Trichoptera larvae and gregarines: Host-parasite relationships

Abstract

The presence of eugregarines (Apicomplexa, Conoidasida, Eugregarinorida) in the larval midgut of several Trichoptera families found in Italy has been well established. Literature and our data indicate that gregarine infestation is influenced by the trichopteran diet and, except for a few cases, there is not a species-specific relationship. In this paper an updated list of Italian Trichoptera species hosting gregarines as well as data on the biology, morphology and ultrastructure of the corresponding parasites are presented. The host-parasite interaction was also investigated showing the involvement of the host diet in the onset of parasitosis and the influence of the host habitat on the degree of infestation.Gregarine infestation was massive in species inhabiting springs, particularly noticeable in close environments like troughs (“trocchi”) which are man-modified springs for drinking water for cattle. Larvae of Drusus improvisus found in the Tiber river springs were heavily infested and the parasite density at every season and the degree of infestation at each larval stage are reported.