Trophic behaviour of the dragonfly Cordulegaster boltoni (Insecta: Odonata) in small creeks in NW Italy

Abstract

The order Odonata comprises many predaceous species that inhabit aquatic systems, and a few that are restricted to flowing waters. Cordulegaster boltoni is a widespread Odonata in Europe, which usually inhabits small lotic systems. In this study we analysed the gut contents of C. boltoni immature stages, collected in the Rocchetta Tanaro Natural Park (Italy, Piemonte). Two hundred and eleven individuals were collected, and their diet analyzed by dissection or clearing. Larvae appeared to be opportunistic predators, feeding on a variety of prey. Aquatic insects dominated their diet, while crustaceans, annelids, molluscs and terrestrial invertebrates were sporadically observed in the gut contents. An ontogenetic shift in the diet was detected, as small larvae consumed different prey than large ones. Our study suggests that C. boltoni is one of the dominant predators in the benthic communities of lowland small order streams of Piemonte, which, because of their environmental characteristics, are devoid of fish and stoneflies.