Parasite-modified behaviour in non-trophic transmission: Trematode parasitism increases the attraction between snail intermediate hosts
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Date
2020-03-13
Authors
Eliuk, Laura K.
Brown, Shelby
Wyeth, Russell C.
Detwiler, Jillian T.
Journal Title
Journal ISSN
Volume Title
Publisher
Canadian Science Publishing
Abstract
Many parasites with complex life cycles cause host behavioral changes that increase the
likelihood of transmission to the next host. Parasite modification is often found in trophic
transmission, but its influence on non-trophic transmission is unclear. In trematodes, transmission from the first to second intermediate host is non-trophic suggesting that
free-swimming larvae (cercariae) emerging in closer proximity to the next host would
have higher transmission success. We performed a series of behavioral experiments with
echinostome trematodes and their snail hosts to determine if potential second hosts
(Planorbella sp.) were more attracted to parasitized first hosts (Lymnaea elodes Say,
1821). In a Y-maze, a responding snail (Planorbella Haldeman, 1842 sp.) was placed in
the base and its response to five treatments was assessed: no stimulus, duckweed (a food
item, Lemna turionifera Landolt), non-parasitized L. elodes, parasitized L. elodes, and
finally parasitized versus non-parasitized L. elodes. Snails showed some attraction to
uninfected snails, but had a stronger response to infected first host snails. These results
indicate that potential second host snails were more attracted to parasitized,
heterospecific first host snails over non-parasitized heterospecific snails. This study
demonstrates that echinostome trematodes alter snail behaviour by changing navigational
choices in uninfected potential hosts through a chemical communication mechanism.
Description
Keywords
Lymnaea elodes, Marsh Pondsnail, Planorbella, Ramshorn Snail, altered behaviour, parasite manipulation, trematode-snail interactions, Y-mazes