Evol Ecol Res 9: 185-197 (2007)     Full PDF if your library subscribes.

Boldness in anti-predator behaviour and immune defence in field crickets

Raine Kortet,1* Markus J. Rantala2 and Ann Hedrick3

1Behaviour, Ecology and Evolution Team (Integrative Ecology Unit), Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland,  2Section of Ecology, Department of Biology, University of Turku, Turku, Finland and  3Section of Neurobiology, Physiology and Behavior, College of Biological Sciences, University of California, Davis, CA, USA

Address all correspondence to Raine Kortet, Department of Biology, University of Oulu, PO Box 3000, FIN-90014 Oulu, Finland.
e-mail: rkortet@cc.jyu.fi

ABSTRACT

Questions: Are prey animals’ behavioural responses against predation associated with their ability to resist parasites and pathogens, and if so, how is this adjusted in different populations?

Methods: We studied the association between anti-predator behaviour and immune defence (encapsulation response and lytic activities of the haemolymph) using laboratory-reared male field crickets originating from two wild populations that differ in predation and parasitism risk. The anti-predator behaviours that we measured were as follows: (1) the animal’s latency to become active inside a safe refuge, (2) its latency to emerge from a safe refuge after disturbance, and (3) the animal’s freezing time following a separate alarm cue.

Results: Crickets originating from a high-parasitoid, high-predation risk population (Arizona) had higher encapsulation responses than crickets from a low-parasitoid, low-predation risk population (California). Lytic activity correlated negatively with freezing time. Encapsulation response was positively correlated with the latency to become active and latency to emerge from a safe refuge in the high-predation risk population, but not in the low-predation risk population.

Conclusion: Predation and parasitoids may increase the cricket’s investment in parasite resistance, despite the potential costs of anti-predator behaviour.

Keywords: anti-predator response, cost, field cricket, Gryllus, immunocompetence.

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