinants of the diversity of intestinal parasite communities in sympatric New World primates Britta Müller ( S a g u i n u s m y s t a x , S a g u i n u s f u s c i c o l l i s , C a l l i c e b u s c u p r e u s ) Hannover 2007 Deter (Saguinus mystax,S minants ofthediversityintestinalparasitecommunities in sympatricN aguinus fuscicollis,Callicebuscupr B ritta Müller ew W orld primates eus)

Bibliografische Informationen der Deutschen Bibliothek

Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; Detaillierte bibliografische Daten sind im Internet über http://dnb.ddb.de abrufbar.

1. Auflage 2007

© 2007 by Verlag: Deutsche Veterinärmedizinische Gesellschaft Service GmbH, Gießen Printed in Germany

ISBN 978-3-939902-34-8

Verlag: DVG Service GmbH Frankfurter Straße 89 35392 Gießen 0641/24466 [email protected] www.dvg.net

Aus dem Deutschen Primatenzentrum Göttingen ______

Determinants of the diversity of intestinal parasite communities in sympatric New World primates (Saguinus mystax, Saguinus fuscicollis, Callicebus cupreus)

I N A U G U R A L – D I S S E R T A T I O N zur Erlangung des Grades einer Doktorin der Veterinärmedizin (Dr. med. vet.) durch die Tierärztliche Hochschule Hannover

vorgelegt von Britta Müller aus Münster

Hannover 2007

Wissenschaftliche Betreuung: Univ. Prof. Dr. F.- J. Kaup PD Dr. E. W. Heymann

1. Gutachter: Univ. Prof. Dr. F.- J. Kaup 2. Gutachterin: Univ. Prof. Dr. E. Zimmermann

Tag der mündlichen Prüfung: 05.06.2007

Diese Promotionssarbeit wurde finanziell gefördert vom Deutschen Akademischen Austauschdienst (DAAD) und der Deutschen Forschungsgemeinschaft (DFG) (HE 1870/13-[1-3]).

Meiner Familie

TABLE OF CONTENTS

1 INTRODUCTION...... 1 2 LITERATURE REVIEW ...... 3 2.1 Parasite diversity and correlates with host ecology...... 3 2.1.1 Host-intrinsic factors...... 8 2.1.1.1 Body size...... 8 2.1.1.2 Sex...... 8 2.1.1.3 Age and longevity ...... 9 2.1.1.4 Dominance rank and social status ...... 10 2.1.1.5 Reproductive status...... 10 2.1.1.6 Group size and host density ...... 11 2.1.1.7 Social and mating system ...... 11 2.1.1.8 Strata use...... 12 2.1.1.9 Diet...... 12 2.1.1.10 Nutritional status ...... 13 2.1.1.11 Home-range size and geographic distribution ...... 14 2.1.2 Host-extrinsic or habitat factors ...... 15 2.1.2.1 Temperature and humidity ...... 15 2.1.2.2 Solar radiation...... 15 2.1.2.3 Soil type...... 16 2.1.2.4 Water bodies...... 16 2.1.2.5 Habitat morphology...... 17 2.1.2.6 Resources for intermediate hosts and vectors...... 17 2.1.2.7 Vegetation type and density...... 18 2.1.2.8 Predation...... 18 2.1.3 Seasonality ...... 18 2.2 Intestinal parasite diversity in New World primates ...... 19 2.2.1 Intestinal protozoa ...... 19 2.2.2 Intestinal helminths ...... 21 2.2.2.1 Trematoda...... 21 2.2.2.2 Cestoda...... 21 2.2.2.3 Nematoda ...... 22 2.2.2.4 Acanthocephala ...... 22 2.3 Study host species ...... 23

2.3.1 Saguinus mystax and Saguinus fuscicollis ...... 23 2.3.2 Callicebus cupreus ...... 24 2.4 Bias in parasitological studies ...... 27 2.4.1 Selection bias...... 27 2.4.2 Information bias...... 27 2.4.3 Confounding bias...... 28 2.5 Objectives of this study...... 28 3 , MATERIALS AND METHODS ...... 33 3.1 Study site...... 33 3.2 Study animals ...... 33 3.3 Study period...... 35 3.4 Parasitological analyses...... 36 3.4.1 Faecal sample collection and preservation...... 36 3.4.2 Sedimentation procedure...... 38 3.4.3 Microscopic examination...... 38 3.4.4 Intra-observer reliability test...... 39 3.4.5 Qualitative and quantitative description of parasite diversity ...... 39 3.4.5.1 Parasite identification...... 39 3.4.5.2 Parasite species richness (PSR) ...... 41 3.4.5.3 Prevalence ...... 41 3.4.5.4 Egg or larvae output...... 41 3.5 Behavioural observations...... 42 3.6 Post-mortem examination...... 44 3.7 Habitat characterization...... 45 3.7.1 Drainage ...... 46 3.7.2 Soil type...... 47 3.7.3 Ground inclination...... 47 3.7.4 Height of leaf litter...... 47 3.7.5 Deadwood abundance...... 48 3.7.6 Vegetation density...... 48 3.7.7 Understorey density...... 49 3.8 Climate ...... 49 3.9 Phenology...... 50 3.10 Statistical analyses ...... 50 3.10.1 Parasite morphology...... 51

3.10.2 PSR and prevalence...... 51 3.10.3 Egg/larvae output...... 53 3.10.4 Behavioural observations and phenology...... 54 4 RESULTS ...... 55 4.1 Parasite diversity...... 55 4.1.1 Helminths...... 55 4.1.2 Protozoa ...... 61 4.2 Parasite ecology ...... 61 4.3 Variation in parasite species richness (PSR) and prevalence...... 63 4.3.1 Host-intrinsic factors...... 64 4.3.1.1 Host species ...... 64 4.3.1.2 Host sex...... 67 4.3.1.3 Strata use...... 70 4.3.1.4 Diet composition...... 72 4.3.1.5 Home-range size...... 76 4.3.1.6 Group size...... 77 4.3.1.7 Host density...... 78 4.3.2 Host-extrinsic or habitat factors ...... 79 4.3.2.1 Home ranges ...... 79 4.3.2.2 Habitat use...... 82 4.3.3 Seasonality ...... 93 4.3.3.1 PSR and prevalences ...... 93 4.3.3.2 Climate...... 94 4.3.3.3 Phenology...... 94 4.3.3.4 Diet...... 96 4.4 Variation in egg and larvae output...... 96 4.5 Post-mortem analyses...... 103 4.5.1 Small and large intestine ...... 103 4.5.2 Liver ...... 104 4.5.3 Abdominal cavity...... 105 4.5.4 Further pathological findings...... 106 5 DISCUSSION...... 107 5.1 Methodological considerations ...... 107 5.1.1 Faecal sampling, fixation and concentration technique ...... 107 5.1.2 Helminth identification...... 111

5.1.3 Metrics of disease risk ...... 112 5.1.4 Avoiding bias...... 114 5.1.4.1 Selection bias...... 114 5.1.4.2 Information bias...... 115 5.1.4.3 Confounding bias...... 115 5.2 Parasite diversity and host-intrinsic correlates ...... 116 5.2.1 Host species ...... 118 5.2.2 Host sex...... 120 5.2.3 Strata use...... 122 5.2.4 Diet ...... 123 5.2.5 Home-range size...... 126 5.2.6 Group size and host density ...... 128 5.3 Parasite diversity and host-extrinsic correlates ...... 131 5.3.1 Ground humidity...... 133 5.3.2 Soil type...... 134 5.3.3 Habitat morphology...... 136 5.3.4 Resources for intermediate hosts ...... 136 5.3.5 Vegetation density...... 138 5.4 Seasonal variation in parasite diversity ...... 140 5.4.1 Host susceptibility related to the nutritional status...... 142 5.4.2 Host exposure...... 143 5.5 Parasites and their impact on the host’s survival...... 145 5.6 Conclusions ...... 149 6 SUMMARY ...... 152 7 ZUSAMMENFASSUNG (GERMAN SUMMARY)...... 155 8 RESUMEN (SPANISH SUMMARY)...... 160 9 REFERENCES ...... 160 10 APPENDICES ...... 190 11 DANKSAGUNG/AGRADECIMIENTOS/ACKNOWLEDGEMENTS ...... 214

Abbreviations

ANOVA analysis of variance °C degree Celsius C.c. Callicebus cupreus cm centimetre DBH diameter at breast height (of trees) df degrees of freedom DPZ Deutsches Primatenzentrum (German Primate Center) e.g. exempli gratia (for example) EBQB field station Estación Biológica Quebrada Blanco et al. et alii (and others) Fig. Figure g gram g acceleration due to gravity (standard gravity, 9.80665 m/s2) GLMM General Linear Mixed Model h hour H.&E. haematoxylin-eosin stain ha hectare i.e. id est (that is) IQR interquartile range km kilometre m metre max maximum min minimum ml millilitre µl microlitre mm millimetre µm micrometre MWU Mann-Whitney U-test

N number NE North East NW North West PAS periodic acid-Schiff reaction PET polyethylene terephthalate POM point of measurement PSR parasite species richness rpm rounds per minute S.f. Saguinus fuscicollis S.m. Saguinus mystax SD standard deviation SE South East SEM scanning electron microscope SW South West syn. synonymous with sp. species (singular) spp. species (plural) Introduction 1

1 INTRODUCTION

Parasites are significant sources of mortality in wild populations (HUDSON et al. 2002; MOORE and WILSON 2002). Thus, it is of basic and applied importance to assess accurately the patterns of parasitism in wild hosts and to identify host-intrinsic and environmental factors that determine parasite diversity. From various field and meta-studies host-intrinsic factors like body size, diet, group size, geographic range (CÔTÉ and POULIN 1995; MORAND and POULIN 1998; NUNN et al. 2003), as well as host-extrinsic factors, namely climate or soil moisture (MÜLLER-GRAF et al. 1996; LILLY et al. 2001), are supposed to affect the composition of parasite communities. However, there has been no study that examined systematically a comprehensive set of both host-intrinsic and -extrinsic factors affecting parasite diversity in sympatric primate host populations.

The primary objectives of this study are to collect baseline data on the intestinal parasite spectrum of three wild, sympatric New World primate species (Saguinus mystax, Saguinus fuscicollis and Callicebus cupreus) and characterize the role of host-intrinsic traits and environmental factors for parasite species richness (PSR) and parasite prevalences. In order to achieve these goals it was aimed to improve and standardize methods for parasitological analyses in terms of sample collection, processing and examination for the needs of primatological field studies. In total, over 2200 faecal samples were collected over a 15 month period from altogether 45 host individuals of the three study species at the field site Estación Biológica Quebrada Blanco (EBQB) in Peru. Data on activity patterns, ranging and group composition was collected to explore the importance of the following host-intrinsic factors on parasitism: host sex, strata use, diet composition, nutritional status, home-range size, host density and group size. In order to elucidate environmental factors that may shape parasite diversity, different habitat variables were measured like ground humidity, soil type, habitat morphology, resource distribution for intermediate hosts and vegetation density.

This comprehensive comparative study is a powerful approach for a better understanding of the factors that determine intestinal parasite diversity. A non- 2 Introduction

invasive year-round study on parasitism of natural host communities provides essential advantages: by multiple sampling of individually recognized hosts the information on parasite patterns is highly reliable (MUEHLENBEIN 2005). Simultaneously, a diverse array of potential factors is considered while the study animals are in their natural environment and not affected by an anthropogenic impact (EZENWA et al. 2006; KEESING et al. 2006). By means of standardized parasitological methods the bias is reduced. A more comprehensive insight into the seasonal variation of parasite diversity is provided by including data from rainy and dry season.

The results of this study are also of particular interest for public health concern: the study host species are commonly kept as pet animals or used for food in rural areas of Peru and other countries and their parasites are potentially zoonotic (ORIHEL 1970; FLYNN 1973; MICHAUD et al. 2003). Furthermore, the deeper understanding of host-parasite interaction and habitat influences can be important for conservation management (STUART and STRIER 1995; GILLESPIE et al. 2004; CHAPMAN et al. 2006). Literature review 3

2 LITERATURE REVIEW

2.1 Parasite diversity and correlates with host ecology

Parasites can exert an important impact on host population regulation in terms of reducing fecundity and/or survival of the host individuals (SCOTT and DOBSON 1989; HUDSON et al. 2002). They can even lead to rapid declines of host populations or host species extinctions (DASZAK 2000; HARVELL et al. 2002). Parasites are assigned a central role in sexual selection and the evolution of male secondary sexual characters that advertise their high parasite resistance because females should benefit from choosing parasite-resistant mates by the means of these sex traits or honest signals (HAMILTON and ZUK 1982; MØLLER 1990; ZUK 1996).

Since parasites play such an important role it is crucial to investigate factors that shape the probability of acquiring parasites and the risk of developing pathology caused by these parasites, the so-called disease risk (NUNN and ALTIZER 2006). Many different factors are assumed to shape parasite diversity in hosts by modulating this disease risk at any stage of the potential infection: parasite encounter, transmission, parasite recruitment, colonization, parasite reproduction or establishment. Disease risk is difficult to measure in wild host populations, thus indirect surrogates are needed: parasite species richness (PSR) describes the number of parasite species encountered per host (MORAND and HARVEY 2000; NUNN et al. 2003). Parasite intensity is the number of parasite individuals of a particular species per host (MARGOLIS et al. 1982; BUSH et al. 1997). Parasite prevalence is the number of hosts infected with a particular parasite as a proportion of all hosts examined (MARGOLIS et al. 1982; BUSH et al. 1997). In summary, these three metrics allow to estimate indirectly the disease risk in host populations.

Since in the ecological sense the term “parasite” encompasses a wide range of organisms like virus, bacteria, fungi, helminths, protozoa and which diverge enormously in their mode of replication and transmission, generation times, elicited immune responses and diseases etc. (HUDSON et al. 2002) it is essential to specify the studied parasite type. This study focuses on protozoan and helminthic

4 Literature review

parasites mainly dwelling in the intestinal tract. Due to the coprological survey of parasites this study also includes protozoan and helminthic parasites inhabiting other sites than the intestine that shed their propagules in the faeces, e.g. parasites that inhabit the stomach, upper parts of the alimentary tract, pancreas, liver, mesenteric vessels, lungs or other tissues. For convenience the protozoa and helminths considered in this study will be simply called intestinal parasites.

As the host represents the well-defined habitat on which the parasite depends strongly for at least one life-history stage it is of great interest to study host traits in search of ecological, behavioural and morphological correlates for parasite diversity. A growing body of studies reveals the importance of host traits for parasite diversity on the individual, population and species level (CÔTÉ and POULIN 1995; GREGORY et al. 1996; MORAND and POULIN 1998; ARNEBERG 2002; ALTIZER et al. 2003; NUNN et al. 2003; EZENWA 2004b; VITONE et al. 2004).

Nevertheless, parasites are also intimately linked to the host’s environment. Although with few exceptions intestinal parasites are obligatory endoparasites they pass their propagules into the external environment to reach the next definitive or intermediate host (ECKERT 2000; BUSH et al. 2001). Parasite diversity cannot be investigated without considering parasite ecology in terms of life cycle, transmission mode, host specificity, and host and parasite habitat characteristics. In order to understand host- parasite-interactions knowledge of the parasites’ life cycle is crucial. Direct life cycle (homoxenous parasites) means that transmission occurs within individuals of one host species where adult parasites reproduce sexually and release propagules. However, some of the directly transmitted parasites spend an obligatory period outside the host, for example in the soil to undergo a development into the infective stages (soil-transmitted parasites, e.g. Strongyloides sp., Trichuris sp. Ascaris sp. and hookworms (DUNN et al. 1968; ASH and ORIHEL 1987; BETHONY et al. 2006). An indirect life cycle (heteroxenous parasites) requires at least one other host species as intermediate host where asexual reproduction of the parasite can take place (BUSH et al. 2001; ECKERT et al. 2005). While reasonable knowledge is available for a number of parasites affecting domestic animals and parasites in

Literature review 5

temperate zones, information on potential intermediate hosts or even life cycles in complex tropical ecology remains extremely rudimentary.

Other important strategies for parasites to persist in the environment and ensure transmission are hypobiosis (developmental arrestment) and the use of reservoir hosts (BUSH et al. 2001; HUDSON et al. 2002). Hypobiosis is a temporary cessation in development of many species. It is an important adaptation to changing ecological conditions and can be induced in three ways: by adverse environmental conditions (e.g. temperature, day length) or by host-intrinsic factors (resistance, reproductive cycles) or parasite intrinsic factors (density dependent and genetically based arrestment) (BUSH et al. 2001). A reservoir host comprises one or more epidemiologically connected populations where the parasite can persist and from which infection is transmitted to the defined target population (HAYDON et al. 2002; HUDSON et al. 2002).

Very few studies have examined the habitat influences on parasite diversity, mostly focussing on human intestinal parasite prevalences and their correlation with climatic factors, elevation, soil type, vegetation density (AUGUSTINE and SMILLIE 1926; SORIANO et al. 2001; MABASO et al. 2003; SÁNCHEZ THEVENET et al. 2004; SAATHOFF et al. 2005a; SAATHOFF et al. 2005b). Most primatological studies on intestinal parasite diversity detected habitat specific variations as a by-product of their main research goals (MCGREW et al. 1989b; STUART et al. 1990; STONER 1993; STUART et al. 1993; STUART and STRIER 1995; MÜLLER-GRAF et al. 1996; STONER 1996; MÜLLER-GRAF et al. 1997).

From this perspective, to get a comprehensive insight into the factors shaping parasite diversity both host-intrinsic and environmental or habitat factors deserve closer attention. The potential effects of host-intrinsic (2.1.1) and -extrinsic factors (2.1.2.) are discussed in chapter 2.1. The chapter titles are underlined if this study design allows investigating the respective factors. A synopsis of these factors is depicted in Fig. 2.1. Since it is not possible to unravel the effects of host-intrinsic and -extrinsic factors on parasite diversity without considering the biology of intestinal parasites it will be presented shortly in the subsequent section (chapter 2.2). In order

6 Literature review

to achieve a better understanding of the examined host-intrinsic and also -extrinsic factors, background information on the three study host species will be outlined in chapter 2.3. Chapter 2.4 outlines some sources of bias that can frequently emerge in parasitological studies especially in non-invasive surveys on wild host populations. In chapter 2.5 the main goals of this study and the hypotheses are presented.

Literature review 7

HABITAT

HOST abiotic biotic • temperature • resources •bodysize • humidity • vegetation density • sex • solar radiation & type • age, longevity • soil type • vector/ intermediate • social status • water bodies host abundance • reproductive status • habitat morpho- •predation IndividuumIndividuum • strata use logy • diet oror populations populations • nutrional status

• home-range size • group size • life cycle Groups Groups • host density • transmission mode •location Species or orSpecies Species metapopulations metapopulations •social& matingsystem • host specificity • geographic distribution • pathogenicity

PARASITE

Fig. 2.1 Host-intrinsic and -extrinsic factors determining parasite diversity. Factors examined in this study are printed in bold letters.

8 Literature review

2.1.1 Host-intrinsic factors Host-intrinsic factors reflect the conditions offered by the host that affect directly the habitat of the parasite. Host-intrinsic factors can influence parasite diversity on different host levels: on an individual (e.g. sex, age), population (population size and density) or species level (geographic distribution) (Fig. 2.1).

2.1.1.1 Body size Large body size is correlated with parameters that can influence parasite diversity: generally, body size is positively correlated with longevity, body surface, home-range size and metabolic rate (BELL and BURT 1991; WATVE and SUKUMAR 1995; GREGORY et al. 1996; MORAND and POULIN 1998; MORAND and HARVEY 2000; NUNN et al. 2003; POULIN and MOUILLOT 2004). As metabolic rate increases with body size also the food uptake increases, augmenting the probability of food-borne parasite infection (POULIN 1995a; WATVE and SUKUMAR 1995; GREGORY et al. 1996; MORAND and POULIN 1998; MORAND and HARVEY 2000; ARNEBERG 2002; POULIN and MOUILLOT 2004). Since large hosts have an increased activity level or mobility and a longer life span, their exposure to infectious stages is longer and more intense; thus leading to a higher parasite accumulation rate and period (CÔTÉ and POULIN 1995; MORAND and HARVEY 2000; ARNEBERG 2002; POULIN and MOUILLOT 2004). Some authors argue that a larger body size can also be associated with an increasing niche diversity that offers potential habitats for parasites (GUEGAN and KENNEDY 1993; POULIN 1995a; GREGORY et al. 1996; MORAND and POULIN 1998; VITONE et al. 2004). Therefore, larger hosts should be able to accommodate more parasite species and offer them more stable and greater “habitat islands” (BELL and BURT 1991; POULIN 1995a; POULIN and MOUILLOT 2004).

2.1.1.2 Sex Adult males of vertebrates, including humans, tend to be more heavily parasitized than adult females (POULIN 1996; ZUK and MCKEAN 1996; SCHALK and FORBES 1997; KLEIN 2000; HUDSON et al. 2002; MOORE and WILSON 2002). Sex

Literature review 9

differences in morphology, metabolism, endocrine-immune system and behaviour can result in varying exposure to parasites and/or higher susceptibility (ZUK and MCKEAN 1996; KLEIN 2000). Sex hormones can have direct effects on growth and development of parasites but they can also modulate the immune responses and indirectly affect the parasite colonization (ZUK and MCKEAN 1996). Testosterone is thought to act as a handicap for males because it is supposed to compromise the immune system (“immunocompetence handicap” (FOLSTAD and KARTER 1992)). It has been shown to suppress the cell-mediated and humoral immunity (ZUK and MCKEAN 1996; SCHALK and FORBES 1997; KLEIN and NELSON 1999; KLEIN 2000; MOUGEOT et al. 2006). In females, oestrogens and prolactin are mostly considered to enhance immune functions (SCHALK and FORBES 1997; KLEIN and NELSON 1999; HUDSON et al. 2002). On the other hand, females’ progesterone and other pregnancy related hormones can play an immunosuppressive role (ZUK and MCKEAN 1996). Host behaviour is inseparably intertwined with sex and stress hormones: sex steroids regulate sex-specific behaviour that may expose males to a higher disease risk, e.g. aggression, competition, territorial defence, mating display, dispersal, sex-specific habitat use and diet (POULIN 1996; ZUK and MCKEAN 1996; SCHALK and FORBES 1997; KLEIN 2000; SEIVWRIGHT et al. 2005; MOUGEOT et al. 2006; NUNN and ALTIZER 2006). Sex-specific behaviour mentioned above seems to expose males to more stressors that are associated with elevated corticosteroid levels and thus reduced immune response (ZUK and MCKEAN 1996; KLEIN and NELSON 1999; BERCOVITCH and ZIEGLER 2002). Taken together, in this study the males are expected to have a higher parasite diversity and prevalence.

2.1.1.3 Age and longevity Susceptibility to parasites and exposure risk varies throughout the life history stages: acquired immunity develops with increasing number of parasite encounters indicating that the older the host individual is the greater is its immune competence (HUDSON et al. 2002). However, animals tend to exhibit lower immune defences towards the end of their life (MORAND and HARVEY 2000). Suckling infants can receive a passive immunity by colostral antibodies, but generally their immune response is weak (NUNN and ALTIZER 2006). Longevity should correlate positively with parasite

10 Literature review

diversity and intensity as a consequence of parasite accumulation over the whole life span (BELL and BURT 1991; MORAND and HARVEY 2000).

2.1.1.4 Dominance rank and social status The degree of parasitism is influenced by dominance rank or social status (BARTOLI et al. 2000; ALTIZER et al. 2003; NUNN and ALTIZER 2006). There are conflicting theories about effects of dominance rank: higher ranking individuals might be more exposed to parasites because of increased mating behaviour, contact rates with females and agonistic encounters (KLEIN 2000; NUNN and ALTIZER 2006). They can be also more susceptible because of alteration in the endocrine-immune system (higher testosterone levels in males, increased corticosteroid levels leading to an impairment of the immune defences, see 2.1.1.2) (BERCOVITCH and ZIEGLER 2002). On the other hand, socially subordinate individuals might suffer an increased disease risk: they might experience elevated stress levels due to intimidation by the dominant individuals, they are likely to have less access to resources and to occupy less favourable habitats (BARTOLI et al. 2000; SAPOLSKY 2005; NUNN and ALTIZER 2006). Dominance rank-related behaviour, e.g. breeding and dispersal, also influences patterns of parasitism (BARTOLI et al. 2000; ALTIZER et al. 2003).

2.1.1.5 Reproductive status Disease risk varies with the reproductive status as a consequence of alteration in energy demands, reproductive effort and in endocrine-immune status. Behaviour which is tied to the reproductive phase can challenge the metabolism and immune system (exhaustive courtship displays, increased contact rates, competition, mate selection, gestation, parturition, lactation or infant care) (GIBBS and BARGER 1986; FESTA-BIANCHET 1989; GUSTAFSSON et al. 1994; ZUK and MCKEAN 1996; KLEIN and NELSON 1999; KLEIN 2000; ALTIZER et al. 2003; NUNN and ALTIZER 2006). In conclusion, energetic and social stress might lead to a decrease in immune functions and increase in parasite prevalence and/or intensity (KLEIN and NELSON 1999; BERCOVITCH and ZIEGLER 2002). Yet, changes in parasite infections varying with the reproductive cycle can potentially be confounded with seasonal variations (ZUK and MCKEAN 1996).

Literature review 11

2.1.1.6 Group size and host density Group or population size and host density is expected to correlate positively with parasite diversity. The parasite transmission, especially of the directly transmitted parasites, depends strongly on the number of actually available hosts at a given time in a given area and on their contact rate (CÔTÉ and POULIN 1995; WATVE and SUKUMAR 1995; MORAND and POULIN 1998; ARNEBERG 2002; NUNN et al. 2003; BAGGE et al. 2004; POULIN and MOUILLOT 2004; VITONE et al. 2004). Epidemiological models predict that host density or number of hosts is an important determinant for the basic parasite reproduction rate (R0) which represents the capacity of a parasite to invade a susceptible host population and become established there (ANDERSON and MAY 1991; HUDSON et al. 2002). A minimum density or threshold density of a population can be derived from this model, below which a specific parasite cannot persist in this host population. Large groups therefore can support a large parasite diversity (FREELAND 1979; PRICE 1990; BELL and BURT 1991; LOEHLE 1995; MORAND and POULIN 1998; BAGGE et al. 2004; EZENWA 2004a; POULIN and MOUILLOT 2004). Thus, larger groups with higher densities and therefore potentially higher contact rates should exhibit a higher parasite diversity and prevalence. Parasites that are transmitted by intermediate hosts, vectors, via contaminated soil and water or by sexual contact should be less dependent on host density or group size (CÔTÉ and POULIN 1995; ALTIZER et al. 2003).

2.1.1.7 Social and mating system Not only host density or number of hosts influences contact rates within a group but also the effective size of a sub-structured group maintained by hierarchy or cohesion. Thus, the social and mating system is considered an important factor to shape parasite diversity (LOEHLE 1995; ALTIZER et al. 2003; NUNN et al. 2003). If the frequency and intensity of interactions within the group members is high, parasite species richness and prevalence is expected to be high as well. Another important aspect of the social system is the stability of groups: with more frequent exchange of group members the contact with diverse parasites increases (CÔTÉ and POULIN 1995; EZENWA 2004a).

12 Literature review

2.1.1.8 Strata use Terrestrial animals should host more diverse communities of parasites in higher prevalences than arboreal animals (DUNN 1968; DUNN et al. 1968). Parasite stages excreted in faeces, urine or other corporal liquids can accumulate on the ground and consequently disease risk in species showing a higher terrestriality should be increased (NUNN and ALTIZER 2006). In addition, so-called soil-transmitted parasites, which strictly require detritus or soil for their larval development, can be transmitted while the animals frequent the ground (DUNN et al. 1968; ASH and ORIHEL 1987). On the ground there is also a higher accumulation of generalist parasites shed by heterospecifics, e.g. rodents (MORERA 1973; SLY et al. 1982; ASH and ORIHEL 1987; POTKAY 1992; MICHAUD et al. 2003). On the other hand, one could argue that the use of diverse strata increases the probability to encounter different parasites (NUNN et al. 2003). Parasites are linked to different strata, especially to the stratified occurrence of intermediate hosts (DUNN et al. 1968).

2.1.1.9 Diet The ingestion of food items can influence parasite diversity mainly in three ways: firstly, hosts can get infected accidentally by the uptake of contaminated food or water. Secondly, parasites can be recruited by ingestion of animal prey which can serve as intermediate hosts for heteroxenous parasites (FREELAND 1983; KENNEDY et al. 1986; GUEGAN and KENNEDY 1993; WATVE and SUKUMAR 1995; NUNN et al. 2003; VITONE et al. 2004). In primate food webs, amphibians, fish, small reptiles, insects and other arthropods, even mammals or other primates can serve as intermediate hosts. As a consequence insectivorous, carnivorous or omnivorous host species should harbour a more diverse parasite community than folivorous or herbivorous host species (DUNN 1968; KENNEDY et al. 1986; POULIN 1995a). Not only the diet components but also the dietary breadth should influence parasite diversity: diet generalists are exposed to a wide array of infection sources leading to a higher diversity in parasite assemblage (DUNN et al. 1968; KENNEDY et al. 1986; PRICE 1990; POULIN 1995a; GREGORY et al. 1996). Thirdly, parasite diversity may be negatively influenced by the intake of diet-derived anti-parasitic plant compounds (NUNN et al. 2003; VITONE et al. 2004): certain secondary plant

Literature review 13

metabolites, such as phenolic or nitrogen-containing metabolites and terpenoids, e.g. tannins, are thought to possess anti-parasitic effects (COOP and KYRIAZAKIS 2001). Folivorous hosts can reduce parasite intensity by the selective ingestion of plants with chemical or physical properties of purging intestinal parasites (HUFFMAN et al. 1997). On the other hand, folivory is also associated with a higher resource intake and thus a higher parasite exposure risk (NUNN et al. 2003; VITONE et al. 2004; NUNN and ALTIZER 2006). Also the accidental uptake of animal prey could play a role in folivorous hosts. A confounding factor for diet can be host body size because body size is positively correlated with food uptake (GREGORY et al. 1996; VITONE et al. 2004), as described in chapter 2.1.1.1. This study focuses on the aspect of intermediate host uptake, and therefore it is expected that the proportion of animal prey in the host’s diet correlates positively with parasite diversity and prevalence.

2.1.1.10 Nutritional status Not only quality but also the quantity of the host’s diet has a major effect on parasite infection. The importance of the host’s nutritional status for the function of the immune system is generally accepted (BUNDY and GOLDEN 1987; FOLSTAD and KARTER 1992; HOLMES 1993; BEISEL 1996; COOP and HOLMES 1996; COOP and KYRIAZAKIS 2001; KOSKI and SCOTT 2001; NELSON and DEMAS 2004). The nutritional status can influence parasitism mainly in two aspects: firstly, it influences host defences which regulate parasite colonization, growth and fecundity (resistance). Secondly, it can affect the capability to cope with the patho- physiological consequences of parasite infection (resilience) (GIBSON 1963; HOLMES 1993; BEISEL 1996; COOP and HOLMES 1996; COOP and KYRIAZAKIS 2001). Malnutrition which is characterized by a deficiency of total energy and protein supply leads to a variety of severe immune dysfunctions and an impaired resilience (GIBSON 1963; BUNDY and GOLDEN 1987; BEISEL 1996; COOP and KYRIAZAKIS 2001). In seasons with low food availability and/or quality or in situations of higher energy demands (growth, late pregnancy and lactation), malnutrition can impair the immune system even more pronounced (COOP and KYRIAZAKIS 2001). Animals suffering malnourishment combined with parasite

14 Literature review

infection enter a vicious circle: malnutrition enhances parasite infection and intestinal parasites in turn reduce food uptake and resource utilization and increase protein loss into the intestinal lumen (GIBSON 1963; KOSKI and SCOTT 2001). In conclusion, the parasite diversity and prevalence is expected to be higher in hosts of a poor nutritional status or in a period of food scarcity.

2.1.1.11 Home-range size and geographic distribution Hosts which are distributed in a large and heterogeneous space should harbour a greater diversity of parasites than hosts with a uniform and small habitat niche (KENNEDY et al. 1986; POULIN and MOUILLOT 2004). On a small scale, travel distances and home-range size, on a larger scale habitat and geographic distribution determine the area that is sampled by the host. Larger spatial distribution also implies a higher probability of encounters with conspecific and heterospecific hosts which can transmit generalist parasites (EZENWA 2003; NUNN et al. 2003; POULIN and MOUILLOT 2004; VITONE et al. 2004). The higher exposure to different parasites should translate into higher parasite diversity (PRICE 1990; BELL and BURT 1991; GUEGAN and KENNEDY 1993; WATVE and SUKUMAR 1995; NUNN et al. 2003; VITONE et al. 2004). Another aspect of spatial distribution is the host’s territoriality. Hosts which are confined to a determined area are expected to be exposed to an increasingly contaminated environment, and thus, to accumulate more parasites over time. Territorial host species or hosts with smaller home ranges should exhibit a higher parasite intensity and prevalence compared to non-territorial host species or hosts with larger home ranges (CÔTÉ and POULIN 1995; EZENWA 2004a). Thus, hosts with larger home ranges should experience a higher PSR but lower parasite prevalence.

Not only the size and heterogeneity of the habitat but also the latitudinal position of geographical range plays an important role (POULIN 1995a; BUSH et al. 2001; NUNN et al. 2005). The higher abundance of intermediate and definitive hosts, the more favourable environmental conditions in the tropics compared to more temperate areas may enhance parasite transmission (NUNN et al. 2005). Thus, with closer proximity to the equator parasite diversity should increase.

Literature review 15

2.1.2 Host-extrinsic or habitat factors Host-extrinsic or habitat factors lead to variation in disease risk changing the host’s exposure to parasites also independently from the host susceptibility. Abiotic and biotic habitat factors are closely interrelated and their complex interaction influences the assemblage of parasite communities by modifying the conditions for free-living parasite stages, intermediate hosts or vectors. Besides the above mentioned aspects of the habitat and the host’s mobility within this habitat, there are numerous host- extrinsic habitat factors that shape parasite diversity.

2.1.2.1 Temperature and humidity Temperature and humidity are key factors for the survival and development of parasite stages (WHARTON 1979; UDONSI and ATATA 1987; ROEPSTORFF and MURRELL 1997; STROMBERG 1997; BUSH et al. 2001; BETHONY et al. 2006). Temperature and humidity are also determining the abundance of intermediate hosts especially of arthropods groups (TANAKA and TANAKA 1982; PEARSON and DERR 1986). Depending on the parasites’ morphological features and physiology, some stages of nematode larvae are particularly vulnerable to climatic conditions (GORDON 1948; STROMBERG 1997). Some authors pointed out that an optimal combination of temperature and humidity is crucial for the viability of free-living stages (GORDON 1948; DIESFELD 1970; UDONSI and ATATA 1987). Deviation from the optimum can reduce egg hatch rates, longevity, infectivity, larval migration and desiccation tolerance (WHARTON 1979; ARENE 1986; UDONSI and ATATA 1987). Climatic conditions on a larger geographical scale play an important role but microclimatic conditions turned out to be of eminent importance (DIESFELD 1970; SMITH 1990). Therefore, this study aims at examining the influence of ground humidity on parasite diversity and prevalence. But not only amount and distribution of precipitation contribute to the local humidity but also soil type, water-retaining leaf litter and vegetation density (PATZ et al. 2000).

2.1.2.2 Solar radiation Ultraviolet light causes damages to parasite eggs (STOREY and PHILLIPS 1985; ROEPSTORFF and MURRELL 1997; SAATHOFF et al. 2005a). In combination with

16 Literature review

higher temperatures, sunlight can reduce longevity and desiccation tolerance (STOREY and PHILLIPS 1985; UDONSI and ATATA 1987).

2.1.2.3 Soil type The soil type can modify parasite diversity and prevalence (PATZ et al. 2000; BUSH et al. 2001). Especially for soil-transmitted parasites it is of major importance (BUNGIRO and CAPPELLO 2004). The soil is also relevant to parasite stages and intermediate hosts: its texture, acidity, salinity, mineral content, degree of water retention and aeration can drive the parasite development and viability (VINAYAK et al. 1979; PEARSON and DERR 1986; MIZGAJASKA 1993; SÁNCHEZ THEVENET et al. 2004; SAATHOFF et al. 2005a).

Depending on the soil texture, the size and the ability of active movement of the parasite stages, they travel into deeper soil layers where they are protected from adverse environmental condition (STOREY and PHILLIPS 1985; MIZGAJASKA 1993; SAATHOFF et al. 2005b). Soil moisture can be an important parameter for intermediate host diversity and abundance: it is positively correlated with beetle species richness (LASSAU et al. 2005). Mineral contents such as calcium in soil limits the abundance of snails which are important intermediate hosts of trematodes and some (BUSH et al. 2001). Soil nutrients and electrolytes can be essential for larvae to reach infectivity (UDONSI and ATATA 1987). The acidity of soil has a significant effect on hatch rate of nematode eggs (UDONSI and ATATA 1987).

Clay soils should be conducive to parasite development and intermediate hosts in terms of the high water retention capacity and moister ground conditions (MABASO et al. 2003). Additionally, clay soils can impede the vertical washout of parasite stages into deeper soil layers where they become unavailable for infection (MIZGAJASKA 1993). This would lead to higher parasite diversity and prevalence in the hosts spending more time on clay soils.

2.1.2.4 Water bodies Parasite diversity also depends on types and amounts of water bodies because these may favour the development of intermediate hosts (PATZ et al. 2000; BUSH et al. 2001). Especially arthropods, e.g. larva and pupa of mosquitoes (culids) and

Literature review 17

blackflies (Simulidae), crustraceans, but also leeches and intermediate hosts of trematodes (molluscs) are intimately linked to the presence of water bodies (BUSH et al. 2001). Size, temperature, acidity, dissolved oxygen, salinity, flow and sedimentation may play an important role in parasite distribution (BUSH et al. 2001).

2.1.2.5 Habitat morphology Habitat morphology like terrain inclination indirectly affects the occurrence of water bodies or flowing water, sun exposure and temperature (PATZ et al. 2000; SAATHOFF et al. 2005a). On flat terrain parasite diversity and prevalence is expected to be higher: the chance of horizontal washout of the parasite stages should be less and soil humidity should be generally higher than in steep terrain.

2.1.2.6 Resources for intermediate hosts and vectors Deadwood and leaf litter represent important food resources and shelters for a great variety of arthropods that can serve as intermediate hosts or vectors (HÖFER et al. 1996; GROVE 2002a; KELLY and SAMWAYS 2003). Additionally leaf litter and deadwood can buffer fluctuations in humidity and temperature (SAYER 2006) favouring survival and development of parasite stages on the ground. Therefore, parasite diversity and prevalence should correlate positively with the abundance of deadwood and leaf litter in the host’s environment.

Animal communities in leaf litter and also soil include a great variety of arthropods representing all major taxa: arachnids, centi- and millipeds, insects (especially collembolans, ants, flies, beetles, termites, true bugs), and (PFEIFFER 1996; DALY et al. 1998). Additionally soil and plant debris offer a habitat for annelids, bacteria, fungi and molluscs (DALY et al. 1998). Litter provides habitat for larval stages of arthropods that later inhabit other forest strata (PFEIFFER 1996). Deadwood is the essential resource of the saproxylic fauna (organisms that depend on dead or dying wood (GROVE 2002a)) representing important intermediate host taxa. Saproxylic organisms comprise all major insect orders (especially beetles and flies) and account for a high proportion of insects in any natural forest (GROVE 2002a; KELLY and SAMWAYS 2003). But the saproxylic organisms also include

18 Literature review

fungi which are important food resources for numerous insect species (EHNSTRÖM 2001).

2.1.2.7 Vegetation type and density Vegetation type and density play an important role for the abundance of intermediate hosts. Vegetation density limits evaporation from the soil surface and reduces exposure to solar radiation which favours parasite development (ROEPSTORFF and MURRELL 1997; PATZ et al. 2000; BUSH et al. 2001; SAATHOFF et al. 2005a). The parasite diversity and prevalence should be associated positively with vegetation density in the host’s home ranges.

2.1.2.8 Predation Predation on hosts and parasites directly affects the parasite abundance. Predation on free-living parasite stages by earthworms, dung beetles, other arthropods, birds or mammals has a strong impact on the parasite population (FINCHER 1973; HAUSFATER and MEADE 1982; STOREY and PHILLIPS 1985; STROMBERG 1997; LARSEN and ROEPSTORFF 1999).

Likewise, predation on the hosts has a negative impact on parasite abundance: host individuals with the highest parasite intensity seem to be more vulnerable to predation (HUDSON et al. 1992). Host species with high predatory pressure should therefore develop a higher parasite resistance. Consequently, these species are expected to harbour a lower parasite diversity (WATVE and SUKUMAR 1995). However, if predation enables trophic parasite transmission from the intermediate to the definitive host, parasite populations would increase with higher predation pressure on intermediate hosts (HOLMES 1995; POULIN 1995b; CEZILLY and PERROT-MINNOT 2005; THOMAS et al. 2005).

2.1.3 Seasonality Parasite diversity or prevalence can fluctuate seasonally (ROEPSTORFF and MURRELL 1997; LARSEN and ROEPSTORFF 1999; PIERANGELI et al. 2003; SÁNCHEZ THEVENET et al. 2004). Seasonally varying key factors for parasite diversity may operate on host-intrinsic and -extrinsic factors as well as on the

Literature review 19

parasite itself. Most notably host-extrinsic climatic factors like humidity and temperature can affect the survival of free-living parasites, the abundance of both intermediate hosts and vectors and the host’s susceptibility. The viability of free-living parasite stages is higher under moist and warm conditions (WHARTON 1979; UDONSI and ATATA 1987; ROEPSTORFF and MURRELL 1997; BUSH et al. 2001; BETHONY et al. 2006, see 2.1.2.1). The abundance of intermediate hosts, important groups of arthropods and amphibians, is generally higher in warmer and more humid seasons (TANAKA and TANAKA 1982; PEARSON and DERR 1986; SHELLY 1988; FRITH and FRITH 1990; WATLING and DONNELLY 2002). Concerning the favourable conditions for parasites and the resulting higher exposure risk, parasite diversity and prevalence in this study should be higher in the rainy season. However, also host-intrinsic factors can be affected by seasonal changes in temperature, day length and resource distribution. Food shortage can result in a poorer nutritional status, higher intra-specific competition which in turn can induce stress and impaired immune reactions (2.1.1.10). Immune responses can also be modulated by changes in temperature and photoperiods or reproduction related efforts (KLEIN 2000; HUDSON et al. 2002; NELSON and DEMAS 2004; NUNN and ALTIZER 2006). Considering the nutritional status of the studied hosts, parasite diversity and prevalence should be higher in the dry season when food availability is low.

2.2 Intestinal parasite diversity in New World primates

This chapter reviews some general characteristics of intestinal protozoa and helminths on life cycle, transmission mode, host specificity, location and pathogenicity. Detailed descriptions of the spectrum of intestinal parasite species of the studied New World primates, egg and larvae morphology for identification, information on their life cycle and pathogenicity, other described host species and their origin are provided in Appendix A.

2.2.1 Intestinal protozoa Intestinal protozoa of New World primates belong to three different phyla: Metamonada (including the genera Giardia, Chilomastix), Axostyla or Parabasala

20 Literature review

(Trichomonas, Tritrichomonas, Pentatrichomonas.), Alveolata (two subphyla: Apicomplexa (e.g. Isospora, Cryptosporidium) and Ciliophora (e.g. Balantidium)), and Amoebozoa (Entamoeba, Endolimax, Iodamoeba) (TOFT and EBERHARD 1998; ECKERT et al. 2005; SCHNIEDER and TENTER 2006). The life cycle of most intestinal protozoa is direct: infective stages (cysts or oocysts) are ingested by contact with infected hosts or via contaminated water or food items (ECKERT et al. 2005). Insects are reported to serve as transport hosts (TOFT and EBERHARD 1998). Reproduction in intestinal protozoa is usually asexual, only species of the phyla Apicomplexa and Ciliophora also reproduce sexually involving micro- and macrogametes or conjugation (ECKERT et al. 2000; BUSH et al. 2001; ECKERT et al. 2005). Intestinal protozoa can have a broad host spectrum (euryxenous). For example Giardia intestinalis can infect a great array of species of mammals, birds and reptiles. Entamoeba histolytica (sensu latu) and Balantidium coli affect diverse primate species, rats, cats and dogs (SHADDUCK and PAKES 1978; TOFT and EBERHARD 1998; ECKERT et al. 2005). But some parasite species have very high host specificity (stenoxenous) like Isospora callimico, Isospora cebi or Isospora saimiriae affecting one single host species (Callimico goeldii, Cebus albifrons, Saimiri sciureus respectively) (DUSZYNSKI et al. 1999). They inhabit generally small (Giardia) or large intestine (Tritrichomonas, Balantidium), but can also dwell stomach or adjacent organs like bile ducts, pancreatic ducts, gall bladder (Cryptosporidium, Entamoeba histolytica sensu latu) (TOFT and EBERHARD 1998). Pathogenicity varies highly across all protozoa taxa and also within one species: Balantidium coli and Entamoeba dispar are apparently nonpathogenic, while Giardia intestinalis and Cryptosporidium sp. can cause gastritis or enteritis. Entamoeba histolytica (sensu latu) infection can be asymptomatic or produce severe diseases in primates (necro- ulcerative colitis, peritonitis, amoebic abscesses in liver, lung, central nervous system) depending on multiple factors like parasite strain, host species, host body condition, intestinal bacterial flora present and environmental factors (KING 1976; SHADDUCK and PAKES 1978; TOFT and EBERHARD 1998).

Literature review 21

2.2.2 Intestinal helminths Helminths comprise a very diverse group of metazoan parasites of the phyla Platyhelmintha (with the digenean Trematoda, monogenean Cercomeromorpha and Cestodea), Nematoda and Acanthocephala (SCHNIEDER and TENTER 2006).

2.2.2.1 Trematoda Trematode infections are considered to be very rare and atypical in New World primates (DUNN 1968; KING 1976). Around 11 species from five families are known to infect New World monkeys (TOFT and EBERHARD 1998), e.g. Athesmia foxi, Athesmia heterolecithoides, Zoonorchis goliath, Neodiplostomum tamarini and Phaneropsolus orbicularis (detailed list see Appendix A). Trematodes exhibit a very complex life cycle involving at least two hosts: intermediate hosts are usually molluscs; definitive hosts are vertebrates (KUNTZ 1972; SHADDUCK and PAKES 1978; ECKERT et al. 2005). Trematode species can infect various primate genera (polyxenous) (DUNN 1968; FLYNN 1973). Adult flukes reside in the intestinal lumen, liver, bile ducts, gall bladder, mesenteric and other abdominal veins, lungs and rarely in other organs (TOFT and EBERHARD 1998). Trematode infections with exception of lung flukes and schistosomes may be less virulent than other helminths (KUNTZ 1972).

2.2.2.2 Cestoda Cestodes are highly diverse and commonly infect New World monkey species (KING 1976). The characteristic cestodes are of the families Anoplocephalidae and Davaineidae (DUNN 1968). At least 13 cestode species are identified to infect New World monkeys (TOFT and EBERHARD 1998), e.g. Atriotaenia megastoma, Bertiella mucronata, Railletina trinitatae, Hymenolepis diminuta, Hymenolepis nana, Hymenolepis cebidarum (further information in Appendix A). Generally cestodes are heteroxenous, except Hymenolepis nana that can also be transmitted indirectly, and euryxenous (FLYNN 1973; KING 1976; SHADDUCK and PAKES 1978). Adult cestodes are located in the small intestine but they are usually not very pathogenic (DUNN 1963; 1968; KING 1976; SHADDUCK and PAKES 1978).

22 Literature review

2.2.2.3 Nematoda Intestinal nematode diversity in New World monkeys is extremely high: to date, approximately 68 species from six genera have been identified (TOFT and EBERHARD 1998). Nematode species of the families Metastrongylidae (lungworms, e.g. Angiostrongylus costaricensis, Filaroides barretoi), Trichostrongylidea (e.g. Longistriata dubia, Molineus vexillarius, Molineus torulosus), Strongyloididae (e.g. Strongyloides cebus), Oxyuridae (pinworms, e.g. Trypanoxyuris tamarini, Trypanoxyuris callithricis) and Spiruridae (e.g. Trichospirura leptostoma, Spirura guianensis, Spirura tamarini) are characteristic for Neotropical primates (DUNN 1968). A detailed list on nematode species infecting the study host species can be found in Appendix A. Nematodes possess the highest variability in life cycles of all helminths (BUSH et al. 2001). Some intestinal nematodes exhibit a direct life cycle with diverse transmission strategies (ingestion of eggs, skin penetration, lactogenic or intrauterine transmission); others have complex life cycles including free-living generations (TOFT and EBERHARD 1998; BUSH et al. 2001). Regarding their host specificity some nematodes are stenoxenous (family Oxyuridae), others can infect various genera of primates (Strongyloides cebus, Longistriata dubia) (HUGOT et al. 1994; TOFT and EBERHARD 1998). The location of the nematodes is diverse as well: they inhabit the oral cavity, oesophagus, stomach, pancreas (Spiruridae), small intestine (Trichostrongyloidea, Spirurida), large intestine (Oxyurida, Trichuroidea) and lungs (Metastrongylidae) (TOFT and EBERHARD 1998). Hence, also pathogenicity is fairly variable: it can range from asymptomatic to severe pathologies like ulcerative enteritis (Molineus torulosus) or lung haemorrhages (Filaroides sp., Strongyloides cebus) (FLYNN 1973; TOFT and EBERHARD 1998).

2.2.2.4 Acanthocephala Acanthocephalan infections are very characteristic for New World primates (DUNN 1968; KUNTZ and MYERS 1972; TOFT and EBERHARD 1998). Taxonomically it is a less diverse parasite group represented by only one genus Prosthenorchis (KUNTZ and MYERS 1972; SCHMIDT 1972; SHADDUCK and PAKES 1978; TOFT and EBERHARD 1998). Acanthocephalans are heteroxenous: cockroaches and beetles act as intermediate hosts (STUNKARD 1965b; SCHMIDT 1972; KING 1993;

Literature review 23

GOZALO 2003). They infect various species across most New World genera (DUNN 1968; KUNTZ and MYERS 1972; KIM and WOLF 1980). The adults of Prosthenorchis sp. inhabit the ileum, caecum and colon (TOFT and EBERHARD 1998). Severe pathologies are associated with infections of Prosthenorchis elegans (DUNN 1968; SCHMIDT 1972; TOFT and EBERHARD 1998). The adult worms can provoke inflammation and perforation at the site of attachment resulting in peritonitis and death (MENSCHEL and STROH 1963; RICHART and BENIRSCHKE 1963; NELSON et al. 1966; SCHMIDT 1972; KIM and WOLF 1980; KING 1993; ECKERT et al. 2005).

2.3 Study host species

2.3.1 Saguinus mystax and Saguinus fuscicollis Saddle-back tamarins (Saguinus fuscicollis, Fig. 2.2 (A)) and moustached tamarins (Saguinus mystax, Fig. 2.2 (B)) are two out of 15 species of the genus Saguinus included in the family Callitrichidae (RYLANDS et al. 2000). S. mystax is the largest member of this genus with a body mass ranging from 360 to 650 g (SOINI and SOINI 1990), and S. fuscicollis is the smallest species of this genus with 290 to 420 g (HEYMANN 2003a). The geographic distribution of tamarins is in western and central Amazonia west of Rio Madeira, in the Guyanas and northern Brazil, and in northwestern Columbia, Panama, and southeastern Costa Rica (RYLANDS et al. 1993; HEYMANN 2003a). The subspecies Saguinus mystax mystax, to which the study groups belong, ranges between the Río Ucayali in the west and the Rio Juruá in the east (GROVES 2001). The subspecies Saguinus fuscicollis nigrifrons, to which the other groups belong, ranges between the Río Ucayali in the west and the Río Javari in the east, south of the Rio Solimoes as far as the Río Blanco (HERSHKOVITZ 1977; GROVES 2001). Tamarins mainly occur in high-ground primary rainforest (“terra firme”) interspersed with patches of secondary vegetation, but can also range into mixed fruit-plantations (SOINI and SOINI 1990; HEYMANN 2003a). Where two species of tamarins occur sympatrically they commonly live in stable mixed-species troops with only one other congeneric troop sharing and

24 Literature review

defending the same home range (TERBORGH 1983). S. mystax and S. fuscicollis are frequently seen together and spend most of their time in such associations (SMITH 1997; HEYMANN and BUCHANAN-SMITH 2000). Their common home range comprises around 40 hectares (reviewed in SMITH 1997), but can vary between 10 and 200 ha according to population (HEYMANN 2003a). The group size of moustached tamarins varies between two to 12 individuals (SOINI and SOINI 1990; LÖTTKER et al. 2004a) and of saddle-back tamarins between three to 10 individuals, with one to two adults of each sex and their offspring from previous years (SNOWDON and SOINI 1988; HEYMANN 2003a). Both tamarin species in the study area exhibit a polyandrous mating system (GOLDIZEN 1989; HEYMANN and BUCHANAN-SMITH 2000). Moustached and saddle-back tamarins feed on fruits, insects, other arthropods, small vertebrates, nectar, soil, gums and other exudates (SNOWDON and SOINI 1988; GARBER 1993; PERES 1993; NICKLE and HEYMANN 1996; SMITH 1997; KNOGGE 1998; HEYMANN and BUCHANAN- SMITH 2000; HEYMANN et al. 2000; HEYMANN 2003a). They spend the night in closed sleeping sites like Jessenia bataua palm trees and tree hollows, dense epiphyte tangles and crotches (HEYMANN 1995; SMITH 1997). Sleeping sites are usually changed on a daily basis, but they may also be reused repeatedly (HEYMANN 1995; SMITH 1997; HEYMANN and BUCHANAN-SMITH 2000).

2.3.2 Callicebus cupreus The red or coppery titi monkey (Callicebus cupreus, Fig. 2.2 (C)) is one of the 28 species of the genus Callicebus belonging to the Callicebus cupreus-group with five other species (VAN ROOSMALEN et al. 2002). The genus belongs to its own subfamily Callicebinae within the family Pitheciidae (RYLANDS et al. 2000; GROVES 2001). The body mass of an adult C. cupreus ranges from 750 to 1000 g (BICCA- MARQUES et al. 2002). The geographic distribution of the genus Callicebus ranges throughout most of the Amazon and Orinoco basin and the Atlantic forest of Eastern Brazil (HERSHKOVITZ 1990). Callicebus is found in primary, riverine and remnant forest in low altitudes (under 500 m elevation) (AQUINO and ENCARNACIÓN 1994). It reaches the highest population densities in open forest areas, riparian forests and

Literature review 25

swamps (KINZEY 1981). Little is known about the species C. cupreus so that we have to rely on information about other species of the Callicebus genus. Titi monkeys are reported to range in areas from 0.5 (Callicebus moloch) to 29 ha (Callicebus torquatus) (KINZEY 1981; ROBINSON et al. 1987). Daily path length of Callicebus varies between 315 m (C. moloch) and 1500 m (C. torquatus) (KINZEY 1981). Estimates on population density give three to 24 individuals per km² (KINZEY 1981). It occupies relatively exclusive and stable home ranges with slight overlaps (TERBORGH 1983; MAYEAUX et al. 2002). Callicebus is reported to be in frequent association with tamarins (S. fuscicollis and Saguinus imperator) (KINZEY 1981). They live in family groups and probably exhibit a monogamous mating system (KINZEY 1981; TERBORGH 1983; MAYEAUX et al. 2002). In all studied Callicebus species groups are formed by up to five individuals (KINZEY 1981; AQUINO and ENCARNACIÓN 1994), exceptionally they were found in larger groups of seven members (BICCA-MARQUES et al. 2002; MAYEAUX et al. 2002). Callicebus has a generalized diet including fruits (pulp and seeds), insects, leaves and flowers (KINZEY 1981; TERBORGH 1983; ROBINSON et al. 1987; AQUINO and ENCARNACIÓN 1994; TIRADO HERRERA and HEYMANN 2003). They eat immature leaves from trees and mature and immature leaves from lianas (AQUINO and ENCARNACIÓN 1994). C. cupreus spends the night in closed microhabitats for example holes in hollow trees or vine tangles (ROBINSON et al. 1987; NUNN and HEYMANN 2005).

26 Literature review

Fig. 2.2 (A-C) Study host species A. S. fuscicollis, B. S. mystax, C. C. cupreus, photographed by J. Diegmann (A, B) and M. Nadjafzadeh (C).

Literature review 27

2.4 Bias in parasitological studies

Scientific studies are almost invariably subject to systematic errors (bias). Biased samples do not give a representative estimate of a study population and can therefore be difficult to analyse or even lead to inaccurate results. As many authors have remarked, errors in selection, processing or measurement of samples can be important and frequent sources for bias in parasitological studies (e.g. GUEGAN and KENNEDY 1993; WALTHER et al. 1995; GREGORY et al. 1996; NUNN et al. 2003; KREIENBROCK and SCHACH 2005). In the following some sources of bias will be outlined which can lead to essential deviations of parasitological results, especially if they are based on non-invasive methods (e.g. faecal sampling). Types of bias can be grouped into three categories: selection, information and confounding bias (GRIMES and SCHULZ 2002; KREIENBROCK and SCHACH 2005).

2.4.1 Selection bias This bias occurs during selection of the studied subpopulation resulting in a non- representative conclusion about the target population (GRIMES and SCHULZ 2002; KREIENBROCK and SCHACH 2005). In studies of wild host populations, opportunistic sampling or selective sampling of a subset of individuals like road kill, captured or hunted animals can be sources of selection bias. If in studies on free- ranging hosts samples are not assigned to single individuals, prevalences or individual PSR cannot be calculated accurately. In addition, it is known that sampling effort correlates positive with parasite species richness (e.g. GUEGAN and KENNEDY 1993; WALTHER et al. 1995; GREGORY et al. 1996; FELIU et al. 1997; ARNEBERG 2002; NUNN et al. 2003; MUEHLENBEIN 2005).

2.4.2 Information bias Information bias, also known as observation, classification, or measurement bias can arise during processing and measuring the samples (GRIMES and SCHULZ 2002; KREIENBROCK and SCHACH 2005). In parasitological analyses information bias can emerge from non-standardized processing, e.g. variation in the concentration procedure (WARNICK 1992), subjective sample examination, uneven examination

28 Literature review

effort in terms of the observer’s experience, the time budget and sample volume. This type of bias can also be caused by imprecise measurements of size and number of parasites.

2.4.3 Confounding bias Confounders are mostly unknown factors which are associated to both disease exposure and disease outcome. Confounding factors account for some of the observed relationship between the two, but they are not affected by the exposure (GRIMES and SCHULZ 2002; MCNAMEE 2003; KREIENBROCK and SCHACH 2005). Sampling hosts from different geographic regions, in different seasons or under specific conditions affecting the host’s immune system can lead to confounder problems. Disregarding confounders can lead to distortion of exposure-disease relation. Especially in such complex ecosystems as the tropical rainforest, the risk of neglecting important confounders is high.

2.5 Objectives of this study

In order to contribute to the knowledge of host-parasite interactions this study has three major goals. Firstly, it aims to collect baseline data on the parasite spectrum of three sympatric New World monkey species in the wild. Most information available on the parasite spectrum in general is collected from laboratory or captured animals. Data on intestinal parasites of S. mystax, S. fuscicollis and C. cupreus is very limited and refers mostly to captured animals where exact origin and time spent in the captivity are uncertain (DUNN 1962; 1963; NELSON et al. 1966; COSGROVE et al. 1968; PORTER 1972; KIM and WOLF 1980; HORNA and TANTALEÁN 1990; TANTALEÁN et al. 1990; MICHAUD et al. 2003). Hitherto, there is only one parasitological study published on wild S. fuscicollis (PHILLIPS et al. 2004). Secondly, this study explores systematically the ecological determinants of parasite diversity of sympatric host species. The influence of host-intrinsic and -extrinsic factors on parasite species richness (PSR), prevalence and egg or larvae output are examined on individual, group and host species level. Thirdly, in order to achieve the two first goals it was aimed to establish standardized methods for parasitological

Literature review 29

analyses in terms of sample collection, processing and examination for the needs of primatological field studies.

This comparative, year-round study is a potentially powerful approach to understand the factors that determine parasite diversity for several reasons: a long-term study of wild host populations with negligible anthropogenic impact is a better model to study host-parasite interactions than experimental studies. Advantages of laboratory and field studies can be combined: the complexity of the ecological interactions is not reduced while the samples can be collected individually because hosts are individually recognizable, and information about sex, age and life history is available.

Three primate species sharing the same habitat were studied at the same time in order to control for confounding factors like predator pressure, resource availability, climatic conditions, and other unknown geographical factors. Especially groups of the two tamarin species have identical home ranges and spend the majority of their time in association so that confounding effects can be minimized. The study period included rainy and dry season which provides a more comprehensive insight into the seasonal variation of parasite diversity.

This study addresses three main question complexes: 1. Do host-intrinsic factors play a role in determining PSR and prevalence? The following factors are considered: ƒ Host species ƒ Host sex ƒ Strata use ƒ Diet composition ƒ Nutritional status ƒ Home-range size ƒ Group size ƒ Host density

30 Literature review

2. Do host-extrinsic and habitat characteristics influence PSR and prevalence? The following factors are considered: ƒ Ground humidity ƒ Soil type ƒ Habitat morphology, especially ground inclination ƒ Resource distribution for intermediate hosts (e.g. leaf litter, deadwood) ƒ Vegetation density

3. What are predictors for variation in egg/larvae output? ƒ Does variation show a host-specific pattern? ƒ Does variation show a seasonal pattern? If there is a seasonal pattern, is it correlated with a) the host’s nutritional status? b) environmental conditions that favour development and survival of parasite stages or intermediate hosts?

From the theoretical background outlined in chapter 2.1, the following, not mutually exclusive hypotheses and predictions are derived for factors that possibly influence intestinal parasite diversity. For a better understanding the chapters to which the hypotheses refer are given in parentheses.

A. Hypotheses concerning host-intrinsic factors

A.1 Host species hypothesis: PSR, prevalence and egg/larvae output is dependent on the host species.

Prediction: PSR, prevalence and egg/larvae output is higher in the host species that offers more diverse and conducive conditions to parasite encounter, survival and reproduction.

Literature review 31

A.2 Sex hypothesis (2.1.1.2): The host’s sex has an influence on PSR and prevalence.

Prediction: Male host individuals harbour more different parasite species than females and exhibit higher prevalences.

A.3 Strata use hypothesis (2.1.1.8): The strata use of the hosts influences PSR and prevalence.

Prediction: PSR and prevalence is positively correlated with time hosts spend on the ground.

A.4 Diet hypothesis (2.1.1.9): The diet composition of the hosts plays a role in determining PSR and prevalence.

Prediction: PSR and prevalence is positively associated with the proportion of animal prey in diet.

A.5 Nutritional status hypothesis (2.1.1.10): PSR, prevalence and egg/larvae output is affected by the nutritional status of the host.

Prediction: PSR, prevalence and egg/larvae output is higher in the season when the host nutritional status is poor (dry season).

A.6 Home-range size hypothesis (2.1.1.11): PSR and prevalence is determined by the host’s home-range size.

Prediction: Hosts with larger home ranges exhibit higher PSR, but lower prevalences.

A.7 Group size hypothesis (2.1.1.6): PSR and prevalence is determined by the host’s group size.

Prediction: Hosts living in larger groups have higher PSR and higher prevalences.

A.8 Host density hypothesis (2.1.1.6): PSR and prevalence is determined by the host’s density.

Prediction: Hosts living at higher densities have higher PSR and higher prevalences.

32 Literature review

B. Hypotheses concerning host-extrinsic or habitat factors

B.1 Habitat use hypotheses: Habitat characteristics that are more conducive to parasite stage survival or development and abundance of intermediate hosts shape PSR and prevalence of the hosts that use this habitat.

Predictions:

(1) Humidity (2.1.2.1): The more time the hosts spend in areas of high ground humidity the higher PSR and prevalence.

(2) Soil type (2.1.2.3): The time hosts spend on clay soil is positively correlated with PSR and prevalence.

(3) Habitat morphology (2.1.2.5): The time hosts spend on flat terrain is positively correlated with PSR and prevalence.

(4) Resources (2.1.2.6): The proportion of time the hosts are in areas of high abundance of leaf litter and deadwood scales positively with PSR and prevalence.

(5) Vegetation density (2.1.2.7): The higher the proportion of time the hosts spend in areas of high vegetation density and dense understorey the higher PSR and prevalence.

B.2 Environment hypothesis: Egg/larvae output is affected by environmental conditions in which the parasite stages are excreted.

Prediction: Egg/larvae output is higher in the season where environmental conditions are more conducive to survival of parasite stages and abundance of intermediate hosts (rainy season).

Animals, materials and methods 33

3 ANIMALS, MATERIALS AND METHODS

3.1 Study site

The study was conducted at the Estación Biológica Quebrada Blanco (EBQB), situated approximately 4°21’S and 73°09’ W on the right bank of Quebrada Blanco, a white water tributary of the Río Tahuayo, in the Amazon lowlands of north-eastern Peru. The study area is located in “bosque de altura” (ENCARNACIÓN 1985) and is not subject to annual inundations. Based on its soil texture, nature of water, geomorphology and dynamics of watercourse this area falls into the subcategories of “bosque de terraza” and “bosque de colina” (ENCARNACIÓN 1985). Some lower parts of the study area can be characterized as “palmal alto” or “aguajal de altura” (ENCARNACIÓN 1985) dominated by palm trees (Mauritia flexuosa, Jessenia bataua) in swampy areas. For further details see HEYMANN (1995). The study site comprises approximately 100 ha and contains a grid system. This grid is based on footpaths every 100 m, in direction from North to South and from East to West (Fig. 3.1).

3.2 Study animals

The subjects of this study were eight wild groups from three species of New World primates: three groups of moustached tamarins (Saguinus mystax mystax), three groups of saddle-back tamarins (Saguinus fuscicollis nigrifrons) and two groups of red titi monkeys (Callicebus cupreus). Each of the three groups of moustached tamarins lived in a mixed-species troop with a group of saddle-back tamarins. Groups West of saddle-back and moustached tamarins have been under observation since May 1999, groups East since January 2000, and groups North since October 2001. The titi monkey group Casa was habituated when the observations started in October 2002, but had not been under routine observation. Habituation of group Puerto started in September 2002, but the female of this group died on the 29th of September 2002, and the remainder of the group disappeared in March 2003. Group composition is provided in Table 3.1. Changes in group composition over time are

34 Animals, materials and methods

shown in Appendix B. Details of the population dynamics are available for the moustached tamarins in LÖTTKER et al. (2004a). All group members were known individually by natural markings (LÖTTKER et al. 2004a). Mean group size was calculated as the mean number of individuals per group over the study period (Table 3.1). The range use of the study groups is depicted by 95% kernel home ranges (HARRIS et al. 1990) which represent the area with a 95% probability to encounter the group. For this purpose, the spatial data on group localization was collected every 15 minutes during the observation time. The position within the grid system was determined with a precision of 50 x 50 m. The Animal Movement extension to ArcView 3.3 was used to perform the home range estimations (HOOGE and EICHENLAUB 1997). The home ranges of all study groups are illustrated in Fig. 3.1. Host density was then derived from the mean group size per home range size.

Table 3.1 Study group composition, initial and mean group size over the study period Initial Mean Adults Subadults Juveniles group size group size Group ♀♀ ♂♂ ♀♀ ♂♂ ♀♀ ♂♂ ♀♂

Sf West 2 2 1 5 5.4

Sm West 1 2 3 3.5

Sf East 1 2 1 4 5.3

Sm East 1 5 2 8 6.7

Sf North 2 2 4 4.9

Sm North 2 2 1 5 5.8

Cc Casa 1 1 1 3 3.8

Cc Puerto 1 1 1 3 -

Sf: S. fuscicollis, Sm: S. mystax, Cc: C. cupreus; age classification refers to the age when the individual was first observed, for both Saguinus species the classes are defined by SOINI and SOINI (1990), for Callicebus cupreus by MAYEAUX et al. (2002) and KINZEY(1981).

Animals, materials and methods 35

N

W E

S 0 10 200

Camp

Fig. 3.1 Map of the grid system at the field site EBQB and 95% kernel home ranges of the study groups. Red represents groups East, blue groups North, green groups West, orange Callicebus group Casa. Dotted line comprises range of S. fuscicollis; solid lines represent S. mystax home ranges.

3.3 Study period

The study was carried out from June 2002 to August 2003. Habitat characterization, behavioural data and faecal sample collection took place in this period. Callicebus group Casa and tamarin group West were followed from October 2002 to August 2003. From Callicebus group Puerto faecal samples were collected between September 2002 and March 2003. During that time unbiased behavioural data could not be collected due to an insufficient habituation of the group. The other study groups were followed during the whole study period. Faecal sample collection and 36 Animals, materials and methods

behavioural observation were carried out during the whole activity period of the primates: from the time that they left their sleeping site (tamarins around 6:00h, titi monkeys around 5:30 h) to the moment that they entered the next sleeping site in the afternoon (around 16:00 h and 16:30 h, respectively). The study period included one rainy and two dry seasons (first dry season: July to October 2002, rainy season: March to June 2003, second dry season: July to September 2003).

3.4 Parasitological analyses

3.4.1 Faecal sample collection and preservation Faecal samples of all individuals were collected as often as possible, at least three times at three different days per rainy and dry season. The samples were put into PET tubes immediately after defecation, in order to avoid contamination by egg laying flies, soil or water. By observation of the defecating individuals and immediate sample collection a correct match of the hosts with the collected faecal samples was ensured. All vials were individually labelled with date and time of defecation, species, group and identification of the defecating animal. The samples were weighed on return to the camp, and then 10% neutral buffered formalin (solution of 10% formaldehyde and sodium phosphate buffer, pH 7.0) was added to the faecal material. The samples were stored at ambient temperature at EBQB, and at 4°C after returning to the DPZ. Each sample was assigned to a specific identification category (provided in Table 3.2) which describes the degree of accuracy of the individual identification. Only samples of category “A” were considered for parasitological analyses. Others were kept as spare samples for further analyses in case essential samples were missing or preservation or centrifugation techniques failed. In total 2226 faecal samples were collected from the eight study groups. The total number of faecal samples per study group and species and their proportion of identification categories are depicted in Table 3.3.

Animals, materials and methods 37

Table 3.2 Identification categories for faecal samples Identification Description category

accurate identification of the defecating individual, precise A localization of the faecal sample and immediate sample collection

accurate identification, but imprecise localization or delayed B collection of the sample

inaccurate identification, but precise localization and immediate C collection

Table 3.3 Faecal sample collection: total number of faecal samples per study group and species and their proportion of identification categories

Total number of % of A- % of B- % of C- Species Group faecal samples samples samples samples

S. fuscicollis West 340 64.4 6.2 29.4

S. fuscicollis East 416 79.3 5.5 15.2

S. fuscicollis North 286 81.8 5.3 12.9

TOTAL Sf 1042

S. mystax West 119 64.7 5.9 29.4

S. mystax East 368 66.8 4.1 29.1

S. mystax North 378 76.2 2.1 21.7

TOTAL Sm 865

C. cupreus Casa 284 49.6 8.1 42.3

C. cupreus Puerto 35 34.3 11.4 54.3

TOTAL Cc 319

38 Animals, materials and methods

3.4.2 Sedimentation procedure The formalin-ethyl acetate-sedimentation technique was performed for all faecal samples. The standard protocol (ASH et al. 1994) was followed except in some points where adjustment to the special needs of this study was required. Faecal solutions were homogenized very well before proceeding with the extraction and analyses. Approximately 5 ml of faecal solution was strained through a polyamide sieve with standardized mesh size (400 µm) into a 15 ml centrifuge tube. The remnants were weighed separately for later reference to total faecal mass. Subsequently more formalin was added to bring the total volume to 10 ml and the faecal solution was stirred well again. About 3 ml of ethyl acetate was added and the tube was shaken vigorously for 30 seconds before centrifugation. The power of centrifugation for this centrifuge was calculated after a nomogram: 2200 rpm was the equivalent for 500 g as recommended in the standard literature. The centrifugation time was 10 minutes. Before pouring off the supernatant, the top layer of fat was detached of the centrifuge tube. The tube was decanted and the layers of fat, debris, ethyl acetate and formalin were discarded and the sediment with parasite propagules was transferred into an Eppendorf tube and weighed. A second centrifugation was not performed as recommended for small faecal amounts (ASH and ORIHEL 1987; ASH et al. 1994). Given the low weight of the faecal samples (mean weight 1.24 g, N=2191, SD=0.64, range: 0.12-6.5 g) and the fact that decanting the top layers after centrifugation bears the risk of losing parasite stages the second centrifugation was omitted in order to preserve as much faecal material as possible.

3.4.3 Microscopic examination All microscopic examinations were done in a blind test. This means that all faecal samples were number coded before starting the sedimentation procedure so that the identification of the samples was unknown at each step of the parasitological analysis. The processed samples were examined microscopically by taking 100 µl sediment of each, and mixing it well with 50 µl of iodine (5%) in order to facilitate the detection and recognition of cyst stages (ASH and ORIHEL 1987). The sediment was examined for helminth eggs and larvae as well as protozoan cysts under three

Animals, materials and methods 39

22 mm-square cover slips at a magnification of 100 to 400 or 650. Each slide was scanned systematically and thoroughly in lanes covering the whole area of the three cover slips. The examination time was limited to 30-45 minutes per sample (15 minutes additionally for protozoa). For all individuals three samples of different, non-consecutive days of each season were examined. Because of the more time- consuming examination for protozoa the analysis was restricted to a subset of faecal samples: where possible two females and two males from each group and three samples for each individual were examined (totally 84 samples of 28 individuals).

3.4.4 Intra-observer reliability test In order to determine the degree of repeatability and precision of the microscopic examination, an intra-observer-reliability test was performed: six samples were selected, and 100 µl sediment of each sample was analysed for three times in a blind test. All parasitic stages were counted in the same way as described above. Then the Kendall Coefficient of Concordance (W) was calculated. It is a non-parametric test to determine the consistency of three or more judgements of a multiple set of rankings (MARTIN and BATESON 1993). W can range from 0 to 1, with 1 indicating perfect agreement and 0 indicating total disagreement (MARTIN and BATESON 1993). In this study, the intra-observer-reliability test revealed a very high agreement in the three judging processes of the parasitic objects (W=0.95, N=3, p<0.001).

3.4.5 Qualitative and quantitative description of parasite diversity

3.4.5.1 Parasite identification For identification mean egg size (length, width) was determined from 10 stages of the same morpho-type per host if eggs were not damaged or deformed. Measurements were made to the nearest 0.08 µm at a magnification of 400 using an ocular micrometer fitted to a compound microscope. Egg and larvae morphology was documented photographically (Axiophot, Olympus Camera DP50, software AnalySIS 3.0). Egg characteristics like shell structure, shape, colour and egg content were also taken into account. If there was a unimodal distribution of the length and width of the parasite stages within one host species or parasite sizes were included in the range

40 Animals, materials and methods

of the parasite of the other host species, it was assumed that this morpho-type belonged to a single morpho-species. For each morpho-species per host species, minimum and maximum size, median size and interquartile range (IQR) were recorded. The median size and IQR were chosen to give a more representative measure for the average when referring to data of a small sample size including outliers (FOWLER et al. 1998).

The parasite identification is presented at the level of family or genus, because a more detailed parasite identification based on microscopic examination of eggs, larvae, cysts and oocysts is often unreliable (ASH and ORIHEL 1987; GILLESPIE et al. 2005). In the case of the acanthocephalan parasite recovered from the intestine of a dead female titi monkey, the binocular microscope examination led to identification up to the species level (see chapter 3.6 and 4.5.1). The adult worm was identified based on morphological criteria and location cited in the literature (SCHMIDT 1972; SHADDUCK and PAKES 1978; BRACK 1987). Identification of the parasite from the abdominal wall was also based on morphological features and location described in the literature (NELSON et al. 1966; SELF and COSGROVE 1972; TOFT and EBERHARD 1998), see chapter 3.6 and 4.5.3. Besides morphological characteristics of the parasite stages recovered from the faecal samples and from the necropsy, reports on geographical distribution and presence in wild S. mystax, S. fuscicollis and C. cupreus or related primate species were taken into account. All this information on possible parasite species was compiled from parasitological standard references (e.g. BURROWS 1972; KUNTZ 1972; MYERS 1972; ORIHEL and SEIBOLD 1972; SCHMIDT 1972; FLYNN 1973; SHADDUCK and PAKES 1978; BRACK 1987; TOFT and EBERHARD 1998; ECKERT et al. 2005; SCHNIEDER 2006) or review articles (e.g. DUNN 1963; 1968; KUNTZ 1982; YAGI et al. 1988; WOLFF 1990; GOZALO 2003) and specific papers. This list and the cited literature on which the final identification was based on are provided in Appendix A. Furthermore, helminth identification was done in collaboration with Prof. Dr. D. W. Büttner, Department of Helminthology, Bernhard Nocht Institute for Tropical Medicine in Hamburg, Dr. C. Epe, Department for Infectious Diseases, Institute of Parasitology, Hannover School of Veterinary Medicine, Dr. M. Tantaleán Vidaurre, Faculty of Biological Sciences,

Animals, materials and methods 41

Universidad Nacional Mayor de San Marcos, Lima, Perú, and Dr. W. Tscherner, Department of Parasitology, Tierpark Berlin Friedrichsfelde. The taxonomic classification follows SCHNIEDER and TENTER (2006) if not otherwise noted.

3.4.5.2 Parasite species richness (PSR) Parasite diversity is expressed as parasite species richness (PSR). This is the number of different parasite species per host (BUSH et al. 1997). PSR is either given as total PSR referring to the total number of different parasite species over the entire study period or as seasonal PSR referring to the total number of different parasite species in rainy or dry season. All host individuals from which at least three unambiguous samples were available (category “A”, see Table 3.2) over the whole study period were included for total PSR. For seasonal PSR only individuals that had three “A” samples per season were included. If animals were present in two dry seasons, the second dry season was chosen for which comparable data was also available on C. cupreus.

3.4.5.3 Prevalence Prevalence was given as the number of hosts infected with one or more individuals of a particular parasite species or taxonomic group divided by the number of hosts examined. It is usually expressed as percentage or proportion (MARGOLIS et al. 1982; BUSH et al. 1997). On the individual level, prevalence was defined either as the presence or absence of a specific parasite over the whole study period or over a specific season. The sample selection was conducted in the same way as described for PSR (3.4.5.2).

3.4.5.4 Egg or larvae output The total number of parasite stages per 100 µl faecal sediment was given as a standard unit for egg or larvae output. This refers to the number of eggs or larvae of one parasite species in the faecal sediment after the removal of feeding residuals during the sedimentation procedure. If there were more than 200 propagules of one morpho-species under the first cover slip and the other cover slip areas were similar in parasite density, the number of counted propagules was multiplied by three as an estimate. For descriptive statistics all samples prepared by the standardized methods

42 Animals, materials and methods

were taken into account, at maximum three samples per individual per season. For comparing the seasonal egg or larvae output per parasite species, the mean output was calculated from exactly three samples of each individual in each season (two dry and one rainy season).

3.5 Behavioural observations

The tamarin groups were followed for three consecutive days each month. Observations were carried out on 182 days yielding a total of 1730 contact hours (Table 3.4). The Callicebus groups were followed for five days per month. In total the Callicebus group Casa was observed for 47 days yielding 403 contact hours (Table 3.4). For group Puerto no unbiased behavioural data could be collected because they disappeared from the study area in March 2002 before the process of habituation had been accomplished.

Table 3.4 Contact time for behavioural observations for all study groups

Species Group Overall contact time (in h)

S. fuscicollis West 230

S. fuscicollis East 370

S. fuscicollis North 316

S. mystax West 160

S. mystax East 384

S. mystax North 270

C. cupreus Casa 403

Behavioural data were recorded by “instantaneous scan sampling” (MARTIN and BATESON 1993): every 15 minutes the group was scanned and the activity of all visible individuals, their height in the forest and their location in the grid system were recorded during the scanning period of two minute duration. Two minutes are an

Animals, materials and methods 43

appropriate scanning period for rather dispersed groups of small-sized primates (MARTIN and BATESON 1993). A 15 minute-interval generates independent data for group positions because in this time period the group is potentially able to reach every point of its home range. The following activity categories were recorded: locomotion, feeding, foraging, grooming and resting (definitions are provided in Table 3.5). If animals were feeding also the category of the food object was recorded (fruit, animal prey, exudate, leaf, nectar, seeds, soil, others). The behaviour of dependent infants was not recorded up to the age of approximately three months.

For each scan all recorded activity categories were taken as a percentage of all active individuals seen in this specific scan. Across all scans the mean was calculated per category and per season and entire study period. If animals were observed feeding, the animals’ food object was expressed as proportion of all food objects which were consumed in this scan. Again means were computed over all scans in which feeding activity was recorded. This method was chosen in order to avoid underestimation of the proportion of consumed animal prey. Feeding on animal prey is likely to be underestimated because it is an individual activity of short duration. So if in one scan a single individual is seen ingesting animal prey it accounts for 100% of feeding activity. By this procedure, it receives the same weight as if all observed individuals were feeding together on a fruit tree.

Height in forest strata was grouped into nine categories (ground, >0-3 m, >3-6 m, >6- 9 m, >9-12 m, >12-15 m, >15-18 m and >18 m). At each scan the height of all animals was estimated from the ground and all individuals at the same height category were summed up. Over all scans the sum of specific height use was expressed as a percentage of all scan events.

44 Animals, materials and methods

Table 3.5 Description of activity categories applied in the “instantaneous scan sampling” (MARTIN and BATESON 1993) Activity Description categories

1. Locomotion movements that result in a displacement of at least two times the body length, including walking, running, jumping but also movements associated with playing and scent marking

2. Feeding manipulation of food items, biting, chewing and swallowing

3. Foraging searching and hunting for animal prey, e.g. visual inspection and manipulation of substrates, and investigation of tree holes, bromeliads etc.

4. Grooming one individual picks through the hair of another individual (allogrooming) or of itself (autogrooming) with its hands or mouth

5. Resting sitting or laying with no activity corresponding to 1.- 4.

3.6 Post-mortem examination

A post-mortem examination was performed on a female titi monkey of the Puerto group immediately after its death. After exenteration the intestinal tract was entirely opened and washed in formalin to remove the ingesta and parasites. The intestinal content and any parasite stages were stored separately for subsequent parasitological analyses. All organs were measured and weighed. The pathological findings were described and documented photographically. A spectrum of representative tissue samples was taken from all organ systems and fixed in 10% buffered formalin.

Further sample processing for histological examinations was conducted at the Department of Infectious Pathology of the German Primate Centre (DPZ) and the Department of Helminthology of the Bernhard Nocht Institute for Tropical Medicine. Tissue samples of brain, liver, kidneys, heart, stomach, small and large intestine, pancreas, adrenal gland were automatically paraffin-embedded (Hypercenter XP, Thermo Shandon, Frankfurt/Main, Germany), sectioned at 3 µm and stained with haematoxylin-eosin (H.&E.). In addition, sections of liver, spleen and intestine were

Animals, materials and methods 45

stained with Ziehl-Neelsen, Grocott, Periodic Acid Schiff reaction (PAS) and Giemsa for detection of bacterial, fungal and protozoan structures. The sections of the abdominal cyst were stained with Masson’s Trichrome stain. The histological analyses were performed by light microscopic examination. Histopathological findings were recorded in an examination protocol and were documented photographically (Axiophot, Olympus Camera DP50, software AnalySIS 3.0). Scanning electron microscope pictures of adult parasites recovered from the intestine were taken at the Bernhard Nocht Institute for Tropical Medicine.

3.7 Habitat characterization

The term “habitat” is used as the sum of resources and conditions present in an area that is occupied by certain species (sensu HALL et al. 1997). From the multitude of biological and physical components some parameters were selected which were thought to affect parasite diversity. Sampling points (spn) were set covering the home ranges of all study groups in order to assess the following habitat variables: ground drainage, soil type, ground inclination, leaf litter height, deadwood abundance, vegetation and understorey density. For this purpose all sampling points were arranged systematically along the established grid system. The quadrants of 100 x 100 m were divided into four sub-quadrants and four sampling points were set up at the centre of each sub-quadrant (Fig. 3.2). From each sampling point (spn) the surrounding area was divided into four sections by the compass bearing in all four cardinal directions. Each sampling point describes the habitat variables for an area of 50 by 50 m. All habitat variables were recorded within the rainy season 2003.

46 Animals, materials and methods

NW2 NW1

WN3 N

Sp3 Sp4

N

Sp2 Sp1

WN2

= d 50 m

Fig. 3.2 Setup of the sampling points and point-quarter method for vegetation density estimation. spn = sampling point; d = distance from sp to the trunk surface, N= North, WN2, NW1 etc. marked trail from grid system

3.7.1 Drainage The drainage was estimated at five meters distance to the sampling point in direction SE, SW, NE and NW. At this point of measurement, in the following referred to as POM, the drainage was determined as good (1) or poor (0) by considering the presence of stagnant water and ground humidity. For description of the drainage

Animals, materials and methods 47

properties of one sub-quadrant the values were averaged and grouped into three categories: poor (0-0.25), intermediate (0.5-0.75) and good (1).

3.7.2 Soil type At the sampling point the soil type of the superficial layer was determined. The soil layer was penetrated up to 15 to 20 cm depth. The substrate was described in three categories according to the soil colour and texture: clay soil, sandy soil and mixed soil. Sandy soil was considered to be of coarse particles, well separated, free draining, with a light colour. Clay soil was denominated soil out of very fine particles, compact, waterlogged, clumped when wet and of a yellowish or reddish tint. Soil samples with intermediate characteristics between clay and sandy soil were denominated mixed soil. In areas of stagnant water bodies and accumulation of decaying material, the soil was denominated swampy.

3.7.3 Ground inclination The ground inclination was assessed by measuring the height differences from the sampling point to the four POMs. If there was less than 50 cm of height difference, the inclination was considered 0-10%, if the difference was 50-100 cm, inclination was 10-20% and if the difference was greater than 100 cm, inclination was annotated with >20%. To study the habitat use, values were averaged and categories were built for the ground inclination of the single sub-quadrant: it was grouped into flat (0-5%), intermediate (>5-20%) and steep (>20%).

3.7.4 Height of leaf litter The height of leaf litter and organic debris was measured at the four POMs. The debris layer was perforated until reaching the forest ground with a sharp pointed pole. The height was measured in cm, and averaged over the four sections and sorted into four categories (0-5 cm, 5-10 cm, 10-15 cm, >15 cm).

48 Animals, materials and methods

3.7.5 Deadwood abundance At each sampling point, the abundance of deadwood was recorded. This was done according to tree diameter (trees between 30 and 100 cm in diameter account for one tree unit, trees greater than 100 cm diameter account for two units) and the number of trees present. Three groups were used to classify the abundance at the sampling point (0=no tree unit present, 1=one tree unit, 2=more than one unit).

3.7.6 Vegetation density The point-quarter method was employed to estimate the vegetation density of the habitat by using distances from the sampling points to the nearest plants (KREBS 1999). In each quarter of the sub-quadrant, the distance from the nearest plant to the sampling point was measured and recorded whether it was a tree or a palm tree (description displayed in Fig. 3.2). The following instructions were carried out: plants were measured that had a diameter at breast height (DBH) of more than 10 cm. Breast height is defined as 1.30 m from the ground. DBH was calculated from the stem circumference. To measure the stem circumference a pole was pushed firmly into the ground. If the tree was buttressed or stilt rooted at 1.30 m height the stem was measured above the top of the buttress or root. If this was not possible the circumference was estimated above the buttress or root. Trees that were fluted for their entire length were measured at breast height. If a tree had multiple stems, all stems of more than 10 cm DBH were recorded and the mean diameter and distance of all stems was calculated. In order to compute the vegetation density the following procedure was applied: tree circumference was transformed into radius r. Since it was impossible to measure exactly the distance D from the sampling point to the centre of the trunks, the radius r of the trunk was added to the distance of the sampling point to the surface of the closest trunk in each section (d1 – d4). Mean distance D was calculated as shown in equation (1). The mean area where a single plant occurs is equal to the mean distance D squared (GANZHORN 2003). Thus, theoretically each plant covers an area mean D². The density of plants (Np) per unit area (A) is then computed following equation (2). The absolute density of trees is defined as the number of trees per unit area. Since it is usually expressed as the

Animals, materials and methods 49

number of trees per hectare the values were subsequently transformed into this unit. In order to compare the habitat use of all study groups the vegetation density was transformed into the following five categories: very low (<400 trees/ha), low (400-800) intermediate (800-1200), high (1200-2000) and very high (>2000).

1 N Equation (1) Mean D = ∑(di + ri ) N i=1

D = distance from the sampling point to the tree centre d = distance from the sampling point to the tree surface r = radius of the tree N = number of trees measured at the sampling point (N=4)

A Equation (2) N = p mean D 2

N p = estimate of tree density at the sampling point A = sampled area, here sub-quadrant of 2500 m²

3.7.7 Understorey density The density of the understorey (vegetation less than three meters of height) was estimated at the POM. The understorey density was ranked according to the relative visibility of the field assistant. It was assigned four ranks: 0=almost full visibility, 1=half visibility, 2=very limited visibility, 3=no visibility. For the analyses of habitat use the categories low (density average per sub-quadrant: <1), intermediate (1-1.75) and high (>2) were employed.

3.8 Climate

Data on precipitation (in mm) was recorded with a rain gauge located on the clearing of the camp and the minimum and maximum temperature (in °C) by a minimum-

50 Animals, materials and methods

maximum thermometer situated in a shaded place at the camp site. These variables were recorded daily throughout the study period.

3.9 Phenology

Food abundance was evaluated by the phenological trail method (CHAPMAN and WRANGHAM 1994; GANZHORN 2003). This method provides a relative measure of food productivity of the forest and food availability for the primates (CHAPMAN 1992; STEVENSON et al. 1998). Since trapping of the study animals would have been incompatible with behavioural observations and faecal sampling the seasonal food availability was used as a surrogate for the nutritional status of the host individuals. The abundance of dietary plant parts was monitored, such as fruit, flowers and young leaves of 220 plant individuals belonging to 113 different species of key feeding trees of the three primate species. Phenological data on the feeding trees were recorded by an experienced field assistant once per month during two consecutive days, on a regular basis throughout the whole study period. The feeding plants had been selected previously as a representative subset of feeding plants of all three primate species. The abundance of leaves, fruit and flowers was ranked on a relative scale from 0 to 3 modified from HEIDUCK (1997) (0=none, 1=few, 2=moderate, 3=abundant). Fruit, flower or leaf availability per month was calculated as the sum of the assigned abundance ranks of the specific food item divided by the total number of monitored trees in this period (GANZHORN 2003).

3.10 Statistical analyses

All statistical analyses were done using SPSS 12.0 (SPSS Inc.) except the nonparametric repeated measures analysis of variance (ANOVA) and the ranked t- test for unequal variances (Satterthwaite) which were performed in SAS (version 9.1). Parametric tests were conducted whenever possible. If tests showed that data did not meet the required assumptions, equivalent non-parametric tests were performed. All tests were two-tailed and significance levels were set to α=0.05. The

Animals, materials and methods 51

p-values in multiple comparisons were adjusted by the Bonferroni procedure to control for type I error.

3.10.1 Parasite morphology Differences in sizes of the parasite morpho-species over the host species were tested by using the Kruskal-Wallis test or Mann-Whitney U-test, respectively. Length and width of parasite taxa varied significantly between host species in the case of small spirurids and strongylids (Appendix C). Since the maximum variance was less than 7% of the medians and/or less than reported in the references (Appendix A), the morpho-types were grouped into one single species.

3.10.2 PSR and prevalence In order to detect the general effects on parasite species richness (PSR) a non- parametric repeated measures analysis of variance (ANOVA) was conducted. Host species, season and home range entered the model as independent variables and their main effects and interaction effects were analysed. Firstly, all tamarin groups and titi monkey group Casa were included. The C. cupreus group Puerto was excluded because it was only present in one season. Since in the home range of group Casa no other host species than C. cupreus occurred, the influence of host species and home range could not be disentangled in this case. Thus, a second ANOVA was conducted including the tamarin species that formed mixed-species troops in the three home ranges. In case a significant effect was detected, a ranked t- test for unequal variances was conducted as a post-hoc test. Since PSR considers only the number of different parasite taxa in the following the differences in prevalence of all parasite species were examined separately: to analyse prevalence differences between the species, home ranges or groups, Chi square (χ²) test or a ’s Exact test (extension by Freeman and Halton for more than two categories) was conducted. In order to detect differences in parasite prevalences over the seasons, a McNemar’s test for paired samples was performed using binomial data on parasite presence/absence.

52 Animals, materials and methods

Sex differences in PSR were examined by using the Mann-Whitney U-test. To analyse differences in parasite prevalence between the sexes a Fisher’s Exact test was performed. To determine the extent of sex bias in prevalence, the prevalence of females was subtracted from the prevalence of males for each parasite taxon and host species separately. A one sample t-test was used to test if the mean value of sex bias over all parasite taxa differed from zero (meaning no sex bias).

In order to explore factors that can cause possible differences of PSR/prevalence over the host species or home ranges, data of all host species was examined by using the Spearman rank correlation calculations. The hypotheses presented before (chapter 2.5) predict specific relationships between host-intrinsic/-extrinsic variables and PSR/prevalence that should be primarily similar for the studied host species belonging all to the New World primates. Thus, even though species might be expected to differ in the magnitude of relationships, there is no a-priori reason why species should differ fundamentally in the direction of the relationship. Hence, the examined host-intrinsic variables are expected to have a similar outcome on the exposed individuals, independent from their species. Data of all species was therefore analysed together. Since there were no significant effects of the host groups within all host species on PSR (ANOVA F2,27=1.17, p=0.307, see chapter 4.3, Table 4.4 and 4.5) the same effects of host-intrinsic and –extrinsic traits on parasite diversity were expected for all host individuals. The same should be true for habitat use: since the results revealed no significant effects of three different home ranges

(West, East, North; ANOVA F2,36=1.23, p=0.312, chapter 4.3, Table 4.4) or significant interactive effects of home range and species (ANOVA F2,36=0.44, p=0.633, see Results, Table 4.4) on PSR, there was no reason to expect diverging effects of habitat use in different home ranges at the field site. In order to assure this pattern found in the first analyses, in a second step the rank correlation coefficients were determined by excluding the Callicebus species. Since for the second group of Callicebus group no data could be collected, the analyses were repeated without this species to exclude the possibility that general patterns were driven by non- representative data from one host species. The second analysis excluding the Callicebus further allowed drawing conclusions about consistency of the observed

Animals, materials and methods 53

pattern within phylogenetically closely related hosts (genus Saguinus). Since the tamarin species shared all recovered parasite taxa and many socio-ecological and immunological traits which might have an impact on their parasite diversity examining an association of parasite diversity and host-intrinsic and habitat factors with a balanced number of host individuals of both species can strengthen the detected patterns.

In order to analyse the relationship between PSR/ parasite prevalences and the host- intrinsic factors the Spearman's Rank Correlation Coefficient (rs) was calculated. The following independent variables were examined: strata use (percent of time hosts spent on the ground), diet (proportion of animal prey), mean group size, home-range size and host density. Of these independent variables proportion of animal prey and home-range size (N=42, rs=0.71, p<0.001) showed a strong intercorrelation (a table of correlations between independent variables is provided in Appendix D).

To examine the relationship between PSR, parasite prevalences and habitat use a

Spearman's Rank Correlation was conducted. The Correlation Coefficient (rs) was calculated for PSR, parasite prevalence and the time the hosts stayed in areas of the following habitat characteristics: dense vegetation (more than 1200 trees per ha), high understorey density, high leaf litter layer (more than 10 cm), clay soil, poor drainage (score 0-0.25), flat terrain (0-5% inclination) and high deadwood abundance (one and more tree units per sampling point). The frequency of use of some habitat characteristics showed a strong multicollinearity (results are displayed in Appendix D).

3.10.3 Egg/larvae output Data on mean parasite stages per season were log (n+1)–transformed to meet criteria of normality. A General Linear Mixed Model (GLMM) was used to analyse the effects of categorical variables (species and season) on a dependent continuous variable (mean egg or larvae output) of each individual. T-tests for independent samples (in case of comparing species) or dependent samples (in case of comparison between seasons) were employed as post hoc tests.

54 Animals, materials and methods

3.10.4 Behavioural observations and phenology Wilcoxon’s test for matched pairs was employed to study the differences of diet composition over both seasons for all host species. Comparison of the relative food availability in rainy and dry season was carried out by the t-test for dependent samples.

Results 55

4 RESULTS

4.1 Parasite diversity

Saguinus fuscicollis and Saguinus mystax harboured seven intestinal parasite taxa while Callicebus cupreus harboured four (see Table 4.1). Nematodes, cestodes and acanthocephalans were found in both Saguinus species. In C. cupreus cestodes were lacking. Trematodes and intestinal protozoa were not detected in either of the studied host species. Nematodes were dominant among the intestinal helminth fauna of the three studied primate species. Adult acanthocephalan parasites of the species Prosthenorchis elegans, and a pentastomid larva were found incidentally at the necropsy of a female C. cupreus (see chapter 3.6 and 4.5). The pentastomid is not an intestinal parasite of the studied primates and thus was excluded from the analyses. The other recovered parasite taxa are described more detailed in the following chapters.

4.1.1 Helminths Seven different helminth taxa were recovered from altogether 432 faecal samples of 45 host individuals: one acanthocephalan species, two cestode species and four nematode species (Table 4.1). The helminth taxa were identified as follows: the acanthocephalan species was Prosthenorchis elegans. One cestode taxon belonged to the family Hymenolepididae, it probably was Hymenolepis cebidarum. The identification of the other cestode species remained uncertain (in the following simply referred to as cestode sp. #2). The nematode taxa were represented by four morpho- species: two taxa of the order Spirurida: a large spirurid, probably Gongylonema sp. or Trichospirura leptostoma and a small spirurid which could not be determined further. Nematode eggs belonging to the polyphyletic group of the “strongylids” were found. “Strongylids” comprise the orders and Tylenchida (Strongylida). The morpho-species was narrowed down to Molineus sp. and Strongyloides cebus. The detected nematode larvae belong either to the group of “strongylids”, probably of the genus Strongyloides, or to the superfamily Metastrongyloidea (genus Filaroides or Angiostrongylus). For convenience this taxon was referred to as nematode larvae. The identification of the recovered helminth taxa, their and the study host

56 Results

species from which they were recovered, are summarized in Table 4.1. The information on which the parasite identification is based on (morphological characteristics, description of potential host species and their origin) including references is given in Appendix A. The descriptive statistics of length and width for each parasite morpho-species are presented in Table 4.2. Nematode larvae are not included in this table because their identification was not primarily based on size but on other morphological features. Results of the statistical comparisons of the parasite sizes are provided in Appendix C. Light microscopical photographs of all parasite taxa are presented in Fig. 4.1 (A-F) and 4.2 (A,B). Fig. 4.3 shows a scanning electron microscope (SEM) picture of an adult P. elegans.

Results 57

Fig. 4.1 (A-F) Light microscope pictures of parasite eggs recovered from faecal samples of all host species. A. P. elegans, B. Hymenolepis sp., C. cestode sp. #2, D. small spirurid, E. large spirurid, F. “strongylid”; scale bar = 25 µm

58 Results

Fig. 4.2 Light microscope pictures of two nematode larvae recovered from faecal samples of all host species. A. posterior, pointed end, B. anterior end (oesophagus); scale bar = 50 µm

Fig. 4.3 SEM picture of adult P. elegans recovered from necropsy of a titi monkey. Anterior end with collar of festoons and proboscis armed with spiral rows of five to seven hooks; scale bar = 100 µm.

Results 59 Table 4.1 Parasite identification and the infected study host species

Infected Parasite morpho- Parasite identification study host species Phylum/Class Order/Family Species or genus species

1. Prosthenorchis Acanthocephala/ Oligacanthorhynchida/ Prosthenorchis elegans Sf, Sm, Cc elegans Archiacanthocephalea Oligacanthorhynchidae

2. Hymenolepis sp. Platyhelmintha/Cestodea Cyclophyllida/Hymenolepididae Hymenolepis cebidarum Sf, Sm

3. Cestode sp. #2 Platyhelmintha/Cestodea Cyclophyllida/Anoplocephalidae1 Paratriotaenia sp. Sf, Sm

4. Small spirurida Nematoda/ Spirurida/unknown unknown Sf, Sm, Cc

5. Large spirurida Nematoda/Chromadorea 1. Spirurida/Gongylonematidae a) Gongylonema sp. Sf, Sm

2. Spirurida/Rhabdochonidae1 b) Trichospirura leptostoma

6. “Strongylids” Nematoda/Chromadorea 1. Tylenchida/Strongyloididae a) Strongyloides cebus Sf, Sm, Cc

2. Rhabditida/Trichostrongylidae b) Molineus sp.

7. Nematode larvae Nematoda/Chromadorea 1. Tylenchida/Strongyloididae a) Strongyloides sp. Sf, Sm, Cc

2. Rhabditida/Metastrongylidae b) Filaroides sp.

3. Rhabditida/Metastrongylidae c) Angiostrongylus costaricensis

Sf: S. fuscicollis, Sm: S. mystax, Cc: C. cupreus. Letters a)-c) give the probable parasite identification. Taxonomy follows SCHNIEDER and TENTER (2006) if not noted otherwise. 1 TOFT and EBERHARD (1998)

60 Results

Table 4.2 Descriptive statistics of length and width for eggs of six parasite morpho-species. N gives the number of parasite stages measured. Median, minimum, maximum and IQR (interquartile ranges) are presented for each parasite taxon and host species in µm.

Parameter S. fuscicollis S. mystax C. cupreus

Prosthenorchis length width length width length width elegans

N 12 12 6 6 - -

Median 69.4 39.0 70.2 41.9

Minimum 63.2 37.4 66.3 34.3

Maximum 74.5 43.3 74.1 44.5

IQR 6.5 3.8 6.3 6.1

Hymenolepis sp. (oncosphere)

N 56 56 4 4 - -

Median 29.6 23.4 30.1 24.2

Minimum 21.8 16.1 28.1 21.1

Maximum 43.7 30.0 31.2 25.7

IQR 2.3 3.0 2.9 3.9

Cestode sp. #2

N 2 2 12 12 - -

Median 65.2 58.9 66.1 54.6

Minimum 62.1 57.7 56.6 39.0

Maximum 68.3 60.0 74.1 64.0

IQR 6.2 2.3 9.1 9.8

Small spirurids

N 77 77 77 77 71 71

Median 26.5 11.7 26.9 11.7 25.0 11.7

Minimum 21.8 10.1 15.6 9.6 21.1 9.8

Maximum 33.9 17.6 34.3 19.5 35.9 14.0

IQR 2.7 1.1 4.1 1.2 3.1 1.2

Results 61

Parameter S. fuscicollis S. mystax C. cupreus

Large spirurids length width length width length width

N 8 8 8 8 - -

Median 57.7 23.4 57.5 32.8

Minimum 42.9 21.8 54.6 31.2

Maximum 64.4 33.5 59.3 33.9

IQR 8.3 10.1 1.5 0.4

"Strongylids"

N 88 88 47 47 27 27

Median 51.5 33.5 52.3 33.2 54.6 36.6

Minimum 46.8 28.9 46.8 23.4 49.9 33.2

Maximum 75.7 50.7 60.5 35.9 72.5 46.8

IQR 3.4 3.1 4.7 1.6 2.3 2.3

4.1.2 Protozoa In a total of 84 samples for a subset of 28 individuals no protozoan oocysts/cysts or trophozoites were found over all seasons.

4.2 Parasite ecology

Ecological data for the parasite taxa recovered from the three study host species is compiled from the literature. In order to explore determinants of parasite diversity it is essential to gather information on life cycle, potential intermediate hosts, transmission modes, host specificity and potential primate host species (Table 4.3). The references for the recovered parasite taxa can be found under the specific parasite in Appendix A.

Table 4.3 Ecology of detected parasite taxa including life cycle, intermediate hosts and transmission modes, host specificity and potential primate host species (the latter is written in brackets). * denotes potential intermediate hosts from closely related parasite species. Letters a) and b) give the probable parasite identification. Life Host specificity (potential Parasite Potential intermediate hosts Transmission mode cycle primate host species) polyxenous (Alouatta, Aotus, Ateles, Blattodea: Blatella sp.; Anobiidae: ingestion of intermediate Callicebus, Callithrix, Cebuella, Cebus, P. elegans indirect Lasioderma sp., Stegobium sp.; other host Lagothrix, Leontopithecus, Saguinus, Coleoptera Saimiri)

* Coleoptera: Tenebrio sp.; polyxenous (Callicebus, Callithrix, Siphonaptera: Xenopsylla sp., ingestion of intermediate Saguinus, Saimiri) Hymenolepis sp. indirect Ctenocephalides sp.; Lepidoptera: host Pyralis sp.; other arthropods Cestode sp. #2 ingestion of intermediate polyxenous (Callimico, Callithrix, indirect insects Paratriotaenia sp. host Saguinus) probably ingestion of ? Small spirurid indirect? ? intermediate host Large spirurids polyxenous (Aotus, Ateles, Callicebus, ingestion of intermediate indirect Blattodea, Coleoptera Callimico, Callithrix, Cebuella, Cebus, a) Gongylonema sp. host b) Trichospirura sp. Saguinus, Saimiri) polyxenous (Alouatta, Ateles, Nematode larvae skin penetration or direct none Cebuella, Cebus, Lagothrix, Saguinus, a) Strongyloides sp. ingestion of larva Saimiri, other Callitrichidae) polyxenous (Alouatta, Ateles, ingestion of intermediate b) Filaroides sp./ Cebuella, Cebus, Saimiri, Callithrix, indirect molluscs (slugs:Vaginulus sp.; snails) host or mucus Angiostrongylus sp. Lagothrix, Saguinus, other Callitrichidae contaminated food items and Cebidae) polyxenous (Alouatta, Aotus, Ateles, “Strongylids” skin penetration or Cebuella, Cebus, Lagothrix, Saguinus, direct none a) Strongyloides sp. ingestion of larva Saimiri, other Callitrichidae and b) Molineus sp. Cebidae)

Results 63

4.3 Variation in parasite species richness (PSR) and prevalence

The results of the ANOVA including all host species revealed a significant effect of host species on PSR. The main effect of season, home range and the interactive effects were not significant (Table 4.4). Excluding Callicebus from the analyses the results confirmed that PSR is significantly influenced by host species (Table 4.5). For this subset, again PSR was not significantly influenced by season, home range and any interaction between the independent variables. Variation in PSR and prevalence related to host-intrinsic and -extrinsic traits and the results of the respective group- wise comparison are described in the following chapters.

Table 4.4 F-, p-values and degrees of freedom (df) for the three host species generated by ANOVA

Effect df F p

Species 1 9.74 0.006

Season 1 0.98 0.323

Home range 2 1.23 0.312

Species * season 1 0.79 0.374

Species * home range 2 0.44 0.633

Season * home range 2 0.27 0.746

Species * home range * season 2 1.17 0.307

64 Results

Table 4.5 F-, p-values and degrees of freedom (df) for both Saguinus spp. generated by ANOVA

Effect df F p

Species 1 9.99 0.005

Season 1 3.78 0.052

Home range 2 1.24 0.306

Species * season 1 0.85 0.355

Species * home range 2 0.42 0.644

Season * home range 2 0.18 0.815

Species * home range * season 2 1.21 0.297

4.3.1 Host-intrinsic factors

4.3.1.1 Host species The maximum number of intestinal parasite taxa per individual was six in S. mystax and seven in S. fuscicollis (Table 4.6). From C. cupreus a maximum of three parasite taxa was recovered by faecal sampling. All 45 individuals had multiple parasite infections with at least two (C. cupreus) or three (Saguinus) parasite taxa over the study period. The frequency distribution of PSR is displayed in Fig. 4.4.

Table 4.6 Total Parasite species richness (PSR) per host species

Host N of host Median IQR Minimum Maximum species individuals

S. fuscicollis 17 5 2 3 7

S. mystax 21 4 2 3 6

C. cupreus 7 3 1 2 3

Results 65

12 S. fuscicollis S. mystax 10 C. cupreus

8

6

4 No. individuals of host

2

0 01234567 Total PSR

Fig 4.4 Distribution of PSR frequencies per host species. Bars denote the number of host individuals with a specific PSR.

Total and seasonal PSR varied significantly over the three host species (PSR total

ANOVA F1,37=11.34, p=0.002; PSR seasonal ANOVA F1,36=9.74, p=0.006, Table 4.4). Both seasonal and total PSR were significantly higher in S. fuscicollis than in

S. mystax and also than in C. cupreus (Fig. 4.5; PSR total: ranked t-test: tSf vs. Sm=3.1, df=34.6, p=0.004; tCC vs. SF=-8.97, df=22, p<0.001; tCC vs. SM=-5.69, df=25.5, p<0.001;

PSR seasonal: ranked t-test: tSf vs. Sm=3.24, df=66.8, p=0.002; tSf vs. Cc=8.51, df=24.4, p<0.001; tSm vs. Cc=5.37, df=23.4, p<0.001).

66 Results

9

8 *** * 7 *** 6

5 Total PSR 4

3

2

1 S. fuscicollis S. mystax C. cupreus Host species

Fig. 4.5 Total parasite species richness (PSR) per host species. The boxes show the interquartile ranges, bold horizontal bars show the median. The ends of the whiskers represent the minimum and maximum values that are not outliers. Asterisks indicate statistical differences between groups: ranked t-test: *p≤ 0.05; ***p≤ 0.001.

Prevalences of P. elegans, Hymenolepis sp., large spirurids and nematode larvae were higher in S. fuscicollis than in S. mystax (Fig. 4.6). S. mystax exhibited a higher prevalence of cestode sp. #2 than S. fuscicollis. Of the shared parasite taxa between tamarins and Callicebus, Callicebus had the same prevalence in small spirurids and nematode larvae but a lower prevalence of strongylids than both tamarin species (Fig. 4.6). Differences of parasite prevalences were significant in the case of Hymenolepis sp. (Fisher’s Exact test: p<0.001) and “strongylids” (χ²=11.362, df=2, p=0.003).

Results 67

Prevalences of all host species

100 *** **

80

60 S. fuscicollis S. mystax

40 C. cupreus Prevalence in %

20

0 Pro Hym Cestode sm Spir lg Spir Nemlarv Strongy Parasite taxa

Fig. 4.6 Prevalences of all parasite taxa per host species (Pro=Prosthenorchis elegans, Hym=Hymenolepis sp., Cestode=cestode sp. #2, smSpir=small spirurid, lgSpir=large spirurid, Nemlarva=Nematode larvae, Strongy=“strongylids”). S. fuscicollis N=17, S. mystax N=21, C. cupreus N=7. Bars denote prevalence per parasite species for all host species. Asterisks indicate statistical differences between groups. Fisher’s Exact test: ***p≤ 0.001, χ² **p≤ 0.01.

4.3.1.2 Host sex Total PSR did not show significant sex-specific variability in S. fuscicollis and

C. cupreus (Fig. 4.7; MWU: S. fuscicollis U=35.0, Nfemale=7, Nmale=10, p=1.0). In

S. mystax males exhibited a lower PSR than females (MWU: U=12.5, Nfemale=5,

Nmale=16, p=0.015).

68 Results

8 Host sex female 7 * male

6

5

4 Total PSR

3

2

1 S. fuscicollis S. mystax C. cupreus Host species

Fig. 4.7 Total parasite species richness (PSR) per sex and host species. The boxes show the interquartile ranges, bold horizontal bars show the median. The ends of the whiskers represent the minimum and maximum values that are not outliers. The circles represent outliers. Asterisks indicate statistical differences between sexes: MWU: *p≤ 0.05.

The prevalences of nematode larvae, large spirurids and P. elegans were higher in females than in males for both tamarin species (Fig. 4.8). Cestode sp. #2 showed a higher prevalence in females of S. mystax and in males of S. fuscicollis. The pattern of Hymenolepis sp. prevalence was inversed (Fig. 4.8). For strongylids and small spirurids the proportion of infected male tamarins was equal to the proportion of infected females. Callicebus did not exhibit a sex bias in small spirurids and nematode larvae prevalence, but a male bias in “strongylid” infection (Fig. 4.8). Sex differences in parasite prevalence were significant for P. elegans when combining the data for both tamarin species: five out of 12 females were infected with the acanthocephalan parasite while only two out of 26 males were infected (Fisher’s exact p=0.022). The mean parasite prevalence over all seven parasite taxa was

Results 69

female biased in both tamarin species and male biased in C. cupreus (Fig. 4.9; mean: S. fuscicollis -0.10, S. mystax -0.13; C. cupreus 0.03). The sex bias was not significantly different from zero (t-test: S. fuscicollis T=-1.08, df=6, p=0.32, S. mystax T=-1.52, df=6, p=0.18).

0 “Strongylids“ 0 0 Nematode larvae

Large Spirurids

0 0 Small Spirurids 0

Parasite taxa Cestode sp. #2

Hymenolepis sp.

P. elegans

-0.60 -0.40 -0.20 0 0.20 0.40 Sex bias in parasite prevalences C. cupreus S. mystax S. fuscicollis

Fig. 4.8 Sex bias in parasite prevalences over all host species. Negative values represent a female bias in parasite prevalence (male prevalence minus female prevalence), positive values a male bias.

70 Results

C. cupreus S. mystax S. fuscicollis Host species

95% confidence interval

mean

-0.40 -0.20 0 0.20

Mean sex bias in parasite prevalences

Fig. 4.9 Mean sex bias in parasite prevalences over all helminth taxa. Negative values represent a female bias in mean parasite prevalence (male prevalence minus female prevalence), positive values a male bias.

4.3.1.3 Strata use In their forest strata use S. mystax and C. cupreus showed a similar distribution pattern: both frequently used elevated heights in a uniform pattern and spent approximately one third of their time in heights between 12 and 18 m (37% in S. mystax, 35% in C. cupreus, Fig. 4.10). In contrast, S. fuscicollis spent almost two thirds of their time (62%) in strata between 0 and 6 m. S. mystax and C. cupreus spent little time on the ground (0.5% in S. mystax, 0.2% in C. cupreus), S. fuscicollis spent 1.6% of the time on the ground.

Results 71

40 S. fuscicollis 35 S. mystax C. cupreus

30

25

20

15 Frequency in % Frequency

10

5

0 ground > 0-3 > 3-6 > 6-9 > 9-12 > 12-15 > 15-18 > 18 Height in m

Fig 4.10 Strata use for all host species. Bars show the frequency at which individuals were found at the given height category.

There was a significant positive association between PSR and the time hosts stayed on the ground (Spearman rank correlation: rs=0.626; N=42, p<0.001, excluding

Callicebus: rs=0.557; N=38, p=0.001). To give a visual picture of the relationship between the two variables, in Fig. 4.11 median group PSR is plotted against the proportion of time the hosts stayed on the ground. For parasite prevalence, a positive and highly significant relationship was found for Hymenolepis sp. (rs=0.509; N=42, p=0.001), cestode sp. #2 (rs=0.360; N=42, p=0.019), large spirurids (rs=0.572; N=42, p<0.001). When omitting Callicebus, the correlation of cestode sp. #2 with time spent on the ground was not significant (p=0.165). Results of all correlations are provided in Appendix E.

72 Results

6

5

4 Median group PSR group Median

3 Host species S. fuscicollis S. mystax C. cupreus 2 0,0 0,5 1,0 1,5 2,0 2,5 3,0 % time on the ground

Fig. 4.11 Relationship between median group PSR and percent time on the ground. Data is presented for all groups of the three host species.

4.3.1.4 Diet composition Callicebus cupreus spent twice as much time (17%) than S. mystax (9%) and S. fuscicollis (8%) on feeding activities (for complete activity budget see Appendix F). The main food components of all study host species were fruit and animal prey. Yet, they diverged in the proportion of the consumed food categories (Fig. 4.12 (A-C)): in S. fuscicollis fruit formed almost half of the diet (49%), in S. mystax almost two thirds (64%) and in C. cupreus 74% of the total diet. Across all primate species the second highest proportion in diet was animal prey: it varied between 12% in C. cupreus, 19% in S. mystax and 25% in S. fuscicollis. Both Saguinus species consumed a fairly high amount of exudates or tree gums (S. mystax 13%, S. fuscicollis 23%) which was not observed in C. cupreus. C. cupreus supplemented its diet with leaves (8%) and flowers (1%) instead.

Results 73

(A) S. fuscicollis (B) S. mystax

3% 4%

19% 25%

64% 13% 49%

23% Diet components Animal prey Exudate Fruit UFO

(C) C. cupreus 5% 8% 12%

1%

Diet components Animal prey Flowers Fruit 74% Leaves UFO

Fig. 4.12 (A-C) Diet composition of all study species. The sectors of the pie chart represent the diet components fruit, animal prey, flowers, exudates, leaves and unknown feeding objects (UFO).

74 Results

The three primate species did not only diverge in their total proportion of animal prey but also in the composition of animal matter (Table 4.7). By far the most abundant component of animal prey in the two tamarin species was formed by orthopteran insects (S. fuscicollis 59%, S. mystax 49%). In Callicebus animal matter was based mainly on Hymenoptera and Isoptera, especially ants, represented in 56% of the animal feeding events. This food category played a subordinate role in the diet of the tamarins (S. fuscicollis 2% and S. mystax 5%) and included mostly termites. The second main component of animal diet for Saguinus were other arthropods (including Phasmatidea, Mantodea and unidentified arthropods): S. fuscicollis ingested 26% and S. mystax 34% of this category. For Callicebus Orthoptera and other arthropods represented the second and third most important animal prey items. They consumed them in almost equal amounts (Orthoptera 13% and other arthropods 10%). Amphibians were eaten by C. cupreus and S. fuscicollis in equally low proportion (both 2%). S. mystax consumed a higher amount of amphibians (8%, especially frogs). S. fuscicollis supplemented their diet with insects of the order Dictyoptera, (1%, mainly cockroaches), Arachnida (4%) and reptilians (4%, mostly lizards), which were not consumed by the other primate species. Both tamarin species ingested Lepidoptera in low amounts (S. fuscicollis 1.6% and S. mystax 2.3%).

Table 4.7 Percentage of animal prey consumed by the three primate species categorized by prey taxa

Animal prey taxon S. fuscicollis S. mystax C. cupreus

Orthoptera 58.9 48.9 12.8

Hymenoptera, Isoptera 1.6 4.5 56.4

Lepidoptera 1.6 2.3 0

Dictyoptera 0.8 0 0

Arachnida 3.9 0 0

Other arthropods 25.6 34.1 10.3

Reptilia 3.9 0 0

Amphibia 2.3 8.0 2.6

Unidentified animal prey 1.4 2.2 17.9

Results 75

PSR is positively and significantly correlated with proportion of animal prey in the host’s diet (Spearman rank correlation: rs=0.480; N=42, p=0.001, excluding

Callicebus: rs=0.325; N=38, p=0.047). The scatter plot (Fig. 4.13) displays the association between group PSR and proportion of animal prey in diet. The prevalence of cestode sp. #2 and large spirurids was also significantly and directly related with the prey proportion consumed by the hosts, also after excluding

Callicebus from the analyses (all host species: cestode sp. #2: rs=0.51, N=42, p=0.01; large spirurid: rs=0.441, N=42, p=0.003, all results see Appendix E). Other parasite prevalences are not correlated with the proportion of animal prey in the host’s diet.

6

5

4 Median group PSR group Median

3 Host species S. fuscicollis S. mystax C. cupreus 2 10 15 20 25 30 35 % animal prey in diet

Fig. 4.13 Relationship between median group PSR and proportion of animal prey in the hosts’ diet. Data is presented for all groups of the three host species.

76 Results

4.3.1.5 Home-range size The home-range size of mixed-species troop West was 29.25 ha, of which 25.46 ha were occupied by S. mystax and 28.47 ha by S. fuscicollis. Troop North was ranging in an area of 30.75 ha (S. mystax 30.04; S. fuscicollis 26.29). The largest area was held by troop East with totally 45.75 ha (S. mystax 39.58; S. fuscicollis 42.05). The Callicebus group Casa had the smallest home range of 6.46 ha, located within the home range of troop West (Fig.3.1). PSR was positively correlated with the home- range size of all host groups (Spearman rank correlation: rs=0.37; N=42, p=0.016, excluding Callicebus: rs=0.176; N=38, p=0.291). Fig. 4.14 depicts the relationship between group PSR and home-range size. The prevalence of large spirurids and the cestode sp. showed a positive relation with the home-range size (large spirurids: rs=0.31; N=42, p=0.046; cestode sp. #2: rs=0.388; N=42, p=0.011). When restricting the analyses to tamarins, no correlation remained significant (see Appendix G).

6

5

4 Median group PSR group Median

3 Host species S. fuscicollis S. mystax C. cupreus 2 10 20 30 40 Home-range size (ha)

Fig. 4.14 Relationship between median group PSR and home-range size. Data is presented for all groups of the three host species.

Results 77

4.3.1.6 Group size In S. mystax mean group size varied between 3.5 individuals in group West, 5.8 in group North and 6.7 in group East. Group size for S. fuscicollis did not vary that much (group North 4.9, group East 5.3, group West 5.4 individuals). Group size of the C. cupreus Casa with 3.8 individuals was comparable with S. mystax West.

PSR was not correlated with the mean host group size (Spearman rank correlation: rs=0.139; N=42, p=0.38, excluding Callicebus: rs=-0.085; N=38, p=0.612). The scatter plot shows the relationship between median PSR and mean size of the study host groups (Fig. 4.15). A positive correlation was found for cestode sp. #2 prevalence

(rs=0.480; N=42, p=0.001), which also remained significant when Callicebus was excluded (rs=0.381; N=38, p=0.018). When titi monkeys were removed from the analysis, group size scaled negatively with prevalence of Hymenolepis sp. (rs=-0.378; N=38, p=0.019). Other correlations were not significant (Appendix G).

6

5

4 Median group PSR group Median

3

Host species S. fuscicollis S. mystax C. cupreus 2 34567 Mean group size

Fig. 4.15 Relationship between median group PSR and mean group size. Data is presented for all groups of the three host species.

78 Results

4.3.1.7 Host density The host density of S. fuscicollis varied between 0.13 (East) and 0.19 individuals per ha (West, North). S. mystax had a similar density pattern: 0.14 (West), 0.17 (East) and 0.19 individuals per ha (North). The Callicebus group showed a higher density: 0.59 individuals were present per ha. Host density was not correlated with either PSR

(Spearman rank correlation: rs=-0.167; N=42, p=0.291, excluding Callicebus: rs=0.073; N=38, p=0.662) or with parasite prevalences (Appendix G). In Fig. 4.16 the group PSR is plotted against host density in all study groups.

6 Host species S. fuscicollis S. mystax C. cupreus

5

4 Median group PSR group Median

3

2 0,1 0,2 0,3 0,4 0,5 0,6 Host density

Fig. 4.16 Relationship between median group PSR and host density. Data is presented for all groups of the three host species.

Results 79

4.3.2 Host-extrinsic or habitat factors

4.3.2.1 Home ranges PSR varied between the host groups across the different home ranges (West, East, North, Casa, Puerto) but the differences were not significant in the overall model

(ANOVA all host species: F2,36=1.23, p=0.312, Saguinus: F2,32=1.24; p=0.306; Table 4.4 and 4.5). Nonetheless, in home range West both tamarin groups had a lower median PSR than in the North (Fig. 4.17). The median PSR in home range East for S. fuscicollis was the highest of all groups, but the median of S. mystax East was in between home range North and West. For C. cupreus there was also a difference in PSR over the two home ranges. The individuals from group Casa had a higher PSR than group Puerto.

8 Host species S. fuscicollis 7 S. mystax C. cupreus

6

5

4 Total PSR

3

2

1 West East North Casa Puerto Home range

Fig. 4.17 Total parasite species richness (PSR) per home range sorted by host species. The boxes show the interquartile ranges, bold horizontal bars show the median. The ends of the whiskers represent the largest and smallest values that are not outliers. The asterisks denote extreme values.

80 Results

The parasite prevalences showed home-range specific patterns. When considering the prevalences separately per host species, the prevalences of cestode sp. #2 and large spirurids varied significantly between the tamarin groups of the three home ranges (Fig. 4.18; extension of Fisher’s Exact test: large spirurids: S. fuscicollis p<0.048; S. mystax p=0.03; cestode sp. #2: S. fuscicollis p<0.035, S. mystax p=0.003). C. cupreus showed similar parasite prevalences over both home ranges (Fig.4.18). Combining the data of individuals of the mixed-species troops within the three home ranges West, East and North significant differences were detected for P. elegans, cestode sp. #2 and large spirurids (Fig. 4.19). In the mixed-species troop North P. elegans was not prevalent, whereas all other troops were infected with this parasite (Extension of Fisher’s Exact test: p=0.048). Cestode sp. #2 prevalence was lower in troop West than in the other troops (Extension of Fisher’s Exact test: p<0.001): in troop West two individuals out of a total of 12 individuals were infected, whereas in troop East 11 out of 15 individuals and North all 11 individuals were infected. Furthermore, differences in prevalence of large spirurids were significant (Extension of Fisher’s Exact test: p=0.027). In troop West none of the individuals harboured large spirurids, in troop East four out of 15 and in North 5 out of 11 hosts.

(A) Saguinus fuscicollis

100 ** SF West SF East 80 SF North

60

40 Prevalence in %

20

0 Pro Hym Cestode sm Spir lg Spir Nemlarv Strongy Parasite taxa

Results 81

(B) Saguinus mystax

100 ** * SM West SM East 80 SM North

60

40 Prevlence in%

20

0 Pro Hym Cestode sm Spir lg Spir Nemlarv Strongy Parasite taxa

(C) Callicebus cupreus

100 CC Casa CC West 80

60

40 Prevalence in %

20

0 Pro Hym Cestode sm Spir lg Spir Nemlarv Strongy Parasite taxa

Fig. 4.18 (A-C) Group prevalences for all parasite taxa per host species (Pro=Prosthenorchis elegans, Hym=Hymenolepis sp., Cestode=cestode sp. #2, smSpir=small spirurid, lgSpir=large spirurid, Nemlarva=Nematode larvae, Strongy=“strongylids”). Bars denote prevalence per parasite species for all groups per host species. Asterisks indicate statistical differences between groups. Extension of Fisher’s Exact test: *p≤ 0.05; **p≤ 0.01.

82 Results

Parasite prevalences for Saguinus mixed-species troops

100 *****

80

60

40 Prevalence in %

20 West East North 0 Pro Hym Cestode sm Spir lg Spir Nemlarv Strongy Parasite taxa

Fig. 4.19 Parasite prevalences for Saguinus mixed species troops (Pro=Prosthenorchis elegans, Hym=Hymenolepis sp., Cestode=cestode sp. #2, smSpir=small spirurid, lgSpir=large spirurid, Nemlarva=Nematode larvae, Strongy=“strongylids”). Bars denote prevalence per parasite species for individuals of mixed-species troops West, East and North. Asterisks indicate statistical differences between home ranges: Extension of Fisher’s Exact test: *p≤ 0.05; **p≤ 0.01, ***p≤ 0.001.

4.3.2.2 Habitat use The host’s use of the specific habitat characteristics is based on the habitat descriptions that were gathered at 426 sampling points equally distributed over all home ranges (West, East, North and Casa; for an overview see Appendix H). Data on habitat use of all primate groups considering the specific habitat characteristics are depicted in Fig 4.20 (A-G). Results of the correlations between PSR, prevalences and the specific habitat use are given in each section separately; statistical parameters are summarized in Table 4.8 and 4.9 at the end of this chapter. All analyses were repeated after excluding Callicebus in order to minimize the risk that the general pattern can be obscured by a non-representative data set of one host species. Small spirurids and “strongylids” did not show any variability and thus were excluded from these analyses.

Results 83

4.3.2.2.1 Drainage All groups ranged the vast majority of their time in areas with good drainage (Fig. 4.20 (A)). Areas characterized by poor drainage were used in around 20% of the time in case of groups West (S. mystax 24%, S. fuscicollis 21%) and Casa (19%); whereas groups East and North were found only in less than 8% of the cases in zones with poor drainage (East: S. mystax 6%, S. fuscicollis 5%; North: S. mystax 8%, S. fuscicollis 7%). There was no relationship between PSR and the use of poorly drained areas. The more time hosts spent in areas of poor drainage the less prevalent was the infection with cestode sp. #2 and large spirurids (Table 4.8). These relationships remained significant when removing Callicebus from the analyses (Table 4.9).

(A) Drainage

100 poor intermediate good 90

80

70

60

50

% of time % of 40

30

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20A Habitat use: drainage. Bars show percentage of time hosts spent in areas of specific drainage.

84 Results

4.3.2.2.2 Soil type Groups West and Casa ranged on clay soil in the majority of their time (Casa 66%, groups West around 52%); while groups North and East used sandy soil areas more often: groups East in more than 75%, and groups North in more than 68% of the cases (Fig. 4.20 (B)). PSR and cestode sp. #2 and large spirurids prevalence scaled negatively with the time hosts spent on clay soil (Table 4.8). When Callicebus was excluded the correlation with PSR was not significant, the other correlations remained significant (Table 4.9).

(B) Soil type

90 clay mixed sand swampy 80

70

60

50

40 % of time % of

30

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20B Habitat use: soil type. Bars show percentage of time hosts spent in areas of specific soil type.

Results 85

4.3.2.2.3 Ground inclination More than two thirds of their time all groups were found in areas that exhibited a flat ground profile (0-5%). Steep terrain of a slope of over 20% was used in less than 9% of their time (Fig. 4.20 (C)). PSR and the prevalences of cestode sp. #2 and large spirurids were positively associated with the use of flat terrain (Table 4.8). For P. elegans the trend was reversed when considering the tamarins only (Table 4.9).

(C) Ground inclination

100 flat intermediate steep 90

80

70

60

50

% of time % of 40

30

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20C Habitat use: ground inclination. Bars show percentage of time hosts spent in areas of specific ground inclination.

86 Results

4.3.2.2.4 Leaf litter height Groups West and Casa ranged around half of their time in areas dominated by scarce leaf litter (layer <5 cm): group Casa spent 56%, groups West around 47% of their time in such areas (Fig. 4.20 (D)). Groups East and North, in contrast, used mainly areas of high leaf litter (>10 cm): groups East in 53%, North S. mystax in 58%, S. fuscicollis in 61% of their time. PSR and prevalence of cestode sp. #2 and large spirurids showed a positive relationship with the time hosts stayed in areas with very abundant leaf litter (>10 cm). There was a negative correlation with P. elegans when Callicebus was removed from the analyses (see Table 4.8 and 4.9).

(D) Leaf litter height

60 0-5 cm 5-10 cm 10-15 cm >15 cm

50

40

30 % of time % of

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20D Habitat use: leaf litter height. Bars show percentage of time hosts spent in areas of specific leaf litter height.

Results 87

4.3.2.2.5 Deadwood abundance All groups ranged primarily in areas that were characterized by low abundance of deadwood (Fig. 4.20 (E)). Areas with higher deadwood abundance (≥1 deadwood unit) were visited in around 5% (groups East), 9% (groups North), 16% (groups East) and 34% (Casa) of the cases. PSR and the use of these areas were not correlated, but the prevalence of cestode sp. #2 scaled negatively with high deadwood abundance (Table 4.8). P. elegans manifested a trend for a positive correlation with the time the hosts spent in areas with high deadwood abundance when the analyses were restricted to tamarins (Table 4.9).

(E) Deadwood abundance

80 0 tree units 1 tree unit >1 tree unit 70

60

50

40 % of time % of 30

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20E Habitat use: deadwood abundance. Bars show percentage of time hosts spent in areas of specific deadwood abundance.

88 Results

4.3.2.2.6 Vegetation density The major part of the time was spent in areas with intermediate vegetation density characterized by an average of 400 to 800 trees (>10 cm DBH) per ha (Fig. 4.20 (F)). In all groups the least amount of time was spent in areas with tree density over 2000 trees/ha (1% in groups East, around 3% in group Casa, groups East, S. mystax North, and 8% in S. fuscicollis North). The time animals stayed in areas with dense vegetation (>1200 trees/ha) scaled significantly positively with PSR and prevalence of cestode sp. #2 and large spirurids (Table 4.8 and 4.9). The correlation with PSR was not significant anymore when excluding Callicebus. There was a trend for a weak negative correlation with prevalence of P. elegans.

(F) Vegetation density

60 0-400 trees/ha 400-800 800-1200 1200-2000 >2000

50

40

30 % of time % of

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20F Habitat use: vegetation density. Bars show percentage of time hosts spent in areas of specific vegetation density.

Results 89

4.3.2.2.7 Understorey density The proportion of time spent in areas with high understorey density varied between 17% (S. mystax West) and 28% (S. fuscicollis North) as depicted in Fig. 4.20 (G). Tamarin groups West and the Callicebus group spent more time in areas with lower understorey density (S. mystax 41%, S. fuscicollis 35%, C. cupreus 43%) compared to groups North and East (groups North 6%, East 16%). The use of areas with high understorey density did neither correlate with PSR nor with any parasite prevalence (Table 4.8). When Callicebus was excluded PSR and cestode sp. #2 prevalence had a trend for a weak positive correlation with time ranging in dense understorey (Table 4.9).

(G) Understorey density

70 low intermediate high 60

50

40

30 % of time % of

20

10

0 Cc Casa Sm West Sf West Sm East Sf East Sm North Sf North

Fig. 4.20G Habitat use: understorey density. Bars show percentage of time hosts spent in areas of specific understorey density.

90 Results

In summary, a positive correlation existed between prevalences of cestode sp. #2 and large spirurids and the host’s time spent on flat terrain, in areas of high vegetation density and high leaf litter abundance (Table 4.9). The relationship between cestode sp. #2 and large spirurids prevalence and time ranged on clay soil and in areas of poor drainage was negative (Table 4.9). The prevalence of P. elegans showed an opposite pattern: prevalence was higher when the hosts spent less time on flat terrain, in areas of high abundance of leaf litter and high vegetation density, while prevalence was higher when spending more time in areas of high deadwood abundance and clay soil. Prevalence of Hymenolepis sp. and nematode larvae did not correlate with any of the measured habitat parameters. Following the pattern of cestodes and large spirurids, the correlation between PSR and host’s time spent on plain terrain and in areas of a high leaf litter layer was positive.

Table 4.8 Spearman's Rank Correlation Coefficient (rs) for total PSR and prevalence for five parasite species and proportion of time that hosts spent in areas of specific habitat morphology; (*) p≤0.1, *p≤0.05; **p≤0.01, ***p≤0.001

All host species (N=42)

Time spent in specific poor clay soil flat terrain leaf litter ≥1 tree high dense habitat morphology/ drainage height ≥10 units vegetation under- Parasite infection cm deadwood density storey

PSR -0.331 -0.420** 0.519*** 0.519*** -0.257 0.379* 0.237

P. elegans 0.232 0.189 -0.275(*) -0.275(*) 0.195 -0.157 -0.072

Hymenolepis sp. -0.138 -0.114 0.170 0.170 0.070 0.178 0.134

Cestode sp. #2 -0.456** -0.512*** 0.665*** 0.665*** -0.544*** 0.488** 0.231

Large spirurid -0.354* -0.499*** 0.504*** 0.504*** -0.213 0.354* 0.048

Nematode larvae -0.070 -0.033 0.079 0.079 0.061 -0.023 0.210

Table 4.9 Spearman's Rank Correlation Coefficient (rs) for total PSR and prevalence for five parasite species and proportion of time that hosts spent in areas of specific habitat morphology; (*) p≤0.1, *p≤0.05; **p≤0.01, ***p≤0.001

Saguinus spp. (N=38)

Time spent in specific leaf litter ≥1 tree high dense poor habitat morphology/ clay soil flat terrain height ≥10 units vegetation under- drainage Parasite infection cm deadwood density storey

PSR -0.266 -0.241 0.371* 0.371* -0.035 0.191 0.284(*)

P. elegans 0.236 0.311(*) -0.412* -0.412* 0.318(*) -0.274(*) -0.072

Hymenolepis sp. -0.119 0.046 0.022 0.022 0.271 0.032 0.154

Cestode sp. #2 -0.371* -0.402* 0.594*** 0.594*** -0.442** 0.371* 0.291(*)

Large spirurid -0.315(*) -0.487** 0.493** 0.493** -0.149 0.315(*) 0.046

Nematode larvae -0.082 -0.082 0.136 0.136 0.027 0.016 0.202

Results 93

4.3.3 Seasonality

4.3.3.1 PSR and prevalences PSR did not differ significantly in dry and rainy season over all host species (Table 4.4 and 4.5). PSR did not follow a general pattern (Fig. 4.21): in S. fuscicollis PSR stayed the same over the seasons; in S. mystax it was higher, whereas in C. cupreus PSR was lower in the wet season. Prevalences of the seven parasite taxa showed no seasonal differences (McNemar: N=35 for all parasites; P. elegans: p=1.0, Hymenolepis sp. p=0.18, cestode sp. #2: p=1.0, small spirurids: p=1.0, large spirurids: p=0.219, nematode larvae: p=0.687, “Strongylids”: p=0.625).

7

6

5

4 PSR 3

2

species 1 S. fuscicollis S. mystax C. cupreus 0 dry wet Season

Fig. 4.21 Parasite species richness (PSR) per season. The boxes show the interquartile ranges, bold horizontal bars show the median. The ends of the whiskers represent the largest and smallest values that are not outliers.

94 Results

4.3.3.2 Climate During the study period mean rainfall ranged from 118 to 495 mm per month with peaks in precipitation in November 2002 and Mai 2003 (Fig. 4.22). The total annual precipitation was around 3460 mm (July 2002 to June 2003). The period between July and October 2002 (mean monthly rain fall 198 mm) and between July and September 2003 (mean 196 mm) was considered as core dry season. The core rainy season lasted from March to June 2003 (mean 376 mm). Mean minimum monthly temperature varied between 22.0 and 23.6°C and mean maximum temperature between 25.4 and 28.3°C (Fig. 4.22).

rainfall Tmin Tmax 30 600

28 500

26 400

24 300

22 200 Temperature in°C Temperature Monthly Rainfall in mm in Rainfall Monthly 20 100

18 0 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr Mai Jun Jul Aug Sep 02 02 02 02 02 02 02 03 03 03 03 03 03 03 03 03 Months

Fig. 4.22 Climate profile. Lines indicate mean minimal and maximal temperature per month (Tmin, Tmax), bars show mean monthly rainfall.

4.3.3.3 Phenology The abundance of ripe fruit and young leaves peaked at the end of the dry season and beginning of the rainy season (Fig. 4.23): 38% of the trees bore ripe fruits and 32% had formed new leaves at the study site. Until the end of rainy season fruit and leaf abundance dropped and reached the minimum level in the middle of the dry season (2% of trees with young leaves and 8% with ripe fruits). The variability in the abundance of flowers was not as high as in leaves and fruits. The abundance pattern

Results 95

of flowers showed an opposite pattern: it had its trough at the beginning of the rainy season (2%) and its maximum at the beginning of the dry season (15%). Food abundance of ripe fruits was higher in the rainy season than in the dry season (Fig. 4.24; t-test for dependent samples: t=7.19, df=3, p= 0.019).

0,40 800 rainfall 0,35 young leaves 700 flowers x 0,30 600 ripe fruits

0,25 500 m

0,20 400

0,15 300 Rainfallm in

Food Abundance Inde 0,10 200

0,05 100

0,00 0

03 03 03 r 03 p p ay e Nov 02 Dec 02 Jan 03 Feb 03 Mar A M Jun 03 July 03 Aug 03 S

Fig. 4.23 Phenology profile: food abundance index and rainfall. Lines indicate variation in food abundance for young leaves, flowers and ripe fruits; bars show mean monthly rainfall.

96 Results

0,5

0,4 *

0,3

0,2

0,1 Relative abundance of ripe fruit

0,0 rainy season dry season

Fig. 4.24 Comparison of relative abundance of ripe fruit in rainy and dry season. The boxes give interquartile ranges, bold horizontal bars give median. The ends of the whiskers represent the largest and smallest values that are not outliers. Asterisks indicate statistical differences between the seasons. T-test for dependent samples: *p≤ 0.05

4.3.3.4 Diet The proportion of animal prey in the host’s diet was slightly higher in the rainy than in the dry season in all groups except group West. Yet, differences were not significant (Wilcoxon’s test for matched pairs: Z=-1.521, N=7, p=0.128). The proportion of fruit was generally higher in wet than in dry season, except for the mixed-species troop in home range East. The results were not significant (Wilcoxon’s test for matched pairs: Z=-1.352, N=7, p=0.176).

4.4 Variation in egg and larvae output

In general, the number of parasite stages emitted in faeces was low regarding all host individuals over all seasons (Table 4.10). The highest parasite output was measured for small spirurids (mean egg output was 47.8 eggs per 100 µl), but for the other parasite taxa mean output was between 1.9 and 9.1 propagules per 100 µl.

Results 97

Table 4.10 Faecal egg and larvae output (refers to number of parasite stages per 100 µl faecal sediment). N gives the number of faecal samples that were positive for a specific parasite, SD the standard deviation, mean and maximum number of parasite stages per sample.

Parasite taxa Mean SD Maximum N

P. elegans 5.0 5.2 25 22

Hymenolepis sp. 9.1 14.1 59 49

Cestode sp. #2 4.6 6.7 28 41

Small spirurid 47.8 184.7 1860 215

Large spirurid 1.9 1.9 8 14

Nematode larvae 6.1 9.5 77 155

“Strongylids” 7.3 7.9 46 212

The results of the General Linear Mixed Model (GLMM) revealed that the effect of species and season and of the interaction between these two variables varied between the different parasite taxa (Table 4.11). For large spirurids, season had a significant effect on egg output. In the case of nematode larvae and “strongylid” egg output, the effect of the host species which shed the propagules was highly significant while season had no effect. For P. elegans and small spirurids, the interaction of species and season had a significant effect. For every parasite taxon the seasonal pattern in egg or larvae output is shown in Fig 4.25 (A-G). The results of the GLMM are displayed in Appendix I.

98 Results

Table 4.11 F values for main effects and interactions generated by GLMM for mean egg/larvae output; *p≤ 0.05; **p≤ 0.01, ***p≤0.001

Parasite taxa Host species Season Host species * season

P. elegans 0.08 0.53 34.48**

Hymenolepis sp. 0.04 2.11 1.05

Cestode sp. #2 0.90 1.45 1.67

Small spirurid 1.59 1.81 4.95 **

Large spirurid 0.42 5.10 * 1.46

Nematode larvae 10.07 *** 2.63 0.55

“Strongylids” 12.78 *** 2.35 0.27

S. fuscicollis excreted more P. elegans eggs in the rainy season than in the dry seasons (Fig. 4.25 (A)). For S. mystax the pattern was opposite. For S. fuscicollis only the difference from the first dry season to the rainy season was significant (t-test for dependent samples: tdry1 vs. rainy=-5.977, df=2, p=0.027, trainy vs. dry 2=9.639, df=1, p=0.066). For small spirurids the sample size for C. cupreus was very limited (N=1 for dry and rainy season, N=4 for rainy season), thus for further tests this host species was excluded. For Saguinus spp. no significant effect of host species and season was detected (Fig. 4.22 (B); species: F1,30.8=0.125, p=0.726; season: F2,52=2.029, p=0.142; season*species: F2,52=0.075, p=0.928). The egg output of large spirurids showed a peak in the rainy season (Fig. 4.25 (C)). But after removing S. mystax from the analyses (S. mystax had only two individuals that were present for dry and rainy season) the results for S. fuscicollis failed to be significant (t-test for dependent samples: tdry1 vs. rainy=-1.674, df=3, p=0.193, trainy vs. dry2=0.968, df=4, p=0.388). The nematode larvae output followed a host-specific pattern (Fig. 4.25 (D)): larvae output was significantly higher in S. fuscicollis than in S. mystax (t-test for independent samples: tSF vs SM=4.037, df=65, p≤0.001) and than in C. cupreus (tSF vs CC=4.008, df=38, p≤0.001). S. mystax excreted also more larvae than C. cupreus over all seasons but the results failed to be significant (tCC vs SM=1.832, df=35, p=0.075). The

Results 99

same pattern was found for the “strongylid” egg output: S. fuscicollis shed more eggs than S. mystax and C. cupreus, and C. cupreus had the lowest egg output of all host species over all seasons (Fig. 4.25 (E); t-test for independent samples: tSF vs

SM=3.297, df=67, p=0.002, tSF vs CC=3.369, df=37, p=0.002, tCC vs SM=1.553, df=36, p=0.129). For both cestode species the results from the GLMM showed no evidence for seasonal or host-specific effects on egg output (Table 4.11, Fig. 4.25 (F, G)).

(A) P. elegans

1,50 Host species S. fuscicollis S. mystax 1,25

1,00

0,75

0,50 log egg output P. elegans egg output P. log

0,25

0,00

dry season 1 rainy season dry season 2

100 Results

(B) Small spirurids

Host species S. fuscicollis 3 S. mystax C. cupreus

2

1 log egg output small spirurids egg output small log

0

dry season 1 rainy season dry season 2

(C) Large spirurids

1,00 Host species S. fuscicollis S. mystax

0,80

0,60

0,40

log egg output large spirurids large output egg log 0,20

0,00

dry season 1 rainy season dry season 2

Results 101

(D) Nematode larvae

Host species S. fuscicollis 1,5 S. mystax C. cupreus

1,0

0,5 log output nematode larvae nematode output log

0,0

dry season 1 rainy season dry season 2

(E) “Strongylids”

Host species S. fuscicollis 1,5 S. mystax C. cupreus

1,0

0,5 log egg output "strongylids" output egg log

0,0

dry season 1 rainy season dry season 2

102 Results

(F) Hymenolepis sp.

2,5 Host species S. fuscicollis S. mystax 2,0

1,5

1,0

log egg output Hymenolepis sp. egg output Hymenolepis log 0,5

0,0

dry season 1 rainy season dry season 2

(G) Cestode sp. #2

1,50 Host species S. fuscicollis S. mystax 1,25

1,00

0,75

0,50 log egg output cestode sp. #2 0,25

0,00

dry season 1 rainy season dry season 2

Fig. 4.25 (A-G) Mean egg/larvae output per season and host species. The boxes show interquartile ranges, the bold horizontal bars give the median. The end of the ‘whiskers’ represent the largest and smallest values that are not outliers or extreme values. The circles represent outliers.

Results 103

4.5 Post-mortem analyses

An adult female titi monkey of group Puerto was found in agony below the sleeping tree of its group. The day before, the individual showed an apathetic behaviour, an increased food uptake and a mild lameness. The female stayed distant to the other group members. In general it was less shy than on the other days of observation. The individual displayed convulsions and opisthotonus (i.e. spasm in which the back arches and the head bends back) shortly before the female died. Death occurred approximately two hours after retrieval. It weighed 720 g. Body condition of the animal was poor: it was skinny, dehydrated and its pelage was dirty. The animal was dissected immediately after death. Gross necropsy findings included severe multifocal subacute to chronic ulcerative enteritis and severe chronic granulomatous hepatitis. In detail the following observations were made.

4.5.1 Small and large intestine Two parasites with a length of 17 and 30 mm were firmly attached to the intestinal wall of the ileum by embedding their hooked proboscis into the mucosa and submucosa (Fig. 4.26). The parasites’ bodies were protruding into the intestinal lumen. The adult parasites were not pseudo-segmented and possessed a spheroid, spinous proboscis (Fig. 4.3). The anterior end had a collar of festoons. The proboscis was armed with six spiral rows each consisting of five to seven hooks. These morphological characteristics determined the species as P. elegans. At the site of attachment of the parasites a sharply delineated mucosal ulcer was present. The ulcers extended into the lamina submucosa and tunica serosa and were surrounded by connective tissue. Microscopically, the infection with P. elegans was associated with diffuse chronic enteritis. The ulcers were surrounded by necrotic debris, fibroblastic tissue and mixed inflammatory cell infiltration composed by neutrophils, eosinophils, lymphocytes and macrophages (Fig. 4.26). In rare sites scar tissue formation was represented by dense connective tissue extended to the serosal surface. Macroscopically, in the large intestine, several ulcers were visible, ranging from 1 to 4 mm in diameter. No parasites were found attached to those lesions.

104 Results

Histologically, severe multifocal chronic-active enteritis was evident; several subacute ulcers were demonstrable.

Fig. 4.26 Light microscope picture of an adult P. elegans in the small intestine of a female titi monkey. Cross section of the anterior end and proboscis of P. elegans which intrudes deeply into the intestinal wall provoking mixed inflammatory cell infiltration. H.&E. stain; scale bar = 1000 µm

4.5.2 Liver Macroscopically, disseminated red pintip-sized lesions were present on the diaphragmatic and visceral surface of the liver. Histology of the liver specimens revealed a severe chronic-active multifocal granulomatous hepatitis, characterized by multiple microgranulomas consisting of necrotic hepatocytes and inflammatory cells, especially lymphocytes, neutrophils and activated Kupffer cells. Multifocal fibrosis with focal calcification was evident in the centrolobular area. Further findings included focal gallstone formation and a mild chronic fibroblastic pericholangitis.

Results 105

4.5.3 Abdominal cavity A cyst of approximately 5 mm in diameter with a white, slender parasite was found retroperitoneally in the paramedian area of the abdominal cavity. Based on morphological features like ventral mouth with four hooks, striated muscles, and the structure of the body (Fig. 4.27) the parasite was identified as an or pentastomid nymph (phylum , order ). Sections of arthropods usually show some chitin structures that could not be detected here. Likewise pentastomid nymphs of the family Linguatulidae possess cuticular spines which were not demonstrable. Since the cyst was located at the inner side of the abdominal wall and spiny cuticles on the parasite’s body were missing, the diagnosis of arthropods and Linguatulidae seemed less likely. Combining the morphological features with findings in the literature, the parasite belongs probably to the pentastomid family Porocephalidae.

Fig. 4.27 Light microscope picture of an abdominal cyst of a female titi monkey. Cross section of a pentastomid nymph located in the centre of the abdominal cyst. Masson’s Trichrome stain; scale bar = 500 µm

106 Results

4.5.4 Further pathological findings There was moderate lymphoid depletion of the spleen with absence of follicular structures. The lung showed mild peripheral alveolar emphysema and mild alveolar histiocytosis. Mild focal lymphocytic infiltration was observed within the adrenal medulla. The sections of intestine, liver and spleen for bacteria and fungi gave negative results.

Discussion 107

5 DISCUSSION

Numerous parasitological studies have been carried out on intestinal parasites of wild primate species, especially on Old World primates (e.g. MCGREW et al. 1989a; APPLETON and BRAIN 1995; LANDSOUD-SOUKATE et al. 1995; MÜLLER-GRAF et al. 1996; HUFFMAN et al. 1997; MUNENE et al. 1998; KARERE and MUNENE 2002; CHAPMAN et al. 2005; GILLESPIE et al. 2005; MUEHLENBEIN 2005; PETRZELKOVA et al. 2006) but few studies have focused on wild New World monkeys (e.g. APPLETON and BOINSKI 1991; GILBERT 1994; STONER 1996; STUART et al. 1998; PACHECO et al. 2003; PHILLIPS et al. 2004).

To our knowledge, this is the first study on wild populations of sympatric primate species to shed light on a diverse array of ecological determinants of parasite species richness and prevalence. This study gathered baseline data on the intestinal helminth spectrum of Saguinus fuscicollis, Saguinus mystax and Callicebus cupreus, and examined various proposed host traits and environmental factors that can affect parasite diversity. In addition, the results are based on a consistent, year-round sampling regime and on standardized parasitological methods aimed at minimizing bias.

5.1 Methodological considerations

Parasitological studies based on non-invasive methods have some limitations but they are often the only feasible and responsible method for endangered or other wild host species (STUART and STRIER 1995). In the following, the emerging methodological problems of non-invasive faecal sampling in terms of the fixation employed, concentration technique and parasite identification will be discussed. There is also an evaluation of the reliability of the used disease metrics and the emerging bias.

5.1.1 Faecal sampling, fixation and concentration technique The faecal sampling regime is of great importance for measuring parasite species richness and prevalence (HUFFMAN et al. 1997; HUDSON et al. 2002). A systematic

108 Discussion

regime for the faecal sample collection was employed. This regime was based on three important aspects: firstly, all group members were sampled equally. Secondly, each host was sampled individually. Thirdly, samples of all hosts were collected on non-consecutive days for three times in each season. This multiple sampling method was validated by a study by MUEHLENBEIN (2005) and seems to reflect reliably the PSR and prevalences (see also 5.1.4.1.).

Both fixation (preservation agent and period) and concentration techniques have a major impact on recovery and identification of parasite stages in faeces (FOREYT 1986; ASH and ORIHEL 1987; DUSZYNSKI et al. 1999; MES 2003). In many field studies, including the present one, fixation of the faecal material prior to examination is inevitable. 10% neutral buffered formalin fixative was chosen because it provides several advantages over other fixatives:

(a) it adequately preserves helminth eggs/larvae and protozoan (oo-)cysts (ASH and ORIHEL 1987);

(b) it is a good long-term fixative even over a few years (ASH and ORIHEL 1987);

(c) for the performed formalin-ethyl acetate-sedimentation method, formalin fixation results in higher recovery rates than fixation with polyvinyl alcohol, for example (CARROLL et al. 1983).

(d) Less distortion of the stages is reported which accounts for a higher diagnostic efficiency (CARROLL et al. 1983).

Despite the reported general advantages of formalin fixation, there are more suitable fixatives for the conservation of specific parasites that can result in higher recovery rates or better parasite identification (e.g. 2-2.5% potassium dichromate solution for coccidian oocysts (DUSZYNSKI et al. 1999)).

Although formalin is suitable for long-term fixation, the parasite recovery rates decrease as a function of the preservation period: for nematode eggs the evaluated recovery rate dropped from 100 to 50% after 200 days of formalin fixation compared to fresh samples (FOREYT 1986). The long storage time of the faecal samples in this study (in some cases more than 24 months) could have caused a declining recovery

Discussion 109

of parasite stages. This in turn could have affected the sensitivity of the following concentration method (KRAEMER 2005). The long preservation period and the unspecific fixative might account for the failure to detect protozoa in the faecal samples of the studied hosts. However, many studies revealed a good recovery rate for protozoa for the same fixative and concentration method used in this study (YOUNG et al. 1979; GARCIA and SHIMIZU 1981; PRICE 1981; TRUANT et al. 1981) including New World primate hosts (HENDRICKS 1974; STUART et al. 1990; APPLETON et al. 1991). Yet, most studies did not report fixation periods prior to examination. Information on the length of preservation time would be desirable to improve comparisons between studies (especially on egg output) and to determine the influence of fixation period.

In order to detect even small numbers of parasitic stages in the faecal samples, it is indispensable to use a concentration procedure (ASH and ORIHEL 1987). The performed formalin-ethyl acetate-sedimentation technique in combination with formalin-fixed faecal samples is quoted as an excellent method for recovering protozoa and helminths (ASH and ORIHEL 1987). Ethyl acetate seems to facilitate the detection of some eggs (Hymenolepis and Taenia species), cysts (Giardia sp., Entamoeba sp.) and larvae (Strongyloides sp.), because they do not get trapped in the debris as much as if centrifuged with ether (YOUNG et al. 1979; ASH and ORIHEL 1987). The procedure of the formalin-ethyl acetate-sedimentation technique was followed consistently for all faecal samples. Diverging from the original method (ASH and ORIHEL 1987; ASH et al. 1994) two minor modifications were made to achieve a greater sensitivity and accuracy: firstly, in order to reduce the variance introduced by plant fibres or seeds in the faeces remnants, a polyamide sieve with standardized mesh size was used instead of two layers of wet gauze (see also chapter 5.3.3). The aim was also to raise the number of recovered parasites after the straining procedure thanks to the non-adhesive property of polyamide. Secondly, the centrifugation time was increased to 10 min because 5 min did not yield a sufficient concentration of the parasite stages in the sediment of the C. cupreus faeces.

It was not possible to determine the efficiency of the preservation method and concentration technique within the study because the faecal samples were too small

110 Discussion

to be split up into various sub-samples to compare the results of alternative methods. The precision of the microscopic examination was determined by an intra-observer reliability test (see chapter 3.4.4). The results concord very largely in the different examination processes of the parasitic stages. Evaluating the consistency of several observations of subsets of the same sample also validated the method: the concordance in the number of parasite stages counted over the different subsets showed that the amount of sediment examined and the homogenization of the samples was sufficient.

Evaluating the precision of this study compared to other studies presents several problems even when they are carried out on the same host-parasite system. In this case, data on prevalences or egg/larvae output on S. fuscicollis, S. mystax and C. cupreus based on faecal samples is very limited, the number of examined hosts is often small, the parasitological methods used diverge (fixation and concentration techniques, necropsy) and often rely on single sampling. Additionally, the data often combines results from animals of different groups or locations. Concerning the three host species studied, there is only one record of S. fuscicollis based on faecal sampling of four wild individuals in Peru (PHILLIPS et al. 2004). Two of them harboured strongylids, Trichuris sp. and one of them was infected with two protozoan taxa (Iodamoeba and Entamoeba). In the present study Trichuris and protozoan species were not detected, but strongylids had a higher prevalence (100%, all 17 individuals were infected). Other reports were based on necropsies of newly imported animals (DUNN 1963; COSGROVE et al. 1968; PORTER 1972; MICHAUD et al. 2003) which should render more exact results given the noticeable size of the adult parasites. The recovery rate of strongylid eggs in this study was consistently higher compared to other studies, even those that were based on large sample sizes and on necropsies: 9-78% in 455 S. fuscicollis (COSGROVE et al. 1968), 12-17% in 78 S. fuscicollis and 0% in 19 S. mystax (PORTER 1972), whereas this study found 100% strongylid prevalence for S. fuscicollis and S. mystax. The detection of these parasite eggs was very efficient although the size and the number of the excreted eggs were relatively small (median size 51-54 µm, mean number of six eggs per 100 µl sediment; see chapter 4.1.1, Table 4.2 and 4.10). Even very small eggs from

Discussion 111

small spirurids (median size 25-27 µm, see chapter 4.1.1, Table 4.2 and 4.10), which are probably one of the smallest intestinal helminth stages of New World primates, were recovered from 100% of the individuals of all host species. Thus, the methods employed in this study seem to yield very good results concerning the recovery rate particularly in comparison with other studies based on faecal sampling or necropsies.

In conclusion, in terms of faecal sampling, parasite fixation and concentration method the parasitological methods used yielded highly satisfying results for the helminths, including compared to other parasitological studies. It can be pointed out that the absence of intestinal protozoa is unlikely to be a consequence of methodological deficiencies. Only if the number of protozoan stages in the faeces at the time of defecation had been extremely low (and lower than in other studies) could the long storage time have lead to an undetectably low number of protozoan stages at the time of microscopic examination.

5.1.2 Helminth identification Exact helminth identification that is exclusively based on coprological examinations and the determination to the species level is limited without adult worms (STUART et al. 1998; GILLESPIE et al. 2004; 2005) or coproculture for nematode larvae (ASH and ORIHEL 1987; ASHFORD et al. 2000). Especially “strongylid” species represent a large group of parasites that generally cannot be differentiated by faecal examination (WARNICK 1992). The stage of development of parasite eggs or larvae at the time of conservation can vary with temperature and intestinal passage time which can further complicate parasite identification (ASH and ORIHEL 1987). Although belonging to the same parasite species, both the excreted eggs in the faeces and the adult worms may vary in size depending on the host species (FAUST 1967). An additional source of identification problems is the unanimity of parasite and host taxonomy. Typographical errors, ambiguous names and synonymy for parasite and host species, and wrong or incomplete host reports hamper parasite classification (DUNN 1968; FREELAND 1983; BRACK 1987; STUART et al. 1998). In many reports the origin of the host individuals remains obscure. Often little or no information is available on the origin of the host individuals (zoo or laboratory animal,

112 Discussion

wild captured or a pet), how much time or contact it had with humans prior to the parasitological examination or where the sample was taken. Parasitological reports often lack descriptions of sizes, life stages, characteristic morphological features and photographical documentation. Thus, the accurate identification especially for rare parasites in wild hosts is a challenging task. DUSZYNSKI and WILBER (1997) proposed guidelines for protozoa, the application of which would be desirable for reports on helminths as well.

The problems of helminth identification described in this study were tackled by exact measuring of a representative number of parasite stages and statistical analyses of their sizes, and by a detailed literature review. Yet, for future studies it would be desirable to apply molecular techniques to confirm morphological parasite identification.

5.1.3 Metrics of disease risk There are many different metrics used in epidemiological studies for measuring disease risk. Which metrics are the most relevant is a controversial issue and depends strongly on the aims and type of study, and on the respective host-parasite system. While some of the employed metrics (prevalence, PSR) rely on the presence or absence of the parasites in the hosts, others (egg/larvae output) rely on the exact number of parasite stages in the faecal samples (MARGOLIS et al. 1982; BUSH et al. 1997). This leads to a varying sensitivity of the metrics of disease risk.

Primarily, prevalence and PSR were chosen in this study because they are relatively robust metrics. Based on presence/absence data and multiple sampling of individually recognized hosts they represent valuable measures of disease risk. However, extrapolating the hosts’ disease risk from their PSR (also from prevalences) is difficult, as it bears the risk of underestimating the actual number of parasite species and neglecting their pathogenic potential. Particularly in non- invasive studies on wild host populations, if the determination of parasite species is based on morphological features, the number of encountered parasite morpho- species might not reflect the true number of parasite species (or what at that time is considered a “species”). Yet, PSR (e.g. KENNEDY et al. 1986; GUEGAN and

Discussion 113

KENNEDY 1993; FELIU et al. 1997; MORAND and HARVEY 2000; NUNN et al. 2003; VITONE et al. 2004; EZENWA et al. 2006) and prevalence (e.g. CÔTÉ and POULIN 1995; MÜLLER-GRAF et al. 1996; CHAPMAN et al. 2005; GILLESPIE et al. 2005; MUEHLENBEIN 2005) has been used in many meta- and field studies and these metrics often represent the only feasible measure of quantifying the disease risk to which the hosts are exposed.

Secondarily, egg or larvae output was taken as a surrogate measure for propagule excretion which represents a parameter of parasite transmission (FESTA-BIANCHET 1989; KAPEL et al. 2006). In many studies on primates, egg output is applied as a measure for parasite intensity (MÜLLER-GRAF et al. 1996; STONER 1996; CHAPMAN et al. 2005). However, there is little evidence that the number of parasite stages shed in the faeces is linearly correlated with the intensity of infection (ANDERSON and SCHAD 1985; WARNICK 1992; CABARET et al. 1998; BUSH et al. 2001). Egg output is considered a poor estimator of parasite intensity because the individual and temporal variability in parasite stage output can be very high. This is mainly due to several aspects of the parasite ecology: propagule shedding depends on the density of adult female worms at the same location within the host individual; some parasite species release eggs or larvae intermittently, and prepatent adults, larvae or adult males do not excrete propagules at all (ANDERSON and SCHAD 1985; WARNICK 1992; CABARET et al. 1998). Another source of high variability in egg output is the fixation and concentration technique (see 5.1.1) (FOREYT 1986; WARNICK 1992; MES 2003). The variation can be particularly high when the number of parasite stages in the faecal samples is low (KRAEMER 2005).

The present study was aimed at reducing the confounding effects on egg and larvae output resulting from fluctuations of undigested food components. The total number of specific parasite stages was referred to faecal sediment after the removal of feeding residuals instead of “original” faecal mass. The contribution of feeding residuals like seeds, plant fibres or other undigested food items to the original faecal mass is very variable in the study species, particularly since the hosts often swallow whole seeds (KNOGGE and HEYMANN 2003, TIRADO HERRERA, unpublished data). Since the amount of feeding residuals can vary seasonally, inter-specifically

114 Discussion

and individually it is necessary to control for this confounding effect. In order to cope with short-term fluctuation and variation resulting from some aspects of parasite ecology (e.g. intermittent egg release, prepatent periods) the mean number of helminth stages was derived from exactly three samples per individual per season.

In conclusion, for the purposes of this study PSR and prevalence are considered robust metrics to assess the disease risk. Egg or larvae output is seen as a variable for probability of parasite transmission but not as an indirect measure of parasite intensity. The detection of seasonal and host-specific patterns of parasite stage output seems reliable due to the improvements of the respective methods undertaken.

5.1.4 Avoiding bias In order to reduce selection, information and confounding bias, additional methodological improvements described in the following chapters were undertaken.

5.1.4.1 Selection bias In order to minimize the selection bias a systematic sampling method was employed: all group members were sampled individually on non-consecutive days three times in each season (see also 5.1.1). MUEHLENBEIN (2005) validated this serial sampling method and showed that it adequately determined the parasite species richness and prevalence. The sampling of individually identified hosts in this study ensures that prevalences are assessed accurately: prevalence refers in fact to the number of infected host individuals divided by the number of host individuals examined (sensu BUSH et al. 1997). HUFFMAN and colleagues (1997) underlined the risk of underestimating the infection rates when prevalence refers to the number of affected samples per number of all examined faecal samples as frequently calculated in studies on wild populations. It is also necessary to consider an equal number of faecal samples per host because the detection of parasites increases with the number of faecal samples examined (MUEHLENBEIN 2005).

Since one group of C. cupreus left the study area very soon after the onset of this study the obtained data for parasitological and ecological analyses for C. cupreus

Discussion 115

was based on a very small sample size. This might have lead to an underestimation of the parasite diversity and prevalence in C. cupreus based on the observation of just one group. Data on strata use, diet composition, home-range size and demographic parameters refer again to just one group. In order to circumvent possible misleading results due to a possibly unrepresentative sample size of C. cupreus all analyses were first performed including all host species and then excluding Callicebus. If the results were consistent over both analyses the detected pattern was considered to be more reliable.

5.1.4.2 Information bias The information bias that can arise during processing and measuring the samples was reduced by several means. First, standardised methods were used, and equal analysis conditions for all samples were achieved (same observer and technical equipment, especially the compound microscope and ocular micrometer). Second, all microscopic examinations were done in a blind test. Third, an intra-observer reliability test was performed in order to determine the degree of repeatability and precision of the microscopic examination. Finally, examination time and amount of sediment were limited for all samples in order to balance the sampling effort.

5.1.4.3 Confounding bias Since there are various confounding factors in complex host-parasite interaction in the tropics, the simultaneous examination of sympatric hosts represents a good approach to control for potential confounders such as climatic factors, predation pressure and food distribution. Particularly, both tamarin species occur in all three home ranges simultaneously, which allows us to draw conclusions about the influence of the host species independently from the influence of the home ranges.

A study based on three host species of which two are very closely related has to consider the confounding effect of phylogenetic relationship. Similarity in parasite diversity may be a consequence of similar ecological traits, but it can also be a product of a shared evolutionary history and shared traits inherited from a common ancestor. Several authors have pointed out the difficulties of studies on parasite diversity and their ecological determinants if the phylogenetic context is not

116 Discussion

considered (e.g. POULIN 1995a; GREGORY et al. 1996; MORAND and HARVEY 2000; NUNN et al. 2003; VITONE et al. 2004). However, the discussion on how far ecological or phylogenetic factors determine parasite diversity is not yet concluded (BUSH et al. 1990; BUSH et al. 2001; NUNN and ALTIZER 2006). Some authors underscore the dominant role of ecological factors including geographical association over phylogenetic traits (BUSH et al. 1990; LILE 1998; ROY 2001). Especially in less host-specific parasites, such as the intestinal helminths detected in this study, host ecology rather than phylogenetic background seems to shape parasite diversity (LILE 1998). Aware of the possible phylogenetic confounders, the associations between ecological traits and PSR/prevalence were examined separately: firstly including all host species and secondly only for the two closely related tamarin species. Future research extending on several groups of various species that are less closely related could provide deeper insights into the role of ecological and phylogenetic determinants.

5.2 Parasite diversity and host-intrinsic correlates

The present study was able to determine the intestinal helminth spectrum of S. fuscicollis, S. mystax and C. cupreus in the wild. Saguinus fuscicollis and S. mystax harboured the same seven intestinal helminth taxa, whereas C. cupreus harboured only three of them (four including the acanthocephalan parasite which was recovered in the necropsy).

No intestinal protozoa (oo-)cysts were detected in 84 samples of a representative subset of 28 host individuals. Besides the methodological concerns outlined above (chapter 5.1.1), the absence of intestinal protozoa infection can be a consequence of a low exposure risk of the host population in this study. Protozoan infection of Neotropical primates seems to be closely associated with infection in humans (KUNTZ and MYERS 1972; VITAZKOVA and WADE 2006). There is a big discrepancy between reports of intestinal protozoa in New World primates in captivity and in the wild. Reviews on possible protozoan species in captive primates are quite extensive (e.g. DUNN 1968; KUNTZ and MYERS 1972; KING 1976; GOZALO and TANTALEÁN 1996), while reports on wild New World primate hosts are rare - also in

Discussion 117

comparison to helminth parasites (e.g. HENDRICKS 1974; STUART et al. 1990; APPLETON and BOINSKI 1991; TOFT and EBERHARD 1998; DUSZYNSKI et al. 1999; PHILLIPS et al. 2004; CARMONA et al. 2005; VITAZKOVA and WADE 2006). To date, records of natural infection with intestinal protozoa in wild Callicebus and Saguinus include Chilomastix, Iodamoeba, Isospora and Entamoeba (HENDRICKS 1974; PHILLIPS et al. 2004). However, records cannot exclude anthropogenic influence because the primates were either purchased from local animal vendors (HENDRICKS 1974) or sampled at a National Reserve where human contact was fairly frequent (approximately 50 people per day visited the area (PHILLIPS et al. 2004)). The primates studied at EBQB are subject to minimal human disturbance: the primates have very limited contact with humans (research staff only, no direct contact) or human waste or faeces.

Knowledge of parasites’ life cycle is fundamental in order to examine the ecology of host-parasite interactions. Transmission modes and obligatory intermediate hosts especially are key factors for understanding parasite diversity. In this study at least five out of seven parasites have an indirect life cycle relying on arthropods or molluscs as intermediate hosts. Probably no recovered parasite taxon is transmitted by physical contact from one primate host to the other. Even the recovered, so-called directly transmitted parasites that do not rely on intermediate hosts are closely linked to environmental factors (nematode larvae and “strongylids”). These are soil- transmitted parasites that involve a free-living stage and develop into the infectious larvae in the soil over several days or weeks before they infect the next definitive host (FLYNN 1973; ASH and ORIHEL 1987; TOFT and EBERHARD 1998). Interestingly, all parasite taxa that are transmitted directly do not show a high variability in prevalence: nematode larvae and “strongylid” infection affects almost all members of all host species (nematode larvae: 90% S. mystax, 100% S. fuscicollis and C. cupreus, “strongylids”: 71% C. cupreus, which means five out of seven, 100% S. fuscicollis and S. mystax).

The parasite infection of S. mystax, S. fuscicollis and C. cupreus can pose an important risk to human health because these species are commonly kept as pet animals or used for food in rural areas of Peru and their parasites are potentially

118 Discussion

zoonotic (ORIHEL 1970; FLYNN 1973; MICHAUD et al. 2003). In combination with poor sanitation, deprived economic background and crowded housing with domestic animals, intestinal parasitism can present a serious public health problem (MICHAUD et al. 2003). The reported low host-specificity of the recovered parasite taxa and the close contact between the host species and the rural population can promote the transmission from primates to humans. Infection and the manifestation of clinical symptoms in humans are possible for all the parasites recovered, especially the directly transmitted parasites. It is recorded explicitly in the literature on the following recovered parasite taxa: Acanthocephala, various Hymenolepis sp., Gongylonema sp., Strongyloides sp. and Angiostrongylus costaricensis (ORIHEL 1970; FLYNN 1973; BRACK 1987; NEAFIE and MARTY 1993; MICHAUD et al. 2003).

5.2.1 Host species Although S. fuscicollis and S. mystax harboured the same parasite species, the manifested individual parasite species richness (PSR) and prevalences were different. On average, S. fuscicollis individuals were infected with one parasite species more than S. mystax. Prevalences of Prosthenorchis elegans, Hymenolepis sp. and large spirurids were consistently higher in S. fuscicollis than in S. mystax whereas the prevalence of cestode sp. #2 was higher in S. mystax. C. cupreus did not harbour these four parasite species. The other parasite species that all host species shared (small spirurids, strongylids, and nematode larvae) did not show variation: they infected almost all individuals in the respective groups. In terms of egg or larvae output, S. fuscicollis had consistently higher strongylid egg and nematode larvae output over all seasons than S. mystax and C. cupreus.

Since taxonomically related hosts are generally more prone to infections by the same parasite species spectrum (THOMAS et al. 1995; GREGORY et al. 1996; BUSH et al. 2001), it is not surprising that S. fuscicollis and S. mystax harboured the same seven parasite species. However, it is remarkable that two host species, which are phylogenetically as close as S. mystax and S. fuscicollis differ in all metrics of disease risk, namely individual PSR, prevalence and egg and larvae output of some parasites. Host specificity of the recovered parasite taxa is low, thus there was no

Discussion 119

reason to expect a different parasite pattern in the three host species. However, closely related host species are not necessarily infected with the same prevalence and intensity or show the same pathology when infected by the same parasite species (FREELAND 1983; THOMAS et al. 1995; LILE 1998; KAPEL et al. 2006). There is a variety of factors that may mediate the compatibility of hosts and parasites including ecology, physiology, immunity and genetics which can vary even between closely related species (FREELAND 1983; KENNEDY et al. 1986; LILE 1998; WHITTINGTON et al. 2000). THOMAS et al. (1995) showed that two closely related and sympatrically occurring host species (amphipods) experience a strongly contrasted parasite-induced mortality. Additionally, one parasite species infecting related hosts can vary in its reproductive capacity as measured by egg output (KAPEL et al. 2006). KAPEL et al. (2006) infected four natural host species of the same family (Canidae: wolves, dogs and relatives) with the same dose of Echinococcus multilocularis protoscolices. Subsequently, the parasite showed differences in life-history parameters between the hosts: life expectancy, daily fecundity, onset of reproduction and total reproductive capacity differed significantly. Although in the present study it cannot be determined whether the differences in egg output are due to a higher helminth reproduction (biotic potential) or a higher intensity per host individual, the results have epidemiological consequences. Given that sympatric host species can differ in their susceptibility to parasites, the host species that adds more infective stages of a given parasite to the shared pool of infective stages than the others increases the disease risk for the others. Thus, interspecific competition can operate indirectly by parasitism when the contribution to the disease risk is asymmetrical (HUDSON et al. 2006). The higher contribution of parasite stages by S. fuscicollis might also represent a cost of species coexistence for S. mystax and C. cupreus (FREELAND 1979; 1983; LOEHLE 1995).

In summary, the intestinal helminth spectrum differs between tamarins and titi monkeys. Both tamarin species share many morphological, behavioural and ecological traits which might cause their similarity in parasitism. Despite their phylogenetic relationship both tamarin species differ significantly in individual PSR,

120 Discussion

prevalence and egg output. This comparative study aims to detect ecological factors of the three host species that can cause the differences in patterns of parasitism.

5.2.2 Host sex In general, it is reported that parasite prevalence and intensity in mammals is higher in males than in females (POULIN 1996; ZUK and MCKEAN 1996; SCHALK and FORBES 1997; KLEIN 2000; HUDSON et al. 2002; MOORE and WILSON 2002). The hypothesis on male bias in parasite diversity and prevalence was not supported by the results of this study. In titi monkeys, the PSR and prevalence was similar for both sexes. In tamarins the females exhibited a higher degree of parasitism than males. In S. mystax, PSR was higher in females than in males and, on average, the females of both tamarin species had a higher prevalence of most parasite species. The female bias was most pronounced in the prevalence of P. elegans.

The majority of primatological studies failed to find evidence for sex-specific patterns (STUART et al. 1990; STONER 1993; GILBERT 1994; STONER 1996; STUART et al. 1998; SLEEMAN et al. 2000; ECKERT et al. 2006). Some studies found support for a male-biased parasitism for certain intestinal parasite taxa (PETTIFER 1984; MÜLLER-GRAF et al. 1997; GILLESPIE et al. 2005). Female-biased parasitism was only found in four primatological studies: female baboons had a higher egg output of a spirurid parasites (Streptopharagus sp.) than males (MÜLLER-GRAF et al. 1996). A study on De Brazza’s monkeys (Cercopithecus neglectus) revealed a higher prevalence of Balantidium coli and Strongyloides sp. in females (KARERE and MUNENE 2002). Female redtail guenons (Cercopithecus ascanius) harboured some parasite species (Strongyloides sp., Oesophagostomum sp.) that males did not harbour (GILLESPIE et al. 2004).

There are two possible principal reasons for the female bias in intestinal parasite infection in Saguinus: either female tamarins are more exposed or susceptible to parasites compared to male tamarins in this study population or the exposure risk or susceptibility of male tamarins is decreased compared to the majority of male mammals. In the case of the titi monkeys, the males and females might be equally exposed or susceptible to pathogens or males might experience a lower disease risk

Discussion 121

than other male mammals. The fact that P. elegans and other female biased parasite taxa are indirectly transmitted parasites puts more emphasis on the sex-specific differences related to food uptake or encounter with intermediate hosts (PETTIFER 1984; MÜLLER-GRAF et al. 1997). The elevated protein demands during the pregnancy and lactation might increase insect uptake and consequently the disease risk (GILLESPIE et al. 2004; 2005; NUNN and ALTIZER 2006). In fact, higher insect consumption during lactation was observed in a female titi monkey (TIRADO HERRERA and HEYMANN 2003). Differences in the endocrine-immune system or other circumstances that result in higher social or energetic stress for females compared to males could render females more susceptible to parasites (FESTA- BIANCHET 1989; ZUK and MCKEAN 1996; KLEIN and NELSON 1999; KLEIN 2000). Susceptibility of the females might be increased by an impaired immune function due to female’s progesterone and other pregnancy related hormones. The energetic demands and stress level might be further increased in tamarins because they give birth to heavy and rapidly developing twins (LÖTTKER et al. 2004b). Tamarins exhibit a polyandrous mating system characterized by a high investment in infant care by males (GARBER and LEIGH 1997; TARDIF et al. 1997). Cooperative infant care in callitrichids and also in titi monkeys means that males transport the young and that in the case of the callitrichids males also share food with them (BICCA-MARQUES et al. 2002; HUCK et al. 2004). These traits are unlikely to be compatible with selection on high, immune-compromising testosterone levels in males (ZUK 1990; FOLSTAD and KARTER 1992). The mating system of the tamarins is also characterized by a high reproductive skew in that only one female per group can reproduce. The female-female competition for the breeding position and competition for helpers in infant care might lead to higher stress levels in female tamarins compared to females in polygynous mating systems. Male mammals mostly live in polygynous mating systems and seem to suffer a higher exposure risk because of a larger body size associated with higher metabolic rate as compared to females (POULIN 1996; ZUK and MCKEAN 1996; HUDSON et al. 2002). Additionally, males usually exhibit costly ornaments or weapons mediated by high testosterone levels which could compromise the immune system (FOLSTAD and

122 Discussion

KARTER 1992). By contrast, male titi monkeys do not exhibit a larger body mass than females, and in tamarins sexual dimorphism is reversed: females are larger than males and develop larger, probably costlier scent glands and show higher frequencies of scent marking (HEYMANN 2000; BICCA-MARQUES et al. 2002; HEYMANN 2003b). Behavioural patterns which can increase the stress level or exposure risk either affect both sexes equally (e.g. territorial defence) or are rare (e.g. aggression within the group) (ROBINSON et al. 1987; GOLDIZEN 1989; HEYMANN 1996; GARBER 1997). Stress and parasite exposure due to dispersal after sexual maturation will also affect both sexes equally in tamarins and titi monkeys, where both males and females leave their natal group (BICCA-MARQUES et al. 2002; LÖTTKER et al. 2004a).

The female bias in parasite prevalences in tamarins might be related to specific characteristics of their mating system. Several aspects, including the larger body size, more pronounced scent glands and scent marking behaviour, higher female- female competition might account for the higher susceptibility or exposure of female tamarins compared to male tamarins or females in polygynous mating systems. These results allows us to assume that the male bias in parasitism known from polygynous mating systems is reversed in both polyandrous primate species (ZUK 1990; MOORE and WILSON 2002).

5.2.3 Strata use The strata use hypothesis, which states that with increasing time on the ground the hosts should have a higher PSR and prevalence, seemed to be supported by the data. PSR and prevalence of large spirurids, cestode sp. #2 and Hymenolepis sp. was higher in hosts that spent more time on the ground. NUNN et al. (2003) could not detect any effects of the host’s strata use on parasite diversity when comparing the data set of 101 primate species. In contrast, DUNN et al. (1968) found that in mammals of a Malayan rain forest including primates (Macaca, Nycticebus, Presbytis, Hylobates), the ground-living mammals had the highest prevalence of cestodes and very high prevalence of nematode parasites compared to mammals mainly using the canopy or intermediate strata. However, these authors argued that

Discussion 123

higher prevalences were associated rather with food preferences than with ground use. They pointed out that prevalence depends largely on the transmission mode of the parasites. The prediction of the present study was based on the assumption that ground contact would enhance the transmission of directly transmitted parasites that accumulate on the ground. This has to be interpreted cautiously because all directly, soil-transmitted parasites (strongylids, nematode larvae) had a prevalence of almost 100% across all host species (see chapter 4.3.1.1). This low variation in soil- transmitted parasites gives us to assume that these parasites colonize the three studied host species very efficiently. On the one hand, short periods of ground contact might be sufficient to infect the hosts: the infective larvae are highly motile and exhibit specific behaviours to locate appropriate hosts (HAWDON and HOTEZ 1996). On the other hand, the so-called soil-transmitted parasites might be less dependent on the actual soil for their development into the infective larvae: the microbes on which they feed might exist not only in the soil but also in detritus material of other forest strata that the primates have more frequent contact with (HAWDON and HOTEZ 1996).

All helminths of higher prevalences in the hosts that spent more time on the ground were indirectly transmitted. This gives us to assume that the stratification of intermediate hosts might be of greater importance rather than the actual contact of hosts with the ground.

5.2.4 Diet The data lends support to the diet hypothesis predicting that parasite richness and prevalences increase with higher proportion of animal prey. In this study PSR and prevalences of two indirectly transmitted parasite taxa (large spirurids and cestode sp. #2) scaled positively with the proportion of animal prey in the host’s diet. S. fuscicollis consumed the largest amount of animal prey over all seasons, followed by S. mystax and C. cupreus which was reflected in their PSR.

A meta-study on primate species showed that diet composition is an important predictor for PSR although the study focused on the proportion of leaves in the primates’ diet (VITONE et al. 2004). The amount of leaves in diet positively

124 Discussion

correlated with PSR which was explained by a larger body mass, higher food uptake per se and a higher probability of consumption of contaminated food. NUNN et al. (2003) did not find support for this hypothesis in anthropoid primates. They attributed these results to a high proportion of directly transmitted parasites in their data set which are decoupled from trophic transmission. A study of twelve mammal species in India did not find empirical support for the effect of diet on either parasite prevalence or propagule output (WATVE and SUKUMAR 1995).

The life cycle of many parasites is as yet poorly understood (STUART and STRIER 1995). Knowledge of intermediate host species of intestinal parasites is extremely scarce and often based on experimental infection. However, the spectrum of intermediate hosts available under natural conditions might be potentially underestimated in experimental studies. Indirectly transmitted parasite species which were recovered in this study require insects of the orders Lepidoptera, Coleoptera, Siphonaptera, or Dictyoptera to complete their life cycles. One parasite (nematode larvae) possibly needs molluscs (e.g. FLYNN 1973; SHADDUCK and PAKES 1978; BRACK 1987; POTKAY 1992; TOFT and EBERHARD 1998; ECKERT et al. 2005).

The studied host species were observed to prey on the majority of reported intermediate host taxa that are known for the detected parasites: the observed prey spectrum of the three host species included amphibians, arachnids (S. fuscicollis), Lepidoptera (only Saguinus), Dictyoptera (only by S. fuscicollis), Orthoptera, Hymenoptera (ants only S. mystax and Callicebus). These observations were in line with those of other research carried out at EBQB (NICKLE and HEYMANN 1996; HEYMANN et al. 2000; SMITH 2000). However, the same study groups were reported to feed on lepidopteran insects (Callicebus), dictyopterans (tamarins) and coleopterans (all three species) (NADJAFZADEH 2005). The most common prey items ingested by tamarins were insects of the order Orthoptera, mainly katydids, whereas C. cupreus consumed mainly insects of the order Hymenoptera represented by ants. Concerning prey diversity, the tamarins’ diversity on the level as regards species was highest in Orthoptera (NADJAFZADEH 2005). Of the two tamarin species, S. fuscicollis had a higher diversity of insect prey than S. mystax (NICKLE and HEYMANN 1996). C. cupreus showed a higher prey species diversity within the

Discussion 125

order Hymenoptera, Lepidoptera and Coleoptera (NADJAFZADEH 2005). While the number of harboured parasite species is considerably higher in both tamarin species (maximum PSR is seven in S. fuscicollis and six in S. mystax, see chapter 4.3.1.1) than in C. cupreus (maximum PSR is three), the proportion of animal prey does not differ so strongly (S. fuscicollis 25%, S. mystax 19%, C. cupreus 12%). Differences in the prey spectrum within the tamarin species might also account for the observed heterogeneity in parasite prevalences: whereas S. fuscicollis exhibits generally higher prevalences in indirectly transmitted parasites, S. mystax has a higher proportion of individuals infected with cestode sp. #2. Thus, for parasite diversity, the amount of animal prey, as well as the type and diversity of animal prey seem to play a fundamental role.

The observed prey taxa cover all orders of potential intermediate hosts of the recovered parasites except molluscs and fleas (Siphonaptera). This incongruity between observed prey taxa and known required intermediate hosts can be due to methodological problems: firstly, behavioural observations can be limited when feeding objects are small, feeding activity is rapid or the foraging occurs in relatively high forest strata. Some of the possible intermediate host taxa are minute and therefore ingestion is difficult to assess (e.g. more than half of the species of land snails are smaller than 5 mm (TATTERSFIELD 1996; TATTERSFIELD et al. 2001) or coleopterans harbouring P. elegans are around 3 mm (STUNKARD 1965b)). Similarly, the ingestion of tiny fleas, responsible for cestode transmission, is concealed to the observer’s view. These fleas could be ingested while grooming. Secondly, any research on diet spectrum based on coprological examinations or remains of insects dropped by the consumer is limited when prey items are wingless or highly digestible. The incongruity of the observed animal prey spectrum and intermediate host spectrum might be also associated with aspects of multi-host systems, for example by introduction of paratenic hosts. These hosts harbour infective stages, but parasites undergo neither development nor reproduction in these hosts. They are not obligatory for the completion of the life cycle, but may close ecological or trophic gaps (BUSH et al. 2001). If certain parasite species can resort to paratenic hosts the infection can be successful although the hosts do not ingest the

126 Discussion

known intermediate hosts for this specific parasite. In many host-parasite systems little is known about which species might serve as paratenic hosts and to which extent they are involved. Furthermore, since in the case of the mollusc-transmitted Angiostrongylus costaricensis the infection can also be elicited by ingestion of mucus contaminated plants, the primates need not eat the snails (SLY et al. 1982; BRACK 1987).

The differences in foraging strategy and foraging height which might expose them to different parasites or intermediate hosts might also account for the observed heterogeneities in PSR and prevalence between the three host species. S. mystax and C. cupreus scan their environment visually for prey and mostly capture exposed prey. S. fuscicollis manipulates substrates, enters hollow tree trunks and investigates leaf litter, capturing mainly concealed prey (NICKLE and HEYMANN 1996; HEYMANN and BUCHANAN-SMITH 2000; NADJAFZADEH 2005). S. mystax and C. cupreus forage mostly in lower and middle canopy strata, whereas S. fuscicollis forages in the understorey and on the ground (NICKLE and HEYMANN 1996; HEYMANN and BUCHANAN-SMITH 2000; NADJAFZADEH 2005). S. mystax and C. cupreus show great similarities in their foraging strategies, but they diverge essentially in their parasite diversity indicating that foraging strategies might account less for variation in parasite patterns than diet composition.

In summary, the general assumption that the amount of animal prey in the host’s diet correlates positively with parasite diversity and prevalence for indirect parasites can be supported. Nevertheless, given the scarcity of knowledge of potential intermediate and paratenic host species and possibly incomplete observations of the host’s animal prey consumption, conclusions as to the influence of host diet can only remain preliminary.

5.2.5 Home-range size Home-range size should be a strong predictor for PSR especially when focusing on indirect parasites. A larger home-range size was expected to translate into a higher PSR because of a larger sampled area and a higher encounter probability with a greater variety of intermediate hosts. In contrast, prevalence should increase in

Discussion 127

smaller areas because of constant infection and re-infection as a consequence of a higher accumulation of parasites and a repeated use of a confined area. The results of this study did not provide support for either of the predictions. PSR and the prevalence of large spirurids and cestode sp. #2 only scaled significantly and positively with home-range sizes when including all host species. The detected relationships between helminth diversity and home-range size do not appear very stable because they are based on analyses where one host species (Callicebus) is represented by a single group in the smallest home range of all study groups.

Some studies on fish (GUEGAN and KENNEDY 1993) and mammals (WATVE and SUKUMAR 1995) did not detect an influence of home-range size on PSR and prevalences, whereas NUNN et al. (2003) found a negative correlation between home-range size and helminth parasite richness in 101 anthropoid primate species. VITONE et al. (2004) found support for the positive association between helminth PSR and home-range size of 69 primate species when restricting the analyses to indirect parasites. Primatological field studies revealed a positive correlation between PSR and prevalence and home-range size for muriquis (Brachyteles arachnoides) in Brazil (STUART et al. 1993), but negative association between home-range size and parasite prevalence in red howling monkeys (Alouatta seniculus) (GILBERT 1994).

An important aspect which cannot be neglected when examining home-range size is host group size or density which can confound the results. Home-range size in this study is positively correlated with group size. Thus, the sampled area for the whole group increases, but since the group includes more members the probability of encountering infected intermediate hosts remains the same per capita. PSR or infection rates do not necessarily increase with larger home-range sizes if available host individuals increase in number or density. In a study on sympatric bovids the intestinal parasite richness and prevalence was positively associated with the degree of habitat overlap between the species (EZENWA 2003). The larger the home-range size the higher the probability of sharing the area with diverse other host species that can contribute to higher parasite diversity (LILE 1998). In this study the effect of actual overlap with hetero-specifics and conspecifics was not further determined because the adjacent Callicebus and Saguinus groups were not under routine

128 Discussion

observation. But it would be of great interest to investigate the correlation between home-range overlap with other primate species and additional host species transmitting generalist parasites, e.g. birds, rodents or other mammals.

In conclusion, the data does not lend support for the hypothesis that large home- range size is correlated with a high PSR and low parasite prevalences. Before drawing conclusions on the general effects of home-range size on parasite diversity studies need to be extended to a larger number of host groups and to host species with a larger variability in home-range sizes. It also appears essential to evaluate the importance of home-range size combined with aspects of host density, host group size and the degree of overlap with other species harbouring generalist parasites.

5.2.6 Group size and host density PSR and prevalence were expected to correlate positively with group size and host density. Since the contact rate between individual hosts is higher in larger groups with higher densities, the parasite transmission should increase. In this study the results did not support this hypothesis: PSR did not correlate with group size. When considering tamarin groups only, group size was positively associated with the prevalence of cestode sp. #2 but negatively with Hymenolepis sp.. Neither PSR nor prevalence was associated with host density.

Many cross-species analyses found a positive association between PSR and host density in mammals in general (MORAND and POULIN 1998; ARNEBERG 2002; POULIN and MOUILLOT 2004) and in primates (NUNN et al. 2003). However, another study on primates that examined the influence of host density on indirectly transmitted parasite diversity failed to find support for the group-size hypothesis (VITONE et al. 2004). Host group size was found to correlate positively with prevalence in birds, primates and insects (CÔTÉ and POULIN 1995) and with ectoparasites species richness in fish (BAGGE et al. 2004). In contrast, in sympatric bovids the influence of group size on species richness and prevalence of directly (soil) transmitted strongylids was not confirmed (EZENWA 2004a). Reports of these demographical effects on parasite diversity in primatological field studies diverge. Two sympatric colobine species (Piliocolobus tephrosceles and Colobus guereza)

Discussion 129

manifested the expected massive increment of Trichuris sp. prevalence after an increase in population size and density (CHAPMAN et al. 2005). But they showed the opposite pattern in the following study period: in one host species, prevalence decreased subsequently with increasing host density and group size; and the other species showed increasing prevalence although host density and group size declined. A study on muriquis (Brachyteles arachnoides) in Brazil revealed the highest PSR and prevalences in the largest population with the lowest population density (STUART et al. 1993). STONER (1993; 1996) found a higher prevalence in howler monkeys (Alouatta palliata) at a lower density compared to other howler populations (STUART et al. 1990). GILBERT (1994) found positive correlations with parasite prevalence and host density but no correlation with group size in Alouatta seniculus at a field site in the central Amazonian basin in Brazil.

In many cases, the studies that found evidence for the group-size and host-density hypothesis referred mainly to parasites transmitted by physical contact (CÔTÉ and POULIN 1995; ARNEBERG 2002) or were not analysed separately with regard to differences in the parasites’ life cycles (STUART et al. 1993; GILBERT 1994; STONER 1996; MORAND and POULIN 1998; NUNN et al. 2003; POULIN and MOUILLOT 2004). Studies that examined indirectly and soil-transmitted parasites did not provide support for these hypotheses (EZENWA 2004a; VITONE et al. 2004). Additionally, the results are often based on estimates of population density or size (STUART et al. 1993) or prevalence (STUART et al. 1993; GILBERT 1994; CHAPMAN et al. 2005) which can distort the actual correlation between prevalence and demographic parameters. In general it is difficult to control for confounding effects when comparing different field studies which employed diverging sampling and parasitological methods at different sites and in different seasons (see chapter 5.1.1.1).

As mentioned above, all recovered helminth taxa in this study are either indirectly or soil (directly) transmitted parasites which are expected to be less related to host traits than parasites transmitted by close physical contact between definitive hosts (ARNEBERG 2002; VITONE et al. 2004). Host group size and density does not seem to play an important role in this study because in general the contact frequency

130 Discussion

among the hosts does not influence the probability of infection with indirect parasites. One exception might be Hymenolepis sp. which can be transmitted by fleas during grooming activities. Yet, host density might even have an opposite effect on other indirectly transmitted parasites compared with directly transmitted ones. In groups with a high density, the per capita probability of ingesting infected prey would decrease faster than the proportion of infected prey of all available prey increases. Infection patterns of indirectly transmitted parasites may thus follow the encounter- dilution theory that was put forward for arthropod-borne or mobile parasites (DAVIES et al. 1991; CÔTÉ and POULIN 1995; NUNN and HEYMANN 2005). If the parasites are not host-specific, the transmission dynamics get even more complicated because the encounter then depends on the abundance of additional host or reservoir species (rodents, primates or other mammals) which can either reduce the disease risk (encounter reduction) or increase it (encounter augmentation) (EZENWA 2004a; KEESING et al. 2006). This aspect is important for S. mystax and S. fuscicollis because they live in very close association which is likely to influence the transmission patterns for shared parasite species.

Even for directly transmitted parasites the social organisation of the hosts might be more important than their actual number per area. BAGGE et al. (2004) argued that in highly aggregated species, dividing the number of host individuals by the area (in that study fish per pond) ignores the possibility that habitat use might be synchronized within the group members. The studied primate species live in stable and cohesive groups with very intense contact between all group members especially during social grooming (LÖTTKER et al. 2004a; LÖTTKER et al. 2007). Thus, the introduction of novel pathogens by immigrated, new group members is reduced and the spread of direct parasites should be even between the highly social hosts (CÔTÉ and POULIN 1995; EZENWA 2004a; NUNN and ALTIZER 2006).

In conclusion, for the host-parasite interaction studied here, demographic factors such as host group size or host density that can modulate contact frequencies play a subordinate role. The predominant helminth taxa (indirect and soil-transmitted parasites) seem to be less related to these definitive host characters.

Discussion 131

5.3 Parasite diversity and host-extrinsic correlates

The habitat influence is of paramount importance considering the fact that almost all intestinal parasites release their propagules into the environment (ECKERT 2000; BUSH et al. 2001). Especially indirectly transmitted parasites depend heavily on favourable conditions for intermediate hosts to complete their life cycle (LILE 1998; ARNEBERG 2002). All recovered helminth species in this study rely on environmental factors: they are either indirectly transmitted parasites which depend on the availability of intermediate hosts, or they are soil-transmitted parasites requiring appropriate environmental conditions for the successful completion of an often prolonged phase of external development (FLYNN 1973; ASH and ORIHEL 1987; TOFT and EBERHARD 1998). In this study, particularly the prevalences of P. elegans, cestode sp. #2 and large spirurids mirror the importance of host-extrinsic factors. Although the overall model did not detect a significant influence of home ranges (see chapter 4.3.2.1), PSR and prevalences varied between the different home ranges, independently from the host species occupying these areas. The lowest PSR was detected in hosts of home range West, while PSR of hosts in home range North and East was higher. The proportion of hosts infected with P. elegans was higher in home range West than in East and missing in North; whereas large spirurids were missing in West and in S. mystax of home range East. Cestode sp. #2 prevalences were low in West, higher in East and the highest in North.

Various studies on intestinal parasites of wild primates have emphasized the importance of environmental factors for parasite diversity, especially humidity and temperature (PETTIFER 1984; MCGREW et al. 1989b; STUART et al. 1990; STONER 1993; STUART et al. 1993; APPLETON and BRAIN 1995; MÜLLER-GRAF et al. 1996; STONER 1996; MÜLLER-GRAF et al. 1997). However, many studies detected a difference in parasitism over the studied groups as a by-product of the actual study and hypothesized that environmental factors might have caused this difference. To date, the present study is the first parasitological study on primates that focuses systematically on a diverse array of potential habitat factors proposed to shape parasite diversity in wild host populations.

132 Discussion

Concerning the methodology of habitat characterization, it has to be taken into account that some of the measured variables are not constant over the seasons, e.g. leaf litter height, ground humidity, understorey density. Leaf litter is especially subject to seasonal variation: it accumulates in the dry season (BOINSKI and FOWLER 1989). In this study, characterization was carried out in one season for all home ranges in order to control for seasonal confounders. Hence, the comparability of the habitat characteristics between the different home ranges should be robust although the habitat variables may change seasonally. The number and density of sampling points (426 points on 100 ha) was relatively high. The sample size of 40 to 60 needed to achieve good precision for all plot-less estimators is by far exceeded (KREBS 1999). Thus, the representation of the habitat characteristics should be relatively accurate. In order to obtain precise and comparable measurements the instructions were followed consistently throughout the whole study area. The methods were chosen with regard to the efficacy, practicability and time investment under field conditions. Although the method yields only estimates with regards to some habitat characteristics, the results can shed light on the relationship between parasitism and habitat use.

The frequency of use of the some habitat characteristics is highly correlated and therefore it is difficult to disentangle the respective influence on parasite diversity. The multicollinearity of the predictor variables is almost unavoidable in this observational study because the variables cannot be manipulated independently. The grouping of habitat characteristics into categories might also create higher correlations between the independent variables. Due to constraints imposed by the necessarily limited duration of the study and the number of habituated groups, it was not possible to collect data over a broader range or over various conditions in order to break up the multicollinearity. Since this is an exploratory study it is of great interest to examine the effects of a broad spectrum of habitat variables; simply eliminating collinear variables would not represent an adequate solution of the problem. Interpreting the detected correlations cautiously and considering important intercorrelations this approach will aid to identify factors that need to be incorporated in future studies.

Discussion 133

5.3.1 Ground humidity Parasite diversity and prevalence was predicted to increase with higher ground humidity. In this study, ground humidity, estimated by categorical measures of ground drainage, had a weak negative influence on parasite prevalence (cestode sp. #2). Therefore, the ground-humidity hypothesis was not supported by the data.

In general, low environmental humidity has a negative impact on the survival of parasite stages even on supposedly resistant parasite eggs such as those of Ascaris sp. (WHARTON 1979; ARENE 1986). When relative humidity was reduced to 75% all eggs collapsed after 8 days compared to less than 2% eggs that collapsed at 96% humidity (WHARTON 1979). Similarly, a number of primatological studies found higher prevalences and intensities of intestinal parasites in areas of higher humidity (MCGREW et al. 1989b; STUART et al. 1990; STUART et al. 1993; STONER 1996; LILLY et al. 2001). Sympatric gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes troglodytes) had higher prevalences of strongylids and ascarids in habitats characterized by large swampy areas and dense vegetation (LILLY et al. 2001). There were higher strongylid prevalences in howling monkeys (Alouatta fusca) from riverine groups than in those from dry forest groups (STUART et al. 1990). Similarly, a riverine troop of Alouatta palliata exhibited higher intensities than a forest troop (STONER 1996). Consistent with this pattern, muriquis (Brachyteles arachnoides) revealed higher prevalences in more humid areas (STUART et al. 1993). Baboons (Papio anubis and Papio papio) and chimpanzees (Pan troglodytes schweinfurthii) had a higher nematode prevalence at Gombe than at Mt. Assirik, the former region showing higher humidity, moister soils and milder temperatures than the latter (MCGREW et al. 1989b).

The conditions at the field site EBQB are described as very humid after the Holdridge system (GARBER 1988). The minimum rainfall per month over the whole study period was 118 mm and the total annual precipitation was over 3400 mm (see chapter 4.3.3.2). Even in the driest month (June 2002), there were no more than five consecutive days without rainfall. The humidity varies generally between 80 and 100%. The generally very moist conditions on the forest ground, further improved by shading vegetation, leaf litter and deadwood, therefore probably offered sufficiently

134 Discussion

favourable conditions for parasite development and survival. In regions where considerably dry and/or hot periods restrict the zones of parasite survival, areas that maintain constant humidity might be of greater importance (MCGREW et al. 1989b). In this study, the “poor drainage” category was characterized by a very moist environment including areas with stagnant water or muddy soil in at least three out of four sections. This very high moisture might exceed the optimum for most parasites. Other important resources for intermediate hosts like leaf litter might be limited. HAUSFATER and MEADE (1982) observed that on moist soils, a substantial part of the deposited parasite eggs were destroyed by fungi and other soil micro-organisms. Another important aspect of the present study is that in areas with very high ground humidity, the hosts do not come to the ground for foraging purposes which would be correlated with lower animal prey consumption as described above.

In summary, it is difficult to draw a final conclusion here as to the role of ground humidity on parasite diversity because the constant, very humid climatic conditions in the study area may already provide advantageous conditions for parasite development. In turn, extreme moisture might even bring about negative effects for external parasite stages.

5.3.2 Soil type The time that hosts spend on clay soil was expected to have a positive influence on parasite diversity and prevalence. The results of this study were contrary to the predictions: PSR and the prevalences of cestode sp. #2 and large spirurids were lower if hosts spent more time on clay soils.

Various studies of human parasites highlighting the importance of soil type for parasite prevalences revealed diverse and opposing results (AUGUSTINE and SMILLIE 1926; SORIANO et al. 2001; MABASO et al. 2003; PIERANGELI et al. 2003; SÁNCHEZ THEVENET et al. 2004; SAATHOFF et al. 2005a; SAATHOFF et al. 2005b). On sandy soils AUGUSTINE and SMILLIE (1926) detected a higher hookworm prevalence in children in Alabama. SAATHOFF et al. (2005a; 2005b) found a strong negative influence of clay soil on prevalence of hookworms, but a positive on Ascaris sp. prevalence in school children in South Africa. However, to our

Discussion 135

knowledge, the influence of soil type on primate parasites had not been studied previously.

The results of the studies mentioned above seem to indicate a different influence of soil type depending on the mobility of the parasite stages. It appears that clay soil provides advantageous conditions for immobile parasites (eggs) but disadvantageous conditions for mobile parasites (larvae). The compact structure of clay soils impedes the escape of mobile parasites from adverse environmental conditions, whereas immobile parasites are not washed out and survive better in clay soils (VINAYAK et al. 1979; MIZGAJASKA 1993; SAATHOFF et al. 2005a; SAATHOFF et al. 2005b). But in this study the parasite prevalences of mobile (larvae of strongylid and other nematodes) and immobile (all excreted eggs) parasites did not seem to depend on the clay soil conditions mentioned. The prevalences of parasites with mobile stages are not likely to depend on soil characteristics because they show high values over all primate groups no matter how frequent their use of clay or sand soil is (mean prevalence of strongylids is 94% and of nematode larvae 93%; see chapter 4.3.1.1). The negative influence of time on clay soil on prevalence of some helminths with immobile stages (large spirurids and cestode sp. #2) might be due to a different aspect. For the study groups the areas of clay soil coincided with steep slopes which in combination probably promotes horizontal washout of the parasite stages. Heavy, tropical rainfall can rinse them out to the creeks where they become unavailable for infection. The frequency of use of clay soils correlated negatively with the use of areas of a high abundance of leaf litter which can serve as important resources for intermediate hosts. This intercorrelation could account for the low parasite prevalences of large spirurids and cestodes in the study groups. The relatively impermeable texture of clay might also inhibit the passive access of parasite stages into deeper layers of the soil which would be essential for protection against adverse environmental conditions and parasite predators, e.g. dung beetles (FINCHER 1973; STOREY and PHILLIPS 1985; STROMBERG 1997; LARSEN and ROEPSTORFF 1999). Experimental studies observed the highest survival rates in Taenia eggs which were buried in the soil deeper than 10 cm (STOREY and PHILLIPS 1985). Especially, the impact of dung beetles on unprotected parasite

136 Discussion

stages is massive: they can destroy up to 35% of the eggs compared to areas without beetles (FINCHER 1973; HAUSFATER and MEADE 1982). At EBQB around 30% of the tamarin faeces were buried and probably preyed on by dung beetles (L. Culot, pers. comm.). Another adverse effect on parasite survival could be the limited aeration in clay soils (MABASO et al. 2003). For example LARSEN and ROEPSTORFF (1999) pointed out that a lack of oxygen reduces the viability of Ascaris eggs. Other important soil characteristics such as acidity, salinity, mineral and nutrient content was not considered in the present study. Laboratory experiments under defined soil conditions analysing a set of abiotic factors separately would enable us to determine their role for parasite diversity. To better understand the effects of soil type, it would be helpful to differentiate between mobile and immobile parasites in future studies. Finally, for indirectly transmitted parasites the soil type might play a subordinate role compared to the factors influencing intermediate host abundance.

5.3.3 Habitat morphology Habitat morphology was expected to influence parasite diversity by shaping the possibility of parasite stage accumulation in the host’s habitat. On even grounds the horizontal washout of parasite stages should be lower than on steep terrains so that parasites can accumulate and develop into infective stages. In agreement with the prediction, PSR and prevalence of cestode sp. #2 and large spirurid were higher in groups that used flat terrain more frequently. However, the use of flat terrain was also highly associated with the use of areas of high leaf litter layers and high deadwood abundance which complicates the interpretation of the data.

5.3.4 Resources for intermediate hosts The high abundance of resources for intermediate hosts, especially leaf litter and deadwood abundance, should translate into a higher PSR and prevalence of indirectly transmitted parasites. The present study found some evidence for the expected favourable effect of leaf litter: the use of zones with high leaf litter contributed to high PSR and high prevalence of two indirectly transmitted parasites

Discussion 137

(cestode sp. #2 and large spirurids). Yet, the prevalence of P. elegans showed an opposite pattern: it was negatively related to leaf litter height. The expected positive effect of deadwood was not confirmed: only cestode sp. #2 prevalence was significantly associated with the time spent in areas with high deadwood abundance, but the correlation was negative.

Leaf litter can have several positive effects on the abundance of parasites and intermediate hosts: it provides nutrients and shelter for a great variety of arthropods, and it can regulate microclimatic conditions (PFEIFFER 1996; DALY et al. 1998; SAYER 2006). Some studies revealed a positive correlation of leaf litter height and litter arthropod abundance (BULTMAN and UETZ 1984; FRITH and FRITH 1990). LASSAU et al. (2005) showed that diversity and abundance of beetles, the largest order of insects and important intermediate hosts, correlated positively with the amount of leaf litter. The higher abundance of intermediate hosts in areas with higher leaf litter layer could have led to higher prevalences in hosts that frequent these areas.

The prevalence of P. elegans did not seem to be influenced positively by deadwood abundance although most of the identified intermediate hosts (generally cockroaches and beetles) live on detritus material. Basic knowledge of the intermediate host spectrum of P. elegans is derived from experimental studies or studies on laboratory animals (STUNKARD 1965b; SCHMIDT 1972; KING 1993; GOZALO 2003). However, experimental studies cannot examine the wide array of potential intermediate host species that may be relevant in the wild. The studies focus on potential intermediate hosts that play a role in primate husbandry but might not even exist in a natural setting. Thus, probably many intermediate host species and their diverse ecological requirements are yet unknown. This complicates the identification of ecological factors in the host’s environment that drive transmission patterns for specific parasites.

Deadwood abundance, counter to expectations, did not influence parasite diversity. This might be due to the relatively rough method of estimating the abundance of deadwood which did not include its quality for potential intermediate hosts. First of all,

138 Discussion

an appropriate surrogate measurement for quantitative deadwood availability is considered the basal area of deadwood (GROVE 2002b). In the same study this parameter correlated strongly with beetle species richness and abundance (GROVE 2002b). Second, the method used in the present study did not include the following aspects of deadwood quality that are potentially relevant for intermediate host abundance: the degree of deadwood decomposition, the tree species, elevation of logs from the ground, the presence of bark and volume of coarse woody debris are also expected to have an influence on the arthropod composition (GROVE 2002a; b; KELLY and SAMWAYS 2003). In tropical areas young logs, elevated from the ground, with 80% of the bark remaining harboured the most species-rich arthropod community (KELLY and SAMWAYS 2003). The role of deadwood abundance on parasite diversity merits further exploration by means of more detailed descriptions of deadwood abundance and quality for intermediate hosts.

In summary, the present results indicate that the general pattern of intestinal helminth diversity can be linked to the abundance of resources for intermediate hosts. However, due to limited knowledge of the life cycles of most parasites and the requirements of their intermediate hosts it is difficult to predict infection patterns on a smaller scale. In order to examine the role of resources for parasite diversity on a larger scale, future studies need to focus on a larger number of host species harbouring various parasites that rely on identified intermediate hosts.

5.3.5 Vegetation density Denser vegetation was expected to offer more favourable conditions for excreted parasite stages and some taxa of intermediate hosts. Thus, hosts ranging more time in dense vegetation should harbour a greater variety of parasites with higher prevalences. In this study, high density of trees more than 10 cm DBH had a positive influence on helminth diversity and on the prevalences of two indirectly transmitted parasites, but correlated negatively with P. elegans prevalence. Understorey density, in contrast, was found to correlate weakly with PSR and prevalence of cestode sp. #2.

Discussion 139

Dense vegetation constitutes more favourable and stable microclimatic conditions for parasite stages in terms of humidity, temperature and protection from sunlight. A study on hookworm and Ascaris infection in South Africa revealed a strong positive association of prevalence and vegetation density (SAATHOFF et al. 2005a; SAATHOFF et al. 2005b). Several experiments have shown the detrimental effect of temperature increases, humidity loss and ultraviolet light on the fitness of parasite stages (WHARTON 1979; ARENE 1986; UDONSI and ATATA 1987). Relatively small changes in temperature or humidity due to forest gaps or lighted spots can reduce viability and infectivity of eggs and larvae. Even supposedly extremely resistant, thick-shelled parasite eggs are vulnerable to such changes (WHARTON 1979; ARENE 1986). Higher temperatures speed up development of the eggs but they have adverse effects on the parasites’ fitness: lower hatching rate, reduced survival, desiccation tolerance and penetration activity of the larvae (ARENE 1986). In the case of Ascaris eggs, temperatures of about 30°C decrease the survival rate by around 30% and the penetration ability by around 60% compared to eggs embryonated at 26°C (ARENE 1986). Reduced humidity significantly decreases the survival of parasite eggs (see chapter 5.3.1). A deleterious effect of ultraviolet light on parasite stages has been proposed by many authors (VINAYAK et al. 1979; STOREY and PHILLIPS 1985; LARSEN and ROEPSTORFF 1999; SAATHOFF et al. 2005a). UDONSI (1987) showed that after two days at a constant temperature (30°C), the survival rate of Necator americanus larvae in the shade was 40% higher than in the sunlight. Additionally, high vegetation density seems to foster the abundance of some intermediate host taxa: SHELLY (1988) found a higher abundance of Coleoptera, Formicidae and Psocoptera in dense, shaded vegetation than in gaps in lowland rainforest.

Surprisingly, the density of trees of more than 10 cm DBH had a significant effect on prevalence of cestode sp. #2 and large spirurids whereas density of the understorey (vegetation height less than three meters) did not. Two aspects of the method might have influenced this outcome. Firstly, the specific composition or characteristics of the vegetation were not determined in this study. This aspect might have a considerable impact on the abundance of some intermediate host taxa that are

140 Discussion

closely linked to certain qualities of the vegetation, e.g. leaf-eating insects (PATZ et al. 2000). Secondly, the method did not assess density quantitatively but by categories of visibility. The category “dense understorey” is characterized by very limited visibility which might be influential on the behaviour of the hosts. In areas with very poor visibility the studied primates rarely come to the ground. This is probably due to an increased risk of predation in habitats where the prey’s visual field is obscured and detection of approaching or hidden, terrestrial predators is more difficult (LAZARUS and SYMONDS 1992; COWLISHAW et al. 2004). In turn, if PSR and parasite prevalences are influenced by the time hosts spend on the ground, ground use might affect the underlying pattern more than the favourable conditions for parasites in dense understoreys.

Taken together, although not reflected in the overall model in this study, habitat characteristics seem to contribute to shaping assemblages of parasite communities particularly of indirectly transmitted parasites like large spirurids and cestode sp. #2. However, some parasite taxa (directly transmitted parasites and the small spirurids) did not seem to depend on the measured environmental factors. The prevalence of P. elegans, large spirurids and cestode sp. #2 showed a correlation with the use of specific areas. The higher the frequency of use of areas of high leaf litter abundance and dense vegetation the higher the prevalences. The use of clay soil and areas with poor drainage and high deadwood abundance were negatively correlated with helminth prevalences. It is unlikely that single habitat characteristics shape parasite diversity, and intercorrelations between various factors make it difficult to disentangle the effect of single habitat factors. Corresponding to the exploratory character of this study it has to be underlined that the results should be seen as preliminary. Studies on a broader array of parasite taxa, host species and habitat variables need to be conducted before a more generalized statement can be made about the impact of habitat characteristics on parasite diversity.

5.4 Seasonal variation in parasite diversity

Seasonally varying factors may operate on host-intrinsic and -extrinsic factors as well as on parasites themselves. Environmental factors like temperature and humidity are

Discussion 141

intimately linked with host-intrinsic factors that can modify the host’s susceptibility. However, environmental factors can also directly affect the viability of parasite stages outside their hosts and the abundance of intermediate hosts, thus increasing the infection risk of the hosts. This study focused on two aspects of seasonality: firstly, the increased exposure risk due to environmental factors that enhance parasite fitness (environment hypothesis); and secondly the increased host susceptibility due to a poorer nutritional status (nutritional-status hypothesis). Both hypotheses lead to diverging predictions: The environment hypothesis leads to the prediction that PSR and prevalence should increase in the rainy season due to increased survival of parasite stages. The nutritional status hypothesis predicts that PSR and prevalence should decrease in the rainy season due to higher food availability.

The results here indicate that PSR did not show a consistent seasonal pattern over all host species. The median PSR was lower in the rainy season for C. cupreus, but did not differ between the seasons in S. mystax and S. fuscicollis. The prevalence of all parasites was similar in the rainy and dry season. The egg output of large spirurids was significantly higher in the rainy season in both host species and the same was true for P. elegans, but only in S. fuscicollis. The observed seasonality in PSR of C. cupreus might be associated with a small sample size of C. cupreus due to the absence of group Puerto in the wet season. Only five individuals were sampled for both seasons. The seasonal variation in egg output of two parasite species was significant but relatively low: the mean egg output raised by two eggs per sample for large spirurids and P. elegans in the rainy compared to the dry season (see chapter 4.4). Comparable studies detected seasonal variations in egg output of two intestinal parasite species of chimpanzees, where mean egg production showed increases from under 50 propagules per 1 g faeces to over 200 (maximum 1000) after the onset of the rainy season (HUFFMAN et al. 1997). The variation in egg output observed in this study is so low that it is difficult to see a significant seasonal effect. Hence, the data provided very limited support for a seasonal pattern in PSR, prevalence and in propagule release.

Some primatological studies lend support for the hypothesis of seasonal variation in parasitism. ECKERT et al. (2006) detected a higher prevalence of nematode larvae

142 Discussion

in Alouatta pigra during the rainy season. Seasonal variability in egg output and prevalences was also evident in chimpanzees (Pan troglodytes schweinfurthii): prevalences of nematode larvae, Oesophagostomum sp. and egg output of Trichuris sp. and Oesophagostomum sp. was higher in the rainy than in the dry season (HUFFMAN et al. 1997). Baboons (Papio ursinus) exhibited higher intensities of a cestode (Bertiella studeri) and a nematode (Oesophagostomum bifurcum), but lower intensities of Trichostrongylus sp. during the rainy season (PETTIFER 1984). Many studies on intestinal parasites in primates did not find seasonal differences either in PSR, parasite prevalences or in egg output (MCGREW et al. 1989b; GILBERT 1994; MÜLLER-GRAF et al. 1997; GILLESPIE et al. 2004; 2005; VITAZKOVA and WADE 2006). The cited studies give a diverse picture of seasonal patterns in parasitism. Clear seasonal changes in prevalences, intensities or egg output were often limited to very few parasite species. Additionally, changes were observed at sites of very pronounced seasonality in terms of temperature and/or rainfall (PETTIFER 1984; HUFFMAN et al. 1997). The majority of the studies did not detect a consistent seasonal pattern.

5.4.1 Host susceptibility related to the nutritional status The nutritional status of wild primates can vary as a function of food availability and quality (GOLDIZEN et al. 1988; KOENIG et al. 1997). When ripe fruit was scarce free-ranging S. fuscicollis suffered a mean weight loss of 5.8% (range 0.5-13.5%) (GOLDIZEN et al. 1988). The phenological method employed in this study is most likely to reflect the seasonal changes of food abundance as a surrogate measure for the nutritional status of the hosts (CHAPMAN 1992; HEIDUCK 1997; STEVENSON et al. 1998). The results demonstrate that at the study site fruit availability is significantly higher in the rainy than in the dry season. Especially frugivorous primates like the three study species rely on the availability of ripe fruit to cover their energetic needs because they provide a rich source of simple sugar (RICHARD 1985; PERES 1994). However, insect consumption is also of importance because primates can supply their demand of proteins, fat, and essential minerals (RICHARD 1985). Animal prey abundance, namely arthropods and amphibians, was not

Discussion 143

determined in this study but is also expected to be higher in the rainy season (TANAKA and TANAKA 1982; PEARSON and DERR 1986; SHELLY 1988; FRITH and FRITH 1990; WATLING and DONNELLY 2002). The observed frequency of feeding on fruit or animal matter did not differ over the seasons across all primate groups although fruit and insect availability is supposed to be higher in the rainy season. Yet, primates do not have to invest as much energy in searching for food as in periods of food scarcity and they can select the best quality items.

Taken together, the overall nutritional status of the studied hosts should be better in the rainy season because of higher food availability. This should translate into better immune responses (BUNDY and GOLDEN 1987; HOLMES 1993; BEISEL 1996; COOP and HOLMES 1996; KOSKI and SCOTT 2001) and a lower PSR and lower parasite prevalences of the hosts.

The inferred better nutritional status in the rainy season does not coincide with lower PSR, prevalence or egg/larvae output. The lack of seasonality in PSR and prevalence in the study species might be due to a less pronounced immuno- supression in the dry season. The degree of malnutrition might be lower than expected because the primates can circumvent bottlenecks of fruit scarcity by shifting their diet to other food plants or components to fulfil their energy demands (PERES 1994). For example, tamarins can switch to Parkia sp. exudates or nectar of Symphonia sp. (PERES 1994; 2000) and titi monkeys to higher seed or leaf consumption (WRIGHT 1989; HEIDUCK 1997). Additionally, the phenological method can mirror a general pattern but single fruiting trees with an irregular fruiting pattern, e.g. Parkia sp., might represent significant resources to alleviate fruit scarcity (PERES 2000). And finally, the overall immune status might be less affected because energetically costly periods like gestation, lactation and infant-carrying fell into the period of maximum fruit availability (SOINI and SOINI 1990; LÖTTKER et al. 2004a).

5.4.2 Host exposure The viability of parasite stages is higher in moist and warm conditions (e.g. WHARTON 1979; UDONSI and ATATA 1987; BETHONY et al. 2006). Similarly, the abundance of arthropods and amphibians, important groups of intermediate hosts, is

144 Discussion

generally higher in warmer and more humid seasons (e.g. TANAKA and TANAKA 1982; PEARSON and DERR 1986; WATLING and DONNELLY 2002). Thus, the exposure risk for the hosts should be higher in the rainy season which in turn, should lead to a higher PSR and parasite prevalence of the hosts.

The climatic conditions at the field site are very humid as outlined above (see chapter 4.3.3.2 and 5.3.1). In addition the minimal temperature did not drop below 17°C (at night time during the few "cold" days of the year). These constantly warm and humid conditions seem not to significantly hinder parasite survival and development so that parasite exposure is similarly high over the seasons. Studies that detect seasonal patterns of infection dynamics were carried out at places where the climate shows pronounced hot and/or dry phases (PETTIFER 1984; HUFFMAN et al. 1997; ROEPSTORFF and MURRELL 1997; PIERANGELI et al. 2003). The expected beneficial influence of increased humidity in the rainy seasons might have had even opposite effects on the viability of excreted parasites stages. For example, parasite stages in the environment can equally be cleared away by heavy precipitations (NUNN and ALTIZER 2006) and the activity of egg destroying organisms is enhanced in humid and warm seasons (HAUSFATER and MEADE 1982; LARSEN and ROEPSTORFF 1999).

The postulated fluctuation of intermediate host abundance might also be a consequence of more marked seasonality (JANZEN and SCHOENER 1968). The dry season during the study period might not have led to such a negative impact on the arthropod abundance that parasites experienced a bottleneck of intermediate hosts. Seasonal arthropod abundance can diverge considerably from the general pattern because the arthropod taxa differ in their main food sources (BUSKIRK and BUSKIRK 1976; BOINSKI and FOWLER 1989; PINHEIRO et al. 2002). Herbivorous arthropod abundance is tied to young leaf occurrence, whereas detritivorous arthropods like collembolans, isopods and cockroaches peak when dead leaves are abundant (BUSKIRK and BUSKIRK 1976; BOINSKI and FOWLER 1989). Thus, a general abundance pattern of arthropod orders may be less relevant for the transmission of a specific parasite species which requires certain intermediate hosts to complete its life cycle. By contrast, high intermediate host abundance might also

Discussion 145

have a negative influence on PSR and prevalence. The abundance of arthropods can increase markedly in wet seasons, in terra firme forests up to 2.3 times (PEARSON and DERR 1986). Since parasite egg/larvae output and arthropod uptake by hosts do not increase considerably, but arthropod abundances increase in the wet season, the per capita probability of encountering infected intermediate hosts decreases in the wet season (encounter reduction) (KEESING et al. 2006). Thus, higher arthropod abundance might translate into a lower individual disease risk.

There are two aspects of parasite ecology that make it difficult to study seasonal effects on parasite exposure: Firstly, even if parasites suffered from deficient transmission pathways in the dry season they could bridge the temporary bottleneck of intermediate hosts by using paratenic hosts (BUSH et al. 2001). Secondly, parasite diversity would not reflect seasonal changes in exposure risk when the life span of the parasites is long enough to outlive the adverse effects of the seasons. Many human intestinal parasites that can also infect primates are known to have a life span or a persistence of infection of over one year up to 25 years, e.g. hookworms, Strongyloides stercoralis, Trichostrongylus spp., Hymenolepis nana (ASH and ORIHEL 1987; BETHONY et al. 2006). Once the infection is established and the host’s defences or self-medication do not expel the parasites, the effects of seasonally varying exposure risk might be less measurable in terms of PSR and prevalence.

In conclusion, the results indicate that in the studied populations the seasonal variation of parasite diversity is not pronounced. The examined aspects of seasonality, namely nutritional status and climatic conditions, might not affect host susceptibility and/or exposure, or parasite viability, in the way that seasonal variation in PSR, prevalences or egg/larvae output was detectable. The possibility cannot be excluded that both aspects have opposite effects which can outweigh each other.

5.5 Parasites and their impact on the host’s survival

It is difficult to measure the actual impact of parasites on the survival of wild hosts. Different metrics, namely parasite species richness (PSR) and prevalence in this

146 Discussion

study, aimed at evaluating the disease risk for host individuals or populations. While prevalence is related to the probability of infection for the host individuals, the number of different parasite species (PSR) is more strongly associated with the outcome of infection, the probability of morbidity or mortality (MORALES-MONTOR et al. 2004; CHAPMAN et al. 2005). However, the quantitative measurement of the number of parasite species does not necessarily reflect the actual pathogenic potential of the parasite assemblage. The potential pathogenicity of each single parasite species and their interactive effects should be taken into account when assessing the outcome of the infection and the impact on the host’s fitness. Infection with one highly virulent parasite species may have a more detrimental effect on the host than the infection with several other, less virulent parasite species. Evaluating parasite pathogenicity is particularly difficult because the manifestation of disease symptoms depends on the interaction of many host- and parasite-intrinsic factors (BUSH et al. 2001). Most insights into pathological impacts are obtained by laboratory studies in which hosts on the one hand might show more severe pathologies because of additional stress, crowding and lack of appropriate nutrition. On the other hand, hosts in captivity might present less severe pathologies because inter- and intraspecific competition for food resources is less than in the wild. Hence, the same parasite species might be almost non-virulent or can cause severe pathologies, depending on the conditions influencing host and parasite (BRACK 1987; TOFT and EBERHARD 1998). This can result in an enormous variation of the impact on host fitness and the regulation of host populations. In the following section the pathological alterations in the female titi monkey are discussed with regard to the impact of the detected parasites.

The adult female titi monkey did not show conspicuous behavioural alterations until one day before it died. On the last day it showed an apathetic behaviour and did not stay close to the other two group members as normally. Its nutritional status was poor; with 720 g the body weight was markedly below the range of mean adult body weight (adult C. cupreus female: 750-1000 g (SMITH and JUNGERS 1997; BICCA- MARQUES et al. 2002)). Parasites belonging to two different species were detected:

Discussion 147

adult acanthocephalan worms of the species Prosthenorchis elegans were recovered from the small intestine and a pentastomid nymph from the abdominal wall.

The major findings of the necropsy concerned alterations in the digestive system, liver, spleen and abdominal cavity. Severe multifocal subacute to chronic enteritis of the small and large intestine was diagnosed. Multiple ulcers affected severely all layers of the intestinal wall. Severest chronic lesions were associated with the presence of P. elegans, others resulted probably from former parasite attachments (KING 1993). Multifocal hepatitis with evidence of granuloma and necrosis accounts for an infectious aetiology. Agents capable of causing such hepatitis include viruses, bacteria, fungi and helminths (KELLY 1992; HERMANNS 1999). In the present case the test for bacteria, viruses and fungi gave negative results. In contrast, the centrolobular liver cell necrosis is usually characteristic for toxic degeneration (KELLY 1992; DAHME and WEISS 1999). Two explanations for the hepatitis seem possible: the hepatitis may have developed as a response to pathogen infection or as a consequence of toxins which stem from the digestive tract. Given that the gut barrier manifested functional disorders due to the parasitic ulcerative enteritis, enteric bacteria, their metabolites and toxins can pass the mucosal barrier and reach extra- intestinal sites, especially the liver via the portal stream (DAHME and WEISS 1999). Lymphoid depletion was observed in the spleen. Secondary follicles, representing activated lymphatic tissue, were not present. The spleen is an important organ for primary and secondary immune responses: the white pulp providing lymphocytes and plasma cells for cellular and humoral specific immune defence (DAHME and WEISS 1999). Lack of secondary follicles may account for reduced immune activity and hence an increased risk of infection.

The parasite recovered from the abdominal wall was probably a pentastomid nymph of the family Porocephalidae. Except for one genus, pentastomids are usually parasites of serpents including arboreal snakes such as boas (SELF and COSGROVE 1972; TOFT and EBERHARD 1998) and use mammals as intermediate hosts (NELSON et al. 1966; SELF and COSGROVE 1972). The two pentastomid genera Porocephalus (South America, Africa) and (cosmopolitan) infect a wide range of New World primate species (Callicebus caligatus, Cebus apella,

148 Discussion

Saimiri sciureus, Callimico goeldii, Saguinus fuscicollis and Saguinus nigricollis) (DUNN 1968; COSGROVE et al. 1970b; SELF and COSGROVE 1972; TOFT and EBERHARD 1998). Primates function as intermediate hosts and get infected orally through water and food contaminated with serpent faeces, nasal secretion or exuvia (SELF and COSGROVE 1968; COSGROVE et al. 1970b; SELF and COSGROVE 1972; TOFT and EBERHARD 1998). Eggs hatch in the gut, and the liberated larvae migrate to various tissues where they moult into nymphs. Snakes ingest pentastomid nymphs when they prey on primates or other infected mammals (SELF and COSGROVE 1972). The usual location of pentastome nymphs are lungs, liver, serosa and other tissues including the leptomeninx (NELSON et al. 1966; SELF and COSGROVE 1968). Inflammatory responses elicited by dead nymphs are of major pathological importance compared to the lesions induced by living nymphs (NELSON et al. 1966). In rare cases, fatal peritonitis is reported (SELF and COSGROVE 1972). In the present case, no signs of inflammation were observed.

In conclusion, the results of the necropsy and histopathological examinations suggest that the acute and chronic infection with P. elegans had a strong detrimental effect on the female titi monkey. The occurrence of ulcers, scar tissue and diffuse chronic enteritis associated with P. elegans reduced the digestive function of the intestine and affected the barrier function against intruding pathogens and toxins. Thus, in the present case infection with P. elegans had a massive and long-term impact on the host’s resource utilisation and the defence mechanisms in the digestive tract. The chronic parasitic infection with P. elegans could have even caused the death of its host due to severe hepatitis. The lymphoid depletion of the spleen may have impaired the immune status additionally. Parasite infection with pentastomids seems not to have caused any local inflammatory reactions or further impairment of health. Since insights into the pathological impacts of parasites on wild hosts are very difficult to obtain, even single cases like the one reported in this study can provide valuable information on how the parasites can damage the host’s tissues and organs. Furthermore, the detection of adult intestinal parasites enabled exact parasite identification and a positive match with the excreted eggs in faecal samples of other studied hosts.

Discussion 149

5.6 Conclusions

This study investigated the role of host-intrinsic traits and environmental factors for parasite species richness (PSR) and parasite prevalences of intestinal helminths of three sympatric New World primate species.

The host species represented an important predictor for PSR. Both tamarin species (Saguinus mystax and Saguinus fuscicollis) had a completely overlapping spectrum of intestinal parasites: they harboured all of the seven detected helminth taxa. Callicebus cupreus harboured only four taxa out of the seven recovered from the tamarins. Despite the overlapping spectrum of intestinal parasites in both tamarin species that are closely related, on average, individuals of S. fuscicollis were infected with a larger number of different parasite species (PSR), exhibited a larger proportion of individuals infected (prevalence) with Prosthenorchis elegans, Hymenolepis sp. and large spirurids, and excreted more eggs of “strongylids” and nematode larvae compared with individuals of S. mystax. Due to higher infection rates and higher egg/larvae output, S. fuscicollis added more infective stages to the shared pool of infective stages than S. mystax and therefore S. fuscicollis potentially increased the disease risk for the other sympatric species. This might also represent a cost of species coexistence.

The results suggest that the male-biased parasitism predominating in polygynous mating systems is reversed in the polyandrous tamarin species. The female bias in intestinal helminth prevalences in tamarins may be associated with specific characteristics related to the hosts’ mating system. Several aspects, including the larger body size and higher female-female competition might account for the higher susceptibility or exposure of female tamarins. Directions for future research need to include specific immunological and endocrine parameters in order to identify possible mechanisms for the observed female bias.

The results reinforce the idea that the spectrum and amount of animal prey play an important role for helminth diversity and prevalence for indirectly transmitted parasites. Nevertheless, given the scarcity of knowledge of potential intermediate and paratenic host species, conclusions on the influence of host diet can only be

150 Discussion

tentative. The effect of group size and host density did not seem to account for the heterogeneity in parasite infection patterns. Since most of the recovered parasite taxa were transmitted by intermediate hosts and therefore do not depend on the physical contact between the primates, these results are not surprising. Future studies need to incorporate information of the parasitic life cycles which should allow a more detailed view of the underlying transmission patterns.

PSR and parasite prevalences of three of the seven parasite taxa varied considerably over the three home ranges of the Saguinus species although the overall statistical model revealed no significant influence of the host’s home range. The prevalences of P. elegans, large spirurids and cestode sp. #2 were associated with the use of specific areas within the home ranges of the groups. The higher the frequency of use of areas with very abundant leaf litter and dense vegetation the higher the prevalences of large spirurids and cestode sp. #2. The time ranging on clay soil was negatively correlated with large spirurids and cestode sp. #2, and the use of areas of high deadwood abundance was negatively correlated with prevalences of the latter. P. elegans showed an opposite trend with respect to the use of the same habitat characteristics. Multiple habitat characteristics are likely to interact to affect parasite diversity. Multicollinearity between the frequencies with which various habitat factors were used made it difficult to disentangle the effects of single habitat variables. Corresponding to the exploratory character of this study it has to be underlined that the results can only be tentative.

No seasonal pattern was detected either in PSR, parasite prevalences or in egg and larvae output. The examined aspects of seasonality, namely the nutritional status and the climatic conditions, might not have affected the host’s susceptibility, exposure or parasite viability in the way that seasonal variation in PSR, prevalences or egg output was detectable. Additionally, the possibility cannot be excluded that both aspects have opposite effects outweighing each other: the expected favourable climatic conditions for parasite viability coincided with the positive effects of high food abundance that can booster the host’s immune system.

Discussion 151

The findings of the necropsy of the female titi monkey provided deeper insights into the parasites’ impact on the survival of wild hosts. The occurrence of ulcers, scar tissue in the small intestine and the diffuse chronic enteritis associated with P. elegans may have reduced the digestive function of the intestine and affected the barrier function against intruding pathogens and toxins. Thus, these results suggest that the infection with P. elegans had a massive and long-term impact on the host’s resource utilisation and the defence mechanisms in the digestive tract.

The standardized and improved parasitological methods (faecal sampling regime, concentration technique and microscopic examination) revealed highly satisfying results, also compared to other studies on wild hosts. Based on consistent methods and the critical use of metrics of disease risk the results are likely to precisely reflect patterns of parasitism of the three host species. In order to cope with problems arising in non-invasive surveys based on faecal sampling, parasite identification was based on exact measurement of a representative number of eggs and statistic analyses of parasite sizes combined with a comprehensive and detailed literature review of possible parasite species. The identification of the acanthocephalan species was possible due to the recovery of adult worms from a necropsied host. Yet, for future studies it would be desirable to apply molecular techniques for parasite identification to the species level.

The results of this study contributed to the understanding of host-parasite interactions. The study encompassed a wide array of host-intrinsic and environmental factors that are assumed to shape the assemblage of parasite communities. Since it focused on intestinal helminths of only few groups sympatric primate species the conclusions have to be drawn cautiously. However, it sheds light on the possible factors of parasite diversity and aids to put forward novel hypotheses.

152 Summary

6 SUMMARY

Britta Müller (2007)

Determinants of the diversity of intestinal parasite communities in sympatric New World primates (Saguinus mystax, Saguinus fuscicollis, Callicebus cupreus)

Parasites can exert an important impact on host population regulation in terms of reducing fecundity and/or survival of the host individuals. They can even provoke rapid declines of host populations or extinctions of host species. Thus, it is of basic and applied importance to accurately assess the patterns of parasitism in wild hosts. Using a comprehensive comparative approach, this is the first study that has systematically explored the role of a diverse array of host-intrinsic traits and environmental factors potentially affecting parasite diversity in sympatric wild primates. Furthermore, this non-invasive, year-round study provided baseline data on the intestinal parasite spectrum of three New World primate species (Saguinus mystax, Saguinus fuscicollis and Callicebus cupreus).

Multiple faecal samples on non-consecutive days were collected over a 15-month period from 45 individually recognized hosts of eight primate study groups at the Estación Biológica Quebrada Blanco (EBQB) field site in Peru. More than 430 faecal samples were processed by the formalin ethyl-acetate sedimentation technique and examined microscopically for propagules of helminths and protozoa. Parasite species richness (PSR), prevalence (proportion of infected hosts with a specific parasite) and egg or larva output were determined as metrics of disease risk. Data on activity patterns, ranging and group composition of the hosts was collected to explore the importance of the following host-intrinsic factors on parasitism: host sex, strata use, diet composition, nutritional status, home-range size, host density and group size. In order to elucidate host-extrinsic environmental factors that may shape parasite diversity, different habitat variables were measured, such as ground humidity, soil type, habitat morphology, resource distribution for intermediate hosts and vegetation

Summary 153

density. Seasonal fruit availability was assessed as a surrogate measure for the nutritional status, as this is assumed to influence the host’s defences against pathogens.

The parasitological methods (faecal sampling regime, adapted concentration technique and microscopic examination) revealed highly satisfying results, particularly in comparison to other parasitological studies on wild hosts. Seven different helminth taxa but no protozoa were detected. One acanthocephalan species (Prosthenorchis elegans), two cestode species (probably Hymenolepis cebidarum and unidentified cestode sp. #2), two Spirurida species (large spirurid: Gongylonema sp. or Trichospirura leptostoma, and a small unidentified spirurid), “strongylids” (Strongyloides sp. or Molineus sp.) and nematode larvae (Strongyloides, Filaroides or Angiostrongylus sp.) were recovered from the three host species. All parasite taxa of this study have a broad host spectrum and at least five out of seven parasites are transmitted by intermediate hosts which are mainly insects. Two parasite taxa were probably soil-transmitted parasites.

Both Saguinus species harboured all seven helminth taxa and had a completely overlapping spectrum of intestinal helminths. C. cupreus harboured only three taxa out of the seven taxa recovered from Saguinus (small spirurids, “strongylids” and nematode larvae). All host species were infected with at least three (Saguinus) or two parasite species (Callicebus). All three host species differed significantly in the number of different parasite species (PSR), with S. fuscicollis showing the highest, S. mystax intermediate and C. cupreus the lowest parasite diversity. This difference was also reflected at the level of prevalences of specific parasites (P. elegans, Hymenolepis sp. and large spirurids). Saguinus fuscicollis individuals also excreted more propagules of “strongylids” and nematode larvae. Females of both Saguinus species showed higher prevalences in most parasite taxa than males. This sex bias was not observed in C. cupreus. Host-intrinsic factors, such as the proportion of animal prey in diet or time spent on the ground were positively associated with PSR and prevalence of two parasite taxa. Other host-intrinsic factors such as group size, host density and home-range size did not seem to account for the heterogeneity in parasite infection patterns.

154 Summary

Over the three home ranges of both Saguinus species, PSR and prevalences of most indirectly transmitted parasite taxa varied considerably although the overall statistical model revealed no significant influence of the host’s home range on PSR and prevalences. The prevalences of P. elegans, large spirurids and cestode sp. #2 were associated with the use of specific areas within the home ranges of the groups. The higher the frequency of use of areas with very abundant leaf litter and dense vegetation the higher the prevalences of large spirurids and cestode sp. #2. The time animals ranged on clay soil was negatively correlated with large spirurids and cestode sp. #2, and the use of areas of high deadwood abundance was negatively correlated with prevalences of the latter. P. elegans showed an opposite trend with respect to the use of the same habitat characteristics.

No seasonal pattern was detected either in PSR, parasite prevalences or in egg and larvae output. Thus, in the present study the examined aspects of seasonality, namely the nutritional status and the climatic conditions, did not seem to have a measurable impact on the host’s susceptibility and/or parasite viability.

By means of standardized and improved methods, the critical use of metrics of disease risk and meticulous parasite identification, the results of this study are likely to accurately reflect patterns of parasitism. In order to characterize the role of host- intrinsic and host-extrinsic factors it is of major importance to take parasite ecology and in particular parasitic life cycle into account. The results of this study on three sympatric New World primate species suggest that host-intrinsic traits like sex, diet and strata use, as well as environmental factors (e.g. vegetation density, soil type, leaf litter and deadwood abundance) can shape the composition of intestinal parasite communities.

Zusammenfassung 155

7 ZUSAMMENFASSUNG (GERMAN SUMMARY)

Britta Müller (2007)

Determinanten der Diversität intestinaler Parasitengemeinschaften sympa- trischer Neuweltaffenspezies (Saguinus mystax, Saguinus fuscicollis, Callicebus cupreus).

Parasiten stellen wichtige ökologische und evolutionäre Faktoren dar. Sie können re- gulierend in die Entwicklung der Populationsdichte ihrer Wirte eingreifen, indem sie die Reproduktions- und/oder die Überlebensrate reduzieren. Sie können sogar zu dramatischen Einbrüchen der Wirtspopulation oder zum Aussterben einer Wirts- spezies führen. Daraus ergibt sich die ebenso zentrale wie grundlegende Bedeutung, die auftretenden Parasitenbefallsmuster und Wirt-Parasit-Interaktionen in Wildtier- populationen genauer zu untersuchen. Der hier angewandte vergleichende Ansatz ist der erste dieser Art, der systematisch und umfassend sowohl potenzielle wirtsspezifische Aspekte als auch Umweltfaktoren bei Primaten untersucht, welche bei der Zusammensetzung von intestinalen Parasitengemeinschaften eine Rolle spielen können. Darüber hinaus lieferte diese nicht-invasive ganzjährige Studie grundlegende Informationen zum intestinalen Parasitenspektrum der drei untersuchten wild lebenden Neuweltaffenspezies (Saguinus mystax, Saguinus fuscicollis und Callicebus cupreus).

Von insgesamt 45 Wirtstieren aus acht Gruppen wurden mehrmals Kotproben an nicht aufeinander folgenden Tagen an der Feldstation „Estación Biológica Quebrada Blanco“ (EBQB) in Peru gesammelt. Die Kotproben konnten den jeweiligen Wirtstieren eindeutig individuell zugeordnet werden. Über 430 Kotproben wurden mit dem Formalin-Ethylacetat-Sedimentations-Verfahren bearbeitet und mikroskopisch auf Parasitenstadien von Helminthen und Protozoen untersucht. Als Messgrößen für das Erkrankungsrisiko (disease risk) wurden Parasitenspeziesreichtum (Anzahl der unterschiedlichen Parasitenarten pro Wirt, PSR), Prävalenz (Anteil der infizierten Tiere an der Gesamtzahl der untersuchten Tiere, bedeutet hier aller

156 Zusammenfassung

Gruppenmitglieder) und Parasiteneier- beziehungsweise -larvenausscheidung herangezogen. Daten zum Verhalten der Wirtstiere, ihrer Gruppenzusammensetzung (Gruppengröße, Geschlechter- und Altersklassen-Verhältnis) und ihrer Habitatnutzung wurden aufgenommen, um den Einfluss folgender wirtsspezifischer Faktoren zu klären: Geschlecht, Aufenthaltshöhe im Wald, Ernährungs- zusammensetzung, Ernährungszustand, Streifgebietsgröße, Wirtsdichte sowie Grup- pengröße. Um die Bedeutung von Umweltfaktoren auf Parasitenbefall eingehender zu untersuchen, wurden verschiedene Habitatcharakteristika in den Streifgebieten der drei Primatenarten erfasst. Untersucht wurden die Bodenfeuchte, der Bodentyp, die Habitatmorphologie (Bodenneigung), die Verteilung der Ressourcen für mögliche Zwischenwirte (insbesondere Laubspreudichte und Totholzabundanz) und die Vegetationsdichte. Da im Rahmen dieser nicht-invasiven Studie der Ernährungszustand der Wirtstiere nicht direkt festgestellt werden konnte, wurde die saisonale Fruchtverfügbarkeit durch phänologische Untersuchung der spezifischen Fruchtbäume der drei Primatenarten ermittelt und als indirektes Maß für den Ernährungszustand der Wirte herangezogen.

Die parasitologischen Methoden (systematische Kotprobensammlung, modifizierte Konzentrationsmethode und mikroskopische Untersuchung) erwiesen sich als sehr effizient, besonders im Vergleich zu anderen parasitologischen Studien an Wild- tieren. Es wurden sieben verschiedene Helminthentaxa (eine Acanthocephala- Spezies, zwei Cestoda- und vier Nematoda-Taxa), und keine Protozoen gefunden. Die Taxa wurden wie folgt identifiziert: Prosthenorchis elegans (Acanthocephala), Hymenolepis sp. (wahrscheinlich Hymenolepis cebidarum) und eine nicht näher bestimmbare Zestoden sp. (eventuell Paratriotaenia sp., im Folgenden Zestoden sp. #2 genannt), zwei Spiruridentaxa („großer Spirurida“: Gongylonema sp. oder Trichospirura leptostoma; „kleiner Spirurida“ [nicht weiter bestimmbar]), “Strongyliden” (Strongyloides sp. oder Molineus sp.) und Nematodenlarven (Strongyloides, Filaroides oder Angiostrongylus sp.). Alle Parasitentaxa zeichnen sich durch ein breites Wirtsspektrum (polyxen) aus, wenigstens fünf von sieben Parasiten besitzen einen indirekten Entwicklungszyklus mit mindestens einem Wirtswechsel (heteroxen), wobei meist Insekten als Zwischenwirte dienen. Zwei

Zusammenfassung 157

Parasitentaxa sind so genannte „soil-transmitted parasites“, die sich zwar direkt entwickeln, aber auf eine verlängerte Phase in der Außenwelt (üblicherweise auf dem Boden) angewiesen sind.

Beide Saguinus-Spezies waren von sieben Parasitentaxa infiziert und überlappten vollkommen in ihrem Parasitenspektrum. Callicebus cupreus war mit drei Parasiten- arten infiziert, die mit denen der Saguinus-Arten identisch waren („kleine Spirurida“, “Strongyliden” und Nematodenlarven). Alle Wirtstiere waren mindestens mit zwei (bei C. cupreus) beziehungsweise drei Helminthenarten (bei Saguinus) befallen. Der PSR unterschied sich signifikant zwischen den drei Wirtsarten: S. fuscicollis wies den höchsten PSR auf, S. mystax einen mittleren und C. cupreus den geringsten PSR. Diese Rangfolge ergab sich besonders aus den erhöhten Prävalenzen für P. elegans, Hymenolepis sp. und „große Spirurida“ bei S. fuscicollis.

Die in zahlreichen Studien postulierte Hypothese der höheren Parasitenprävalenz bei männlichen Säugetieren wurde in dieser Studie nicht bestätigt. Die polyandrisch lebenden Saguinus-Weibchen zeigten im Durchschnitt eine höhere Prävalenz bei Magen-Darm-Parasiten als ihre männlichen Artgenossen. Die erwartete Tendenz für höhere Prävalenzen bei den Männchen wurde auch bei den monogamen C. cupreus nicht bestätigt. Da das vorherrschende Paarungssystem bei Säugetieren die Polygynie ist und sich daraus bestimmte Eigenschaften für die darin lebenden Männchen ergeben, ist es plausibel, dass die generellen Muster nicht unkritisch auf Säuger in monogamen oder polyandrischen Systemen übertragen werden dürfen. Besonders der fehlende (C. cupreus) beziehungsweise inverse (Saguinus) Geschlechtsdimorphismus und die geringere intrasexuelle Konkurrenz der Männchen könnten die fehlende männchenspezifische Tendenz in der Parasitenprävalenz erklären.

Als weitere wirtsspezifische Faktoren, die maßgeblich die Parasitendiversität beeinflussen können, stellten sich die Nahrungszusammensetzung (Anteil an tierischer Beute an der Gesamternährung) und die Aufenthaltshöhe im Wald (Bodenaufenthaltszeit) heraus. PSR und Prävalenz der Zestoden sp. #2 und „großen Spirurida“ korrelierten positiv mit dem Anteil an tierischer Beute und der

158 Zusammenfassung

Bodenaufenthaltszeit der Wirte. Mit zunehmendem Anteil tierischer Beute kann die Aufnahme von potenziellen Zwischenwirten in der Nahrung und daraus resultierend das Infektionsrisiko ansteigen. Gleiches gilt für verlängerte Bodenaufenthaltszeit, während derer Kontakt zu den dort häufiger akkumulierten Parasitenstadien möglich ist. Hierbei darf aber nicht unbeachtet bleiben, dass dieser grundlegende Erklärungsansatz für indirekt übertragene Parasiten weniger plausibel ist, da hier die Aufnahme von Zwischenwirten zur Infektion führt. Andere wirtsspezifische Faktoren, wie Streifgebietsgröße, Gruppengröße und Wirtsdichte zeigten keinen signifikanten Zusammenhang mit PSR und Parasitenprävalenz. Dies dürfte gleichfalls mit dem hohen Anteil an indirekt übertragenen Parasitenspezies zusammenhängen, die unabhängiger von Kontaktraten der Wirtstiere innerhalb einer Gruppe sind.

PSR und Parasitenprävalenz variierten erheblich zwischen den drei Streifgebieten (West, Ost, Nord) der Saguinus-Arten, obwohl sich diese Divergenzen nicht in den Ergebnissen des statistischen Modells widerspiegelten. Insbesondere die Prä- valenzen von „großen Spirurida“ und Zestoden sp. #2 korrelierten signifikant positiv mit der Nutzung von Streifgebietsanteilen, wo hohe Laubspreudichte (über 10 cm) und erhöhte Vegetationsdichte (dichtes Unterholz und Baumdichte über 1200 Bäume pro ha) vorherrschte. Diese Ergebnisse entsprechen den Vorhersagen der Hypothesen, da für höhere Vegetationsdichte günstigere Bedingungen für Parasitenstadien und für höhere Laubspreu mehr Ressourcen für potenzielle Zwischenwirte erwartet wurden. Die Prävalenzen von „großen Spirurida“ und Zestoden sp. #2 korrelierten signifikant negativ mit der Zeit, die sich die Wirte auf Tonböden aufhielten. Dieser Zusammenhang wurde auch in anderen Studien gefunden. Besondere Aspekte der Parasitenökologie, wie zum Beispiel die Mobilität der Parasitenstadien in verschiedenen Substraten sowie biochemische Eigenschaften des Bodens dürften hierbei eine Rolle spielen. Die Prävalenz der Zestoden sp. #2 korreliert negativ mit der Zeit, welche die Wirte in Arealen mit hoher Totholzabundanz verbrachten. Dieses unerwartete Ergebnis könnte auf andere, in dieser Studie nicht erfasster Variablen – wie zum Beispiel Degradierungszustand oder Rindenanteil des Totholzes - zurückzuführen sein. Die Prävalenz von P. elegans zeigte ein entgegengesetztes Muster in Bezug auf die oben genannten

Zusammenfassung 159

Habitatcharakteristika. Dies verdeutlicht, dass Erkenntnisse, die durch experimentelle Studien über Zwischenwirte gewonnen wurden, nicht ohne weiteres auf komplexe Ökosysteme übertragen werden können. Da die Nutzungsfrequenz der einzelnen Habitatcharakteristika stark korreliert, ist die Aussage zum Einfluss einzelner Variablen schwierig. Daher kann diese explorative Studie vor allem Hypothesen generierend wirken und Faktoren identifizieren, die in zukünftigen ökologisch- parasitologischen Studien Berücksichtigung finden sollten.

Ein saisonales Muster des PSR, der Prävalenzen und Parasitenstadienausschei- dung, wie es sich aus günstigeren Überlebensbedingungen für Parasitenstadien in der Regenzeit ergeben könnte, wurde nicht beobachtet. Ebenso wenig scheint sich der verschlechterte Ernährungszustand der Wirte in der Trockenzeit und die damit eventuell verbundene reduzierte Parasitenabwehr auf den Parasitenbefall auszuwirken. Vermutlich haben die saisonalen Einflüsse von Ernährungsstatus und klimatischen Bedingungen eine geringe Wirkung auf die Wirtsempfänglichkeit bezie- hungsweise auf das Expositionsrisiko in dem untersuchten Wirts-Parasiten-System, sodass sich Veränderungen kaum an den gewählten Variablen messen ließen. Es ist außerdem denkbar, dass sich die entgegengesetzten Effekte aufheben (besserer Abwehrstatus zu Zeiten der größeren Überlebenschancen der Parasiten).

Durch die konsequente Anwendung standardisierter und für diese Studie adaptierter parasitologischer Methoden und aufgrund des kritischen Gebrauchs der epidemio- logischen Maßzahlen und Messgrößen des „disease risk“, konnte diese Studie einen Beitrag dazu leisten, auftretende Muster von Parasitismus bei drei sympatrischen Neuweltprimatenarten zu identifizieren. Generell dürfen Aspekte der Parasiten- ökologie, insbesondere der Entwicklungszyklus und die möglichen Zwischenwirte, nicht unberücksichtigt bleiben, wenn die Bedeutung der wirts- und umweltspezi- fischen Faktoren auf Parasitendiversität ermittelt werden soll. Die Ergebnisse dieser vergleichenden parasitologischen Studie liefern Hinweise darauf, dass gleicher- maßen wirtsspezifische (Wirtsgeschlecht, Nahrungszusammensetzung, Aufenthalts- höhe), wie auch habitatspezifische Faktoren (Laubspreu-, Vegetationsdichte, Boden- typ, Totholzabundanz) Einfluss auf die Zusammensetzung von intestinalen Helmin- thengemeinschaften nehmen können.

160 Resumen

8 RESUMEN (SPANISH SUMMARY)

Britta Müller (2007)

Determinantes de la diversidad de comunidades de parásitos intestinales en primates simpátricos neotropicales (Saguinus mystax, Saguinus fuscicollis, Callicebus cupreus).

Los parásitos pueden tener un importante impacto sobre las poblaciones de huéspedes en libertad al reducir la fecundidad y/o la supervivencia de éstos. Los parásitos pueden incluso provocar la extinción completa de las especies afectadas. Es por lo tanto esencial, a nivel teórico y aplicado, examinar con precisión los patrones de parasitismo en huéspedes en libertad. Éste es el primer estudio que evalúa sistemáticamente el papel de una serie de factores intrínsicos de los huéspedes y ambientales que pueden afectar la diversidad de parásitos en primates silvestres a través de un enfoque comprensivo y comparativo. Este estudio no invasivo, efectuado durante un ciclo de un año, proporciona además informaciones básicas sobre el espectro de parásitos intestinales de tres especies de primates neotropicales (Saguinus mystax, Saguinus fuscicollis y Callicebus cupreus).

Se recogieron múltiples muestras fecales de 45 individuos en días no consecutivos durante 15 meses en la Estación Biológica Quebrada Blanco (EBQB) en Perú. Se analizaron más de 430 muestras por el método de sedimentación con formol y acetato de etilo y luego se examinaron microscópicamente para identificar los distintos estadios de helmintos y protozoos. Se tomaron medidas como la riqueza de especies de parásitos (PSR), la prevalencia (número de animales infectados por un cierto parásito comparado con el número total de animales examinados) y la eliminación de huevos y larvas para evaluar el riesgo de enfermedad (disease risk). Se recogieron datos de actividad, movimiento y composición de los grupos para estudiar la influencia de los siguientes factores intrínsicos de los huéspedes: sexo de los huéspedes, uso de estratos del bosque, composición de la dieta, estado nutricional, tamaño del área domiciliar (home range), densidad de huéspedes y

Resumen 161

tamaño del grupo. Para explorar factores extrínsecos o ambientales que pueden modificar la diversidad de parásitos, se midieron las siguientes variables del hábitat: humedad y tipo de suelo, morfología del hábitat (inclinación del terreno), distribución de los recursos para huéspedes intermedios (abundancia de hojarasca y de madera muerta). La estado nutricional puede afectar a las defensas contra los patógenos, y se midió indirectamente a través de la disponibilidad de frutas.

Los métodos parasitológicos (recogida sistemática de muestras fecales, técnica modificada de sedimentación, examen microscópico) brindaron resultados muy satisfactorios, especialmente en comparación con otros estudios parasitológicos de fauna silvestre. Se identificaron siete taxones de helmintos: una especie de acantocéfalo (Prosthenorchis elegans), dos especies de céstodos (una especie indeterminada: Cestoda sp. y otra, probablemente Hymenolepis cebidarum), dos especies de Spirurida (Gongylonema sp. o Trichospirura leptostoma; y una especie indeterminada), “strongylids” (Strongyloides sp. o Molineus sp.) y larvas de nematodos (Strongyloides, Filaroides o Angiostrongylus sp.). Todos los parásitos encontrados tenían un espectro de huéspedes muy amplio y por lo menos cinco de los siete son transmitidos por huéspedes intermedios, sobre todo insectos. Dos taxones se transmiten a través del suelo (soil-transmitted).

Ambas especies de Saguinus hospedaron siete taxones de parásitos intestinales. C. cupreus hospedó únicamente tres de las siete especies halladas en Saguinus. Todas las especies huéspedes presentan distintas PSR. S. fuscicollis mostró la más alta PSR, seguido por S. mystax y C. cupreus. Esta diferencia se mostró igualmente en la prevalencia de P. elegans, Hymenolepis sp. y Cestoda sp..

Las hembras de Saguinus presentaron una prevalencia de parásitos en promedio más alta que los machos conespecíficos. Factores como la proporción de presa animal en la dieta y el tiempo pasado en el suelo correlacionan positivamente con la PSR y la prevalencia de dos de los parásitos. En cuanto a los factores ambientales, la frecuencia de uso de áreas con abundante hojarasca y vegetación densa influyó positivamente la prevalencia de dos parásitos. Sin embargo, el uso de un hábitat de suelo arcilloso y madera muerta abundante disminuyó la prevalencia de esos

162 Resumen

mismos parásitos. No se pudo detectar variabilidad estacional ni en la PSR, ni en la prevalencia ni en la excreción de huevos o larvas. Por lo tanto, ni el cambio de la disponibilidad de los frutos (que altera el estado físico y las defensas), ni el cambio de las condiciones climáticas (que probablemente modifica la viabilidad de los parásitos) parecen influir en las variables medidas de disease risk en este estudio.

Mediante el empleo de métodos mejorados y estandardizados, el uso de las medidas del disease risk de forma crítica y la meticulosa identificación morfológica de los parásitos, el presente estudio ayuda a elucidar los patrones de parasitismo en los tres primates neotropicales estudiados. Para caracterizar el papel de los factores ambientales e intrínsicos de los huéspedes es de gran importancia tener en cuenta la ecología de los parásitos, en particular su ciclo de vida. Los resultados de este estudio sobre los parásitos intestinales de tres especies de primates sugieren que factores intrínsicos de los huéspedes como sexo, dieta y uso de los estratos del bosque, junto con factores ambientales tales como la densidad de vegetación, tipo de suelo, abundancia de hojarasca y madera muerta, pueden influir la composición de las comunidades de parásitos.

References 163

9 REFERENCES

ALTIZER, S., C. NUNN, P. H. THRALL, J. L. GITTLEMAN, J. ANTONOVICS, A. A. CUNNINGHAM, A. DOBSON, V. EZENWA, K. E. JONES, A. B. PEDERSEN, M. POSS and J. R. C. PULLIAM (2003): Social organization and disease risk in mammals: Integrating theory and empirical studies. Annu. Rev. Ecol. Syst. 34, 517-547

ANDERSON, R. C. (2000): Nematode parasites of vertebrates-their development and transmission. 2. edn., CABI Publishing, Wallingford (vol. 1)

ANDERSON, R. M., and G. A. SCHAD (1985): Hookworm burdens and faecal egg counts: an analysis of the biological basis of variation. T. Roy. Soc. Trop. Med. H. 79, 812-825

ANDERSON, R. M., and R. M. MAY (1991): A framework for discussion the population biology of infectious diseases. in: R. M. ANDERSON, and R. M. MAY (eds.): Infectious diseases of humans: dynamics and control. Oxford University Press, Oxford, pp. 13-23

APPLETON, C. C., and S. BOINSKI (1991): A preliminary parasitological analysis of fecal samples from a wild population of Costa Rican squirrel monkey (Saimiri oerstedi). J. Med. Primatol. 20, 402-403

APPLETON, C. C., and C. BRAIN (1995): Gastro-intestinal parasites of Papio cynocephalus ursinus living in the central Namib desert, Namibia. Afr. J. Ecol. 33, 257-265

APPLETON, C. C., S. P. HENZI and S. I. WHITEHEAD (1991): Gastro-intestinal helminth parasites of chacma baboon, Papio cynocephalus ursinus, from the coastal lowlands of Zululand, South Africa. Afr. J. Ecol. 29, 149-156

AQUINO, R., and F. ENCARNACIÓN (1994): Primates of Peru. Primate Rep. 40, 1-130

ARENE, F. O. I. (1986): Ascaris suum - influence of embryonation temperature on the viability of the infective larva. J. Therm. Biol. 11, 9-15

ARNEBERG, P. (2002): Host population density and body mass as determinants of species richness in parasite communities: comparative analyses of directly transmitted nematodes of mammals. Ecography 25, 88-94

ASH, L. R., and T. C. ORIHEL (1987): Parasites: a guide to laboratory procedures and identification. American Society of Clinical Pathologists Press, Chicago

ASH, L. R., T. C. ORIHEL and L. SAVIOLI (1994): Bench aids for the diagnosis of intestinal parasites. in: Programme on Intestinal Parasitic Infections, Division of Communicable Diseases. World Health Organization, Geneva

164 References

ASHFORD, R. W., G. D. F. REID and R. W. WRANGHAM (2000): Intestinal parasites of the chimpanzee Pan troglodytes in Kibale Forest, Uganda. Ann. Trop. Med. Parasit. 94, 173-179

AUGUSTINE, D. L., and W. G. SMILLIE (1926): The relation of type of soils of Alabama to the distribution of hookworm disease. Am. J. Hyg. 6, 36-62

BAER, J. G. (1927): Die Cestoden der Säugetiere Brasiliens. Abh. Senckenb. Nat. Ges. 409, 377-386

BAGGE, A. M., R. POULIN and E. T. VALTONEN (2004): Fish population size, and not density, as the determining factor of parasite infection: a case study. Parasitology 128, 305-313

BARTOLI, P., S. MORAND, J. J. RIUTORT and C. COMBES (2000): Acquisition of parasites correlated with social rank and behavioural changes in a fish species. J. Helminthol. 74, 289-293

BEISEL, W. R. (1996): Nutrition and immune function: overview. J. Nutr. 126, 2611-2615

BELL, G., and A. BURT (1991): The comparative biology of parasite species diversity: internal helminths of freshwater fish. J. Anim. Ecol. 60, 1047-1063

BERCOVITCH, F. B., and T. E. ZIEGLER (2002): Current topics in primate socioendocrinology. Annu. Rev. Anthropol. 31, 45-67

BETHONY, J., S. BROOKER, M. ALBONICO, S. M. GEIGER, A. LOUKAS, D. DIEMERT and P. J. HOTEZ (2006): Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. Lancet 367, 1521-1532

BICCA-MARQUES, J. C., P. A. GARBER and M. A. O. AZEVEDO-LOPES (2002): Evidence of three resident adult male group members in a species of monogamous primate, the red titi monkey (Callicebus cupreus). Mammalia 66, 138-142

BLANCHARD, J. L., and M. L. EBERHARD (1986): Case report: esophageal Spirura in a Squirrel Monkey (Saimiri sciureus). Am. J. Primatol. 10, 279-282

BOINSKI, S., and N. L. FOWLER (1989): Seasonal patterns in a tropical lowland forest. Biotropica 21, 223-233

BRACK, M. (1987): Agents transmissible from simians to man. Springer-Verlag, Berlin

References 165

BRACK, M., H. GASS and E. STIRNBERG (1994): Intestinal capillariasis in New World monkeys. J. Med. Primatol. 23, 37-41

BULTMAN, T. L., and G. W. UETZ (1984): Effect of structure and nutritional quality of litter on abundances of litter-dwelling arthropods. Am. Midl. Nat. 111, 165-172

BUNDY, D. A. P., and M. H. N. GOLDEN (1987): The impact of host nutrition on gastrointestinal helminth populations. Parasitology 95, 623-635

BUNGIRO, R., and M. CAPPELLO (2004): Hookworm infection: new developments and prospects for control. Curr. Opin. Infect. Dis. 17, 421-426

BURROWS, R. B. (1972): Protozoa of the intestinal tract. in: R. N. T.-W. FIENNES (ed.) Pathology of simian primates- infectious and parasitic diseases. S. Karger, Basel, vol. 2, pp. 2-28

BUSH, A. O., J. M. AHO and C. R. KENNEDY (1990): Ecological versus phylogenetic determinants of helminth parasite community richness. Evol. Ecol. 4, 1-20

BUSH, A. O., K. D. LAFFERTY, J. M. LOTZ and A. W. SHOSTAK (1997): Parasitology meets ecology on its own terms: Margolis et al. revisited. J. Parasitol. 83, 575-583

BUSH, A. O., J. C. FERNÁNDEZ, G. W. ESCH and R. J. SEED (2001): Parasitism: The diversity and ecology of animal parasites. Cambridge University Press, Cambridge

BUSKIRK, R. E., and W. H. BUSKIRK (1976): Changes in arthropod abundance in a highland Costa-Rican forest. Am. Midl. Nat. 95, 288-298

CABARET, J., N. GASNIER and P. JACQUIET (1998): Faecal egg counts are representative of digestive-tract strongyle worm burdens in sheep and goats. Parasite 5, 137-142

CAMPOS Q., M., and M. VARGAS-VARGAS (1978): The biology of Protospirura muricola and Mastophorus muris (Nematoda: Spiruridae) in Costa Rica. II. Definitive hosts. Rev. Biol. Trop. 26, 199-211

CARMONA, M. C., O. G. BERMUDEZ, G. A. GUTIERREZ-ESPELETA, R. S. PORRAS and B. R. ORTIZ (2005): Intestinal parasites in howler monkeys Alouatta palliata (Primates: Cebidae) of Costa Rica. Rev. Biol. Trop. 53, 437-445

CARROLL, M. J., J. COOK and J. A. TURNER (1983): Comparison of polyvinyl alcohol- and formalin-preserved fecal specimens in the formalin-ether sedimentation technique for parasitological examination. J. Clin. Microbiol. 18, 1070-1072

166 References

CEZILLY, F., and M.-J. PERROT-MINNOT (2005): Studying adaptive changes in the behaviour of infected hosts: a long and winding road. Behav. Process. 68, 223-228

CHAPMAN, C. A. (1992): Estimators of fruit abundance of tropical trees. Biotropica 24, 527-531

CHAPMAN, C. A., and R. W. WRANGHAM (1994): Indices of habitat-wide fruit abundance in tropical forests. Biotropica 26, 160-171

CHAPMAN, C. A., T. R. GILLESPIE and M. L. SPEIRS (2005): Parasite prevalence and richness in sympatric colobines: effects of host density. Am. J. Primatol. 67, 259-266

CHAPMAN, C. A., M. L. SPEIRS, T. R. GILLESPIE, T. HOLLAND and K. M. AUSTAD (2006): Life on the edge: gastrointestinal parasites from the forest edges and interior primate groups. Am. J. Primatol. 68, 397-409

COOP, R. L., and P. H. HOLMES (1996): Nutrition and parasite interaction. Int. J. Parasitol. 26, 951-962

COOP, R. L., and I. KYRIAZAKIS (2001): Influence of host nutrition on the development and consequences of nematode parasitism in ruminants. Trends Parasitol. 17, 325-330

COSGROVE, G. E. (1966): The trematodes of laboratory primates. Lab. Anim. Care 16, 2339

COSGROVE, G. E., B. M. NELSON and A. W. JONES (1963): Spirura tamarini sp. n. (nematoda: Spiruridae) from Amazonian primate, Tamarinus nigricollis (Spix, 1823). J. Parasitol. 49, 1010-1013

COSGROVE, G. E., B. NELSON and N. GENGOZIAN (1968): Helminth parasites of the tamarin, Saguinus fuscicollis. Lab. Anim. Care 18, 654-656

COSGROVE, G. E., M. A. GRETCHEN HUMANSON and C. C. LUSBAUGH (1970a): Trichospirura leptostoma, a nematode of the pancreatic ducts of marmosets (Saguinus spp.) J. Am. Vet. Assoc. 157, 696-698

COSGROVE, G. E., B. M. NELSON and J. T. SELF (1970b): The pathology of pentastomid infections in primates. Lab. Anim. Care 20, 354-360

CÔTÉ, I. M., and R. POULIN (1995): Parasitism and group size in social animals: a meta-analysis. Behav. Ecol. 6, 159-165

References 167

COWLISHAW, G., M. J. LAWES, M. LIGHTBODY, A. MARTIN, R. PETTIFOR and J. M. ROWCLIFFE (2004): A simple rule for the costs of vigilance: empirical evidence from a social forager. P. Roy. Soc. B-Biol. Sci. 271, 27-33

DAHME, E., and E. WEISS (1999): Grundriß der speziellen pathologischen Anatomie der Haustiere. 5. edn., Enke Verlag, Stuttgart

DALY, H. V., J. T. DOYEN and A. H. PURCELL (1998): Introduction to insect biology and diversity. 2. edn., Oxford University Press, Oxford

DASZAK, P. (2000): Emerging infectious diseases of wildlife - threats to biodiversity and human health. Science 287, 443-449

DAVIES, C. R., J. M. AYRES, C. DYE and L. M. DEANE (1991): Malaria infection rate of Amazonian primates increases with body weight and group size. Funct. Ecol. 5, 655-662

DE MELO, A. L., F. M. NERI and M. B. FERREIRA (1997): Helmintos de Sauás, Callicebus personatus nigrifrons (Spix, 1823, Primates: Cebidae), colectados em resgate faunístico durante a construcao da usina hidrelétrica nova Ponte-MG. in: M. B. C. SOUSA, and A. A. L. MENEZES (eds.): A primatologia no Brasil. Sociedade Brasileira de Primatologia, Natal, vol. 6, pp. 193-198

DE RESENDE, D. M., L. H. PEREIRA, A. L. DE MELO, W. L. TAFURI, N. BRANT MOREIRA and C. L. DE OLIVEIRA (1994): Parasitism by Primasubulura jacchi (Marcel, 1857) Inglis, 1958 and Trichospirura leptostoma Smith and Chitwood, 1967 in Callithrix penicillata marmosets, trapped in the wild environment and maintained in captivity. Mem. I. Oswaldo Cruz 89, 123-125

DEINHARDT, F., A. W. HOLMES, J. DEVINE and J. DEINHARD (1967): Marmosets as laboratory animals, IV. The microbiology of laboratory kept marmosets. Lab. Anim. Care 17, 48-47

DIAZ-UNGRIA, C. (1964): Nematodes de primates venezolanos. Bol. Soc. Venez. Sci. Nat. 25, 393-398

DIESFELD, H. J. (1970): Correlation between hookworm findings and climate, as indicated by temperature-humidity relation, in Kenya. Z. Tropenmed. Parasit. 21, 84-&

DUNN, F. L. (1961): Molineus vexillarius sp. n. (Nematoda: Trichostrongylidae) from a Peruvian primate, Tamarinus nigricollis (Spix, 1823). J. Parasitol. 47, 953-956

DUNN, F. L. (1962): Raillietina (R.) trinitate (Camron and Reesal, 1951), Baer and Sandars, 1956 (Cestoda) from a Peruvian primate. P. Helm. Soc. Wash. 29, 148-152

168 References

DUNN, F. L. (1963): Acanthocephalans and cestodes of South American monkeys and marmosets. J. Parasitol. 49, 717-722

DUNN, F. L. (1968): The parasites of Saimiri: in the context of platyrrhine parasitism. in: L. A. ROSENBLUM, and R. W. COOPER (eds.): The squirrel monkey. Academic Press, New York, pp. 31-68

DUNN, F. L., B. L. LIM and L. F. YAP (1968): Endoparasite patterns in mammals of Malayan rain forest. Ecology 49, 1179-1184

DURETTE-DESSET, M.-C., and M. CORVIONE (1998): Une nouvelle espèce de Molineus (Nematoda, Trichostrongylina, Molineoidea), parasite d´un primate sud-américain. Zoosystema 20, 445-450

DUSZYNSKI, D. W., and P. G. WILBER (1997): A guideline for the preparation of species descriptions in the Eimeriidae. J. Parasitol. 83, 333-336

DUSZYNSKI, D. W., W. D. WILSON, S. J. UPTON and N. D. LEVINE (1999): Coccidia (Apicomplexa: Eimeriidae) in the primates and the Scandentia. Int. J. Primatol. 20, 761-797

ECKERT, J. (2000): Parasiten als umwelthygienisches Problem. in: M. ROMMEL, J. ECKERT, E. KUTZER, W. KÖRTING and T. SCHNIEDER (eds.): Veterinärmedizinische Parasitologie. 5. edn., Parey Buchverlag, Berlin, pp. 94-119

ECKERT, J., M. ROMMEL and E. KUTZER (2000): Erreger von Parasitosen: Systematik, Taxonomy und allgemeine Merkmale. in: M. ROMMEL, J. ECKERT, E. KUTZER, W. KÖRTING and T. SCHNIEDER (eds.): Veterinärmedizinische Parasitologie. 5. edn., Parey Buchverlag, Berlin, pp. 2-39

ECKERT, J., K. T. FRIEDHOFF, H. ZAHNER and P. DEPLAZES (2005): Lehrbuch der Parasitologie für Tiermedizin. Enke Verlag, Stuttgart

ECKERT, K. A., N. E. HAHN, A. GENZ, D. M. KITCHEN, M. D. STUART, G. A. AVERBECK, B. E. STROMBERG and H. MARKOWITZ (2006): Coprological surveys of Alouatta pigra at two sites in Belize. Int. J. Primatol. 27, 227-238

EHNSTRÖM, B. (2001): Leaving dead wood for insects in boreal forests - suggestions for the future. Scand. J. Forest Res. 91-98

ENCARNACIÓN, F. (1985): Introducción a la flora y vegetación de la Amazonía peruana: estado actual de los estudios, medio natural y ensayo de una clave de determinación de las formaciones vegetales en al llanura amazónica. Candollea 40, 237-252

References 169

EZENWA, V. (2003): Habitat overlap and gastrointestinal parasitism in sympatric African bovids. Parasitology 126, 379-388

EZENWA, V. O. (2004a): Host social behavior and parasitic infection: a multifactorial approach. Behav. Ecol. 15, 446-454

EZENWA, V. O. (2004b): Interactions among host diet, nutritional status and gastrointestinal parasite infection in wild bovids. Int. J. Parasitol. 34, 535-542

EZENWA, V. O., S. A. PRICE, S. ALTIZER, N. D. VITONE and K. COOK (2006): Host traits and parasite species richness in even and odd-toed hoofed mammals, Atriodactyla and Perissodactyla. Oikos 115, 526-536

FAUST, E. C. (1967): Athesmia (Trematoda: Dicroeliidae) Odhner, 1911, liver fluke of monkeys from Columbia, South America, and other mammalian hosts. Trans. Am. Microsc. Soc. 86, 113-119

FELIU, C., F. RENAUD, F. CATZEFLIS, J. P. HUGOT, P. DURAND and S. MORAND (1997): A comparative analysis of parasite species richness of Iberian rodents. Parasitology 115, 453-466

FESTA-BIANCHET, M. (1989): Individual differences, parasites, and the cost of reproduction for bighorn ewes (Ovis canadensis). J. Anim. Ecol. 58, 785-795

FINCHER, G. T. (1973): Dung beetles as biological control agents for gastrointestinal parasites of livestock. J. Parasitol. 59, 396-399

FLYNN, R. J. (1973): Parasites of laboratory animals. The Iowa State University Press

FOLSTAD, I., and A. J. KARTER (1992): Parasites, bright males, and the immunocompetence handicap. Am. Nat. 139, 601-622

FOREYT, W. J. (1986): Recovery of nematode eggs and larvae in deer - evaluation of fecal preservation methods. J. A. V. M. A. 189, 1065-1067

FOWLER, J., L. COHEN and P. JARVIS (1998): Practical statistics for field biology. 2. edn., Chichester

FREELAND, W. J. (1979): Primate social groups as biological islands. Ecology 60, 719-728

170 References

FREELAND, W. J. (1983): Parasites and the coexistence of animal host species. Am. Nat. 121, 223-236

FRITH, D., and C. FRITH (1990): Seasonality of litter invertebrate populations in an Australian upland tropical rain forest. Biotropica 22, 181-190

GALLATI, W. W. (1959): Life history, morphology and taxonomy of Atriotaenia (Ershovia) procyonis (Cestoda: Linstowiidae), a parasite of the raccoon. J. Parasitol. 45, 363-377

GANZHORN, J. U. (2003): Habitat description and phenology. in: J. M. SETCHELL, and D. J. CURTIS (eds.): Field and laboratory methods in primatology: a practical guide. Cambridge University Press, Cambridge, pp. 40-56

GARBER, P. A. (1988): Diet, foraging patterns, and resource defense in a mixed species troop of Saguinus mystax and Saguinus fuscicollis in Amazonian Peru. Behaviour 105, 18-34

GARBER, P. A. (1993): Feeding ecology and behaviour of the genus Saguinus. in: A. B. RYLANDS (ed.) Marmosets and tamarins. Systematics, behaviour, and ecology. Oxford University Press, Oxford, pp. 271-295

GARBER, P. A. (1997): One for all and breeding for one: cooperation and competition as a tamarin reproductive strategy. Evol. Anthropol. 6, 187-199

GARBER, P. A., and S. R. LEIGH (1997): Ontogenetic variation in small-bodied New World primates: Implications for patterns of reproduction and infant care. Folia Primatol. 68, 1-22

GARCIA, L. S., and R. SHIMIZU (1981): Comparison of clinical results for the use of ethyl acetate and diethyl ether in formalin-ether sedimentation technique performed on polyvinyl alcohol-preserved specimen. J. Clin. Microbiol. 13, 709-713

GEBAUER, O. (1933): Beitrag zur Kenntnis von Nematoden aus Affenlungen. Z. Parasitenk. 5, 724-735

GIBBONS, L. M., and V. KUMAR (1980): Boreostrongylus romerolagi n. sp. (Nematoda, Heligmonellidae) from mexican volcano rabbit, Romerolagus diazi. Syst. Parasitol. 1, 117-122

GIBBS, H. C., and I. A. BARGER (1986): Haemonchus contortus and other trichostrongylid infections in parturient, lactating and dry ewes. Vet. Parasitol. 22, 57-66

References 171

GIBSON, T. E. (1963): Influence of nutrition on relationships between gastro-intestinal parasites and their hosts. P. Nutr. Soc. 22, 15-20

GILBERT, K. A. (1994): Endoparasitic infection in red howling monkeys (Alouatta seniculus) in the central Amazonian basin: A cost of sociality? New Brunswick, Rutger The State Univ. of New Jersey, Ph.D. thesis

GILLESPIE, T. R., E. C. GREINER and C. A. CHAPMAN (2004): Gastrointestinal parasites of the guenons of western Uganda. J. Parasitol. 90, 1356-1360

GILLESPIE, T. R., E. C. GREINER and C. A. CHAPMAN (2005): Gastrointestinal parasites of the colobus monkeys of Uganda. J. Parasitol. 91, 569-573

GOLDIZEN, A. W. (1989): Social relationships in a cooperatively polyandrous group of tamarins (Saguinus fuscicollis). Behav. Ecol. Sociobiol. 24, 79-89

GOLDIZEN, A. W., J. TERBORGH, F. CORNEJO, D. T. PORRAS and R. EVANS (1988): Seasonal food shortage, weight loss, and the timing of births in saddle-back tamarins (Saguinus fuscicollis). J. Anim. Ecol. 57, 893-901

GORDON, M. L. (1948): The epidemiology of parasitic diseases, with special reference to studies with nematode parasites of sheep. Aust. Vet. J. 24, 17-45

GOZALO, A. (2003): Spontaneous diseases in New World monkeys. in: ALAS-American Association of Laboratory Animals, Seattle, USA, 2003, pp. 1-29

GOZALO, A., and M. TANTALEÁN (1996): Parasitic protozoa in Neotropical primates. Lab. Primate Newsl. 35, 1-7

GREGORY, R. D., A. E. KEYMER and P. H. HARVEY (1996): Helminth parasite richness among vertebrates. Biodivers. Conserv. 5, 985-997

GRIMES, D. A., and K. F. SCHULZ (2002): Bias and causal associations in observational research. Lancet 359, 248-252

GROVE, S. J. (2002a): Saproxylic insect ecology and the sustainable management of forests. Annu. Rev. Ecol. Syst. 33, 1-23

GROVE, S. J. (2002b): Tree basal area and dead wood as surrogate indicatiors of saproxylic insect faunal integrity: a case study form the Australian lowland tropics. Ecol. Indic. 1, 171-188

172 References

GROVES, C. P. (2001): Platyrrhini. in: E. D' ARAUJO (ed.) Primate taxonomy. Smithsonian Institution Press, Washington, pp. 126-195

GUEGAN, J. F., and C. R. KENNEDY (1993): Maximum local helminth parasite community richness in british fresh-water fish - a test of the colonization time hypothesis. Parasitology 106, 91-100

GUSTAFSSON, L., D. NORDLING, M. S. ANDERSSON, B. C. SHELDON and A. QVARNSTROM (1994): Infectious diseases, reproductive effort and the cost of reproduction in birds. Philos. T. Roy. Soc. B 346, 323-331

HALL, L. S., P. R. KRAUSMAN and M. L. MORRISON (1997): The habitat concept and a plea for standard terminology. Wildlife Soc. B. 25, 173-182

HAMILTON, W. D., and M. ZUK (1982): Heritable true fitness and bright birds: a role for parasites? Science 218, 384-387

HARRIS, S., W. J. CRESSWELL, P. G. FORDE, W. J. TREWHELLA, T. WOOLLARD and S. WRAY (1990): Home range analysis using radio-tracking data - a review of problems and techniques particularly as applied to the study of mammals. Mammal Rev. 20, 97-123

HARVELL, C. D., C. E. MITCHELL, J. R. WARD, S. ALTIZER, A. P. DOBSON, R. S. OSTFELD and M. D. SAMUEL (2002): Ecology - climate warming and disease risks for terrestrial and marine biota. Science 296, 2158-2162

HAUSFATER, G., and B. J. MEADE (1982): Alternation of sleeping groves by yellow baboons (Papio cynocephalus) as a strategy for parasite avoidance. Primates 23, 287-296

HAWDON, J. M., and P. J. HOTEZ (1996): Hookworm: developmental biology of the infectious process. Curr. Opin. Genet. Dev. 6, 618-623

HAYDON, D. T., S. CLEAVELAND, L. H. TAYLOR and M. K. LAURENSON (2002): Identifying reservoirs of infection: a conceptual and practical challenge. Emerg. Infect. Dis. 8, 1468-1473

HEIDUCK, S. (1997): Nahrungsstrategien Schwarzköpfiger Springaffen (Callicebus personatus melanochir). Göttingen, Georg-August-Univ., Mathemat.-nat. Fak., Diss.

HENDRICKS, L. D. (1974): A rediscription of Isospora arctopitheci Rodhain, 1933 (Protozoa: Eimeriidae) from primates of Panama. P. Helm. Soc. Wash. 41, 229-233

References 173

HERMANNS, W. (1999): Leber. in: E. DAHME, and E. WEISS (eds.): Grundriß der speziellen pathologischen Anatomie der Haustiere. Enke Verlag, Stuttgart, pp. 200-232

HERSHKOVITZ, P. (1977): Living New World monkeys (Platyrrhini). With an introduction to primates. University of Chicago Press, Chicago (vol. 1)

HERSHKOVITZ, P. (1990): Titis. New World monkeys of the genus Callicebus (Cebidae, Platyrrhini): a preliminary taxonomic review. Field Museum of Natural History, Chicago Fieldiana: Zoology, New Series, No.55

HEYMANN, E. W. (1995): Sleeping habits of tamarins, Saguinus mystax and Saguinus fuscicollis (Mammalia; Primates; Callitrichidae), in north-eastern Peru. J. Zool. 237, 211-226

HEYMANN, E. W. (1996): Social behavior of wild moustached tamarins, Saguinus mystax, at the Estacion Biologica Quebrada Bianco, Peruvian Amazonia. Am. J. Primatol. 38, 101-113

HEYMANN, E. W. (2000): The number of adult males in callitrichine groups and its implication for callitrichine social evolution. in: P. M. KAPPELER (ed.) Primate males. Cambridge University Press, Cambridge, pp. 64-71

HEYMANN, E. W. (2003a): New World monkeys II: Marmosets, tamarins, and Goeldi's monkeys (Callitrichidae). in: D. G. KLEIMAN, V. GEIST, M. HUTCHINS and M. C. MC DADE (eds.): Grzimek's Animal Life Encyclopedia, Mammals III. Gale Group, Farmington Hills, Mich., vol. 14, pp. 115-133

HEYMANN, E. W. (2003b): Scent marking, paternal care, and sexual selection in callitrichines. in: C. B. JONES (ed.) Sexual selection and reproductive competition in primates: New perspective and directions. American Society of Primatologists, Norman, Oklahoma, vol. 3, pp. 305-325

HEYMANN, E. W., and H. BUCHANAN-SMITH (2000): The behavioural ecology of mixed-species troops of callitrichine primates. Biol. Rev. 75, 169-190

HEYMANN, E. W., C. KNOGGE and E. R. TIRADO HERRERA (2000): Vertebrate predation by sympatric tamarins, Saguinus mystax and Saguinus fuscicollis. Am. J. Primatol. 51, 153-158

HÖFER, H., C. MARTIUS and L. BECK (1996): Decomposition in an Amazonian rain forest after experimental litter addition in small plots. Pedobiologia 40, 570-576

HOLMES, J. C. (1995): Population regulation - a dynamic complex of interactions. Wildlife Res. 22, 11-19

174 References

HOLMES, P. H. (1993): Interactions between parasites and animal nutrition - the veterinary consequences. P. Nutr. Soc. 52, 113-120

HOOGE, P. N., and B. EICHENLAUB (1997): Animal movement extension to ArcView, version 1.1. Alaska Science Center—Biological Science Office, U.S. Geological Survey, Anchorage, AK, USA.

HORNA, M., and M. TANTALEÁN (1990): Parásitos de primates peruanos: helmintos del "mono fraile" y del "pichico barba blanca". in: N. E. CASTRO-RODRÍGUEZ (ed.) La primatología en el Perú. Investigaciones primatológicas (1973-1985). Imprenta Propaceb, Lima, pp. 555-564

HUCK, M., P. LÖTTKER and E. W. HEYMANN (2004): The many faces of helping: possible costs and benefits of infant carrying and food transfer in wild moustached tamarins (Saguinus mystax). Behaviour 141, 915-934

HUDSON, P. J., A. P. DOBSON and D. NEWBORN (1992): Do parasites make prey vulnerable to predation - red grouse and parasites. J. Anim. Ecol. 61, 681-692

HUDSON, P. J., A. P. DOBSON and K. D. LAFFERTY (2006): Is a healthy ecosystem one that is rich in parasites? Trends Ecol. Evol. 21, 381-385

HUDSON, P. J., A. RIZZOLI, B. T. GRENFELL, H. HEESTERBEEK and A. DOBSON (2002): Ecology of wildlife diseases. Oxford University Press, Oxford

HUFFMAN, M. A., S. GOTOH, L. A. TURNER, M. HAMAI and K. YOSHIDA (1997): Seasonal trends in intestinal nematode infection and medicinal plant use among chimpanzees in the Mahale Mountains, Tanzania. Primates 38, 111-125

HUGOT, J.-P. (1984): Sur le genre Trypanoxyuris (Oxyuridae, Nematoda); II. Sous-genre Hapaloxyuris-parasite de primates Callitrichidae. B. Mus. Natl. Hist. Nat. 6, 1007-1019

HUGOT, J.-P. (1985): Sur le genre Trypanoxyuris (Oxyuridae, Nematoda); III. Sous-genre Trypanoxyuris-parasite de primates Cebidae et Atelidae. B. Mus. Natl. Hist. Nat. 7, 131-155

HUGOT, J.-P., and C. VAUCHER (1985): Sur le genre Trypanoxyuris (Oxyuridae, Nematoda); IV. Sous-genre Trypanoxyuris-parasite de primates Cebidae et Atelidae (suite). Etude morphologique de Trypanoxyuris callicebi n. sp. B. Mus. Natl. Hist. Nat. 7, 633-636

HUGOT, J.-P., S. MORAND and R. GUERRERO (1994): Trypanoxyuris croizati n. sp. and T. callicebi Hugot&Vaucher, 1985 (Nematoda: Oxyuridae), two vicariant forms parasitic in Callicebus spp. (Primatia, Cebidae) Syst. Parasitol. 27, 35-43

References 175

INGLIS, W. G., and F. L. DUNN (1964): Some oxyurids (Nematoda) from Neotropical primates. Z. Parasitenk. 24, 83-87

INGLIS, W. G., and G. E. COSGROVE (1965): The pin-worm parasites (Nematoda: Oxyuridae) of the Hapalidae (Mammalia: Primates). Parasitology 55, 731-737

JANZEN, D. H., and T. W. SCHOENER (1968): Differences in insect abundance and diversity between wetter and drier sites during a tropical dry season. Ecology 49, 96-110

KAPEL, C. M. O., P. R. TORGERSON, R. C. A. THOMPSON and P. DEPLAZES (2006): Reproductive potential of Echinococcus multilocularis in experimentally infected foxes, dogs, raccoon dogs and cats. Int. J. Parasitol. 36, 79-86

KARERE, G. M., and E. MUNENE (2002): Some gastro-intestinal tract parasites in wild De Brazza´s Monkeys (Cercopithecus neglectus) in Kenya. Vet. Parasitol. 110, 153-157

KEESING, F., R. D. HOLT and R. S. OSTFELD (2006): Effects of species diversity on disease risk. Ecol. Lett. 9, 485-498

KELLY, J. A., and M. J. SAMWAYS (2003): Diversity and conservation of forest-floor arthropods on a small Seychelles island. Biodivers. Conserv. 12, 1793-1813

KELLY, R. W. (1992): The liver and biliary system. in: K. V. F. JUBB, P. C. KENNEDY and N. PALMER (eds.): Pathology of domestic animals. 4. edn., Academic Press, Inc., San Diego, vol. 2, pp. 319-406

KENNEDY, C. R., A. O. BUSH and J. M. AHO (1986): Patterns in helminth communities: why are birds and fish different? Parasitology 93, 205-215

KIM, J. C. S., and R. J. WOLF (1980): Diseases of moustaches marmosets. in: R. J. MONTALI, and G. MIGAKI (eds.): The comparative pathology of zoo animals. Smithsonian Institution Press, Washington, pp. 431-435

KING, N. W. (1976): Synopsis of the pathology of New World monkeys. Sci. Publ. Pan. Am. Health Org. 317, 169-198

KING, N. W. (1993): Prosthenorchiasis. in: T. C. JONES, U. MOHR and R. D. HUNT (eds.): Nonhuman primates. Springer-Verlag, Berlin, vol. 2, pp. 65-68

176 References

KINGSTON, N., and G. E. COSGROVE (1967): Two new species of Platynosomum (Trematoda: Dicrocoeliidae) from South American Monkeys. P. Helm. Soc. Wash. 34, 147-151

KINZEY, W. G. (1981): The titi monkey, genus Callicebus. in: R. A. MITTERMEIER, and A. F. COIMBRA-FILHO (eds.): Ecology and behavior of Neotropical primates. Academia Brasileira de Ciencias, Rio de Janeiro, vol. 1, pp. 241-276

KLEIN, S. L. (2000): The effects of hormones on sex differences in infection: from genes to behavior. Neurosci. Biobehav. R. 24, 627-638

KLEIN, S. L., and R. J. NELSON (1999): Influence of social factors on immune function and reproduction. Rev. Reprod. 4, 168-178

KNOGGE, C. (1998): Tier-Pflanze-Interaktion im Amazonas-Regenwald. Samenausbreitung durch die sympatrischen Tamarinarten, Saguinus mystax und Saguinus fuscicollis (Callitrichidae, Primates). Bielefeld, Univ. Bielefeld, Fak. für Biologie, Diss.

KNOGGE, C., and E. W. HEYMANN (2003): Seed dispersal by sympatric tamarins Saguinus mystax and Saguinus fuscicollis: Diversity and characteristics of plant species. Folia Primatol. 74, 33-47

KOENIG, A., C. BORRIES, M. K. CHALISE and P. WINKLER (1997): Ecology, nutrition, and timing of reproductive events in an Asian primate, the Hanuman langur (Presbytis entellus). J. Zool. 243, 215-235

KOSKI, K. G., and M. E. SCOTT (2001): Gastrointestinal nematodes, nutrition and immunity: breaking the negative spiral. Annu. Rev. Nutr. 21, 297-321

KRAEMER, A. (2005): Validierung ausgewählter koproskopischer Untersuchungsmethoden zum direkten Nachweis parasitärer Stadien verschiedener Parasitenspezies der Haussäugetiere. Hannover, Hannover School of Veterinary Medicine, Dep. for Infectious Diseases, Institute of Parasitology, Diss.

KREBS, C. J. (1999): Ecological methodology. 2. edn., Addison Wesley Longman, Menlo Park

KREIENBROCK, L., and S. SCHACH (2005): Epidemiologische Methoden. 4. edn., Heidelberg

KUNTZ, R. E. (1972): Trematodes of the intestinal tract and biliary passages. in: R. N. T.-W. FIENNES (ed.) Pathology of simian primates- infectious and parasitic diseases. S. Karger, Basel, vol. 2, pp. 104-123

References 177

KUNTZ, R. E. (1982): Significant infections in primate parasitology. J. Hum. Evol. 11, 185-194

KUNTZ, R. E., and B. J. MYERS (1972): Parasites of South American primates. Int. Zoo Yearb. 12, 61-68

LANDSOUD-SOUKATE, J., C. E. G. TUTIN and M. FERNANDEZ (1995): Intestinal parasites of sympatric gorillas and chimpanzees in the Lopé Reserve, Gabon. Ann. Trop. Med. Parasit. 89, 73-79

LARSEN, M. N., and A. ROEPSTORFF (1999): Seasonal variation in development and survival of Ascaris suum and Trichuris suis eggs on pastures. Parasitology 119, 209-220

LASSAU, S. A., D. F. HOCHULI, G. CASSIS and C. A. M. REID (2005): Effects of habitat complexity on forest beetle diversity: do functional groups respond consistently? Divers. Distrib. 11, 73-82

LAZARUS, J., and M. SYMONDS (1992): Contrasting effects of protective and obstructive cover on avian vigilance. Anim. Behav. 43, 519-521

LEE, G. Y., W. M. BOYCE and K. ORR (1996): Diagnosis and treatment of lungworm (Filariopsis arator; Metastrongyloidea: Filaroididae) infection in white-faced capuchins (Cebus capucinus). J. Zoo Wildlife Med. 27, 197-200

LILE, N. K. (1998): Alimentary tract helminths of four pleuronectid flatfish in relation to host phylogeny and ecology. J. Fish Biol. 53, 945-953

LILLY, A. A., P. T. MEHLMANN and D. DORAN (2001): Intestinal parasites in gorillas, chimpanzees, and humans at Mondike Research Site, Dzanga-Ndoki National Park, Central African Republic. Int. J. Primatol. 23, 555-573

LOEHLE, C. (1995): Social barriers to pathogen transmission in wild animal populations. Ecology 76, 326-335

LÖTTKER, P., M. HUCK and E. W. HEYMANN (2004a): Demographic parameters and events in wild moustached tamarins (Saguinus mystax). Am. J. Primatol. 64, 425-449

LÖTTKER, P., M. HUCK, E. W. HEYMANN and M. HEISTERMANN (2004b): Endocrine correlates of reproductive status in breeding and nonbreeding wild female moustached tamarins. Int. J. Primatol. 25, 919-937

LÖTTKER, P., M. HUCK, D. P. ZINNER and E. W. HEYMANN (2007): Grooming relationships between breeding females and adult group members in cooperatively breeding moustached tamarins (Saguinus mystax). Am. J. Primatol. in press

178 References

LUCKER, J. (1933a): Gongylonema macrogubernaculum (Lubimov 1931) from two new hosts. J. Parasitol. 19, 243

LUCKER, J. (1933b): Two new host of Gongylonema pulchrum (Molin 1857). J. Parasitol. 19, 248

MABASO, M. L. H., C. C. APPLETON, J. C. HUGHES and E. GOUWS (2003): The effect of soil type and climate on hookworm (Necator americanus) distribution in KwaZulu-Natal, South Africa. Trop. Med. Int. Health 8, 722-727

MARGOLIS, L., G. W. ESCH, J. C. HOLMES, A. M. KURIS and G. A. SCHAD (1982): The use of ecological terms in parasitology (report of an ad hoc committee of the American Society of Parasitologists) J. Parasitol. 68, 131-133

MARTIN, P., and P. BATESON (1993): Measuring behaviour: An introductory guide. 2. edn., Cambridge University Press

MATERN, B., and N. FIEGE (1989): Befall mit Pterygodermatites sp. (Nematoda: Spirurida) bei Krallenaffenarten im Frankfurter Zoo. Erkr. Zootiere 31, 23-27

MAYEAUX, D. J., W. A. MASON and S. P. MENDOZA (2002): Developmental changes in responsiveness to parents and unfamiliar adults in a monogamous monkey (Callicebus moloch). Am. J. Primatol. 58, 71-89

MCGREW, W. C., C. E. G. TUTIN and S. K. FILE (1989a): Intestinal parasites of two species of free-living monkeys in far western Africa, Cercopithecus (aethiops) sabaeus and Erythrocebus patas patas. Afr. J. Ecol. 27, 261-262

MCGREW, W. C., C. E. G. TUTIN, D. A. COLLINS and S. K. FILE (1989b): Intestinal parasites of sympatric Pan troglodytes and Papio spp. at two sites: Gombe (Tanzania) and Mt. Assirik (Senegal). Am. J. Primatol. 17, 147-155

MCNAMEE, R. (2003): Confounding and confounders. Occup. Environ. Med. 60, 227-234

MENSCHEL, E., and R. STROH (1963): Helminthologische Untersuchungen bei Pincheäffchen (Oedipomonas oedipus). Z. Parasitenk. 23, 376-383

MES, T. H. M. (2003): Technical variability and required sample size of helminth egg isolation procedures. Vet. Parasitol. 115, 311-320

References 179

MICHAUD, C., M. TANTALEÁN, C. IQUE, E. MONTOYA and A. GOZALO (2003): A survey for helminth parasites in feral New World non-human primate populations and its comparison with parasitological data from man in the region. J. Med. Primatol. 32, 341-345

MIZGAJASKA, H. (1993): The distribution and survival of eggs of Ascaris suum in six different natural soil profiles. Acta Parasitol. 38, 170-174

MØLLER, A. P. (1990): Parasites and sexual selection - current status of the Hamilton and Zuk hypothesis. J. Evolution. Biol. 3, 319-328

MONTALI, R. J., C. H. GARDINER, R. E. EVANS and M. BUSH (1983): Pterygodermatites nycticebi (Nematoda: Spirurida) in golden lion tamarins. Lab. Anim. Sci. 33, 194-197

MOORE, S., and K. WILSON (2002): Parasites as a viability cost of sexual selection in natural population of mammals. Science 297, 2015-2018

MORALES-MONTOR, J., A. CHAVARRIA, M. A. DE LEON, L. I. DEL CASTILLO, E. G. ESCOBEDO, E. N. SANCHEZ, J. A. VARGAS, M. HERNANDEZ-FLORES, T. ROMO-GONZALEZ and C. LARRALDE (2004): Host gender in parasitic infections of mammals: An evaluation of the female host supremacy paradigm. J. Parasitol. 90, 531-546

MORAND, S., and R. POULIN (1998): Density, body mass and parasite species richness of terrestrial mammals. Evol. Ecol. 12, 717-727

MORAND, S., and P. H. HARVEY (2000): Mammalian metabolism, longevity and parasite species richness. P. Roy. Soc. B-Biol. Sci. 267, 1999-2003

MORERA, P. (1973): Life history and redescription of Angiostrongylus costaricensis Morera and Céspedes. Am. J. Trop. Med. Hyg. 22, 613-621

MOUGEOT, F., S. M. REDPATH and S. B. PIERTNEY (2006): Elevated spring testosterone increases parasite intensity in male red grouse. Behav. Ecol. 17, 117-125

MOVTSCHAN, A. T. (1974): Helminthenbefall bei Cebidae und Callitrichidae des Primatenzentrums Suchumi nach der Ankunft aus Südamerika. in: Labortiere in der medizinischen Forschung, Moskau, 1974, pp. 241-242

MUEHLENBEIN, M. P. (2005): Parasitological analyses of the male chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda. Am. J. Primatol. 65, 167-179

180 References

MÜLLER-GRAF, C. D. M., D. A. COLLINS and M. E. J. WOOLHOUSE (1996): Intestinal parasite burden in five troops of olive baboons (Papio cynocephalus anubis) in Gombe Stream National Park, Tanzania. Parasitology 112, 489-497

MÜLLER-GRAF, C. D. M., D. A. COLLINS, C. PACKER and M. E. J. WOOLHOUSE (1997): Schistosoma mansoni infection in natural population of olive baboons (Papio cynocephalus anubis) in Gombe Stream National Park, Tanzania. Parasitology 115, 621-627

MUNENE, E., M. OTSYULA, D. A. N. MBAABU, W. T. MUTAHI, S. M. K. MURIUKI and M. G. M. (1998): Helminth and protozoan gastrointestinal tract parasites in captive and wild-trapped African non-human primates. Vet. Parasitol. 78, 195-201

MYERS, B. J. (1972): Echinococcosis, coenurosis, cysticercosis, sparganosis, etc. in: R. N. T.-W. FIENNES (ed.) Pathology of simian primates- infectious and parasitic diseases. S. Karger, Basel, vol. 2, pp. 124-143

NADJAFZADEH, M. (2005): Strategien und Techniken des Beuteerwerbs von Kupferroten Springaffen, Callicebus cupreus, im Vergleich zu den sympatrischen Tamarinarten Saguinus mystax und Saguinus fuscicollis im Nordosten Perus. Bochum, Ruhr-Univ. Bochum, Verhaltensbiologie und Didaktik der Biologie, Diploma thesis

NEAFIE, R. C., and A. M. MARTY (1993): Unusual infections in humans. Clin. Microbiol. Rev. 6, 34-56

NELSON, B., G. E. COSGROVE and N. GENGOZIAN (1966): Diseases of an imported primate Tamarinus nigricollis. Lab. Anim. Care 16, 255-275

NELSON, R. J., and G. E. DEMAS (2004): Seasonal patterns of stress, disease, and sickness responses. Curr. Dir. Psychol. Sci. 13, 198-201

NICKLE, D. A., and E. W. HEYMANN (1996): Predation on Orthoptera and other orders of insects by tamarin monkeys, Saguinus mystax mystax and Saguinus fuscicollis nigrifrons (primates: Callitrichidae), in north-eastern Peru. J. Zool. 239, 799-819

NUNN, C., S. M. ALTIZER, K. E. JONES and W. SECHREST (2003): Comparative tests of parasite species richness in primates. Am. Nat. 162, 597-614

NUNN, C., S. ALTIZER, W. SECHREST and A. A. CUNNINGHAM (2005): Latitudinal gradients of parasite species richness in primates. Divers. Distrib. 11, 249-256

NUNN, C. L., and E. W. HEYMANN (2005): Malaria infection and host behavior: a comparative study of Neotropical primates. Behav. Ecol. Sociobiol. 59, 30-37

References 181

NUNN, C. L., and S. ALTIZER (2006): Infectious diseases in primates- behavior, ecology and evolution. Oxford University Press, New York

ORIHEL, T. C. (1970): The helminth parasites of nonhuman primates and man. Lab. Anim. Care 20, 395-4001

ORIHEL, T. C., and H. R. SEIBOLD (1971): Trichospirurosis in South American monkeys. J. Parasitol. 57, 1366-1368

ORIHEL, T. C., and H. R. SEIBOLD (1972): Nematodes of the bowel and tissues. in: R. N. T.-W. FIENNES (ed.) Pathology of simian primates- infectious and parasitic diseases. S. Karger, Basel, vol. 2, pp. 76-103

PACHECO, L. R., F. M. NERI, V. T. FRAHIA and A. L. DE MELO (2003): Parasitismo natural em Sauás, Callicebus nigrifrons (Spix, 1823): Variacao na eliminacao de ovos de nematoda e cestoda. Neotrop. Primates 11, 29-32

PATZ, J. A., T. K. GRACZYK, N. GELLER and A. Y. VITTOR (2000): Effects of environmental change on emerging parasitic diseases. Int. J. Parasitol. 30, 1395-1405

PEARSON, D. L., and J. A. DERR (1986): Seasonal patterns of lowland forest floor arthropod abundance in Southeastern Peru. Biotropica 18, 244-256

PERES, C. A. (1993): Diet and feeding ecology of saddle-back (Saguinus fuscicollis) and moustached (Saguinus mystax) tamarins in an Amazonian terra firme forest. J. Zool. 230, 567-592

PERES, C. A. (1994): Primate responses to phenological changes in an Amazonian terra firme forest. Biotropica 26, 98-112

PERES, C. A. (2000): Identifying keystone plant resources in tropical forests: the case of gums from Parkia pods. J. Trop. Ecol. 16, 287-317

PETRZELKOVA, K. J., H. HASEGAWA, L. R. MOSCOVICE, T. KAUR, I. MWANAHAMISSI and M. A. HUFFMAN (2006): Parasitic nematodes in the chimpanzee population on Rubondo Island, Tanzania. Int. J. Primatol. 77, 767-777

PETTIFER, H. L. (1984): The helminth fauna of the digestive tracts of chacma baboons, Papio ursinus, from different localities in the Transvaal. Onderstepoort J. Vet. 51, 161-170

182 References

PFEIFFER, W. J. (1996): Litter invertebrates. in: D. REAGAN, and R. B. WAIDE (eds.): The food web of a tropical rain forest. University of Chicago Press, Chicago, pp. 137-181

PHILLIPS, K. A., M. E. HAAS, B. W. GRAFTON and M. YRIVARREN (2004): Survey of the gastrointestinal parasites of the primate community at Tambopata National Reserve, Peru. J. Zool. 264, 149-151

PIERANGELI, N. B., A. L. GIAYETTO, A. M. MANACORDA, L. M. BARBIERI, S. V. SORIANO, A. VERONESI, B. C. PEZZANI, M. C. MINVIELLE and J. A. BASUALDO (2003): Seasonality of intestinal parasites in soils along the outskirts of Neuquen (Patagonia, Argentina). Trop. Med. Int. Health 8, 259-263

PINHEIRO, F., I. R. DINIZ, D. COELHO and M. P. S. BANDEIRA (2002): Seasonal pattern of insect abundance in the Brazilian cerrado. Austral. Ecology 27, 132-136

PORTER, J. A. (1972): Parasites of marmosets. Lab. Anim. Sci. 22, 503-506

POTKAY, S. (1992): Diseases of Callitrichidae: A review. J. Med. Primatol. 21, 189-236

POULIN, R. (1995a): Phylogeny, ecology and the richness of parasite communities in vertebrates. Ecol. Monogr. 65, 283-302

POULIN, R. (1995b): ''Adaptive'' changes in the behaviour of parasitized animals: A critical review. Int. J. Parasitol. 25, 1371-1383

POULIN, R. (1996): Sexual inequalities in helminth infections: A cost of being a male? Am. Nat. 147, 287-295

POULIN, R., and D. MOUILLOT (2004): The evolution of taxonomic diversity in helminth assemblages of mammalian hosts. Evol. Ecol. 18, 231-247

PRICE, D. L. (1981): Comparison of three collection-preservation methods for detection of intestinal parasites. J. Clin. Microbiol. 14, 656-660

PRICE, P. W. (1990): Host populations as resources defining parasite community organization. in: G. W. ESCH, A. O. BUSH and J. M. AHO (eds.): Parasite communities: patterns and processes. Chapman & Hall, London, pp. 21-40

PRIETO, O. H., A. M. SANTA CRUZ, N. SCHEIBLER, J. T. BORDA and L. G. GÓMEZ (2002): Incidence and external morphology of the nematode Trypanoxyuris (Hapaloxyuris) callithricis, isolated from Black-and-Gold Howler monkeys (Alouatta caraya) in Corrientes, Argentina Lab. Primate Newsl. 41, 12-14

References 183

QUENTIN, J.-C. (1973): The presence of Spirura guianensis (Ortlepp, 1924) in Neotropical marsupials. Life cycle. Ann. Parasitol. Hum. Comp. 48, 117-133

RIBEIRO AMATO, J. F., P. T. DE CASTRO and L. GRISI (1976): Spirura guianensis (Ortlepp, 1924), parasite of Philander opossum quica (Temminck, 1825) in the state of Rio de Janeiro, Brazil (Nematoda, spiruridae). Rev. Bras. Biol. 36, 122-127

RICHARD, A. F. (1985): Primates in nature. W.H. Freeman and Company, New York

RICHART, R., and K. BENIRSCHKE (1963): Causes of Death in a Colony of Marmoset Monkeys. J. Pathol. Bacteriol. 86, 221-223

ROBINSON, J. G., P. C. WRIGHT and W. G. KINZEY (1987): Monogamous cebids and their relatives: intergroup calls and spacing. in: B. B. SMUTS, D. L. CHENEY, R. M. SEYFARTH, R. W. WRANGHAM and T. T. STRUHSACKER (eds.): Primate societies. Chicago Press, Chicago, pp. 44-53

ROEPSTORFF, A., and K. D. MURRELL (1997): Transmission dynamics of helminth parasites of pigs on continuous pasture: Oesophagostomum dentatum and Hyostrongylus rubidus. Int. J. Parasitol. 27, 553-562

ROY, B. A. (2001): Patterns of association between crucifers and their flower-mimic pathogens: host jumps are more common than coevolution or cospeciation. Evolution 55, 41-53

RYLANDS, A. B., A. F. COIMBRA-FILHO and R. A. MITTERMAIER (1993): Systematics, geographic distribution and some notes on conservation status of the Callitrichidae. in: A. B. RYLANDS (ed.) Marmosets and tamarins. Systematics, behaviour, and ecology. Oxford University Press, Oxford, pp. 11-77

RYLANDS, A. B., H. SCHNEIDER, A. LANGGUTH, R. A. MITTERMAIER, C. P. GROVES and E. RODRÍGUEZ-LUNA (2000): An assessment of the diversity of New World primates. Neotrop. Primates 8, 61-93

SAATHOFF, E., A. OLSEN, J. D. KVALSVIG, C. C. APPLETON, B. SHARP and I. KLEINSCHMIDT (2005a): Ecological covariates of Ascaris lumbricoides infection in schoolchildren from rural KwaZulu-Natal, South Africa. Trop. Med. Int. Health 10, 412-422

SAATHOFF, E., A. OLSEN, B. SHARP, J. D. KVALSVIG, C. C. APPLETON and I. KLEINSCHMIDT (2005b): Ecologic covariates of hookworm infection and reinfection in rural Kwazulu-natal/South Africa: A geographic information system-based study. Am. J. Trop. Med. Hyg. 72, 384-391

184 References

SÁNCHEZ THEVENET, P., A. NANCUFIL, C. M. OYARZO, C. TORRECILLAS, S. RASO, I. MELLADO, M. E. FLORES, M. G. CORDOBA, M. C. MINVIELLE and J. A. BASUALDO (2004): An eco-epidemiological study of contamination of soil with infective forms of intestinal parasites. Eur. J. Epidemiol. 19, 481-489

SAPOLSKY, R. M. (2005): The influence of social hierarchy on primate health. Science 308, 648-652

SAYER, E. J. (2006): Using experimental manipulation to assess the roles of leaf litter in the functioning of forest ecosystems. Biol. Rev. 81, 1-31

SCHALK, G., and M. R. FORBES (1997): Male biases in parasitism of mammals: effect of study type, host age, and parasite taxon. Oikos 78, 67-74

SCHMIDT, G. D. (1972): Acanthocephala of captive primates. in: R. N. T.-W. FIENNES (ed.) Pathology of simian primates- infectious and parasitic diseases. S. Karger, Basel, vol. 2, pp. 144-156

SCHNIEDER, T. (2006): Veterinärmedizinische Parasitologie. 6. edn., Parey Buchverlag, Stuttgart

SCHNIEDER, T., and A. TENTER (2006): Erreger von Parasitosen: Taxonomie, Systematik und allgemeine Merkmale. in: T. SCHNIEDER (ed.) Veterinärmedizinische Parasitologie. 6. edn., Stuttgart, pp. 26-73

SCOTT, M. E., and A. P. DOBSON (1989): The role of parasites in regulating host abundance. Parasitol. Today 5, 176-183

SEIVWRIGHT, L. J., S. M. REDPATH, F. MOUGEOT, F. LECKIE and P. J. HUDSON (2005): Interactions between intrinsic and extrinsic mechanisms in a cyclic species: testosterone increases parasite infection in red grouse. P. Roy. Soc. B-Biol. Sci. 272, 2299-2304

SELF, J. T., and G. E. COSGROVE (1968): Pentastome larvae in laboratory primates J. Parasitol. 54, 969

SELF, J. T., and G. E. COSGROVE (1972): Pentastomida. in: R. N. T.-W. FIENNES (ed.) Pathology of simian primates- infectious and parasitic diseases. S. Karger, Basel, vol. 2, pp. 194-204

SHADDUCK, J. A., and S. P. PAKES (1978): Protozoal and metazoal diseases. in: K. BENIRSCKE, F. M. GARNER and T. C. JONES (eds.): Pathology of laboratory animals. Springer-Verlag, New York, vol. 2, pp. 1587-1696

References 185

SHELLY, T. E. (1988): Relative abundance of day-flying insects in treefall gaps vs. shaded understory in a Neotropical forest. Biotropica 20, 114-119

SLEEMAN, J. M., L. L. MEADER, A. B. MUDAKIKWA, J. W. FOSTER and S. PATTON (2000): Gastrointestinal parasites of mountain gorillas (Gorilla gorilla beringei) in the Parc National des Volcans, Rwanda. J. Zoo Wildlife Med. 31, 322-328

SLY, D. L., J. D. TOFT, C. H. GARDINER and W. T. LONDON (1982): Spontaneous occurrence of Angiostrongylus costaricensis in marmosets (Saguinus mystax). Lab. Anim. Sci. 32, 286-288

SMITH, A. C. (1997): Comparative ecology of saddleback (Saguinus fuscicollis) and moustached (Saguinus mystax) tamarins. Reading, Univ. of Reading, Dep. of Psychol., Ph.D. thesis

SMITH, A. C. (2000): Interspecific differences in prey captured by associating saddleback (Saguinus fuscicollis) and moustached (Saguinus mystax) tamarins. J. Zool. 251, 315-324

SMITH, G. (1990): The population biology of the free-living phase of Haemonchus contortus. Parasitology 101, 309-316

SMITH, R. J., and W. L. JUNGERS (1997): Body mass in comparative primatology. J. Hum. Evol. 32, 523-559

SMITH, W. N., and M. CHITWOOD (1967): Trichospirura leptostoma gen. et. sp. n. (Nematoda, Thelazioidea) from pancreatic ducts of the white- eared marmoset Callithrix jacchus. J. Parasitol. 53, 1270-1272

SNOWDON, C. T., and P. SOINI (1988): The tamarins, genus Saguinus. in: R. A. MITTERMEIER, A. B. RYLANDS, A. F. COIMBRA-FILHO and G. A. B. DE FONSECA (eds.): Ecology and behavior of Neotropical primates. World Wildlife Fund, Washington, vol. 2, pp. 223-298

SOINI, P., and M. D. SOINI (1990): Distribución geográfica y ecología poblacional de Saguinus mystax. in: N. E. CASTRO-RODRÍGUEZ (ed.) La primatología en el Perú. Investigaciones primatológicas (1973-1985). Imprenta Propaceb, Lima, pp. 272-313

SORIANO, S. V., L. M. BARBIERI, N. B. PIERANGELI, A. L. GIAYETTO, A. M. MANACORDA, E. CASTRONOVO, B. C. PEZZANI, M. C. MINVIELLE and J. A. BASUALDO (2001): Intestinal parasites and the environment: frequency of intestinal parasites in children of Neuquén, Patagonia, Argentina. Rev. Lat. Am. Microbiol. 43, 96-101

186 References

STEVENSON, P., R., M. J. QUIÑONES and J. A. AHUMADA (1998): Annual variation in fruiting pattern using two different methods in a lowland tropical forest, Tinigua National Park, Colombia. Biotropica 30, 129-234

STONER, K. E. (1993): Habitat preferences, foraging patterns, intestinal parasitic infections, and diseases in mantled howler monkeys, Alouatta palliata (Mammalia). Kansas, Univ. of Kansas, Dep. System. Ecol., Ph.D. thesis

STONER, K. E. (1996): Prevalence and intensity of intestinal parasites in manteled howling monkeys (Alouatta palliata) in Northeastern Costa Rica: implications for Conservation Biology. Conserv. Biol. 10, 539-546

STOREY, G. W., and R. A. PHILLIPS (1985): The survival of parasite eggs throughout the soil profile. Parasitology 91, 585-590

STROMBERG, B. E. (1997): Environmental factors influencing transmission. Vet. Parasitol. 72, 247-256

STUART, M. D., and K. B. STRIER (1995): Primates and parasites: a case for multidisciplinary approach. Int. J. Primatol. 16, 577-593

STUART, M. D., K. B. STRIER and S. M. PIERBERG (1993): A coprological survey of parasites of wild muriquis, Brachyteles arachnoides, and brown howling monkeys, Alouatta fusca. J. Helminthol. Soc. W. 60, 111-115

STUART, M. D., L. L. GREENSPAN, K. E. GLANDER and M. R. CLARKE (1990): A coprological survey of parasites of wild mantled howling monkeys (Alouatta palliata palliata). J. Wildlife Dis. 26, 547-549

STUART, M. D., V. PENDERGAST, S. RUMFELT, S. M. PIERBERG, L. L. GREENSPAN, K. E. GLANDER and M. R. CLARKE (1998): Parasites of wild howlers (Alouatta sp.). Int. J. Primatol. 19, 493-512

STUNKARD, H. W. (1965a): Paratriotaenia oedipomidatis gen. et sp. n. (Cestoda) from a marmoset. J. Parasitol. 51, 545-551

STUNKARD, H. W. (1965b): New intermediate hosts in the life cycle of Prosthenorchis elegans (Diesing, 1851), an acanthocephalan parasite of primates. J. Parasitol. 51, 645-649

TANAKA, L. K., and S. K. TANAKA (1982): Rainfall and seasonal changes in arthropod abundance on a tropical oceanic island. Biotropica 14, 114-123

References 187

TANTALEÁN, M., A. GOZALO and E. MONTOYA (1990): Notes on some helminth parasites from Peruvian monkeys. Lab. Primate Newsl. 29, 6-8

TARDIF, S. D., M. L. HARRISON and M. A. SIMEK (1997): Communal infant care in marmosets and tamarins: relation to energetics, ecology and social organization. in: A. B. RYLANDS (ed.) Marmosets and tamarins. Systematics, behaviour, and ecology. Oxford University Press, Oxford, pp. 220-234

TATTERSFIELD, P. (1996): Local patterns of land snail diversity in a Kenyan rain forest. Malacologia 38, 161-180

TATTERSFIELD, P., M. B. SEDDON and C. N. LANGE (2001): Land-snail faunas in indigenous rainforest and commercial forestry plantations in Kakamega Forest, western Kenya. Biodivers. Conserv. 10, 1809-1829

TERBORGH, J. (1983): Five New World primates. A study in comparative ecology. Princeton University Press, Princeton

THATCHER, V. E., and J. A. PORTER (1968): Some helminth parasites of Panamanian primates. Trans. Am. Microsc. Soc. 87, 186-196

THOMAS, F., S. ADAMO and J. MOORE (2005): Parasitic manipulation: where are we and where should we go? Behav. Process. 68, 185-199

THOMAS, F., F. RENAUD, F. ROUSSET, F. CEZILLY and T. DEMEEUS (1995): Differential mortality of two closely-related host species induced by one parasite. P. Roy. Soc. B-Biol. Sci. 260, 349-352

TIRADO HERRERA, E. R., and E. W. HEYMANN (2003): Does Mom need more protein? Preliminary observation on differences in diet composition in a pair of red titi monkeys (Callicebus cupreus). Folia Primatol. 807, 1-4

TOFT, J. D., and M. L. EBERHARD (1998): Parasitic diseases. in: B. T. BENNET, C. R. ABEE and R. HENRICKSON (eds.): Nonhuman primates in biomedical research. Diseases. Academic Press, San Diego, pp. 111-205

TRUANT, A. L., S. H. ELLIOT, M. T. KELLY and J. H. SMITH (1981): Comparison of formalin-ethyl ether sedimentation, formalin-ethyl acetate sedimentation, and zinc sulfate flotation techniques for detection of intestinal parasites. J. Clin. Microbiol. 13, 882-884

UDONSI, J. K., and G. ATATA (1987): Necator americanus: temperature, pH, light, and larval development, longevity, and desiccation tolerance. Exp. Parasitol. 63, 136-142

188 References

VAN ROOSMALEN, M. G. M., T. VAN ROOSMALEN and R. A. MITTERMAIER (2002): A taxonomic review of the titi monkeys, Genus Callicebus Thomas 1903, with the description of two new species, Callicebus bernhardi and Callicebus stephennashi, from Brazilian Amazonia. Neotrop. Primates 10, 1-52

VINAYAK, V. K., N. L. CHITKARA and P. N. CHHUTTANI (1979): Soil dynamics of hookworm larvae. Indian J. Med. Res. 70, 609-614

VINCENTE, J. J., R. M. PINTO and Z. FARIA (1992): Spirura delicata sp. n. (Spiruridae, Spirurinae) from Leontocebus mystax (Callitrichidae) and a check list of other nematodes of some Brazilian primates. Mem. I. Oswaldo Cruz 87, 305-308

VITAZKOVA, S. K., and S. E. WADE (2006): Parasites of free-ranging black howler monkeys (Alouatta pigra) from Belize and Mexico. Am. J. Primatol. 68, 1089–1097

VITONE, N. D., S. ALTIZER and C. NUNN (2004): Body size, diet and sociality influence the species richness of parasitic worms in anthropoid primates. Evol. Ecol. Res. 6, 183-199

WALTHER, B. A., P. COTGREAVE, R. D. PRICE, R. D. GREGORY and D. H. CLAYTON (1995): Sampling effort and parasite species richness. Parasitol. Today 11, 306-310

WARNICK, L. D. (1992): Daily variability of equine fecal strongyle egg counts. Cornell Vet. 82, 453-463

WATLING, J. I., and M. A. DONNELLY (2002): Seasonal patterns of reproduction and abundance of leaf litter frogs in a Central American rainforest. J. Zool. 258, 269-276

WATVE, M. G., and R. SUKUMAR (1995): Parasite abundance and diversity in mammals: correlates with host ecology. Proc. Natl. Acad. Sci. USA 92, 8945-8949

WEBSTER, W. A. (1978): Resurrection of Filariopsis Van-Thiel 1926 (Metastrongyloidea-Filaroididae) for filaroidid lungworms from primates. Can. J. Zoolog. 56, 369-373

WHARTON, D. A. (1979): Ascaris sp.: water loss during desiccation of embryonating eggs. Exp. Parasitol. 48, 398-406

WHITTINGTON, I. D., B. W. CRIBB, T. E. HAMWOOD and J. A. HALLIDAY (2000): Host-specificity of monogenean (platyhelminth) parasites: a role for anterior adhesive areas? Int. J. Parasitol. 30, 305-320

WOLFF, P. L. (1990): The parasites of New World primates: a review. P. Am. Assoc. Zoo Vet. 87-94

References 189

WORMS, M. J. (1967): Parasites in newly imported animals. J. Inst. Anim. Tech. 18, 39-47

WRIGHT, P. C. (1989): The nocturnal primate niche in the New World. J. Hum. Evol. 18, 635-658

YAGI, K., M. MINEZAWA and T. P. GROCK (1988): Helminth parasites of Bolivian Cebid monkeys. Kyoto Univ. Overseas Res. Rep. Stud. New W. Mon. 6, 51-55

YAMASHITA, J. (1963): Ecological relationships between parasites and primates. I. Helminth parasites and primates. Primates 4, 1-96

YOUNG, K. H., S. L. BULLOCK, D. M. MELVIN and C. L. SPRUILL (1979): Ethyl acetate as a substitute for diethyl ether in formalin-ether sedimentation technique. J. Clin. Microbiol. 10, 852-853

ZUK, M. (1990): Reproductive strategies and disease susceptibility - an evolutionary viewpoint. Parasitol. Today 6, 231-233

ZUK, M. (1996): Disease, endocrine-immune interactions, and sexual selection. Ecology 77, 1037-1042

ZUK, M., and K. A. MCKEAN (1996): Sex differences in parasite infections: patterns and processes. Int. J. Parasitol. 26, 1009-1024

190 Appendix

10 APPENDICES

APPENDIX A: List of intestinal helminths found in Saguinus and Callicebus species, including morphological features of eggs and larvae, potential hosts, origin of hosts, pathological alterations 1. TREMATODA

Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces A. Diplo- stomidae S. nigricollis, not known, molluscs, unknown 9; 21; 35; 54 Neodiplostomum S. fuscicollis, insects, amphibians, tamarini Saguinus sp. reptiles or fish Neodiplostomum Saguinus sp. 7; 38; 54 sp. B. Echino- stomatidae Echinostoma S. geoffroyi, 37; 64; 65 aphylactum Saguinus sp. C. Dicro- coeliidae 17-21x27- ovoid, C. albifrons, c, w not known, molluscs, non- syn. A. 7; 9; 18; 20; 34 thick shell, C. apella, insects, amphibians, pathogenic/ heterolecitho- 21; 26; 37; operculum C. capucinus, reptiles or fish obstruction des, A. 47; 53; 54; S. oedipus, and inflam- heterolecithoi- 59; 63-65; S. sciureus, mation of des 68 Athesmia foxi S. fuscicollis, bile ducts S. nigricollis, S. geoffroyi, Cebus sp., Saimiri sp., Saguinus sp., Callicebus sp.

Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- Appendix 191 species µm -logy origin hosts genicity ces 17-21x27- ovoid, A. trivirgatus, c not known, molluscs, non- syn. A. 20; 21; 26; 34 thick shell, C. capucinus, insects, amphibians, pathogenic heterolecithoi- 37; 44; 54; Athesmia operculum S. geoffroyi, reptiles or fish des, A. foxi 59; 63-65 heterolecithodes S. mystax, S. labiatusf C. caligatus, 7; 18; 37; 38 C. apella, Athesmia sp. Saguinus sp., Callicebus sp. 20-35x34- ovoid, C. goeldii, w, i not known, molluscs, unknown syn. 7; 9; 21; 26; 50 (for thick shell, S. nigricollis, insects, amphibians, Conspicuum 35-37; 53; Platynosomum P. concin- operculum S. mystax, reptiles or fish conspicuum 54; 59; 63; amazonensis num) S. fuscicollis, 65 C. jaccus, Saguinus sp. 20-35x34- ovoid, S. fuscicollis, i not known, molluscs, unknown syn. 9; 21; 26; Platynosomum 50 (for thick shell, S. nigricollis, insects, amphibians, Conspicuum 35-37; 59 marmoseti P. concin- operculum Saguinus sp. reptiles or fish conspicuum num) Platynosomum Saguinus sp. 7; 18; 54 sp. 22-26x34- operculu- A. trivirgatus, 26; 35; 37; Zoonorchis 41 lated S. geoffroyi, Aotus 64; 65 goliath sp., Saguinus sp. D. Lecito- dendriidae 40 opercu- A. trivirgatus, w not known, molluscs, unknown 7; 9; 18; 21; lated S. fuscicollis, insects, amphibians, 26; 37; 53; Phaneropsolus S. mystax, Aotus reptiles or fish 54; 59; 64; orbicularis sp., Saimiri sp., 65 Cebus sp., Saguinus sp. 23-29x S. fuscicollis, I not known, molluscs, 9; 18; 38; 54 Phaneropsolus 12-15 (for Saguinus sp. insects, amphibians, sp. P. bonnei) reptiles or fish

192 Appendix 2. CESTODA Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces A. Davaineidae 22-25 oval C. cupreus c unknown, beetles, 4; 16 Railletina flies, ants, snails trinitatae (Raillietina sp.) spindle C. cupreus, i not known, beetles, Raillietina 4; 13; 17; shape, Alouatta sp., flies, ants, snails demerariensis in 21; 25; 35; packed in Callithrix sp., (Raillietina sp.) A. caraya, 38; 47-49; capsules, Callicebus sp., A. seniculus, 54; 64; 65 Raillietina sp. each of 4 Saimiri sp. A. pigra eggs (for R. deme- rariensis) B. Anoploce- phalidae egg: 25- S. nigricollis, w, c insects, coleoptera enteritis syn. Artiotaenia 11; 17; 18; 41x33-45, C personatus ni- megastoma, 21; 26; 27; onco- grifrons, Matheovataenia, 35; 38; 48; sphere: S. sciureus, Oochoristica 52; 65 Atriotaenia 24-33x30- Callithrix sp., megastoma 41 Saguinus sp., Callicebus sp., Cebus sp., Alouatta sp., Ateles sp. egg: thin shell, C. moloch, Cebus w oribatid mites, unknown 4; 17; 21; 46x50, irregular sp., Alouatta sp., experimentally: 35; 38; 48; onco- ovoid Callicebus sp. Scholoribates 54; 59; 65; sphere contour, laevigatus, Galumma 70 Bertiella 18-20 (for inner shell spp. (B. studeri) mucronata B. studeri) with bicor- nuate protru- sion

Appendix 193 Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces egg: 25- Saguinus sp., coleoptera, syn. 11; 22; 35; 41x33-45, Saimiri sp., lepidoptera, Tribolium Matheovataenia 38; 47; 48; Mathevotaenia onco- Callicebus sp. sp. 52; 65 sp. sphere: 24-33x30- 41 46-56, S. fuscicollis, w, i, l insects unknown P. oedipomi- 4; 9; 21; 35; with S. fuscicollis datus in 38; 48; 53; mucus 86- illigeri, Callithrix sp. 62; 65 96, onco- S. leucopus, sphere S. oedipus, Paratriotaenia sp. 37-43, C. goeldii, hooks 18 Saguinus sp., (for Callithrix sp. P. oedi- pomidatis) C. Hymeno- lepididiae egg 68, S. nigricollis, c unknown unknown 2; 11; 17; onco- C. nigrifrons, 18; 21; 35; Hymenolepis sphere Callicebus sp., 38; 52; 65 cebidarum 30x27, Saguinus sp., hooks 16 Callithrix sp. 52-81x62- sphaerical S. mystax, NWP c beetles (Tenebrio rarely 4; 21; 26; 88 thick molitor, T. obscurus), enteritis and 38; 44; 48; mem- fleas (Xenopsylla abscessa- 59 brane, cheopsis, Nosopsyllus tion of straw fasciatus, lymph Hymenolepis coloured, Ctenocephalides nodes diminuta three canis), mealmoth pairs of (Pyralis farinalis), hooks in arthropods the onco- sphere

194 Appendix Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces 30-35x44- greyish, Saimiri sp., NWP flour beetles, fleas or rarely 4; 17; 21; 62 oval, 2 no intermediate host enteritis and 35; 38; 48; membra- abscessa- 59; 65 neous tion of Hymenolepis shells, the lymph nana inner one nodes with 2 poles, 3 pairs of hooks

3. NEMATODA

A. Capil- Size in Morpho Host species Host Intermediate Patho- Comments Referen- lariidae µm -logy origin hosts genicity ces 29-37x48- barrel Cebus sp., Saimiri no intermediate host hepatitis, syn. Hepaticola 5; 21; 26; 62 shaped, 2 sp., Ateles sp., nodules in hepatica, 51; 59; 65; Capillaria polar Cebidae liver, spurious 68 hepatica "plugs", cirrhosis passage of eggs striated if animals ingest shell infected prey B Trichuridae 22x54 Saimiri sp., no intermediate host typhlitis, Trichuris 21; 35; 51; Alouatta sp., colitis, trichuria for 65; 68 Trichuris sp. Lagothrix sp., secondary humans and Cebidae infections some NWP sp. C. Gnathosto- matidae Gnathostoma Saguinus sp. 54 weinberg Leontopithecus 18; 54 Gnathostoma sp. sp., Saguinus sp.

Appendix 195 Size in Morpho Host species Host Intermediate Patho- Comments Referen- D. Oxyuridae µm -logy origin hosts genicity ces Callithrix sp., l no intermediate host anal syn. Buckley- 21; 65 Enterobius Callitrichidae pruritus, Enterobius vermicularis irritation 21-24x45- thin- C. moloch, w no intermediate host 30; 31 Trypanoxyuris 52 shelled, callicebi symme- trical 45x90 thin- S. geoffroyi, w, l, c no intermediate host syn. 28; 33; 64; Trypanoxyuris shelled, C jacchus Hapaloxyuris 65 callithricis symme- callithricis trical Trypanoxyuris 21x36-42 symme- C. torquatus w no intermediate host 31 croizati trical 21x40 relatively S. oedipus, w no intermediate host unknown syn. 14; 21; 29; thick- A. pigra, Trypanoxyuris 32; 43; 51; Trypanoxyuris shelled, A. seniculus, oedipi, 64; 65; 71 minutus symme- Cebus sp., Ateles Enterobius trical sp., Alouatta sp., minutus Callithrix sp. 75x35 thin- S. nigricollis, w, i no intermediate host unknown syn. 9; 13; 21; Trypanoxyuris shelled, Saguinus sp. Paraoxyurone- 28; 32; 33; tamarini symme- ma tamarini 51; 54; 65 trical 20-32x46- C. moloch w no intermediate host 18; 26; 28; Trypanoxyuris 60 29; 32; 33; spp. 54; 55; 70

196 Appendix E. Physalopte- Size in Morpho Host species Host Intermediate Patho- Comments Referen- ridae µm -logy origin hosts genicity ces 30-40x40- oval eggs S. geoffroyi, insects, beetles, gastritis, syn. Abbreviata 4; 18; 21; 60 with Cebus sp., katydids, cockroaches oesopha- sp., 35; 38; 64; smooth Lagothrix sp., (Blatella sp.) gitis, Physaloptera 65; 68 thick shell, Callithrix sp., ulcerative dilatata in NWP embryo- Callicebus sp., enteritis Physaloptera spp. nated Saguinus sp., (P.caucasi Alouatta sp., ca) Pithecia sp., Callitrichidae, Cebidae, NWP F. Rictulariidae Cebus sp., l, z cockroaches, enteritis syn. Rictularia 21; 65; 71 Pterygodermati- Saguinus sp., arthropods tes alphi Callithrix sp. 26-36x39- thick- L. rosalia, z cockroaches enteritis syn. Rictularia 26; 42; 45; Pterygodermati- 45 shelled, Saguinus sp., nycticebi 65; 68 tes nycticebi embryo- Callitrichidae nated Rictularia sp. Callicebus sp. 38; 65 G. Rhabdo- chonidae 23-30x50- thick- C. moloch, i, w roaches pancreatitis, 9; 10; 21; 55 shelled, S. fuscicollis, cholangitis, 26; 35; 38; containing S. oedipus, fibrosis, 50-52; 61; embryo C. jacchus, occasionally 65; 68 Trichospirura with tooth Callimico, obstructive leptostoma Saguinus sp., jaundice Aotus sp., Saimiri sp., Callitrichidae, Cebidae

Appendix 197 H. Gongylo- Size in Morpho Host species Host Intermediate Patho- Comments Referen- nematidae µm -logy origin hosts genicity ces 23-26x40- ovoid, C. capucinus, l, z cockroaches, beetles non- Gongylonema 4; 21; 23; 50 thick, Saimiri sp. Cebus pathogenic capucini in 26; 35; 40; transpa- sp, Ateles sp., C. capucinus, 41; 51; 65 rent shell, Callicebus sp. Gongylonema larvated saimirisi in Gongylonema Saimiri sp., spp. Cebus sp., Callicebus sp., Gongylonema pulchrum in C. capucinus, Ateles sp. I. Spiruridae 40x55 larvated C. jacchus, c, l cockroach non- 6; 53; 54; Protospirura S. fuscicollis, (Leucophaea madera) pathogenic 64; 65 muricola C. capucinus Spirura delicata S. mystax w 66 58x33 S. nigricollis, w, c, l arthropods, locusts oesopha- syn. Spirura 3; 9; 21; 49; S. fuscicollis, (experimentally gitis, death tamarini, 51; 53; 54; Spirura S. geoffroyi, Locusta migratoria) Protospirura 56; 57; 64; guianensis Saimiri sp., guianensis 65 Saguinus sp. 30-40x54- subglobu- S. nigricollis, c, i, l syn. Spirura 3; 8; 49; 64; 60 lar egg S. mystax, Saimiri guianensis, 65 with thick, sp. Protospirura hyalin, guianensis Spirura tamarini smooth shell, embryo- nated 30-40x54- thick- 9; 54 60 (for shelled Spirura sp. Spirura egg with tamarini) larva

198 Appendix J. Ascarididae Size in Morpho Host species Host Intermediate Patho- Comments Referen- µm -logy origin hosts genicity ces 35-45x45- S. geoffroyi , no intermediate host non- unfertilized 4; 21; 51; rounded, 70 A trivirgatus, pathogenic, eggs: elongated 54; 59; 64; thick shell, C. capucinus, in large and larger than 65; 68 Ascaris sp. brown A. fusciceps numbers fertilized eggs, mammil- occlusion of shell is thinner lated layer bowl K. Subuluridae 53 C. jacchus, w, c cockroaches unknown syn. Subulura 9; 11; 12; C. pygmaea, jacchi 18; 21; 26; S. mystax, 27; 38; 44; S. leucopus, 52-54; 63- S. oedipus, 65 Primasubulura S. geoffroyi, jacchi C. aurita, C. nigrifrons, Saguinus sp., Callithrix sp., Callicebus sp. L. Strongyloi- didae eggs: 20- ovoid, S. fuscicollis, no intermediate host enterocoli- 4; 8; 18; 21; 35x40-70, thin- Cebus sp., tis, derma- 35; 38; 47; larva : shelled, Lagothrix sp., titis, pulmo- 51; 53; 54; Strongyloides 1 150-190 embryo- Ateles sp., Saimiri nary hae- 59; 65; 68 cebus nated or sp., Saguinus sp., morrhages, with larva Callitrichidae broncho- pneumonia M. Ancylosto- 51; 59; 68 matidae L. lagothricha, c, p no intermediate host enteritis with 4; 38; 54; Ancylostoma sp. Saimiri sp., haemo- 63-65 Saguinus sp. rrhages

Appendix 199 Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces Ateles sp., no intermediate host enteritis with 4; 21; 51; Necator C. capucinus, haemo- 59; 64; 65; americanus Cebidae rrhages, 68 anaemia C. calvus, c, p no intermediate host enteritis with 63-65 C. capucinus haemo- Necator sp. rrhages, anaemia N. Metastron- 1; 59 gylidae

larva1: 14- larva1: S. mystax, c, i slugs (Vaginulus granuloma- 4; 46; 54; 15x260- notch Callitrichidae plebius), fresh water tous appen- 60; 65; 68 290 close to snails, molluscs dicitis, intes- Angiostrongylus the tip, tinal ulcera, costaricensis slender peritonitis, esopha- arteritis, gus, nerve thrombosis ring

larva1: long, C. apella, unknown unknown syn. Filaroides 18; 21; 35; 10x340- tapered C. capucinus, arator, 39; 65; 67 Filariopsis arator 350 tail C. albifrons, Filaroides cebi (80µm) Alouatta sp., Cebus sp. A. seniculus, unknown 18; 35; 65; Filariopsis asper Alouatta sp., 67 Cebus sp. Filariopsis C. pygmaea syn. Filaroides 67 cebuellae cebuellae S. mystax, w unknown non- syn. 18; 21; 26; S. labiatus, pathogenic/ Oslerus/Filari- 35; 44; 65; Filaroides Callithrix sp, atelectasis, opsis barretoi 67 barretoi Saimiri sp., pulmonary Saguinus sp. haemo- rrhages

200 Appendix Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces

larva1: 9- C. apella, unknown syn. 23; 65; 67 11x250- C. macrocepha- Filaroides/Filari- Filaroides cebi 260 lus, C. capucinus, opsis cebi C. albifrons, Cebus sp. S. fuscicollis, unknown non- syn. 18; 21; 35; S. nigricollis, pathogenic/ Oslerus/Filari- 65; 67 Filaroides S. sciureus, atelectasis, opsis gordius gordius Saimiri sp. pulmonary haemorrhag es S. fuscicollis, unknown unknown 9; 21; 34; Saimiri sp., 38; 49; 54; Lagothrix sp., 65; 68 Callithrix sp., Filaroides sp. Alouatta sp., Cebus sp., Saguinus sp., Callitrichidae, Cebidae O. Tricho- strongylidae 31-41x62- S. sciureus, w, c no intermediate host unknown syn. 9; 18; 21; 79 S. nigricollis, Boreostrongylus 24; 35; 51; S. fuscicollis, romerolagi n. 53; 54; 59; Longistriata C. moloch, sp. 65; 70 dubia Saguinus sp., Alouatta sp., Saimiri sp. Longistriata sp. Saguinus sp. no intermediate host 38; 54 30-37x59- ellypsoid, S. mystax, w no intermediate host non- 18; 21; 26; 63 thin shell S. sciureus, pathogenic 27; 35; 54; Molineus elegans slightly Cebus sp., Saimiri 59 tapered at sp. one end

Appendix 201 Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces 30x50 morula S. midas c 19 Molineus midas stage 20-29x40- Cebus sp., Saimiri w,c no intermediate host ulcerative or 18; 21; 26; Molineus 52 sp., Aotus sp., haemo- 35; 51; 54; torulosus Saimiri sp., rrhagic 59; 65; 68 Cebidae, NWP enteritis 20-29x40- S. fuscicollis, w, c no intermediate host non- 9; 15; 18; Molineus 52 S. leucopus, pathogenic 21; 35; 53; vexillarius S. oedipus, 54 Saguinus sp.

4. ACANTHOCEPHALA

Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces A. Oligacan- thorhynchidae 41-43x60- thick- S. nigricollis, w, c cockroaches (Blattella granuloma- 9; 16; 17; 65 walled S. oedipus, germanica, Blabera tous, 21; 26; 27; eggs, fine S. fuscicollis, fusca, Rhyparobia ulcerative 35; 38; 44; reticular S. mystax, madera), beetles enteritis, 47; 49; 53; sculptu- S. geoffroyi, (Lasioderma occasionally 54; 58; 59; ring in C. pygmaea, serricorne, Stegobium mechanical 63-65; 68- outer S. boliviensis, paniceum), insects blockage of 70 Prosthenorchis shell, S. sciureus, the intestine elegans raphe of C. cupreus, or perfo- middle Cebuella sp., ration, shell Ateles sp., Saimiri peritonitis sp, Alouatta sp., Aotus sp., Lagothrix sp., Callitrichidae

202 Appendix Parasite Size in Morpho Host species Host Intermediate Patho- Comments Referen- species µm -logy origin hosts genicity ces 49-53x78- Outer S. oedipus, cockroaches syn 9; 18; 21; 81 shell C. jacchus Prosthenorchis 53; 54; 58; Prosthenorchis lightly sigmoides 64; 65 spirula sculp- tured, no raphe S. fuscicollis, cockroaches P. lenti 53; 54; 64 S. mystax, Prosthenorchis S. oedipus, sp. C. jacchus S. geoffroyi Legend: A.-O.=families of the cited parasite species, taxonomy follows SCHNIEDER and TENTER (2006) if not otherwise noted in the references. grey shaded cells= parasite taxa recovered in this study

Host species: Alouatta: A. carata, A. pigra, A. seniculus Aotus: A. trivirgatus Ateles: A. fusciceps Cacajao: C. calvus Callicebus: C. cupreus, C. moloch, C personatus nigrifrons, C. caligatus, C. nigrifrons, C. torquatus Callimico: C. goeldii Callithrix: C. jacchus, C. aurita Cebuella: C. pygmaea Cebus: C. albifrons, C. apella, C. capucinus, C. macrocephalus Lagothrix: L. lagothricha Leontopithecus: L. rosalia Saguinus: S. nigricollis, S. fuscicollis, S. mystax, S. oedipus, S. geoffroyi, S. labiatus, S. fuscicollis illigeri, S. leucopus, S. midas Saimiri: S. sciureus, S. boliviensis

NWP: New World primates

Host origin: w=wild, c=captured wild animals, i=imported, l=laboratory, p=pet, z=zoo animal

Appendix 203

REFERENCES (LIST OF HELMINTH PARASITES OF STUDY SPECIES) 1. ANDERSON (2000); 2. BAER (1927); 3. BLANCHARD and EBERHARD (1986); 4. BRACK (1987); 5. BRACK et al. (1994); 6. CAMPOS and VARGAS-VARGAS (1978); 7. COSGROVE (1966); 8. COSGROVE et al. (1963); 9. COSGROVE et al. (1968); 10. COSGROVE et al. (1970a); 11. DE MELO et al. (1997); 12. DE RESENDE et al. (1994); 13. DEINHARDT et al. (1967); 14. DIAZ-UNGRIA (1964); 15. DUNN (1961); 16. DUNN (1962); 17. DUNN (1963); 18. DUNN (1968); 19. DURETTE-DESSET and CORVIONE (1998); 20. FAUST (1967); 21. FLYNN (1973); 22. GALLATI (1959); 23. GEBAUER (1933); 24. GIBBONS and KUMAR (1980); 25. GILBERT (1994); 26. GOZALO (2003); 27. HORNA and TANTALEÁN (1990); 28. HUGOT (1984); 29. HUGOT (1985); 30. HUGOT and VAUCHER (1985); 31. HUGOT et al. (1994); 32. INGLIS and DUNN (1964); 33. INGLIS and COSGROVE (1965); 34. KIM and WOLF (1980); 35. KING (1976); 36. KINGSTON and COSGROVE (1967); 37. KUNTZ (1972); 38. KUNTZ and MYERS (1972); 39. LEE et al. (1996); 40. LUCKER (1933a); 41. LUCKER (1933b); 42. MATERN and FIEGE (1989); 43. MENSCHEL and STROH (1963); 44. MICHAUD et al. (2003); 45. MONTALI et al. (1983); 46. MORERA (1973), 47. MOVTSCHAN (1974); 48. MYERS (1972); 49. NELSON et al. (1966); 50. ORIHEL and SEIBOLD (1971); 51. ORIHEL and SEIBOLD (1972); 52. PACHECO et al. (2003); 53. PORTER (1972); 54. POTKAY (1992); 55. PRIETO et al. (2002); 56. QUENTIN (1973); 57. RIBEIRO AMATO et al. (1976); 58. SCHMIDT (1972); 59. SHADDUCK and PAKES (1978); 60. SLY et al. (1982); 61. SMITH and CHITWOOD (1967); 62. STUNKARD (1965); 63. TANTALEÁN et al. (1990); 64. THATCHER and PORTER (1968); 65. TOFT and EBERHARD (1998); 66. VINCENTE et al. (1992); 67. WEBSTER (1978); 68. WOLFF (1990); 69. WORMS (1967); 70. YAGI et al. (1988); 71. YAMASHITA (1963)

204 Appendix

APPENDIX B: Group composition over the study period

1. Group composition of S. fuscicollis

Individuals sex age* 2002 2003 per group 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 West: Carlos m ad Bryan m ad Vidal m inf Racna f ad Arsénica f ad Emilia f juv total 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 East: P. pela. m ad Abrán m ad Asrael m juv Cuerno m inf Gordita f ad Brittita f inf total 4 4 4 4 4 6 6 6 6 6 6 6 6 6 6 North: Codito m ad Tito m ad Shaolín m inf Kali f ad Tablita f ad total 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5

Appendix 205

2. Group composition of S. mystax

Individuals sex age* 2002 2003 per group 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 West: Quinto m ad Victor m ad Piwi m ad Beto m ad Diablo m juv Petronila f ad total 3 3 3 3 3 3 1 1 1 1 4 4 4 4 4 East: Blanco m ad Moli m ad Adán m ad Pit m ad Prado m ad Chavo m sub Isma. m sub Gaston m inf Punta f ad total 8 8 8 8 6 6 7 7 6 6 6 6 6 6 6 North: Muno m ad Joel m ad Virilo m inf Sipuca f ad Mauricia f ad Pitufina f juv Jenni f inf total 5 5 5 5 6 6 6 6 6 6 6 6 7 6 6

206 Appendix

3. Group composition of C. cupreus

Individuals sex age* 2002 2003 per group 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 Casa: Pluto m ad Cocoliso m juv Cría f inf Olivia f ad total 3 3 4 4 4 4 4 4 4 4 4 Puerto: Mocho m ad Roki m juv H. repro. f ad Gloria f ad total 3 3 3 3 3 3 Legend: sex: f= female, m=male *Age classes: ad = adult, sub = subadult, juv = juvenile, inf = infant; refers to the age when the individual was first observed, for both Saguinus species defined by SOINI and SOINI (1990), for Callicebus cupreus by MAYEAUX et al. (2002) and KINZEY (1981) grey field: animal was present, hatched field: presence of adult was uncertain or infant was carried by group members

APPENDIX C: Parasite morphology: comparison of length and width of parasite stages Results of Kruskal-Wallis test, Mann-Whitney U-test, respectively

Length Width Parasite taxa H U p H U p Prosthenorchis elegans 30 0.616 24 0.291 Hymenolepis sp. 105.5 0.853 102.5 0.786 Cestode sp. #2 Small spirurida 13.391 0.001 6 0.042 Large spirurida 32.0 1.0 10.5 0.021 “Strongylids” 21.241 <0.001 30.279 <0.001

Appendix 207

Results of post hoc tests (Mann-Whitney U-test)

1. Small spirurids

Host species Sf Sm Cc Sf (N=77) U=2752.5 U=2318.0 p=1.0 p=0.321 width Sm (N=77) U=2639.0 U=2080.5 p=0.714 p=0.033 Cc (N=71) U=2039.5 U=1844.0 p=0.021 p=0.003 length

2. “Strongylids”

Host species Sf Sm Cc Sf (N=88) U=1786.5 U=182.5 width p=0.57 p≤0.001 Sm (N=47) U=1873.5 U=59.0 p=1.0 p≤0.001 Cc (N=27) U=589.5 U=389.5 p≤0.001 p=0.015 length

208 Appendix APPENDIX D: Correlations between independent variables

Spearman Rank Correlation, N=42

variable HRS GS HD AP GT clay flat drain US VD LL DW

HRS 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.19 0.00 0.01 0.71

GS 0.70 . 0.43 0.12 0.21 0.00 0.16 0.00 0.20 0.00 0.16 0.97

HD -0.47 0.13 0.00 0.54 0.00 0.32 0.01 0.00 0.00 0.32 0.67

AP 0.71 0.24 -0.62 0.00 0.00 0.00 0.00 0.39 0.00 0.00 0.01

GT 0.57 0.20 -0.10 0.68 0.00 0.00 0.00 0.01 0.00 0.00 0.29

clay -0.84 -0.45 0.45 -0.81 -0.63 0.00 0.00 0.09 0.00 0.00 0.02

p s r flat 0.42 0.22 -0.16 0.79 0.71 -0.74 0.00 0.14 0.00 . 0.00

drain -0.83 -0.51 0.38 -0.85 -0.61 0.76 -0.54 0.58 0.00 0.00 0.97

US -0.21 0.20 0.73 -0.14 0.39 0.26 0.23 0.09 0.05 0.14 0.37

VD 0.85 0.43 -0.67 0.95 0.54 -0.86 0.64 -0.90 -0.31 0.00 0.10

LL 0.42 0.22 -0.16 0.79 0.71 -0.74 1.00 -0.54 0.23 0.64 0.00

DW 0.06 0.01 0.07 -0.40 -0.17 0.35 -0.78 0.01 -0.14 -0.26 -0.78

HRS GS HD AP GT clay flat drain US VD LL DW

Legend: HRS=Home-range size, GS=mean group size, HD=host density, AP=% animal prey. GT=% ground time, clay=clay soil, flat=flat terrain, drain=poor drainage, US=dense understorey, VD=high vegetation density, LL=leaf litter >10 cm, DW=high deadwood abundance

bold printed cells if rs <-0.7 or >0.7 and if p<0.05

Appendix 209

APPENDIX E: PSR/prevalences and correlations with proportion of animal prey and time spent on the ground Spearman Rank Correlation, N=42, all host species

Parasite % animal prey % ground time

rs p rs p

PSR 0.48 0.001 0.63 0.000

P. elegans -0.18 0.243 -0.11 0.470

Hymenolepis sp. 0.30 0.052 0.51 0.001

Cestode sp. #2 0.51 0.001 0.36 0.019

Large spirurid 0.44 0.003 0.57 0.000

Nematode larvae 0.02 0.883 0.23 0.145

Spearman Rank Correlation, N=38, excluding Callicebus

Parasite % animal prey % ground time

rs p rs p

PSR 0.32 0.047 0.56 0.000

P. elegans -0.30 0.063 -0.17 0.299

Hymenolepis sp. 0.18 0.272 0.48 0.003

Cestode sp. #2 0.40 0.014 0.23 0.165

Large spirurid 0.42 0.009 0.57 0.000

Nematode larvae 0.07 0.672 0.27 0.105

210 Appendix

APPENDIX F: Activity budgets of all study species

1. S. fuscicollis 2. S. mystax

6% 7% 3% 4% 8% 29% 36% 9%

47% 51%

3. C. cupreus

8% 1%

38% 17%

Activity Foraging Grooming Ingestion 36% Locomotion Resting

Appendix 211

APPENDIX G: PSR/prevalences and correlation with home-range size, mean group size and host density Spearman Rank Correlation, N=42, all host species

Parasite Home-range size Mean group size Host density

rs p rs p rs p

PSR 0.37 0.016 0.14 0.380 -0.17 0.291

P. elegans -0.05 0.776 -0.07 0.650 -0.12 0.449

Hymenolepis sp. 0.18 0.260 -0.19 0.229 -0.29 0.063

Cestode sp. #2 0.39 0.011 0.48 0.001 0.01 0.950

Large spirurid 0.31 0.046 -0.01 0.951 -0.12 0.445

Nematode larvae 0.03 0.837 0.01 0.930 0.15 0.330

Spearman Rank Correlation, N=38, excluding Callicebus

Parasite Home-range size Mean group size Host density

rs p rs p rs p

PSR 0.18 0.291 -0.08 0.612 0.07 0.662

P. elegans -0.14 0.397 -0.12 0.463 -0.05 0.750

Hymenolepis sp. 0.03 0.850 -0.38 0.019 -0.17 0.313

Cestode sp. #2 0.25 0.138 0.38 0.018 0.26 0.122

Large spirurid 0.26 0.110 -0.11 0.493 -0.04 0.811

Nematode larvae 0.08 0.625 0.02 0.922 0.14 0.414

212 Appendix

APPENDIX H: Habitat characteristics of the home ranges

Habitat Home range characteristic

categories Casa West East North

0-400 24.2 17.9 12.0 14.6

400-800 42.4 45.3 49.2 50.4 vegetation density 800-1200 24.2 23.9 20.8 22.0 (trees/ha) 1200-2000 6.1 10.3 16.9 8.9

>2000 3.0 2.6 1.1 4.1

low 42.4 30.6 16.0 13.5 understorey intermediate 39.4 47.7 63.3 51.9 density high 18.2 21.6 20.7 34.6

0-5 48.5 39.3 10.9 15.4 leaf litter height 5-10 33.3 39.3 34.4 36.6 (cm) 10-15 15.2 15.4 36.1 34.1

>15 3.0 6.0 16.9 11.4

clay 66.7 53.4 10.4 6.5

mixed 6.1 11.2 13.7 19.5 soil type sand 18.2 29.3 71.4 67.5

swampy 9.1 6.0 4.4 6.5

poor 15.2 14.5 6.6 10.6 drainage intermediate 3.0 3.4 3.8 4.9

good 81.8 82.1 89.6 84.6

flat 69.7 75.2 86.9 92.7 ground inclination intermediate 21.2 12.8 8.7 5.7

steep 9.1 12.0 4.4 1.6

0 51.5 66.7 67.2 67.5 deadwood abundance 1 30.3 23.9 27.3 26.0 (tree units) >1 18.2 9.4 5.5 6.5

Appendix 213

APPENDIX I: Variation in egg and larvae output including all host species

Degrees of freedom (df), F-, p-values generated by GLMM

Effect per parasite df F p P. elegans species 1 0.08 0.799 season 2 0.53 0.632 species * season 2 34.48 0.007 Hymenolepis sp. species 1 0.04 0.847 season 2 2.11 0.142 species * season 2 1.05 0.363 Cestoda sp species 1 0.90 0.351 season 2 1.45 0.245 species * season 2 1.67 0.201 small Spirurids species 2 1.59 0.217 season 2 1.81 0.173 species * season 3 4.95 0.004 Large Spirurids species 1 0.42 0.529 season 2 5.10 0.025 species * season 2 1.46 0.270 Nematode larvae species 2 10.07 0.000 season 2 2.63 0.080 species * season 3 0.55 0.649 “Strongylids” species 2 12.78 0.000 season 2 2.35 0.104 species * season 3 0.27 0.850

214 Danksagung

11 DANKSAGUNG/AGRADECIMIENTOS/ACKNOWLEDGEMENTS

Dass diese Arbeit soweit gediehen ist, verdanke ich der Unterstützung einer Vielzahl von Menschen, denen ich an dieser Stelle ganz herzlich danken möchte.

Zunächst möchte ich mich bei Herrn Univ. Prof. Dr. F.-J. Kaup für seine freundliche Betreuung und die gute Zusammenarbeit bedanken. Ein großes Dankeschön gebührt Herrn PD Dr. Eckhard W. Heymann für die Grundsteinlegung dieser Arbeit, die unermüdliche und uneingeschränkte Unterstützung während der Feldarbeit, die konstruktiven Diskussionen und die allzeit mögliche Rücksprache bei der Auswer- tung und Zusammenstellung dieser Arbeit. Ich möchte ihm an dieser Stelle auch danken, dass er mir diese großartige Möglichkeit gegeben hat, das für mich neue Feld der Verhaltensökologie zu betreten, und mir dabei so viel Vertrauen entgegen gebracht hat. Herrn Dr. Christian Epe möchte ich für seine tatkräftigen und auch „postwendenden“ Anregungen bei der parasitologischen Methodenerarbeitung, sowie bei Durchsicht der Manuskripte danken. Frau Dr. Kerstin Mätz-Rensing sei gedankt für ihre Unterstützung besonders während der Laborphase, wo sie den reibungslosen Ablauf ermöglichte, für ihre pathologisch-histologischen Anregungen und die sorgfältige Überarbeitung der vorläufigen Versionen. Mein Dank gilt ebenso Frau Dr. Martina Zöller für die Korrekturen des pathologischen Teils. Sehr, sehr herzlich möchte ich Herrn Prof. D. W. Büttner danken. Von seiner engagierten und detaillierten Einweisung in einige Grundsätze der parasitologischen Methodologie und der Helminthologie, der kritischen Auseinandersetzung mit meinem Thema und seiner unbestechlichen Durchsicht des Manuskripts hat meine Arbeit an vielen entscheidenden Stellen profitiert. Bei Herrn Prof. Dr. E. Tannich bedanke ich mich für die Einladung ans Bernhard-Nocht-Institut, seine konstruktiven Anregungen und das Interesse an meiner Arbeit.

Gracias a todos los que hicieron posible la realización de mi “gran obra” en el Perú. En primer lugar quiero decirles gracias a los asistentes de campo Camilo Flores Amasifuén, Ney y Jeisen Shahuano Tello y Jenni Pérez Yamacita. ¡Sin su gran

Danksagung 215

apoyo este trabajo no hubiera sido el mismo! Ebenso wäre diese Arbeit um einiges ärmer, wenn die zahlreichen PraktikantInnen nicht so engagiert mitgewirkt hätten. Deswegen ein besonderer Dank an Wolf-Christian Saul, Jenny „Pen“ Kröger, Barbara Kremeyer und die anderen StudentInnen aus der bunten internationalen Mischung. Quisiera darle un especial agradecimiento al director de la Estación Experimental del Instituto Veterinario de Investigaciones Tropicales y de Altura (IVITA) Dr. Enrique Montoya por su hospitalidad y su colaboración mientras desarrollaba el trabajo en Perú. Muchisimas gracias también a los médicos veterinarios de la estación, Dra. Nofre Sánchez Perrea y Dr. Hugo Gálvez Carillo, y al biológo Dr. Carlos Ique por apoyarme en el trabajo de campo y de laboratorio. De igual manera quiero agradecerles su ayuda a Arnulfo, Lester, Zoilita y los demás del equipo IVITA que siempre me han dado un gran apoyo. Gracias muy especiales a Nelly Tanchiva Flores y su familia por resolver cualquier problemita del trabajo y por compartir muchos momentos de la vida “pishcota” que nunca voy a olvidar. A mi familia limeña le agradezco de todo corazón por siempre estar presente.

In der methodologischen Selbstfindungsphase erfuhr ich besonders viel Unterstützung von den technischen AssistentInnen der Sektion Parasitologie des Bernhard-Nocht-Institutes, von Frau Scholz vom Institut für Medizinische Mikrobiologie der Universitätskliniken Göttingen und Frau Rudloff aus der Parasitologischen Abteilung des Tierparks Berlin Friedrichsfelde. Besonders gedankt sei auch Frau Hafiza Zuri, Elke Lischka und Herrn Wolfgang Henkel der Abteilung Infektionspathologie des Deutschen Primatenzentrums, die mir bei allen möglichen und fast unmöglichen Dingen im Labor geholfen haben. Herausstellen möchte ich auch die großartige, Theorie- und Praxis-bezogene Hilfe von Frau Dr. Christina Schlumbohm.

Den Mitgliedern der Abteilung Verhaltensökologie & Soziobiologie des DPZ (Ehemalige und Assoziierte eingeschlossen) sei ebenfalls ausdrücklich gedankt! Die zahlreichen Seminare mit kritischen Diskussionen und stimulierenden Denkanstößen haben mein wissenschaftliches Vorankommen entscheidend geprägt. Namentlich möchte ich mich bei Prof. Dr. Peter M. Kappeler für die feinsinnigen Kommentare, die kritische Auseinandersetzung mit meinem Projekt und die wissenschaftliche

216 Danksagung

Förderung in Form von Kongress- und Kurs- Teilnahmen bedanken. Ein herzliches Dankeschön gilt besonders Dagmar Lorch und Markus Port für die „akkurate“ und überaus produktive Überarbeitung meiner Entwürfe und den Beistand in allen Hoch-, Tief-, Schräg- und Querlagen, aber auch Dr. Manfred Eberle, Dr. Antje Engelhardt, Dr. Dietmar P. Zinner, Dr. Daniel Stahl, Dr. Yann Clough für diverse, unverzichtbare Hilfestellungen. Ein Riesendankeschön geht an Dr. Maren Huck und Dr. Petra Löttker, die im wahrsten Sinne des Wortes vom Mehrzellstadium bis zur Geburt mit logistischer, fachlicher und persönlicher Unterstützung Patinnen standen und so manches Mal die „shalupa“ aus dem Schlamm gezogen haben...

Die Parasitendiversität lebte durch die Diversität der an ihrer Identifikation beteiligten Personen. Bei der Literaturrecherche und Parasitenbestimmung waren mir Dr. M. Brack, Dr. A. Gozalo, Prof. Dr. A. L. De Melo, Dr. M. Tantaleán Vidaurre und Dr. W. Tscherner eine unersetzliche Hilfe. Thanks to Dr. Sonia Altizer and Dr. Amy Pederson for teaching inspiring classes in disease ecology at Mountain Lake Biological Station. I benefited greatly from the fruitful discussions and helpful comments on my project. Thanks to all y’all! Frage fünf StatistikerInnen und …letzten Endes verdanke ich Frau Dr. Karin Neubert von der Abteilung Medizinische Statistik des Universitätsklinikums Göttingen den Abschluss meiner statistischen Erkundungszüge, wunderbare Erste-Hilfe-Pakete inklusive! Dass dieses Werk sprachlich noch abgerundet und poliert wurde, verdanke ich Frau Ingrid Rossbach, Katie Gascoigne, Petra Schnüll und Don Yvan Lledo Ferrer.

The study was conducted under a letter of understanding between the Universidad Nacional de la Amazonía Peruana (UNAP), Iquitos (Peru), and the German Primate Center (DPZ) in Göttingen. I especially thank the German Academic Exchange Service (DAAD) and the German Research Foundation (DFG) for financial support; and the Boehringer Ingelheim Fonds (B.I.F) and Sanofi-Aventis (i-lab Award) for the travel allowances. Ein besonderer Dank gebührt Frau Maria-Luise Nünning für Ihre tolle Betreuung während des DAAD finanzierten Aufenthaltes in Peru. Frau C. Schmetz vom Bernhard-Nocht-Institut möchte ich sehr danken für die Präparation und REM-Aufnahme des Acanthocephalen; und Julia Diegmann und Mirjam Nadjafzadeh für das freundliche Überlassen der „Wirtsfotos“.

Danksagung 217

Eine Danksagung ist wohl nie vollständig, aber irgendwann muss sie zu Ende gehen...To all these people, my sincere thanks! ¡MuchisSIsimas gracias!

Zum Schluss möchte ich meinen Freundinnen und Freunden danken, die zum Teil fachlich, zum Teil auch erfrischend unfachlich zum Gedeihen dieses Werkes beigetragen haben. Der alles umfassende, abschließende Dank gehört meinen Eltern. Weit über die biologische Ermöglichung dieser für mich wichtigen Arbeit hinausgehend, bedanke ich mich auch von ganzem Herzen bei ihnen für die uneingeschränkte Unterstützung, die unzählbaren Aufmunterungen und das immer spürbare An-mich-Glauben!

35392 Gießen ·FrankfurterStr V e-mail: [email protected] ·Homepage: http://www erlag: Deutsche V eterinärmedizinische GesellschaftService GmbH ISBN 978-3-939902-34-8 . 89·T el. 0641/24466 ·Fax:0641/25375 .dvg.net

Determinants of the diversity of intestinal parasite communities in sympatric New World primates Britta Müller ( S a g u i n u s m y s t a x , S a g u i n u s f u s c i c o l l i s , C a l l i c e b u s c u p r e u s ) Hannover 2007 Deter (Saguinus mystax,S minants ofthediversityintestinalparasitecommunities in sympatricN aguinus fuscicollis,Callicebuscupr B ritta Müller ew W orld primates eus)