Use of trade-off theory to advance understanding of herbivore-parasite interactions

Mammal Review

Volumn 36, Issue 1, 2006, Pages 1-16

  Hutchings, Michael R ^a   Judge, Johanna ^a   Gordon, Iain J ^b   Athanasiadou, Spiridoula ^a   Kyriazakis, Ilias ^a,c  

^a SCOTTISH AGRICULTURAL COLLEGE   (United Kingdom)

^b CSIRO   (Australia)

^c UNIVERSITY OF THESSALY   (Greece)

Author keywords

Faeces; Host; Nutrition; Optimal foraging; Parasite; Self medication

Indexed keywords

FORAGING BEHAVIOR; HERBIVORE; HOST-PARASITE INTERACTION; MAMMAL; NUTRIENT UPTAKE; PREDATION RISK; TRADE-OFF;

ANIMALIA; MAMMALIA;

EID: 33745019584     PISSN: 03051838     EISSN: 13652907     Source Type: Journal    
DOI: 10.1111/j.1365-2907.2006.00080.x     Document Type: Review

References (116)

1. Adewunmi, C. O., Agbedahunsi, J. M., Adebajo, A. C., Aladesanmi, A. J., Murphy, N. & Wando, J. (2001) Ethno-veterinary medicine: Screening of Nigerian medicinal plants for trypanocidal properties. Journal of Ethnopharmacology, 77, 19-24.
2. Akhtar, M. S. & Ahmad, I. (1992) Comparative efficacy of Mallotus philippinensis fruit (Kamala) or Nilzan drug against gastrointestinal cestodes in Beetal goats. Small Ruminant Research, 8, 121-128.
3. Applebaum, S. W. & Birk, Y. (1979) Saponins. In: Herbivores, Their Interactions with Secondary Plant Metabolites (Ed. by G. A. Rosental & T.H. Janzen), pp. 539-566. Academic Press, London.
4. Armour, J. (1980) The epidemiology of helminth disease in farm animals. Veterinary Parasitology, 6, 7-46.
5. Athanasiadou, S., Kyriazakis, I., Jackson, F. & Coop, R. L. (2001) Direct anthelmintic effects of condensed tannins towards different gastrointestinal nematodes of sheep: In vitro and in vivo studies. Veterinary Parasitology, 99, 205-219.
6. Bao, J., Giller, P. S. & Stakelum, G. (1998) Selective grazing by dairy cows in the presence of dung and the defoliation of tall grass dung patches. Animal Science, 66, 65-73.
7. Barnard, C. J. & Behnke, J. M. (1990) Parasitism and Host Behaviour. Taylor & Francis, London.
8. Barry, T. N. & McNabb, W. C. (1999) The implications of condensed tannins on the nutritive value of temperate forages fed to ruminants. British Journal of Nutrition, 81, 263-272.
9. Basset, A., Fedele, M. & DeAngelis, D. L. (2002) Optimal exploitation of spatially distributed trophic resources and population stability. Ecological Modelling, 151, 245-260.
10. Bazely, D. R. (1990) Rules and cues used by sheep foraging in monocultures. In: Behavioural Mechanisms of Food Selection (Ed. by R. N. Hughes), pp. 343-367. Springer-Verlag, London.
11. Bazely, D. R. & Ensor, C. V. (1989) Discrimination learning in sheep with cues varying in brightness and hue. Applied Animal Behaviour Science, 23, 293-299.
12. Beard, P. M., Daniels, M. J., Henderson, D., Piri, A., Rudge, K., Buxton, D., Rhind, S., Greig, A., Hutchings, M. R., McKendrick, I., Stevenson, K. & Sharp, J. M. (2001a) Paratuberculosis infection of nonruminant wildlife in Scotland. Journal of Clinical Microbiology, 39, 1517-1521.
13. Beard, P. M., Rhind, S., Buxton, D., Henderson, D., Daniels, M. J., Pirie, A., Rudge, K., Greig, A., Hutchings, M. R., Stevenson, K. & Sharp, J. M. (2001b) Natural paratuberculosis infection in rabbits in Scotland. Journal of Comparative Pathology, 124, 290-299.
14. Black, J. L. & Kenney, P. A. (1984) Factors affecting diet selection by sheep. II height and density of pasture. Australian Journal of Agricultural Research, 35, 565-578.
15. Bown, M. D., Poppi, D. P. & Sykes, A. R. (1991) The effects of post-ruminal infusion of protein or energy on the pathophysiology of Trichostrongylus colubriformis infection and body composition in lambs. Australian Journal of Agricultural Research, 42, 253-267.
16. Coop, R. L. & Kyriazakis, I. (1999) Nutrition-parasite interaction. Veterinary Parasitology, 84, 187-204.
17. Coop, R. L. & Kyriazakis, I. (2001) Influence of host nutrition on the development and consequences of nematode parasitism in ruminants. Trends in Parasitology, 17, 325-330.
18. Coop, R. L., Sykes, A. R. & Angus, K. W. (1982) The effect of three levels of intake of Ostertagia circumcincta larvae on growth rate, food intake and body composition of growing lambs. Journal of Agricultural Science, 98, 247-255.
19. Cooper, J., Gordon, I. J. & Pike, A. W. (2000) Strategies for the avoidance of faeces by grazing sheep. Applied Animal Behaviour Science, 69, 15-33.
20. Cosgrove, G. P. & Niezen, J. H. (2000) Intake and selection for white clover by grazing lambs in response to gastrointestinal parasitism. Applied Animal Behaviour Science, 66, 71-85.
21. Courchamp, F., Rasmussen, G. S. A. & Macdonald, D. W. (2002) Small pack size imposes a trade-off between hunting and pup guarding in the painted hunting dog Lycaon pictus. Behavioural Ecology, 13, 20-27.
22. Crawley, M. J., Albon, S. D., Bazely, D. R., Milner, J. M., Pilkington, J. G. & Tuke, A. L. (2004) Vegetation and sheep population dynamics. In: Soay Sheep: Dynamics and Selection in an Island Population (Ed. by T. H. Clutton-Brock & J.M. Pemberton), pp. 89-112. CambridgeUniversity Press, Cambridge.
23. D'Mello, J. P. F. (1992) Chemical constraints to the use of tropical legumes in animal nutrition. Animal Feed Science and Technology, 38, 237-261.
24. Daniels, M. J., Ball. N., Hutchings, M. R. & Greig, A. (2001) The grazing response of cattle to pasture contaminated with rabbit faeces and the implications for the transmission of paratuberculosis. The Veterinary Journal, 161, 306-313.
25. Daniels, M. J., Hutchings, M. R., Beard, P. M., Henderson, D., Greig, A., Stevenson, K. & Sharp, J. M. (2003a) Do non-ruminant wildlife pose a risk of paratuberculosis to domestic livestock and vice versa. Scotland? Journal of Wildlife Disease, 39, 10-15.
26. Daniels, M. J., Henderson, D., Greig, A., Stevenson, K., Sharp, J. M. & Hutchings, M. R. (2003b) The potential role of wild rabbits Oryctolagus cuniculus in the epidemiology of paratuberculosis in domestic ruminants. Epidemiology and Infection, 130, 553-559.
27. Daniels, M. J., Lees, J. D., Hutchings, M. R. & Greig, A. (2003c) The ranging behaviour and habitat use of rabbits on farmland and their potential role in the epidemiology of paratuberculosis. The Veterinary Journal, 165, 248-257.
28. Dantzer, R., Konsman, J. P., Bluthe, R. M. & Kelley, K. W. (2000) Neural and humoral pathways of communication from the immune system to the brain: Parallel or convergent? Autonomic Neuroscience-Basic and Cliny, 85, 60-65.
29. Deharo, E., Bourdy, G., Quenevo, C., Munoz, V., Ruiz, G. & Sauvain, M. (2001) A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part V. Evaluation of the antimalarial activity of plants used by the Tacana Indians. Journal of Ethnopharmacology, 77, 91-98.
30. Dohi, H., Yamada, A. & Entsu, S. (1991) Cattle feeding deterrents emitted from cattle feces. Journal of Chemical Ecology, 17, 1197-1203.
31. Dunn, A. M. (1983) Winter Deaths in red deer: A preliminary report on abomasal parasite burdens. Publication of the Veterinary Deer Society, 5, 17-25.
32. Elenkov, I. J., Wilder, R. L., Chrousos, G. P. & Vizi, E. S. (2000) The sympathetic nerve - an integrative interface between two supersystems: The brain and the immune system. Pharmacological Reviews, 52, 595-638.
33. Engel, C. (2002) Wild Health. Weidenfeld and Nicolson, London.
34. Familton, A. S. & McAnulty, R. W. (1997) Life cycles and developments of nematode parasites of ruminants. In: Sustainable Control of Internal Parasites in Ruminants (Ed. by G. K. Barrell), pp. 67-79. Lincoln University, Lincoln.
35. Folstad, I., Nilssen, A. C., Halvorsen, O. & Andersen, J. (1991) Parasite avoidance - the cause of post-calving migrations in rangifer. Canadian Journal of Zoology, 69, 2423-2429.
36. Fox, M. T. (1997) Pathophysiology of infection with gastrointestinal nematodes in domestic ruminants: Recent developments. Veterinary Parasitology, 72, 285-308.
37. Gibb, M. J., Huckle, C. A., Nuthall, R. & Rook, A. J. (1999) The effect of physiological state (lactating or dry) and sward surface height on grazing behaviour and intake by dairy cows. Applied Animal Behaviour Science, 63, 269-287.
38. Gilbert, K. A. (1997) Red howling monkey use of specific defecation sites as a parasite avoidance strategy. Animal Behaviour, 54, 451-455.
39. Gill, R. M. A. (1992) A review of damage by mammals in northern temperate forests 1. Deer. Forestry, 65, 145-169.
40. Guarrera, P. M. (1999) Traditional antihelmintic, antiparasitic and repellent uses of plants in Central Italy. Journal of Ethnopharmacology, 68, 183-192.
41. Gubernick, D. J. & Teferi, T. (2000) Adaptive significance of male parental care in a monogamous mammal. Proceedings of the Royal Society London B, 267, 147-150.
42. Hammond, J. A., Fielding, D. & Bishop, S. C. (1997) Prospects for plant anthelmintics in tropical veterinary medicine. Veterinary Research Communications, 21, 213-228.
43. Harborne, J. B. (1991) The chemical basis of plant defence. In: Plant Defences against Mammalian Herbivory (Ed. by R. T. Palo & C.T. Robbins), pp. 45-59. CRC Press, Boca Raton, FL.
44. Hart, B. L. (1990) Behavioural adaptations to pathogens and parasites: five strategies. Neuroscience and Biobehavioural Reviews, 14, 273-294.
45. Hassall, M., Tuck, J. M., Smith, D. W., Gilroy, J. J. & Addison, R. K. (2002) Effects of spatial heterogeneity on feeding behaviour of Porcellio scaber (Isopoda: Oniscidea). European Journal of Soil Biology, 38, 53-57.
46. Haynes, R. J. & Williams, P. H. (1993) Nutrient cycling and soil fertility in the grazed pasture ecosystem. Advances in Agronomy, 49, 119-199.
47. Henry, R. E. & Winkler, L. (2001) Foraging, feeding and defecation site selection as a parasite avoidance strategy of Alouatta palliata in a dry tropical forest. American Journal of Physical Anthropologysupplement, 32, 79.
48. Hirsch, B. T. (2002) Social monitoring and vigilance behaviour in brown capuchin monkeys (ebus apella). Behavioural Ecology Social Biology, 52, 458-464.
49. Hoskin, S. O., Wilson, P. R., Barry, T. N., Charleston, W. A. G. & Waghorn, G. C. (2000) Effects of forage legumes containing condensed tannons on lungworm (Dictoycaulus sp.) and gastrointestinal parasitism in young red deer (Cervus elaphus). Research in Veterinary Science, 68, 223-230.
50. Houdijk, J. G. M., Jessop, N. S., Knox, D. P. & Kyriazakis, I. (2005a) Secondary infection of Nippostrongylus brasiliensis in lactating rats is sensitive to dietary protein content. British Journal of Nutrition, 93, 493-499.
51. Houdijk, J. G. M., Kyriazakis, I., Jackson, F., Huntley, J. F. & Coop, R. L. (2005b) Effects of protein supply and reproductive status on local and systemic immune responses to Teladorsagia circumcincta in sheep. Veterinary Parasitology, 129, 105-117.
52. Houdijk, J. G. M., Jackson, F., Coop, R. L. & Kyriazakis, I. (2006) Rapid improvement of immunity to Teladorsagia circumcinta is achieved through a reduction in the demand for protein in lactating ewes. International Journal for Parasitology, 36, 219-227.
53. Huffman, M. A. (2001) Self-medicative behaviour in the African Great Apes: An evolutionary perspective into the origins of human traditional medicine. Bioscience, 51, 651-661.
54. Huffman, M. A. (2003) Animal self medication and ethnomedicine: exploration and exploitation of the medicinal properties of plants. Proceedings of the Nutrition Society, 62, 371-381.
55. Huffman, M. A. & Seifu, M. (1989) Observations on the illness and consumption of a possibly medicinal plant Vernonia amygdalina (Del.) by a wild chimpanzee in the Mahale Mountains National Park, Tanzania. Primates, 30, 51-63.
56. Huffman, M. A. & Wrangham, R. W. (1994) The diversity of medicinal plant use by chimpanzees in the wild. In: Chimpanzee Cultures (Ed. by R. W. Wrangham, W. C. McGrew, F. B. de Waal & P. G. Heltne), pp. 129-148. Harvard Press, Cambridge, MA.
57. Huffman, M. A., Gotoh, S., Turner, L. A., Hamai, M. & Yoshida, K. (1997) Seasonal trends in Intestinal Nematode Infection and medicinal plant use among chimpanzees in the Mahale mountains, Tanzania. Primates, 38, 111-125.
58. Hutchings, M. R. & Harris, S. (1997) The effects of farm management practices on cattle grazing behaviour and the potential for transmission of bovine tuberculosis from badgers to cattle. The Veterinary Journal, 153, 149-162.
59. Hutchings, M. R., Kyriazakis, I., Anderson, D. H., Gordon, I. J. & Coop, R. L. (1998) Behavioural strategies used by parasitised and non-parasitised sheep to avoid ingestion of gastrointestinal nematodes. Animal Science, 67, 97-106.
60. Hutchings, M. R., Kyriazakis, I., Gordon, I. J. & Jackson, F. (1999) Trade-offs between nutrient intake and faecal avoidance in herbivore foraging decisions: The effect of parasitic status, level of feeding motivation and sward nitrogen content. Journal of Animal Ecology, 68, 310-323.
61. Hutchings, M. R., Gordon, I. J., Robertson, E., Kyriazakis, I. & Jackson, F. (2000a) Effects of parasitic status and level of feeding motivation on the diet selected by sheep grazing grass/clover swards. Journal of Agricultural Science, 135, 65-75.
62. Hutchings, M. R., Kyriazakis, I., Papachristou, T. G., Gordon, I. J. & Jackson, F. (2000b) The herbivore's dilemma: Trade-offs between nutrition and parasitism in foraging decisions. Oecologia, 124, 242-251.
63. Hutchings, M. R., Gordon, I. J., Kyriazakis, I. & Jackson, F. (2001a) Herbivore avoidance of faeces-contaminated patches leads to a trade-off between intake rate of forage and parasitism in subsequent foraging decisions. Animal Behaviour, 62, 955-964.
64. Hutchings, M. R., Kyriazakis, I. & Gordon, I. J. (2001b) Herbivore physiological state affects foraging trade-off decisions between nutrient intake and parasite avoidance. Ecology, 82, 1138-1150.
65. Hutchings, M. R., Milner, J. M., Gordon, I. J., Kyriazakis, I. & Jackson, F. (2002a) Grazing decisions of Soay sheep (Ovis aries) on St Kilda: A consequence of parasite distribution? Oikos, 96, 235-244.
66. Hutchings, M. R., Gordon, I. J., Kyriazakis, I., Robertson, E. & Jackson, F. (2002b) Grazing in heterogeneous environments: Infra- and supra-parasite populations determine herbivore grazing decisions. Oecologia, 132, 453-460.
67. Iason, G. (2005) The role of plant secondary metabolites in mammalian herbivory: Ecological perspectives. Proceedings of the Nutrition Society, 64, 123-131.
68. IIRR. (1994) Ethnoveterinary medicine in Asia: An information kit on traditional animal health care practices. International Institute of Rural Reconstruction, 2nd edn. Silang, Cavite, Philippines.
69. Illius, A. W. & Gordon, I. J. (1993) Diet selection in mammalian herbivores - constraints and tactics. In: Diet Selection (Ed. by N. Hughes), pp. 157-181. Blackwell Scientific Publications, Oxford.
70. Inglefield, C. & Begon, M. (1983) The ontogeny and cost of migration of Drosophila subobscura Collin. Biology Journal of the Linnean Society, 15, 9-15.
71. Ingrand, S., Agabriel, J., Dediey, B. & Lassalas, J. (2000) Effects of within-group homogeneity of physiological state on individual feeding behaviour of loose-housed Charolais cows. Annales de Zootechnie, 49, 15-27.
72. Judge, J., Kyriazakis, I., Greig, A., Allcroft, D. J. & Hutchings, M. R. (2005a) Clustering of Mycobacterium avium subsp paratuberculosis in rabbits and the environment: How hot is a hotspot? Applied Environmental Microbiology, 71, 6033-6038.
73. Judge, J., Kyriazakis, I., Greig, A. & Hutchings, M. R. (2005b) Ingestion of faeces by grazing herbivores - risk of inter-species disease transmission. Agriculture, Ecosystems and Environment, 107, 267-274.
74. Judge, J., Kyriazakis, I., Greig, A., Davidson, R. S. & Hutchings, M. R. (2006) Routes of intra-specific transmission of Mycobacterium avium subsp paratuberculosis in rabbits (Oryctolagus cuniculus): A field study. Applied Environmental Microbiology, 72, 398-403.
75. King, E. J., Lovell, D. J. & Harris, S. (1999) Effect of climate on the survival of Mycobacterium bovis and its transmission to cattle herds in south-west Britain. In: Advances in Vertebrate Pest Management (Ed. by D. P. Cowan & C.J. Feare), pp. 147-162. Filander verlag, Furth.
76. Kruuk, H. (1978) Spatial organisation and territorial behaviour of the European badger Meles meles. Journal of Zoology, London, 184, 1-19.
77. Kyriazakis, I., Oldham, J. D., Coop, R. L. & Jackson, F. (1994) The effect of subclinical intestinal nematode infection on the diet selection of growing sheep. British Journal of Nutrition, 72, 665-677.
78. Kyriazakis, I., Anderson, D. H., Oldham, J. D., Coop, R. L. & Jackson, F. (1996) Long-term subclinical infection with Trichostrongylus colubriformis: Effects on food intake, diet selection and performance of growing lambs. Veterinary Parasitology, 61, 297-313.
79. Lewis, C. E., Clark, T. W. & Derting, T. L. (2001) Food selection by the white-footed mouse (Peromyscus leucopus) on the basis of energy and protein contents. Canadian Journal of Zoology, 79, 562-568.
80. Lochmiller, R. L. & Deerenberg, C. (2000) Trade-offs in evolutionary immunology: Just what is the cost of immunity? Oikos, 88, 87-98.
81. Lozano, G. A. (1991) Optimal foraging theory: A possible role for parasites. Oikos, 60, 391-395.
82. Lozano, G. A. (1998) Parasitic stress and self-medication in wild animals. Advances in the Study of Behaviour, 27, 291-317.
83. Mabry, T. J. & Gill, J. E. (1979) Sesquiterpenes lactones and other terprnoids. In: Herbivores, Their Interactions with Secondary Plant Metabolites (Ed. by G. A. Rosental & T.H. Janzen), pp. 501-537. Academic Press, London.
84. Marion, G., Swain, D. L. & Hutchings, M. R. (2005) Understanding foraging behaviour in spatially heterogeneous environments. Journal of Theoretical Biology, 232, 127-142.
85. Marley, C. L., Cook, R., Keatinge, R., Barrett, J. & Lampkin, N. H. (2003) The effects of birdsfoot trefoil (Lotus corniculatus) and chicory (Cichorium intybus) on parasite intensities and performance of lambs naturally infected with helminth parasites. Veterinary Parasitology, 112, 147-155.
86. Milgate, J. & Roberts, D. C. K. (1995) The nutritional and biological significance of saponins. Nutrition Research, 15, 1223-1249.
87. Mohamed, A. S. A., Mori, T., Islam, S. Q., Sato, M. & Yamasaki, T. (2000) Lethal activity of gallo-and condensed tannins against the free-living soil-inhabiting nematode, Caenorhabditis elegans. Journal of Pesticide Science, 25, 410-415.
88. Molan, A. P., Hoskin, S. O., Barry, T. N. & McNabb, W. C. (2000a) The effect of condensed tannins extracted from four forages on deer lungworm and gastrointestinal nematode larval viability. Veterinary Record, 147, 44-48.
89. Molan, A. P., Waghorn, G. C., Min, B. R. & McNabb, W. C. (2000b) The effects of condensed tannins from seven herbages on Trichostrongylus colubriformis larval migration in vitro. Folia Parasitologica, 47, 39-44.
90. Norris, K. & Evans, M. R. (2000) Ecological immunology: Life history trade-offs and immune defence in birds. Behavioural Ecology, 11, 19-26.
91. Parsons, A. J., Newman, J. A., Penning, P. D., Harvey, A. & Orr, R. J. (1994) Diet preference of sheep - effects of recent diet, physiological state and species abundance. Journal of Animal Ecology, 63, 465-478.
92. Penning, P. D., Parsons, A. J., Orr, R. J., Harvey, A. & Champion, R. A. (1995) Intake and behaviour responses by sheep, in different physiological states when grazing monocultures of grass or white clover. Applied Animal Behaviour Science, 45, 63-78.
93. Phillips-Conroy, J. E. (1986) Baboons, diet and disease: Food plant selection and schistosomiasis. In: Current Perspectives in Primate Social Dynamics (Ed. by D. M. Taub & F. A. King), pp. 287-304. Van Nostrand Reinhold, New York.
94. Phillips-Conroy, J. E. & Knopf, P. M. (1986) The effects of ingesting plant hormones on schistosomiasis in mice: An experimental study. Biochemical Systematics and Ecology, 14, 637-645.
95. Poppi, D., MacRae, J., Brewer, A. & Coop, R. L. (1986) Nitrogen transactions in the digestive tract of lambs exposed to the intestinal parasite, Trichostrongylus colubriformis. British Journal of Nutrition, 55, 593-602.
96. Putman, R. J., Fowler, A. D. & Tout, S. (1991) Patterns of use of ancient grassland by cattle and horses and effects on vegetational composition and structure. Biological Conservation, 56, 329-347.
97. Richner, H. (1998) Host-parasite interactions and life history evolution. Zoology Analysis of Complex Systems, 101, 333-344.
98. Robbins, C. T., Mole, S., Hagerman, A. E. & Hanley, T. A. (1987) Role of tannins in defending plants against ruminants: Reduction in dry matter digestion. Ecology, 68, 1606-1615.
99. Robertson, H. A., Neizen, J. H., Waghorn, G. C., Charleston, W. A. G. & Jinlong, M. (1995) The effect of six herbages on liveweight gain, wool growth and faecal egg count of parasitised ewe lambs. Proceedings of the New Zealand Society of Animal Production, 55, 199-201.
100. Satou, T., Koga, M., Matsuhashi, R., Koike, K., Tada, I. & Nikaido, T. (2002) Assay of nematocidal activity of isoquinoline alkaloids using third-stage larvae of Strongyloides ratti and S. Venezuelensis. Veterinary Parasitology, 104, 131-138.
101. Scantlebury, M., Hutchings, M. R., Allcroft, D. J. & Harris, S. (2004) Risk of disease from wildlife reservoirs: Badgers, cattle and Bovine Tuberculosis. Journal of Dairy Science, 87, 330-339.
102. Schlage, C., Mabula, C., Mahunnah, R. L. A. & Heinrich, M. (2000) Medicinal plants of the Washambaa (Tanzania): Documentation and ethnopharmacological evaluation. Plant Biology, 2, 83-92.
103. Sheldon, B. C. & Verhulst, S. (1996) Ecological immunology: Costly parasite defenses and trade-offs in evolutionary ecology. Trends in Ecology and Evolution, 11, 317-321.
104. Sinervo, B. (1990) The evolution of maternal investment in lizards: An experimental and comparative analysis of egg size and its effects on offspring performance. Evolution, 44, 279-294.
105. Sneddon, I. A. (1991) Latrine use by the European Rabbit (Oryctolagus cuniculus). Journal of Mammologyology, 72, 769-775.
106. Sparg, S. G., van Staden, J. & Jager, A. K. (2002) Pharmacological and phytochemical screening of two Hyacinthaceae species: Scilla natalensis and Ledebouria ovatifolia. Journal of Ethnopharmacology, 80, 95-101.
107. Sweeney, R. W. (1996) Transmission of paratuberculosis. In: Paratuberculosis (Johne's Disease) (Ed. by R. W. Sweeney), pp. 305-312. W.B. Saunders Company, Philadelphia, PA.
108. Sweitzer, R. A. (1996) Predation or starvation: Consequences of foraging decisions by porcupines (Erethizon dorastum). Journal of Mammalogy, 77, 1068-1077.
109. Taylor, C. E. & Murant, A. F. (1966) Nematicidal activity of aqueous extracts from raspberry canes and roots. Nematologica, 12, 488-494.
110. Taylor, J. L. S., Rabe, T., McGaw, L. J., Jager, A. K. & van Staden, J. (2001) Towards the scientific validation of traditional medicinal plants. Plant Growth Regulation, 34, 23-37.
111. van der Wal, R., Irvine, J., Stien, A., Shepherd, N. & Albon, S. D. (2000) Faecal avoidance and the risk of infection by nematodes in a natural population of reindeer. Oecologia, 124, 19-25.
112. Waller, P. J., Bernes, G., Thamsborg, S. M., Sukura, A., Richter, S. H., Ingebrigsten, K. & Hoglund, J. (2001) Plants as de-worming agents of livestock in the Nordic countries: Historical perspectives, popular beliefs and prospectives for the future. Acta Veterinaria Scandinavica, 42, 31-44.
113. Webb, J. N., Szekely, T., Houston, A. I. & McNamara, J. M. (2002) A theoretical analysis of the energetic costs and consequences of parental care decisions. Philosophical Transactions of the Royal Society of London Series B, 357, 331-340.
114. Wright, J., Both, C., Cotton, P. A. & Brynant. D. (1998) Quality vs. quantity: Energetic and nutritional trade-offs in parental provisioning strategies. Journal of Animal Ecology, 67, 620-634.
115. Wynne-Edwards, K. E. (1998) Evolution of parental care in Phodopus: conflict between adaptations for survival and adaptations for rapid reproduction. American Zoologist, 38, 238-250.
116. Zera, A. J. & Harshman, L. G. (2001) The physiology of life history trade-offs in animals. Annual Review of Ecology and Systematics, 32, 95-126.