New host-parasite associations of Hydrachnidia (Acari) on Chironomidae (Diptera) from Poland

We present the first data from Poland concerning parasitism of Hydrachnidia on Chironomidae. Larvae of Hygrobates sp., H. setosus, Unionicola aculeata and Piona stjoerdalensis were found attached to adult Chironomidae (Cricotopus triannulatus, Tanytarsus sp., Paratanytarsus sp., Critocopus sp. and Orthocladius sp.). Intensity of infestation ranged between 1 to 2 larvae. All of the parasites were attached to abdomens of the hosts. The determination of parasitism of U. aculeata on Paratanytarsus and Tanytarsus genera extends the list of the hosts of this water mite species to the mentioned genera of Chironomidae. In case of H. setosus, the parasitism of this water mite on currently known hosts from the family Chironomidae has been confirmed.