FEEDING IN EPIPHYTIC, CARNIVOROUS INSECTS - RESOURCE PARTITIONING ANDTHE AVOIDANCE OF INTRAGUILD PREDATION

The gut contents of larval Enallngma cyathigerum (Zygoptera: Odonata), Cyrnus flavidus (Polycentropodidae: Trichoptera) and Ablabesmyia moni lis (Tanypodinae: Chironomidae) feeding in nature and in experimental aquaria, were analysed. The diet of C. flavidus overlapped greater wit h the diet of A. monilis than with the diet of E. cyathigerum. Feeding intensity and diet composition in C. flavidus and A. monilis were dif ferent in experimental aquaria with and without E. cyathigerum. Weight s of their food and mean weights of their prey were lower in the prese nce of the latter when compared with the control, while the number of prey items was not. The proportions of active prey items in diets of C . flavidus and A. monilis were higher in the presence of E. cyathigeru m but the numbers of such prey items were higher in the diet of C. fla vidus only. These differences are probably caused by reduced predator mobility during feeding, not by a behavioural response from prey. Indu ced changes in feeding activity are considered an effect of a behaviou ral defence mechanism reducing the risk of intraguild predation.