Attraction of the land snail Anguispira alternata to fresh faeces of white-tailed deer: implications in the transmission of Parelaphostrongylus tenuis

Terrestrial gastropods serving as intermediate hosts of Parelaphostrongylus tenuis (Dougherty, 1945) are infected either by crawling over infected faeces or by contact with larvae washed off faecal pellets onto surrounding soil. Some studies have concluded that gastropods avoid faeces; therefore, transmission must occur from soil. During two trials, Anguispira alternata (Say, 1816) were offered a choice of two types of larva-free (U) white-tailed deer (WTD; Odocoileus virginianus (Zimmermann, 1780)) faeces (trial 1) and a choice of larva-containing (L) or larva-free (U) WTD faeces (trial 2) in a laboratory setting. The snails were observed in proximity to U faeces 2.5 times more than expected in trial 1. They were found on faeces 3.4 times more than expected in trial 2, but showed a preference for U faeces, frequenting U faeces 3.1 times more than expected, while frequenting L faeces 1.7 times more than expected. In addition, we feel that this laboratory design could be a useful tool for further investigation of the epizootiology of P. tenuis in important intermediate host species.

The life history of Scaphiostomum pancreaticum McIntosh, 1934 (Trematoda: Brachylaemidae)

The life cycle of the brachylaemid trematode Scaphiostomum pancreaticum McIntosh, 1934, was completed experimentally in the laboratory. Eggs were obtained from trematodes removed from naturally infected Tamias striatus. Eggs are mature when laid and hatch naturally only after ingestion by a snail. In vitro hatching and subsequent examination of the miracidium was accomplished in snail gastric juice. Sporocysts developed in Anguispira alternata and cercarial emergence began 129 days after infection. Metacercariae developed in the kidney of A. alternata, Triodopsis albolabris, and Haplotrema concavum and were infective to the chipmunk after 5 months, and ovigerous adults were obtained in 30 days. This is the first description of the life cycle of a member of this genus.

ON THE MORPHOLOGY AND LIFE CYCLE OF THE TREMATODE TANAISIA ZARUDNYI (SKRJABIN, 1924) BYRD AND DENTON, 1950, FROM THE RUFFED GROUSE, BONASA UMBELLUS L.

Tanaisia zarudnyi occurs in the ureters and kidney tubules of ruffed grouse from Ontario and Michigan. The dark brown, operculate eggs are fully developed when oviposited. They remain viable for long periods of time at 2 to −15 °C and can withstand a temperature of −49 °C for 1 to 2 days. They hatch only when ingested by some mollusc. Development occurs in the digestive gland of the terrestrial snails Anguispira alternata and Succinea ovalis. Daughter sporocysts complete development in 6 weeks, by which time they contain undeveloped cercarial bodies. Within the next 2 weeks, most of the distomate. brevicercous cercariae are fully developed. The cercariae encyst within the daughter sporocyst, utilizing the contents of subcuticular glands to form the cyst. Encysted metacercariae are killed in the gizzard when fed to chickens, but excyst when inoculated directly into the duodenum. Excystation apparently results from secretions of the anterior glands of the stimulated metacercaria rather than from digestion of the cyst wall by the host. A 6-week-old ruffed grouse became infected when fed metacercariae, but 9 older ruffed grouse, 17 chickens, 4 white-throated sparrows, and 6 pheasants, fed similarly, were not infected. Apparently there is both host and age resistance to infection with this parasite.

THE SYSTEMATICS AND TRANSMISSION OF NEW AND PREVIOUSLY DESCRIBED METASTRONGYLES (NEMATODA : METASTRONGYLIDAE) FROM MUSTELA VISON

Crenosoma hermani n. sp., Aelurostrongylus pridhami n. sp., and Filaroides martis from mink are described. A. pridhami developed in the terrestrial gastropods Zonitoides arboreus, Discus cronkhitei, Deroceras gracile, Succinea ovalis, and Anguispira alternata and the aquatic snails Physa integra, Gyraulus deflexus, Armiger crista, and Ampullaria cuprina. F. martis developed in P. integra and G. deflexus as well as in the foregoing terrestrial gastropods. Larvae of A. pridhami and F. martis infected gastropods by penetrating the foot but those ingested penetrated the gut wall and developed successfully. Besides the foot, larvae developed on, or within, the body wall, in the mantle, on the gut, on the surface of the liver, in the buccal mass, salivary gland, and rarely in the albumen gland of molluscs. At 22–23 °C the first molt occurred on the 5th to 6th day, the second on the 13th; the three larval stages are described. The prepatent period of A. pridhami was 21–28 days, F. martis 41–53 days. Mink invariably vomited when fed infective larvae of A. pridhami but not when fed F. martis. Infective larvae of A. pridhami became encapsulated in the liver of mice, small birds, and frogs but on the intestines and mesenteries of goldfish. F. martis larvae became encapsulated in the liver of mice. There is a sigmoidal relationship between temperature and activity of first-stage larvae of A. pridhami. Young D. gracile fed and became infected with A. pridhami and F. martis at temperatures as low as 5 °C. Desiccation killed larvae in a few minutes and they survived freezing temperatures for only 4 to 5 days.