Can the behaviour of threespine stickleback parasitized with Schistocephalus solidus be replicated by manipulating host physiology?
Sticklebacks infected by the parasitic flatworm Schistocephalus solidus show dramatic changes in phenotype, including a loss of species-typical behavioural responses to predators. The timing of host behaviour change coincides with the development of infectivity of the parasite to the final host (a piscivorous bird), making it an ideal model for studying the mechanisms of infection-induced behavioural modification. However, whether the loss of host anti-predator behaviour results from direct manipulation by the parasite, or is a by-product (e.g. host immune response) or side effect of infection (e.g. energetic loss), remains controversial. To understand the physiological mechanisms that generate these behavioural changes, we quantified the behavioural profiles of experimentally infected fish and attempted to replicate these in non-parasitized fish by exposing them to treatments including immunity activation and fasting, or by pharmacologically inhibiting the stress axis. All fish were screened for the following behaviours: activity, water depth preference, sociability, phototaxis, anti-predator response and latency to feed. We were able to change individual behaviours with certain treatments. Our results suggest that the impact of S. solidus on the stickleback might be of a multifactorial nature. The behaviour changes observed in infected fish might result from the combined effects of modifying the serotonergic axis, lack of energy and activation of the immune system.
Département de Biologie et Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec, Canada, G1V 0A6.
Lucie
L
Grécias
Département de Biologie et Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec, Canada, G1V 0A6.
François Olivier
FO
Hébert
Département de Biologie et Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec, Canada, G1V 0A6.
Chloé Suzanne
CS
Berger
Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester LE1 7RH, UK.
Iain
0000-0003-3955-6674
I
Barber
Département de Biologie et Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Quebec, Canada, G1V 0A6 Nadia.Aubin-Horth@bio.ulaval.ca.
Nadia
0000-0002-9030-634X
N
Aubin-Horth
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002589:Cestoda / Q000502:physiology*; D002590:Cestode Infections / Q000469:parasitology / Q000662:veterinary*; D005260:Female; D005393:Fish Diseases / Q000469:parasitology*; D006790:Host-Parasite Interactions; D008297:Male; D023701:Smegmamorpha / Q000276:immunology / Q000502:physiology
Fasting; Fluoxetine; Gasterosteus aculeatus; Immunity; Manipulation; Oxazepam; Parasite; Serotonin