Behavioral Ecology Advance Access originally published online on March 31, 2006
Behavioral Ecology 2006 17(4):515-521; doi:10.1093/beheco/arj062
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Habitat assessment by parasitoids: mechanisms for patch use behavior
a Unité Mixte de Recherche 1112, Réponse des Organismes aux Stress Environmentaux, Institut National de la Recherche Agronomique, 400 route des Chappes BP 167, 06903 Sophia Antipolis Cedex, France and b Unité Mixte de Recherche 5558 "Biométrie et Biologie Evolutive," Université Claude Bernard Lyon 1, 43 Boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France
Address correspondence to C. Tentelier, who is now at the Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65, FIN-00014 Helsinki, Finland. E-mail: cedric.tentelier{at}helsinki.fi.
Animals foraging for patchily distributed resources may optimize their foraging decisions concerning the patches they encounter, provided that they base these decisions on reliable information about the profitability of the habitat as a whole. Females of the parasitoid Lysiphlebus testaceipes exploit aphid hosts, which typically aggregate in discrete colonies. We show here how between-colony travel time and the number of aphids in previously visited colonies affect parasitoid foraging behavior. We first assumed that parasitoids use travel time and previous colony size to estimate a mean rate of fitness gain in the habitat and derived quantitative predictions concerning the effect of these two variables on patch residence time and patch-leaving rate of attack. We then tested these theoretical predictions in laboratory experiments in which female parasitoids were allowed to visit two successive colonies. As predicted, the observed residence time in the second colony increased with increasing travel time and decreasing size of the first colony. Patch-leaving rate of attack decreased with increasing travel time but was not affected by previous colony size. These results suggest that parasitoids use these two variables to assess habitat quality. However, discrepancies between the data obtained and quantitative predictions show that the effect of travel time on patch use may be more complex than assumed in our model.
Key words: learning, Lysiphlebus testaceipes, marginal value theorem, optimal foraging theory, patch size, travel time.