Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2000
Publication Date: N/A
Citation: Interpretive Summary: Biology and development of lungworms with complex life cycles are poorly known, although such parasites are known as significant pathogens in ruminants. Host-parasite systems in ruminants are influenced by temperature which can control the distribution and development of infective stages. Temperature and development of larval nematodes interact leading to changes in parasite populations and the distribution of disease. In order to learn more about these interactions and to articulate a model for the relationship between global climate and parasite distribution, we studied the development of the Arctic lungworm Umingmakstrongylus for which molluscs are intermediate hosts. We discovered that parasite development is determined by environmental factors, and ecological and phylogenetic features of parasites and molluscan intermediate hosts. Parameters defined in our study contribute to a model for predicting effects of global climate change on geographic distribution and transmission of a parasite in northern ruminants. This model system is significant in predictions for emergence of parasites and disease caused by lungworms in ruminant hosts.
Technical Abstract: The morphological and morphometric aspects of larval development of Umingmakstrongylus pallikuukensis in Deroceras laeve were investigated under laboratory conditions. Larval stages were best defined by the separation of the cuticular sheaths, tail structure, and viability following digestion. There was some growth in body and esophagus width during the first-stage within the intermediate host, but the majority of the growth in body length and width occurred immediately following the second molt. Larval development in D. laeve and Deroceras reticulatum occurred more rapidly at warmer temperatures. The calculated threshold temperatures were 8.5 C and 9.5 C in D. Laeve and D. reticulatum, respectively, and 167 degree-days were required for development to third-stage larvae in both intermediate hosts. These thresholds are high compared to that established based on published data for the closely related Muellerius capillaris (4.2 C), but are similar to those for the more distantly related northern protostrongylid, Elaphostrongylus rangiferi (8.3-10.3 C). Conversely, degree-days required for development to infective L3 were more similar among the Muelleriinae than between this group and the Elaphostrongylinae. Development parameters for protostrongylid larvae may be influenced both by environment and by features of parasite and intermediate hosts, including phylogeny.