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Echinostoma trivolvis (Digenea: Echinostomatidae) second intermediate host preference matches host suitability
Jeremy M Wojdak1, Letitia Clay, Sadé Moore
1Department of Biology, Radford University, Radford, VA 24142, USA. jmwojdak@radford.edu
Parasitology Research
|December 15, 2012
Summary
Trematode parasites Echinostoma trivolvis lineage a (ETa) strongly preferred Physa snails over Helisoma snails in preference trials. This host preference protects Helisoma snails from infection when alternative hosts or snail predators are present.
Area of Science:
- Parasitology
- Ecology
- Evolutionary Biology
Background:
- Trematodes often utilize a single mollusk species as a first intermediate host and then infect various second intermediate hosts.
- Understanding host specificity is crucial for deciphering trematode infection dynamics and transmission.
Purpose of the Study:
- To investigate the factors influencing host specificity in the trematode Echinostoma trivolvis lineage a (ETa).
- To determine if ETa exhibits host preference between two potential second intermediate hosts: Physa gyrina and Helisoma trivolvis.
- To test the hypothesis that trematodes may avoid hosts associated with higher mortality risks.
Main Methods:
- Laboratory preference trials were conducted with ETa cercariae and both snail species (P. gyrina and H. trivolvis).
- Host suitability was assessed by quantifying encystment and excystment success in each snail species individually.
- The impact of the symbiotic oligochaete Chaetogaster limnaei on ETa infection in H. trivolvis was also examined.
Main Results:
- ETa showed similar encystment success in both P. gyrina and H. trivolvis when offered alone.
- Excystment success was higher in P. gyrina compared to H. trivolvis.
- The presence of C. limnaei reduced ETa encystment success in H. trivolvis.
- When both snail species were available, ETa cercariae strongly preferred P. gyrina, leading to significantly reduced infection prevalence and intensity in H. trivolvis.
Conclusions:
- ETa exhibits strong host preference for P. gyrina over H. trivolvis as a second intermediate host.
- The presence of an alternative host (P. gyrina) or a predator (C. limnaei) provides significant protection to H. trivolvis from ETa infection.
- These findings highlight the ecological factors that can shape host specificity and influence parasite transmission dynamics.
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