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Site Selection, Growth, and Survival of Leptorhynchoides thecatus (Acanthocephala) during the Prepatent Period in Lepomis cyanellus

Richard L. Uznanski and Brent B. Nickol
The Journal of Parasitology
Vol. 68, No. 4 (Aug., 1982), pp. 686-690
DOI: 10.2307/3280929
Stable URL: http://www.jstor.org/stable/3280929
Page Count: 5
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Site Selection, Growth, and Survival of Leptorhynchoides thecatus (Acanthocephala) during the Prepatent Period in Lepomis cyanellus
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Abstract

Lepomis cyanellus were fed 10, 20, or 40 Leptorhynchoides thecatus cystacanths, and examined after 1, 3, 7, 14, 28, or 56 days. Some cystacanths remained in the stomach 1 day, and in the small intestine for 7 days. By 14 days, worms were restricted to the pyloric ceca and mesenteries. Parenteric L. thecatus, first observed at 14 days, were encapsulated and destroyed by host cells. After 8 wk, cecal males averaged 3.7 mm in length, and females, 4.8 mm. The number of worms recovered from fish fed 40 cystacanths declined between days 3 and 14, to levels similar to those observed in fish fed 20 cystacanths. No decline was detected at either of the lower dosages. Leptorhynchoides thecatus establishes and matures in the pyloric ceca of this host species. Parasites that enter the mesenteries must be capable of surviving in the alimentary canal for at least 7 days. Lepomis cyanellus is a poor transport host for L. thecatus. Parasite activation and site selection are density-independent processes, but establishment and survival are apparently density-dependent. Lepomis cyanellus provides sufficient resources for the establishment of 10 to 15 L. thecatus. Excess parasites are lost within 14 days.

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