We report the incidence of Mermithidae (Nematoda) parasitism in Chironomus gr. decorus larvae (Diptera: Chironomidae) at Rio dos Peixes, Dois Córregos, central west region of São Paulo State, Brazil. In this study, of a total of 791 larvae, 205 (25.9%) were infected by mermithid worms, indicating that Chironomidae larvae are commonly parasitized by Mermithidae worms.
Chironomus gr. decorus; nematode; ecology; stream