CHANGES IN FEEDING-BEHAVIOR OF THE LARVAE OF THE DAMSELFLY ENALLAGMA-CYATHIGERUM IN RESPONSE TO STIMULI FROM PREDATORS

1. The feeding rates, diet composition and diel periodicity in feeding activity among larvae of the damselfly Enallagma cyathigerum Charp., exposed to chemical, visual and mechanical stimuli from the predators Ranatra linearis (L.), Notonecta glauca L. and Rutilus rutilus (L.) we re investigated. 2. In response to chemical cues produced by all the p redator species, larvae reduced their rate of feeding significantly (e specially on large, sedentary prey). 3. Small larvae reacted more stro ngly than large ones to the kairomone produced by N. glauca. 4. The fi sh kairomone induced a reduction in feeding activity during daylight h ours only. This reaction was more intense than the reaction to non-che mical cues. 5. Observed predator-induced changes in diet composition, caused directly by reduced activity during feeding, are discussed as a n antipredator behaviour of damselfly larvae.