Unikaryon slaptonleyi sp.nov. (Microspora: Unikaryonidae) isolated from echinostome and strigeid larvae from Lymnaea peregra: observations on its morphology, transmission and pathogenicity

Abstract

SUMMARYA microsporidium, isolated from echinostome and strigeid larval trematodes in Lymnaea peregra, is described as a new species Unikaryon slaptonleyi sp.nov. The nuclei isolated at all stages of development, the disporoblastic sporogony and development in contact with host cell cytoplasm are used to assign the species to the genus Unikaryon. The absence of a vacuolar membrane to isolate the meronts and stages of sporulation from the host cell cytoplasm differentiates this genus from Encephalitozoon. Spores are uninucleate, have 17–21 turns of the polar filament coil and measure 5·0 × 2·8/μm fresh. U. slaptonleyi was isolated from rediae and metacercariae of Echinoparyphium recurvatum and sporo-cysts and cercariae of an unidentified strigeid trematode in L. peregra. It was transmitted in the laboratory to unidentified echinostomes in L. peregra and to unidentified strigeids in Planorbis planorbis by feeding the spores to field-collected snails from which cercariae were already emerging. In these natural and experimental hyperinfections the snail tissues were lightly infected but, in the helminths, much of the parenchyma and germinal tissue was destroyed, so that few cercariae were released and most of those were distorted. Similar heavy infections were produced in Fasciola hepatica in Lymnaea truncatula, when spores were fed to the snails 14 days after miracidial penetration, but even high doses (106 spores/snail) produced only light infections in Schistosoma mansoni in Biomphalaria glabrata, in only 2 out of 9 snails. No infections were obtained in larvae producing xiphidiocercariae in P. planorbis although echinostomes became infected under the same conditions. Of a number of aquatic and terrestrial arthropods tested for susceptibility by feeding or by inoculation of spores into the haemocoele, only Pieris brassicae became infected. In a small proportion of pupae surviving from larvae which had been inoculated with spores at 3rd or 4th instar, there was clear evidence of spore replication.

Cytological variation and pathogenicity of the bumble bee parasite Nosema bombi (Microspora, Nosematidae)

“…The initiation of the exospore as wide Welds of electron-dense material diVers from the parallel electron dense exospore strands typically seen in the genus Nosema and a few other genera (Barker, 1975;Canning et al, 1983;Larsson, 1981). The rearrangement of the Golgi region, from the typical vesicular arrangement in the microsporidian sporoblast (Fig.…”

Pollution toxicity to the transmission of larval digeneans through their molluscan hosts

“…The presence of microsporidia in a digenean population may be susceptible to environmental factors. Canning et al (1983) found that 19 out of 20 L. peregra infected with E. recurvatum carried microsporidian infections. These snails were collected from Slapton Ley, a large freshwater lake that lies just inland of the sea in southwest England.…”

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“…Juvenile plant-root nematodes, for example, can be infected and killed by bacteria (parasite mortality) (Sayre and Wergin, 1979). Similarly, trematode rediae and cercariae become infected with microsporidian parasites (Knapp et al, 1972;Canning et al, 1983); infected cercariae exhibit physical degeneration and are less successful in infecting new hosts relative to uninfected cercariae (transmission reduction). Antagonism between different trematode species is also common within snail hosts.…”