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1 July 2016 The Role of Light and Dark on the Dispersal and Transmission of Echinostoma caproni (Digenea: Echinostomatidae) Cercariae
Thomas R. Platt, Francesca Gifford, Derek A. Zelmer
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Abstract

Abiotic stimuli are critical in the dispersal and transmission of trematode cercariae from the first intermediate host to the next host in the life cycle. The role of 2 abiotic stimuli, light and gravity, were examined in the dispersal and transmission of the cercariae of Echinostoma caproni in a laboratory setting. Nearly 100% of cercariae placed in a vertical chamber that permitted upward migration with a marginal probability of return swam to the surface in both light and dark conditions, suggesting that a positive phototaxis is not involved in dispersal and that a negative geotaxis may be the critical component in the vertical migration. The presence of a sentinel snail (Biomphalaria glabrata) in the bottom portion of the transmission chamber resulted in a significant reduction of cercariae dispersing upward and a significantly higher intensity of metacercariae in snails under lighted conditions than in the dark. In a light/dark choice experiment the prevalence and intensity of metacercariae was significantly higher in snails in the dark. The results suggest that although a positive phototaxis is not important in the dispersal of E. caproni cercariae, a negative phototaxis enhances host finding and transmission of cercariae to snails functioning as the second intermediate host.

The Helminthological Society of Washington
Thomas R. Platt, Francesca Gifford, and Derek A. Zelmer "The Role of Light and Dark on the Dispersal and Transmission of Echinostoma caproni (Digenea: Echinostomatidae) Cercariae," Comparative Parasitology 83(2), 197-201, (1 July 2016). https://doi.org/10.1654/4826i.1
Published: 1 July 2016
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