Multidimensionality in host manipulation mimicked by serotonin injection.

Area of Science:

• Parasitology
• Ecology
• Animal Behavior

Background:

• Manipulative parasites alter host phenotypes across multiple dimensions.
• Host manipulation can involve independent pathway alterations or cascade effects from a key disruption.

Purpose of the Study:

• To compare multidimensional host manipulation in two amphipod species infected with Pomphorhynchus laevis.
• To investigate if serotonin (5-HT) disruption can replicate the observed 'infection syndrome'.

Main Methods:

• Calculated effect sizes for six traits (activity, phototaxis, geotaxis, conspecific attraction, refuge use, metabolic rate) in infected vs. uninfected amphipods.
• Compared phenotypic alterations from P. laevis infection with those induced by experimental 5-HT injection in Gammarus pulex.

Main Results:

• Effect sizes for host traits were highly correlated between host-parasite associations, indicating a consistent 'infection syndrome'.
• Experimental 5-HT injection significantly correlated with the infection syndrome across all six traits.
• This suggests disruption of a major physiological mechanism, like serotonin, underlies multidimensional host manipulation.

Conclusions:

• Multidimensional host manipulation by parasites may stem from the disruption of a central physiological mechanism.
• Serotonin (5-HT) disruption can serve as a model for understanding parasite-induced phenotypic changes.
• This research provides experimental evidence for a unified mechanism in host manipulation.