Seasonal population dynamics and maturation of Neoechinorhynchus pungitius (Acanthocephala: Neoechinorhynchidae) infecting brook stickleback, Culaea inconstans, from Sioux Creek, Wisconsin, U.S.A.

Abstract

Seasonal population dynamics and maturation of the acanthocephalan Neoechinorhynchus pungitius from brook stickleback (Culaea inconstans) were investigated. Stickleback were collected monthly at Sioux Creek, Wisconsin from April 1981 to May 1982 (excluding December, January, and February). Forty-seven percent (292/620) were infected with N. pungitius, which exhibited seasonal periodicity in prevalence, mean intensity, and maturation. Prevalence and mean intensities were lowest in summer and increased through autumn owing to recruitment of juvenile and immature worms. Prevalence and mean intensity reached their peaks by April and May, and N. pungitius infrapopulations were composed primarily of mature worms. Egg production began in May and continued throughout early summer. Neoechinorhynchus pungitius males appeared shorter lived than females, as the June and July infrapopulations were comprised mostly of females. Prevalence and mean intensity of N. pungitius increased as brook stickleback length increased. There was no significant difference between numbers of male and female fish infected or between mean intensity and host sex.