Retrospective: The effect of Schistocephalus Solidus (Cestoda: Pseudophyllidea) on the foraging and shoaling behaviour of three-spined sticklebacks, Gasterosteus Aculeatus: Article published in Behaviour volume 132 (1995), p. 1223-1240

In this paper we review recent experimental work on the effects of the parasite Schislocephalus solidus (Cestoda: Pseudophyllidea) on the feeding behaviour of three-spined stick-lebacks {Gasterosttus aculeatus L) We also discuss how increased feeding motivation and subsequent altered foraging behaviour may be a mechanism for parasite-associated changes in the shoaling behaviour of infected sticklebacks The presence of S solidus procercoids in the body cavity constricts the stomach, increases the handling time for large prey and consequently reduces the profitability of such prey for infected fish This is reflected in a switch in dietary preference from large to small prey in the laboratory and in altered stomach contents and impaired nutrient reserves in the wild By altering their hosts' nutritional slate by direct competition for nutrients from digested food (and possibly indirectly by altering diet and reducing competitive ability] and also by altering the fishes' appearance, such parasites have the potential to alter the costs and benefits involved in joining a shoal of conspccifics Experimental work on ihc shoaling decisions of S solidus-infected siiclclehacks supports this hypothesis, and such behavioural modification is dis- cussed in the context of the manipulation hypothesis of parasite transmission