Odonata (insecta) Larvae As the Second Intermediate Hosts of the Trematodes of Genus Plagiorchis in the Basin of Chany Lake, Western Siberia

Trematodes of the genus Plagiorchis are widespread endoparasites with a life cycle involving several hosts. The second intermediate hosts of the trematodes of genus Plagiorchis are studied for the first time in the basin of Lake Chany in the forest-steppe zone of Western Siberia, which is crossed by the migration way of many species of aquatic and near-water birds—final hosts of these trematodes. This study was conducted in 2014–2015 in the reed beds of Lake Fadikha, which is a habitat of the first intermediate hosts of plagiorchiids: snails. Invertebrates from classes Insecta, Malacostraca, and Gastropoda, as possible second intermediate hosts of the Plagiorchiidae trematodes, are studied for the prevalence and intensity of trematode infection. Metacercariae (larvae inhabiting the second intermediate hosts) of genus Plagiorchis (P. elegans and P. multiglandularis) are found only in the insects from order Odonata. The largest portion among infected larvae is comprised of larvae of Sympetrum vulgatum (68