bassianolide and Helminthiasis

The degree to which host suitability is a reflection of host community structure in generalist parasites was studied experimentally in the common fish acanthocephalan Leptorhynchoides thecatus. Previous study has shown that green sunfish (Lepomis cyanellus) are required, and largemouth bass (Micropterus salmoides) are suitable (but not required) hosts, where they occur sympatrically in natural communities. The present study examined populations of L. cyanellus and M. salmoides held separately in mesocosms and exposed to L. thecatus cystacanths via laboratory-infected Hyalella azteca (Amphipoda). Recruitment, maturation, and transmission of worms were examined over a 17-wk period and compared between fish species. Infections with L. thecatus were found as early as 2 wk after the introduction of cystacanth-infected amphipods, and by week 11 fishes of both species harbored gravid worms. Immature worms were observed in both host species by week 17 and were presumed to be a result of natural egg production and release resulting in infections of amphipods and the subsequent reinfection of fish. No significant difference in the prevalence, abundance, percentage of worms gravid, or time of parasite maturation was found between host populations. Results indicate that the different roles played by these host species in the maintenance of L. thecatus supra-populations in natural systems are not due to intrinsic factors but rather to differences in host autecology and community structure.

Topics: Acanthocephala; Animals; Bass; Female; Fish Diseases; Helminthiasis; Helminthiasis, Animal; Male; Nebraska; Perciformes; Prevalence; Species Specificity

The original description of Polyacanthorhynchus kenyensis Schmidt and Canaris, 1967 from 2 species of fish in Lake Naivasha, Kenya was primarily based on measurements of 2 male cystacanths. That description is herein emended based on the availability of a larger number of immature worms of both sexes obtained from the freshwater teleosts Orechromis leucostictus, Tilapia zillii (new paratenic host records), and Micropterus salmoides. A secretory function for the apical organ is suggested.

Topics: Acanthocephala; Animals; Bass; Female; Fish Diseases; Fresh Water; Helminthiasis; Helminthiasis, Animal; Kenya; Male; Microscopy, Electron, Scanning; Perciformes; Tilapia

The acanthocephalan Pomphorhynchus patagonicus was found in 3 species of fish in the Alicura Reservoir (Patagonia, Argentina). These included Oncorhynchus mykiss, Patagonina hatcheri, and Percichthys trucha. Prevalence, intensity, size of the parasites, and percentage of gravid females were analyzed. The relatively low prevalence and intensity were probably due to the low consumption of the intermediate host, Hyalella patagonica. The highest values of intensity, length, and percentage of gravid females were found in Percichthys trucha. This species is considered to be the preferred host of P. patagonicus in the reservoir. No mature eggs were found in O. mykiss; this, together with the parasite's low growth rate, underlines the hypothesis that this species is not a suitable host for P. patagonicus.

Topics: Acanthocephala; Animals; Argentina; Bass; Female; Fish Diseases; Fishes; Fresh Water; Helminthiasis; Helminthiasis, Animal; Host-Parasite Interactions; Oncorhynchus mykiss; Prevalence; Species Specificity

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

Topics: Acanthocephala; Analysis of Variance; Animals; Bass; Cecum; Digestive System; Female; Fish Diseases; Fresh Water; Helminthiasis; Helminthiasis, Animal; Intestinal Diseases, Parasitic; Male; Random Allocation; Regression Analysis

The number of plerocercoids of the bass tapeworm, Proteocephalus ambloplitis, in wild largemouth bass was negatively correlated (r = -0.94) with the number of Neoechinorhynchus sp. Competitive inhibition between the 2 parasites appeared to exist. Similarly, the numbers of Neoechinorhynchus sp. in wild bass decreased when adult bass tapeworms were present in the intestine. Proteocephalus ambloplitis plerocercoids used to challenge bass vaccinated with either P. ambloplitis adult or Neoechinorhynchus sp. antigens were smaller (P less than 0.05) when recovered than those used to challenge control bass. Based on preliminary results, both antigens might have enabled the bass to limit growth and/or development of the invading bass tapeworm, plerocercoids. Cross-protective immunity may be the reason for this occurrence, in which case, it could offer an explanation for competitive inhibition existing between P. ambloplitis and Neoechinorhynchus sp.

Topics: Acanthocephala; Animals; Antigens, Helminth; Bass; Cestoda; Cestode Infections; Cross Reactions; Fish Diseases; Helminthiasis; Helminthiasis, Animal; Immunization; Perciformes

Topics: Acanthocephala; Animals; Bass; Fishes; Gastrointestinal Tract; Helminthiasis