North Pole Parasites, Part I

I’m one of those people who starts listening to Christmas music when I’m working in lab before Thanksgiving. I enjoy the holiday season so much that I always do something holiday-themed on the blog. For instance, one year I made up pond/parasite ecology carols and Christmas cards that very few people found humorous. Another year I made a parasite-themed Christmas tree cartoon that again was vastly under-appreciated. And a third year I dressed up trematode cercariae as Santa and some elves, which I’m pretty sure earned at least one dry chuckle from some dude somewhere. This year is going to be the year that I officially and fantastically merge Christmas and parasite ecology forever. This year I’m going to give you


And I promise to use that color scheme only once. Today’s post is just a short introduction, so you know what’s coming in the month of December. But I will leave you with a bit of North Pole parasite ecology. Once upon a time, I repeated Mark Siddall’s joke that hippos are such angry beasts because they have leeches living in their rectums. Today, I will repeat Tommy Leung’s joke that Rudolph’s nose is so red because he’s infected by a nose bot fly. (Disclaimer: if you’re searching for your Christmas spirit, you might want to hold off on googling “reindeer nose bot fly.”) I’m promise to think up some jokes of my own for the following posts.

Migration and Parasites, Revisted

Last year, I blogged about a neat meta-analysis showing that migratory bird species have more nematodes than non-migratory bird species. Tommy and Janet have recently extended that work, and you can learn more about that here. But today, I want to talk about how migration affects parasite assemblages within a single bird species, instead of between species.

Double-crested cormorants are funky-looking birds with funky geographic distributions. There are several subspecies with unique geographic locations (e.g., California, Southeastern-ish places), and some of the southern populations migrate, while others don’t. The non-migratory populations are sometimes protected, while the migrating populations are sometimes controlled via culling to reduce potentially detrimental impacts of cormorants on fisheries. So, if you were a manager, how could you figure out whether the cormorants hanging out in a given water body were migratory or not?

Having them all recite some Shakespeare and then guessing based on their regional dialects probably wouldn’t work. But don’t lose hope! There’s another way! After sampling migratory and non-migratory birds’ parasites from many sites, Sheehan et al. (2016) found that discriminatory analysis based on parasite data alone could predict whether a bird was migratory or not with 78% accuracy. That’s pretty good! (Also, check out the paper for some sweet graphics!)


This is a good reminder that we can learn a lot about host ecology by looking at hosts’ parasites. We can even figure out what some of the world’s most elusive sea creatures eat – and what eats them – just by looking at their parasites. Yeah. Parasites are cool.


Sheehan, K., D. Tonkyn, G. Yarrow, and R. Johnson. 2016. Parasite assemblages of Double-crested Cormorants as indicators of host populations and migration behavior. Ecological Indicators 67: 497-503.

14 great papers

In my last post, I jokingly suggested several papers that might “Make the Parasite Ecology Blog Great Again.” Today, Nov. 14, I want to tell you about 14 actually great papers that came out (very) recently. Most of these are still on my to-read list, but I’m hoping that sharing them helps to motivate me to prioritize some reading time in the near future. Feel free to make more suggestions in the comments!

  1. Ok, not a paper, but CHECK. OUT. THIS. DATASET! Doña, J., Proctor, H., Mironov, S., Serrano, D. and Jovani, R. (2016), Global associations between birds and vane-dwelling feather mites. Ecology, 97: 3242. doi:10.1002/ecy.1528
  2. Manlove, K., Cassirer, E. F., Cross, P. C., Plowright, R. K. and Hudson, P. J. (2016), Disease introduction is associated with a phase transition in bighorn sheep demographics. Ecology, 97: 2593–2602. doi:10.1002/ecy.1520
  3. Nowakowski, A. J., Whitfield, S. M., Eskew, E. A., Thompson, M. E., Rose, J. P., Caraballo, B. L., Kerby, J. L., Donnelly, M. A. and Todd, B. D. (2016), Infection risk decreases with increasing mismatch in host and pathogen environmental tolerances. Ecol Lett, 19: 1051–1061. doi:10.1111/ele.12641
  4. Woodroffe, R., Donnelly, C. A., Ham, C., Jackson, S. Y. B., Moyes, K., Chapman, K., Stratton, N. G. and Cartwright, S. J. (2016), Badgers prefer cattle pasture but avoid cattle: implications for bovine tuberculosis control. Ecol Lett, 19: 1201–1208. doi:10.1111/ele.12654
  5. Scheele, B. C., Hunter, D. A., Banks, S. C., Pierson, J. C., Skerratt, L. F., Webb, R. and Driscoll, D. A. (2016), High adult mortality in disease-challenged frog populations increases vulnerability to drought. J Anim Ecol, 85: 1453–1460. doi:10.1111/1365-2656.12569
  6. Leung, T. L. F. and Koprivnikar, J. (2016), Nematode parasite diversity in birds: the role of host ecology, life history and migration. J Anim Ecol, 85: 1471–1480. doi:10.1111/1365-2656.12581
  7. Iverson, S. A., Gilchrist, H. G., Soos, C., Buttler, I. I., Harms, N. J. and Forbes, M. R. (2016), Injecting epidemiology into population viability analysis: avian cholera transmission dynamics at an arctic seabird colony. J Anim Ecol, 85: 1481–1490. doi:10.1111/1365-2656.12585. (I want to read this if for no other reason than because the term “smoldering infection” occurs in the abstract.)
  8. Ingersoll, T. E., Sewall, B. J. and Amelon, S. K. (2016), Effects of white-nose syndrome on regional population patterns of 3 hibernating bat species. Conservation Biology, 30: 1048–1059. doi:10.1111/cobi.12690
  9. Dougherty, E. R., Carlson, C. J., Bueno, V. M., Burgio, K. R., Cizauskas, C. A., Clements, C. F., Seidel, D. P. and Harris, N. C. (2016), Paradigms for parasite conservation. Conservation Biology, 30: 724–733. doi:10.1111/cobi.12634
  10. Friesen, O. C. and Roth, J. D. (2016), Alternative prey use affects helminth parasite infections in grey wolves. J Anim Ecol, 85: 1265–1274. doi:10.1111/1365-2656.12544
  11. Wood, C.L. and P. T. J. Johnson (2016) How Does Space Influence the Relationship Between Host and Parasite Diversity?. Journal of Parasitology: October 2016, Vol. 102, No. 5, pp. 485-494.
  12. VanderWaal, K. L. and Ezenwa, V. O. (2016), Heterogeneity in pathogen transmission: mechanisms and methodology. Funct Ecol, 30: 1606–1622. doi:10.1111/1365-2435.12645
  13. Loss, S.R., Noden, B.H., Hamer, G.L. et al. (2016). A quantitative synthesis of the role of birds in carrying ticks and tick-borne pathogens in North America. Oecologia 182: 947.
  14. Hopkins, S.R., J.M. Wojdak, and L.K. Belden. (2016). Defensive symbionts mediate host-parasite interactions at multiple scales. Trends in Parasitology. *wink*


Make the Parasite Ecology Blog Great Again

[I’m a few days late for my very spooky Halloween post. Can you guess who I went as?]

This blog used to be a great blog. The best blog. But some things have been happening on this blog that aren’t that great. Believe me – I’ve seen it. That cartoon of a starfish eating mussels? Terrible. You know it. I know it. We’re going to completely get rid of it and replace it. We’re going to create competition and then you can have any starfish cartoon you want. The best starfish cartoon. And it has been three weeks without a post. Where has the blogger been for the last few weeks? Where is she? She can’t keep up with blogging while writing proposals? I don’t think she has the stamina to be the Parasite Ecology blogger. She’s a nasty blogger. I’m the only one who can run this blog. I’m going to make this blog great again. I’m going to do it, and I’m going to do it big time. We’re going to put some law and order back into this blog. We’re going to have posts every week, and The Readers are going to pay for them! And there are posts on this blog – bad posts. I mean really bad posts. We’re going to find those posts, and we’re going to export them to a PDF. Because the blogger wants to keep them! She wants to keep all of them! But I heard that she deleted 33,000 posts that were never shared with the blog. 35,000 posts. Gone. Who does that? 39,000 posts. Ask anybody: nobody respects bloggers like I do. Nobody. I love bloggers. Really. Listen, this all started simple. It’s called, “Make the Parasite Ecology Blog Great Again.” And I have recommended 20 supreme parasite ecology papers to be voted onto the Parasite Ecology Blog. These are highly respected, conservative papers. Here are their titles, because the other credentials are irrelevant:

  1. One hundred new parasite species discovered from a single flannel moth caterpillar (family Megalopygidae).
  2. Parasites of China. In China. From China. China.
  3. Drain the swamp: Wetland modification removes all parasites from the ecosystem. And everything else, too.
  4. You’re fired: Flame throwers are a highly effective control for larval nematodes.
  5. Infection economy: Hosts’ net fitness goes up and down with attitudes and feelings.
  6. The number of emerging infectious diseases caused by illegal immigrants is unfortunately zero.
  7. Very small sample size suggests that there are zero parasite species in Russia.
  8. Report on ten methods unlikely to successfully control radical parasitism.
  9. Surprising new insights regarding The World’s best known microphallid.
  10. Despite extensive contrary morphological and molecular data, these parasites are totally from Africa. [600 page opinion paper]
  11. Response to “No, these parasites are definitely not from Africa”: Other people totally said these parasites were from Africa first, but we said it longest and loudest, and that benefited parasitology because reasons.
  12. Discovery of the best model system that is the just the best, really.
  13. Compensating for reduced reproductive success: Why microphallids and their male hosts should both drive Ferraris.
  14. An anecdotal study: Can mind controlling parasites cause hosts to apply for jobs for which they are unqualified?
  15. Newly discovered louse species uses absurdly tiny grasping structures to cling to domestic cats.
  16. WRONG: Weird, Really Orange, Narcissistic…Giardia.
  17. Grab ’em by the footsie: Echinostome metacercariae stunt growth of cockle foot, increasing likelihood of predation by final host.
  18. Intermediate virulence hypothesis falsified: Parasite can kill all of its hosts without losing fitness – it’s like, incredible!
  19. Host defense doesn’t stop at the end of the epidermis: Concealed antibodies carried by tens of millions of American leucocytes.
  20. Miss Piggy goes to market: Is pork tapeworm cysticerci in our food supply?

World’s Cutest Parasite

Last week, I invited you to make nominations for the World’s Cutest Parasite. Here’s a compilation of all of the nominations that I received, in order that I received them. Look through, and then vote on your favorite!

(1) Euhaplorchis californiensis

(2) The adult, non-parasitic stages of botflies.


(3) Giardia was nominated several times (HT Dan Metz, Alex Lee, etc.)

(4) Transversotrema was another popular nomination (HT Kevin Lafferty, etc.; photo by RF Hechinger) 


(5) Water mites

(6) Fish tongue isopods



(7) Trypanorhynchs

(8) Here’s something crazy hoisted from an email nomination: “There are rust fungi that cause their host to form flowerlike structures (even with nectar) in order to attract insects by which they are dispersed.” (Photo from Wikipedia)



(9) Naegleria fowleri, the brain-eating amoeba, was a nomination pulled from the comments. I guess if you look very closely, like this, it’s cute?

(10) And finally, my nomination: Trichinella nativa. (Photo from Wikipedia)



So, which of these excellent nominations is the World’s Cutest Parasite?



Nominations for World’s Cutest Parasite

Yesterday morning, I was having one of “those” conversations at the dog park. You know, those conservation where a stranger asks what you study, and you tell them, and they get super grossed out, and you insist that, “No, really, parasites are cute,” and they still don’t believe you, so you use your phone to Google a photo of the World’s Cutest Parasite to prove it to them, and they totally agree that said parasite is pretty stinkin’ cute. I’m not going to tell you which parasite I Googled…yet. First, I want to hear your nominations for the World’s Cutest Parasite. You can send me your nominations on Twitter (@dinoverm #worldscutestparasite) or via email (dinoverm @ I’ll share your nominations next week!

Harry Potter, Cannibalism, and Parasites

I recently read this very interesting blog post about structuring your scientific talks like a Pixar movie. I thought it would be fun to structure some Parasite Ecology blog posts that way, so I’ve tried that for today’s post. I found it easier to model the post after a specific and well-loved story, so I’ve included the model story, too. If you want to follow along, the format is:

Once upon a time there was ___. Every day, ___. One day ___. Because of that, ___. Because of that, ___. Until finally ___.


Once upon a time, there was a pet animal who did not seem to be particularly important to the age-old struggle between good and evil wizards: Scabbers the Rat.

Scabbers was not a glamorous animal, and was perhaps even somewhat revolting or pathetic. But anyone who knew him would have said that he was quite harmless – except, perhaps, for the people who had nearly had their fingers bitten off by Scabbers.

Every day, people went around thinking that Scabbers couldn’t possibly be a significant source of upheaval in the struggle between good and evil wizards.

After all, there were very many animals in the world, but how many had anything to do with important wizarding affairs? Even if you searched very hard, you would only find a few reports of notable pet rats. In fact, it seemed impossible that animals could ever cause much of a stir, because the actions of single animal could never spread among wizards as fast as the ideas or actions of the wizards themselves.

One day, Harry, Ron, and Hermoine found out that their simplifying assumptions about Scabbers had blinded them to a vital detail: Scabbers was actually a key player in the war between good and evil wizards who was hiding in plain sight.

By assuming that Scabbers was an animal, the Hogwarts students had not realized that Scabbers was actually a man. And that man, Peter Pettigrew, had been hiding as a rat for years after betraying The Potters to The Dark Lord.

Because of that, Harry, Ron, and Hermoine became very interested in Scabbers, and scrutinized his history carefully.

They even listened to a supposed murderer who had dragged them into a creepy old shack while he explained all about the role of animals in the struggle between good and evil wizards.

Because of that, Harry, Ron, and Hermoine found out that it is actually quite common and entirely plausible for animals to be key players in the war between good and evil wizards.

A terrifying black dog turned out to be none other than Harry’s Godfather – a very good wizard. And a very scary werewolf was actually Remus Lupin, an excellent professor and a member of the Order of the Pheonix. Even Harry’s own father had been an animagus.

Until finally, Harry, Ron, Hermoine stopped ignoring the potential for animals to be important wizards.

Hermoine even realized that the rotten Daily Prophet reporter, Rita Skeeter, was able to sneak into Hogwarts to find juicy information because she was an unregistered animagus who could turn into a beetle.


Once upon a time, there was an ecological interaction that did not seem to be particularly important to parasite transmission: cannibalism. 

Cannibalism is not glamorous, and is perhaps even somewhat revolting – like when big male polar bears eat little baby polar bears. But as far as parasite transmission is concerned, ecologists generally assume that cannibalism is quite harmless (except, perhaps, for the ecologists who have nearly had their fingers bitten off by cannibals?).

Every day, parasite ecologists went around thinking that cannibalism couldn’t possibly be a significant source of parasite transmission.

After all, cannibalism is very common, but how many parasite systems use cannibalism as a main transmission route? Even when parasite ecologists searched very hard, they only found a few systems where cannibalism was notably important to transmission (Rudolf and Antonovics 2007, Sadeh et al. 2007). In fact, it seemed impossible that cannibalism could be broadly important, because most acts of predation seem to involve one predator eating one prey. In order for a parasite to actually spread in a cannibalistic population, multiple cannibals would need to feed on each victim.

One day, Sadeh et al. (2016) found out that ecologists’ simplifying assumptions about cannibals had blinded them to a vital detail: cannibalism can actually be a key mechanism in parasite transmission that is hiding in plain sight.

By assuming that cannibalism occurs in homogeneous populations, ecologists had missed something important: age or stage structure may mediate the influence of cannibalism on parasite transmission.

Because of that, Sadeh et al. (2016) became very interested in cannibalism, and scrutinized the roles of cannibalism versus other modes of parasite transmission carefully.

In structured populations where older hosts are less susceptible to direct contact parasite transmission, cannibalism on younger hosts by older hosts can be an important mode of transmission, where parasites are moved from susceptible, young hosts who are experience high mortality risk to older hosts who may be more infectious when infected.

Because of that, ecologists found out that it is actually entirely plausible for cannibalism to be important to parasite transmission.

Age- or stage-structured populations are very common, and in many of the known examples of parasite transmission via cannibalism, the host population has age or stage structure. So the conditions required for cannibalism to be an important transmission route may occur in many systems.

Until finally, the person writing this blog post stopped ignoring the potential for cannibalism to be important to parasite transmission.

I can’t speak for everyone, but I think transmission-by-cannibalism is worthy of more attention by parasite ecologists. Because surely there are even more cool examples than the ones we already know about.