Occurrence, pathology, and ultrastructure of iridovirus and cytoplasmic polyhedrosis viruses in daphnids from the Czech Republic

•Iridovirus infection is identified in the fat body of a Daphnia species.•Cytoplasmic polyhedrosis virus infection is identified in two Daphnia species.•Virions maturing inside versus outside occlusion bodies differ in size and structure.•Virion position within resin section influences its visualization by EM & AFM.•IV’s and CPV’s are probably more common in daphnids than realized.

Iridescent (IVs, family Iridoviridae, genus Iridovirus) and cytoplasmic polyhedrosis viruses (CPVs; family Reoviridae, genus Cypovirus) are well known in insects, with thirteen IV species recognized from various orders, and sixteen CPV species known from lepidopterans. In 1975, an IV and CPV were reported in the daphnid, Simocehpalus expinosus, in Florida, but other reported daphnid virus infections seem to be rare. Here we report infected daphnids from woodland and carp ponds in the Czech Republic, Daphnia curvirostris with an IV, and D. pulex and D. ambigua, with CPVs. This suggests these viruses are more common in daphnids, the rarity of reports due to few surveys.

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