Predatory Foraging Behaviour and Activity Patterns of Larvae of Two Species of Limnephilid Cased Caddis

Abstract

Temporal feeding behaviour, locomotory activity patterns and functional responses of larvae of two species of cased caddis were investigated in the laboratory. The temporal pattern of locomotory activity of both Potamophylax cingulatus (Stephen) and Halesus radiatus (Curtis) was examined under constant conditions of 12 h light/12 h darkness, continuous light and continuous darkness. Larvae of both showed a similar endogenous rhythm of activity consistent with the species being nocturnal and were most active at night during a 4 h period (2000-2400 h). They also demonstrated a greater consumption of prey at night and under the continuous darkness conditions. This feeding activity pattern appears to be based primarily on intrinsic predator activity patterns rather than generated as a response to prey activity