A predator's dilemma: prey choice and parasite susceptibility in three-spined sticklebacks.
The acanthocephalan parasite Pomphorhynchus laevis is transmitted by a suitable intermediate host such as the amphipod Gammarus pulex to its definitive fish host. Parasite-induced alterations in both appearance and behaviour concur to render infected gammarids more vulnerable to predation, thus promoting parasite transmission. Experimental infection of laboratory bred full- and half-sib groups of three-spined sticklebacks (Gasterosteus aculeatus) provided evidence that the parasite imposes a survival cost proportional to the severity of infection on its final host. Variation among sibships in the susceptibility to infection was consistent. When given a choice, fish consumed significantly more infected than uninfected prey. Overall, more resistant fish did not prey upon infected gammarids more often than did relatively susceptible fish. Only fish with a relatively high physical condition properly adjusted prey selection to the extent of their parasite susceptibility, thus exploiting the enhanced profitability of infected prey.
Mazzi
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Division of Behavioural Ecology, Institute of Zoology, University of Bern, Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland. Dominique.Mazzi@ebc.uu.se
Bakker
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TC
D000049:Acanthocephala / Q000502:physiology; D000818:Animals; D002755:Choice Behavior; D004198:Disease Susceptibility; D004199:Disease Vectors; D005260:Female; D005393:Fish Diseases / Q000401:mortality / Q000469:parasitology* / Q000635:transmission; D005399:Fishes / Q000469:parasitology* / Q000502:physiology*; D006790:Host-Parasite Interactions; D008297:Male; D011235:Predatory Behavior