Research Article

The effect of salinity on transovarial transmission of a microsporidian infecting Gammarus duebeni

A. M. DUNN a1 and M. J. HATCHER a1
a1 Department of Biology, University of Leeds, Leeds LS2 9JT, UK


This is an investigation of the impact of salinity on transovarial transmission and burden of a microsporidian sex ratio distorter in the inter-tidal crustacean Gammarus duebeni. Exposure of parasitized mothers to increased salinity during the gonotrophic cycle caused an increase in parasite burden in the follicle cells and a decrease in burden in the oocytes. It appears that salinity impedes parasite transmission from the follicle cells to the oocytes during host oogenesis. A lower proportion of the young were infected in broods from elevated salinity and, in infected offspring, parasite burden was lower than in control embryos. Parasite replication occurred during embryogenesis. However, the pattern of parasite growth did not differ between salinities, indicating that differences in parasite burden could be attributed to a reduction in the initial parasite burden transmitted to the gamete, rather than to a reduction in parasite replication during host embryogenesis. We discuss our findings with respect to parasite/host dynamics and the ecology of the host.

(Received March 23 1997)
(Revised April 23 1997)
(Accepted April 23 1997)

Key Words: microsporidian; salinity; parasite burden; transovarial transmission; Gammarus duebeni.


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