Date of this Version
Occurrence of the acanthocephalan Paulisentis missouriensis Keppner, 1974, in Semotilus atromaculatus of Richardson County, Nebraska, was monitored from September 1974 through July 1975. Six hundred nineteen fish were examined of which 78% were infected with 1 to 32 worms. A relatively high prevalence of infection, 72% to 81%, was noted throughout the study. There was no significant difference in the mean density of parasites between the months. Overall mean density was 4.0 (2.9 to 4.6). Fish of all lengths (35 mm to 215 mm standard length) were infected. Both prevalence and mean density increased as fish age/length increased. There were consistently fewer male worms than female worms. The number of males to females best fit a 2:3 ratio as verified by a Chi-square test. Worms appeared to live slightly more than one year with recruitment occurring in early summer and old worms disappearing from the population late the following summer.