Chemical Attraction in the Genus Trichinella

Chemical attraction in the genus Trichinella was studied in vitro. Male adult worms of Trichinella spiralis, T. spiralis var. pseudospiralis, and Trichinella sp. isolate (polar bear isolate) were attracted to females of their own isolates. The intensity of heterosexual chemical attraction between T. spiralis and the Trichinella sp. isolate was similar, whereas T. spiralis var. pseudospiralis males were attracted less by either T. spiralis or the Trichinella sp. isolate females. Female worms of all three nematodes were significantly repulsed by members of the same sex. The repulsion of T. spiralis and the Trichinella sp. isolate females by each other's females was similar, whereas T. spiralis var. pseudospiralis females were repulsed more by females of the other two parasites. On the basis of our experiments, we concluded that the Trichinella sp. isolate and T. spiralis are more closely related members of the genus Trichinella, and view with caution identification of Trichinella isolates from Arctic regions as a distinct species. Differences in chemical attraction of T. spiralis var. pseudospiralis is further evidence indicating that it is distinct from T. spiralis.