A new host, Simulium argyreatum Meig., for the cytoplasmic polyhedrosis virus of blackflies in Czechoslovakia.

The cytoplasmic polyhedrosis virus (CPV) from the midgut of blackfly larvae is recorded from a population of Simulium argyreatum in Czechoslovakia. A 7.7% infection of 2766 sampled larvae was manifested by white spots in their body. 85% of the white-spotted larvae were infected with CPV when sampled in June. In August 9% of 1377 larvae had white spots but only 10.6% of them were with CPV. Out of 823 collected pupae, only 3 imperfect pupae had the virus in apparent form. Other infections producing white spots in larvae were due to the microsporidia Plistophora multispora, P. simulii, P. debaisieuxi, Thelohania fibrata, the fungus Coelomycidium simulii and the mermithids.