Life Span and Monthly Mortality Rate of Bulinus truncatus and Planorbis boissyi, the Intermediate Hosts of Schistosomiasis in Egypt

Abstract

Life table functions were obtained for each of 4 groups of snails, 2 of B. truncatus and 2 of P. boissyi. These functions indicate that "infant mortality" was high for all groups, that mortality dropped to a low point when snails were about 8 mos. old and then rose sharply. The life span of B. truncatus was 14 mos., while that of P. boissyi was 5 mos. longer. The avg. age-size relationship of each group was determined and a size scale was made for further measurement values.