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Title: EMERGENCE OF THIRD=STAGE LARVAE OF UMINGMAKSTRONGYLUS PALLIKUUKENSIS FROM THREE SPECIES OF GASTROPOD INTERMEDIATE HOSTS

Author
item KUTZ, SUSAN - UNIV SASKATCHEWAN, CANADA
item Hoberg, Eric
item POLLEY, LYDDEN - UNIV SASKATCHEWAN, CANADA

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Lungworms of the family Protostrongylidae have complex life cycles involving gastropods and ruminants, and transmission is completed when the ruminant definitive host ingests larvae contained in the slug or snail intermediate host (IH). Departures to this pattern, involving emergence of infective larvae from the IH have largely been discounted, but have never been explored in a rigorous experimental setting. We investigated the emergence of third-stage larvae (L3) of Umingmakstrongylus pallikuukensis from the slugs Deroceras laeve, D. reticulatum and the snail Catinella sp. in the laboratory, and from D. laeve on the tundra. Third- stage larvae emerged from the IH's across varying regimes of temperature, light and intensity of infection The majority of L3 emerged from most of the Deroceras spp. by 58 or 60 days post infection (PI). Larvae emerged from D. laeve on the tundra by 10 weeks PI, and were recovered from the vegetation of some experiments the following year after over-wintering. Emergence of L3 of U. pallikuukensis from the intermediate host may increase the temporal and spatial availability of L3 and enhance survival and transmission. Recognition that emergence of L3's for U. pallikuukensis and perhaps other protostrongylids may be a natural and epidemiologically significant phenomenon serves to broaden our understanding of transmission dynamics and life history for pathogenic lungworms in ruminants and establishes a fundamentally new view of life cycles among Protostrongylidae.

Technical Abstract: We investigated the emergence of third-stage larvae (L3) of Umingmakstrongylus pallikuukensis from the slugs Deroceras laeve, D. reticulatum and the snail Catinella sp. in the laboratory, and from D. laeve on the tundra. Third-stage larvae emerged from 8 of 8 D. reticulatum housed at 20 degrees C in darkness and from 9 of 10 D. laeve and 5 of 5 Catinella sp. housed at 21 degrees C with 10-12 hours of light/day. Larvae emerged from D. laeve and D. reticulatum over a wide range of infection intensities (2-179 and 20-65, respectively) and the patterns of emergence were independent of intensity. The majority of L3 emerged from most of the Deroceras spp. by 58 or 60 days post infection (PI). Lower rates of emergence were observed for Catinella sp. Larvae emerged from D. laeve on the tundra by 10 weeks PI, and were recovered from the vegetation of some experiments the following year after over-wintering. Live L3 survived in tap water and distilled water at 0-4 degrees C for 13 months. Emergence of L3 of U. pallikuukensis from the intermediate host may increase the temporal and spatial availability of L3 and enhance survival and transmission.