John Brattey

The effects of larval Acanthocephalus lucii on the pigmentation, reproduction, and susceptibility to predation of the isopod Asellus aquaticus

C. plica in the urinary bladder. Butterworth and Beverley-Burton reviewed the taxonomy of Capillaria spp. in carnivorous mammals in Canada (1980, Syst. Parasitol. 1: 211-236) and discussed prevalence and intensity of these species (1981, Proc. Helminthol. Soc. Wash. 48: 24-37). Notable by their absence in Wisconsin foxes were three helminth species of veterinary or medical importance: Dirofilaria immitis (Leidy, 1856), Trichinella spiralis (Owen, 1835), and Echinococcus multilocularis. Schlotthauer (1964, J. Parasitol. 50: 801-802) reported a low prevalence of D. immitis in Minnesota foxes compared with its occurrence in Canis familiaris. Extensive investigations of E. multilocularis by Leiby and his coworkers (Leiby, Carney, and Woods, 1970, J. Parasitol. 56: 1141-1150; Leiby and Kritsky, 1974, Amer. J. Trop. Med. Hyg. 23: 667-675) have provided ecological and epidemiological information for E. multilocularis, and these authors have described the southerly spread of this tapeworm from the boreal regions of North America into the northcentral United States. Recently, Ballard and Vande Vusse (1983, J. Parasitol. 69: 790-791) reported E. multilocularis from rodents and foxes in the prairie biome of southwestern Minnesota. Our results indicate that except for these species of veterinary or medical significance, parasites of west central Wisconsin foxes are similar to those reported in other surveys of foxes in this geographical area.

Life history and population biology of larval Acanthocephalus lucii (Acanthocephala: Echinorhynchidae) in the isopod Asellus aquaticus

Hemocoels of 8,731 Asellus aquaticus collected from the Forth and Clyde canal in Glasgow, Scotland, from January 1980 to March 1981 were examined for larvae of Acanthocephalus lucii. Prevalence and mean intensity were generally low (1.5-8.3% and 1.0-1.6, respectively), but there was a slight seasonal infection pattern with fewer infected isopods during summer, reflecting the appearance of a new isopod generation. Although there were no distinct seasonal trends in the proportions of each larval stage, recruitment of larvae probably occurred mainly during summer and autumn. Some larvae reached the cystacanth stage by late summer or autumn; others overwintered as acanthors or acanthellae and completed development the following spring. The maximum life span of larvae was limited to 1 yr by annual turnover of the isopod population. The distribution of larval A. lucii among isopods was slightly aggregated. There was a peaked pattern in the relationship between isopod length and the prevalence, abundance, and degree of parasite aggregation. The rate of parasite development in laboratory-infected isopods was linearly related to temperature between 9 and 22 C; the temperature threshold was 5.7 C, and the larval parasite required 598 degree-days above threshold to complete development. Among laboratory-infected isopods, 2 mechanisms that could regulate the larval parasite population were detected: intraspecific competition and direct, parasite-induced isopod mortality. However, the intensity of infection in the natural habitat was consistently low and may have remained below the level at which these mechanisms operated.

Life history and population biology of adult Acanthocephalus lucii (Acanthocephala: Echinorhynchidae).

The life history and population biology of adult A. lucii in perch, Perca fluviatilis L., from the Forth and Clyde canal, Scotland, was investigated during May 1979-September 1981. There was an annual cycle in the size of the parasite population; prevalence and abundance (+/- SE) were highest during late spring and summer (70-90% and 14 +/- 4.3 to 16 +/- 5.6 worms/fish, respectively) but declined during late autumn and reached a minimum during winter (50-60% and 2.1 +/- 0.9 to 3.2 +/- 0.6 worms/fish). Parasite maturation was associated with higher water temperatures during spring and summer and most shelled acanthors were probably produced during summer and fall. There was only 1 generation of A. lucii per year, although generations tended to overlap and individuals within each generation did not develop synchronously. The sex ratio of adults was initially near unity but favoured females in the later stages of the infection. The distribution of A. lucii among perch was highly aggregated and stomach content analysis suggested that this was partly due to heterogeneity in perch feeding behaviour. The negative binomial and Poisson lognormal models fitted the data on worm distribution. Seasonal changes in the degree of parasite aggregation were detected, but no conclusive evidence of density-dependent controls on parasite population growth was obtained.

Helminth parasites of swordfish (Xiphias gladius L.) from the northwest Atlantic Ocean.

William E. Hogans, John Brattey, Leslie S. Uhazy,* Fundy Isles Marine Enterprises, Ltd., P.O. Box 381, St. Andrews, New Brunswick EOG 2X0, Canada; and Peter C. F. Hurley, Marine Fish Division, Bedford Institute of Oceanography, P.O. Box 1006, Dartmouth, Nova Scotia B2Y 4A2, Canada. *Present address: Division of Biological Sciences, 106 Tucker Hall, University of Missouri-Columbia, Columbia, Missouri 65211

A simple technique for recovering larval ascaridoid nematodes from the flesh of marine fish.

This paper describes and evaluates the efficiency of a simple technique for recovering larval ascaridoid nematodes (Anisakis simplex and Pseudoterranova decipiens) from the flesh of marine fish. The technique involves mechanical disintegration of the flesh in a domestic food processor, followed by visual inspection of diluted portions of the resulting homogenate under short-wave ultraviolet light. The nematodes, which remain intact, fluorescence brightly and are easily detected, particularly if the musculature has been frozen and thawed previously. The technique recovers a much higher proportion of the total number of nematodes than candling and slicing, is more rapid than pepsin-HCl digestion, and would therefore be suitable for large-scale surveys of ascaridoid nematodes in the flesh of marine fish.

Pennella filosa and Pennella instructa (Copepoda: Pennellidae) on swordfish (Xiphias gladius L.) from the Northwest Atlantic Ocean

chiura of fishes. Interscience Publishers, New York, 1104 p.). Their life cycle involves a series of free-swimming planktonic larval stages. Females are parasitic after metamorphosis and they attach to and penetrate the body surface of the host, whereas males are not parasitic (Wilson, 1917, Proceedings of the United States National Museum 53: 1-150). The cephalothorax of females eventually anchors in the musculature or internal organs of the host and the remaining portions of the parasite (trunk, abdominal brush) protrude from the flesh. The present paper describes the prevalence and distribution of pennellids on 303 swordfish collected in the northwest Atlantic Ocean during 1980. Helminth parasites of these fish are reported in a separate publication (Hogans et al., 1984, Journal of Parasitology 69: 1178-1179).