Euhaplorchis prefers two areas of killifish brains

Ryan Hechingernews

In a new collaborative paper, we present the distribution of the brain-infecting host-behavior-modifying Euhaplorchis californiensis (Euha) parasite along the antero-posterior axis of California killifish brains. We find that, although Euha metacercariae cover the whole brain, they are really dense in two areas. The density peaks provide clues to the route of parasite entry into the brain and the neurological mechanisms underlying the parasite’s manipulation of host behavior. This work was part of Siri Helland-Riise’s thesis, who spent many many months with us as part of our collaboration with Oyvind Overli and Kelly Weinersmith. link to paper

Horn snail trematode guide is finally here

Ryan Hechingernews

It took a while, but Ryan finally completed the guide to the trematodes infecting the California horn snail. Although these parasites have been subject to a large amount of taxonomic,
biological, evolutionary, and ecological research–and we’ve even proposed to use them as ecological indicator tools–we’ve lacked a satisfactory guide. This should help fill the void for a while. It’s out at Zootaxa: https://www.mapress.com/j/zt/article/view/zootaxa.4711.3.3 .

 

Scaling theory works for ectoparasites

Ryan Hechingernews

In a new lab publication, out today in Proceedings of the Royal Society–Biology, we report our finding that the Metabolic Theory of Ecology accurately predicts the specific increase in total ectoparasite load across birds of different sizes. We also found what appears to be a novel macroecological pattern–a shift in dominance from mites to lice moving from smaller to larger birds–that was only apparent when using total ectoparasite biomass or energy flux. On the whole, the results suggest we’d benefit from using energy flow as a fundamental currency in parasitology (and all ecology), on top of highlighting the possibility of generating unified and efficient scaling theory for parasitism.

Parasitism & sex allocation in hermaphroditic host

Ryan Hechingernews

In another paper from Cat’s PhD (congrats!) published in Scientific Reports, we document that when hermaphroditic Chthamalus fissus barnacles invest in female reproduction, it comes with greater risk of being infected by the ovary-eating isopod parasite Hemioniscus balani. In fact, this parasite may partly explain our surprising finding–which is contrary to standard theoretical expectations–that the largest barnacles were not investing at all in female function. For the full story, see Fong et al. (2019) Hermaphrodites and parasitism: size-specific female reproduction drives infection by an ephemeral parasitic castrator.