DAMSELFLY LARVAE LEARN TO RECOGNIZE PREDATORS FROM CHEMICAL CUES IN THE PREDATORS DIET

Chemosensory recognition of predators by naive prey may be facilitated if the predator's diet chemically 'labels' the predator. In a laborat ory experiment, behaviour patterns were quantified in individual damse lfly larvae, Enallagma spp., that had never been exposed to pike, Esox lucius, before and after exposing the damselflies to one of three che mical stimuli: water from a tank that held pike fed a diet of (1) dams elflies, (2) fathead minnows, Pimephales promelas, or (3) mealworms, T enebrio molitor. Damselflies decreased their frequency of feeding bite s, head bends and moves in response to stimuli from pike fed damselfli es and pike fed fathead minnows, but not to stimuli from pike fed meal worms. Damselflies are sympatric with fathead minnows in the populatio n tested, and probably have many of the same predators. A response to stimuli from pike fed fathead minnows indicates that damselflies assoc iate predation risk with stimuli from injured minnows. In a second exp eriment, responses of damselflies previously exposed to stimuli from p ike fed one of the three treatment diets (damselfly, fathead minnow or mealworm) were tested for a response to stimuli from pike fed mealwor ms. Damselflies that had been exposed to stimuli from pike fed damself lies or fathead minnows in the first experiment responded to stimuli f rom pike fed mealworms in the second experiment, but damselflies expos ed to pike fed mealworms in the first experiment did not. Thus (1) pik e-naive damselflies may initially respond to chemical stimuli from pik e based on stimuli of conspecifics or familiar heterospecifics in the pike's diet, and (2) damselflies can learn to recognize chemical stimu li of pike irrespective of the pike's recent feeding regime based on t he initial association with damselflies or minnows in the pike's diet. (C) 1996 The Association for the Study of Animal Behaviour