Natal experience and conspecifics influence the settling behaviour of the juvenile terrestrial isopod Armadillidium vulgare

Abstract

Cues used by dispersing juveniles to assess habitat quality can be based on public information available to all individuals or on private information obtained from experience in the natal habitat. The presence of conspecifics (public information) and natal habitat quality (private information) have been shown to influence habitat preferences in many species, but the relative importance of these two cue types is seldom investigated. We examined whether habitat quality relative to the natal habitat had a stronger influence on the settling decisions of the juvenile terrestrial isopod Armadillidium vulgare (Latreille, 1804), than sign of conspecifics. We raised juvenile A. vulgare in either high- or low-quality habitats and then observed how the presence of conspecific sign influenced their preference for each of these habitats. When conspecific sign was absent, juveniles preferred high-quality habitat, regardless of their natal habitat. When the low-quality habitat was treated with conspecific sign, juveniles born on low-quality habitat continued to prefer the high-quality habitat, but juveniles raised on high-quality habitat displayed no preference. This suggests juvenile isopods respond to these cues hierarchically: they first search for habitats higher in quality than their natal habitat and then cue into conspecific sign when the preferred habitat is unavailable.