Propagation of Nosema eurytremae (Microsporida: Nosematidae) from trematode larvae, in abnormal hosts and in tissue culture

Abstract

SUMMARYPropagation of Nosema eurytremae, a microsporidian pathogen of trematode larvae, was investigated by inoculation of spores into the haemocoele of insects and by growth in tissue cultures. Locusts and the larvae of three lepidopteran species were good hosts but cockroaches were not. Low replication was obtained in one lepidopteran species after per os infection. Antibiotics controlled bacterial growth in suspensions of microsporidian spores but fungi were unaffected by all antibiotics tested, except at concentrations detrimental to the microsporidia. All stages of the microsporidium developed in cell lines of Xenopus laevis and Aedes pseudoscutellaris when spores were induced to hatch in contact with cell monolayers: the Aedes culture was contaminated by yeasts. Repeated washing of the Xenopus cells with fresh medium, after the sporoplasms of N. eurytremae had penetrated the cells, removed yeast contaminants and sterile cultures were obtained. Replication during 4 passages over 53 days was only 100 to 200-fold compared with the original inoculum but spores harvested from the cultures were infective to a fresh culture and to Pieris brassicae by inoculation into the haemocoele.