ESTABLISHMENT, SURVIVAL, SITE SELECTION AND DEVELOPMENT OF LEPTORHYNCHOIDES-THECATUS IN LARGEMOUTH BASS, MICROPTERUS-SALMOIDES

Establishment, survival and distribution of Leptorhynchoides thecatus (Acanthocephala) were investigated in largemouth bass, Micropterus sal moides, fed 10, 25, or 40 cystacanths and examined at 1, 3 or 5 weeks post-infection. Worms established widely in the alimentary tracts of b ass but by 5 weeks post-infection had localized in the pyloric caeca a nd intercaecal region. Other individuals moved to parenteral sites whe re they remained immature, though viable. In the 10- and 25-level expo sures, establishment and survivorship in the alimentary tract were rou ghly proportional to the dose of cystacanths. After 1 week post-infect ion in the 40-level exposure class, numbers of worms in the alimentary tract decreased significantly and parenteral occurrence increased sig nificantly. Total survival of L. thecatus appeared to be density-indep endent. Maturation of worms was retarded temporarily as intensity of i nfection increased, but by 5 weeks post-infection worms from all doses were at roughly the same stage of development within sex. The caeca a nd intercaecal area apparently did not differ in their suitability for maturation.