Bulletin of Entomological Research

Research Paper

Life begins when the sea lion is ashore: microhabitat use by a louse living on a diving mammal host

M.S. Leonardia1 c1, E.A. Crespoa1, D.G. Valesa1, M. Feijooa2, J.A. Ragaa3 and F.J. Aznara3

a1 Laboratorio de Mamíferos Marinos, Centro Nacional Patagónico (CONICET), Boulevard Brown 2915, PC U9120ACV, Puerto Madryn, Argentina

a2 Laboratorio de Evolución, Facultad de Ciencias, Universidad de la República. Casillas 12106, PC 11400, Montevideo, Uruguay

a3 Unidad de Zoología Marina, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universidad de Valencia, PC 46071 Valencia, España

Abstract

Among Anoplura, the family Echinophthiriidae includes species that infest pinnipeds and otters. Previous evidence obtained from pinnipeds infested by echinophthiriids, specifically from seals, indicates that flippers are the preferred infestation sites, while lice from fur seals select areas in the pelage. We studied habitat selection of Antarctophthirus microchir on South American sea lion pups (Otaria flavescens Shaw, 1800) from Patagonia, Argentina, during the austral summer of 2009. We found a clear pattern of habitat selection: eggs are laid on the dorsal surface; nymphs 1 hatch there and then migrate to the belly, where they develop into adults and copulate; and then ovigerous females return to the dorsal surface. On the one hand, nymphs 1 are characterised by their low locomotory ability; therefore, the fact that they migrate as soon as they hatch suggests a clear pressure leading to microhabitat restriction. On the other hand, the described pattern of microhabitat selection seems to respond to the physiological requirements of each stage, which vary according to the physiological process considered, e.g. oviposition, morphogenesis, hatching and development. Accordingly, it appears that A. microchir would prefer the host's ventral area for development and copulation and the dorsal area for oviposition. However, the causes of this pattern are not clear, and many factors could be involved. Considering that sea lion pups periodically soak at high tides, and that prolonged immersion and very high humidity are known to be lethal for lice eggs, selecting the dorsal area would be advantageous for oviposition because it dries much faster. Furthermore, because humidity should be retained for longer periods on the ventral surface of the pup, wetter conditions on the sea lion would prevent desiccation of the nymphs in the very arid environment where O. flavescens breeds.

(Accepted December 02 2011)

(Online publication January 16 2012)

Correspondence:

c1 Author for correspondence Fax: (+54) 2965 451543 E-mail: leonardi@cenpat.edu.ar