Electrophoretic studies on planorbid egg-proteins. The Bulinus africanus and B. forskalii species groups.

It is possible that physiological differences between populations of an intermediate snail host of schistosomes may be linked with differences in the pathogenicity of the parasite strains they harbour. With a view to differentiating between local populations of bulinid snails, a previous electrophoretic study of snail egg-proteins has been extended to cover all the recognized species of the Bulinus africanus group and most of those of the B. forskalii group.The results show that in general the level of variation between populations of the same morphological species is greater than the differences between species in the same group. However, at the specific level there are similarities suggesting close affinities between B. nasutus and B. abyssinicus, and the electrophoretic pattern for B. jousseaumei shows close relationships with West African populations of B. globosus. In the B. forskalii group the patterns for various populations of B. reticulatus differ from each other and from those of other members of the group.