Taste test: prawns prefer infected snails, good news for disease control

Freshwater prawn about to eat a Biomphalaria glabrata snail in the laboratory

Prawns preferentially attack schistosome-infected snails
A new laboratory study published in the Journal of Experimental Biology provides insight into the impacts of parasitic infection on predator–prey dynamics. In aquaria, freshwater prawns preferentially attacked infected snails, with an attack rate 25% higher than seen for uninfected snails.  Why?

The answer is unclear, but this new research by Upstream Alliance scientists demonstrates that the infected snails have a sluggish response to predatory threats.  "In [snail] behavior trials, infected snails moved less quickly and less often than uninfected snails, and were less likely to avoid predation by exiting the water or hiding under substrate," say the authors.

The changes in snail behavior could be the result of deliberate manipulation on the part of the parasite (to keep snail hosts in the most beneficial position for the parasite, despite predation risks) or a side effect of infection.  Either way, these results support the idea that boosting natural rates of snail predation using freshwater prawns may be a useful strategy for reducing transmission in schistosomiasis hotspots.

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Reference:

Swartz, S.J., DeLeo, G.A., Wood, C.L., Sokolow, S.H. 2015. Infection with schistosome parasites in snails leads to increased predation by prawns: implications for human schistosomiasis control. Journal of Experimental Biology. [Download PDF] or link to online article

Press coverage:

Schistosome parasite alters snail behaviour
Kathryn Knight, J Exp Biol, 2015

Contact Us:

The Upstream Alliance, info@theupstreamalliance.org

Susanne Sokolow, ssokolow@stanford.edu