I have always considered mushrooms the colorful and uplifting sight to enjoy during a walk in the forest or the perfect ingredient for a winter risotto. But I had never stopped to think about how many different mushrooms and, more in general, how many fungi are out there. Nor had I ever thought how diverse and extraordinary they are. Until I had the opportunity to talk with Dr. Danny Haelewaters, a postdoctoral research assistant at Purdue University.

I interviewed Dr. Haelewaters for the “Draw My Science” series, and made illustrations inspired by our chat. And “oh boy” (as Danny would say), this chat changed my perspective of the amazing kingdom of fungi. Dr. Haelewaters is studying complex fungi-host associations, like the one occurring with fungi hosted by bat flies (flies that in their turn are parasites of bats), and understudied fungi.

Our chat filled me with a sense of wonder and adventure. Danny’s enthusiasm about his work and about field biology reminded me of one of my childhood heroes: I felt like interviewing a real-life Indiana Jones that studies forgotten fungi instead of lost archeological treasures.

If you want to learn more about the world of fungi, the life of a field mycologist and the challenges to become a successful researcher, read on the extract below or listen to the full interview on YouTube.

The Interview

Hi Danny! – Let’s start with introductions.

My name is Danny Haelewaters. I am a biologist and I come from Belgium. I got my Ph.D. at Harvard University: I studied organismic evolutionary biology, focusing on mycology.
I am mainly interested in associations, in fungi that are parasites of arthropods, although I am also interested in other things such as multitrophic interactions, and understudied groups of fungi in understudied habitats.

Did you move in the US for your Ph.D.?

In Belgium, I got my Bachelor’s degree in veterinary medicine. I wanted to be a vet in a research team and I had this dream to go to Africa and study the Big Five (ed. lions, leopards, rhinoceros, elephants, and buffalos). But it is a dream I never really fully developed. Before you get to travel to Africa to study elephants, the “sexiest” of the Big Five, you have to do a lot of hospital work -at least in Belgium- and I just did not see that happening for me.

So I switched to biology, which seemed closer to me because it would focus more on the research part. Still, I wanted to work with animals, until I got inspired by this professor at Ghent University who studied mycology. That’s how I became a mycologist.

What did you find so interesting in mycology that compelled you to switch subjects? Who is a mycologist?

A mycologist is someone who studies fungi. Fungi are their own kingdom of organisms, in addition to animals and plants. Something that not many people know is that they are much closer to animals than plants.

Fungi are very diverse. You have fungi that occur in the forest, the mushrooms that have a stem and cap and that everyone knows about. But there are so many that we cannot see: parasites, microscopic fungi, yeast, food spoilers (people can actually see food spoilers but they rarely think of them in different contexts). And many fungi are understudied. As I am progressing as a researcher, I am realizing more and more how little we know about this kingdom. It really makes for interesting research and approaches trying to find, discover and describe diversity.

What are you studying right now?

My main project right now involves microscopic ectoparasites of bat flies. Bat flies are blood-sucking parasites on bats. The flies themselves can be infected by the fungi I am studying.

Nobody really focused on this system before I started to work on it back in 2016. In 1917 and in 1931 there were the last publications of species descriptions in this group of fungi from bat flies. Since then there were two papers published on development and host association — and that’s it.

Since I took on this project, I looked at more than 8000 bat flies, described several species, thought about patterns of morphological diversity, and phylogenetic diversity. And realized that there is more to this system than meets the eye.

You measured more than 8000 subjects. Were they all in the same location, or do you travel a lot for your studies?

I work both with entomologists who send me materials but I also travel to different countries. I often travel to Panama and Honduras, where I have collaborators and students. I go the field and I capture bats, which are processed in the field. They are weighted, their forearm is measured, they are sexed, they are identified based on morphology. Sometimes we take a wing sample if we are unsure about morphology identification, so we can check their identity based on DNA. And, of course, we also screen them for bat flies. Whenever we have the bat flies in hand, we travel to the laboratory -which is mostly the day after- and then we screen the bat flies for the presence of the fungi. When I find the fungi, I process them, which means DNA extraction, morphological analyses, and then even further processing, like host association, taxonomy, things like that.

The prevalence of these fungi on the bat flies is very low: we have to screen 100 bat flies before finding 2 to 6 infected with those fungi. And so it is really hard to get large amounts of data. It is easy to collect a lot of bat flies, but it is not easy to collect a lot of bat flies that are infected with the fungi.

It seems like there are three pieces of puzzles and they all have to fit together. There is the fly on the bat, and then the fungus on the fly. And you and your team have to reconstruct this puzzle to understand why certain associations happen and where and how.

These fungi are grouped in the order Laboulbeniales and are usually very host-specific. We do see that there is a trend for a certain species to be associated with one host, and for a sister-species very close to the first that instead is associated with another. But in some cases, that’s not 100% true. So it is really important to have a strong identification of the fungus, as well as of the host. That’s the reason that I work together with other scientists so that we can always put a good name down when looking at the hosts.

I work with mammalogists, to deal with the bats. And I also go out and capture bats with a mist nets myself, which is a lot of fun — bats are so cute! But then there is the entomologist part to recognize the bat flies and the associations with their bat host, which can also be very specific. Finally, there is the association of the fungi with the bat flies. So yes, there are indeed three parts of the puzzle. And the last thing, of course, is putting it all together in an integrated framework understanding these multitrophic interactions.

What is the part of your job that you enjoy the most?

I enjoy fieldwork the most. I consider myself more of a field biologist than anything else. When I started this bat fly – fungi research project I started working with collections, which is cool because you have lots of bat flies without having to leave the lab. You can be lazy -so to speak- because the data are there. And you just have to sit at a microscope, look at the bat flies, find the fungi and then deal with them. But then on the other end, you really do not understand the ecosystem that they occur in. You don’t really know where they are from or where they were collected. Or how the associations are formed. Or at least, that’s the way I feel about it.

Since I have been in the field myself, I understand this system much better, because I see those bats interacting with each other. I see which bats interact with which species, where those bats occur, some occur only in tunnels while other bats occur everywhere in the forest. There are certain bats that you can’t capture with low mist nets but that you have to capture with high mist nets. You can only learn these things in the field, doing the work yourself. That’s what I find so rewarding with fieldwork.

Also with doing fieldwork, you have to interact with many people, both locals, and collaborators as well as students, and I enjoy a lot to be dealing with these different people.

Studying these fungi and their hosts surely sounds a lot of fun. But why people should care about this research? What is the takeaway message?

There are two components of this research. The first one is trying to understand how much diversity is out there. A very big overarching question is: how many fungi are out there? That’s mostly what lies at the forefront of everything I do. And it is very important, because how can one think about conservation, about protecting landscapes or forests if one does not know what occurs there?

And the second thing is that these things are parasites (presumed parasites – I should say, because we really do not know the interactions yet, but we presume that they do have some sort of negative effect on the fitness of their host). The idea of studying parasites on bats is to test this hypothesis of the dilution effect that stipulates that a healthy ecosystem reduces the risk of diseases in a certain area. And I would like to test it on these different levels. Bats provide so many different services, for example, they are important pollinators. And so it is quite important to look at bat assemblages and bats associates, like these parasites, to study hypotheses like this one.

What’s next? How long do you think you are going to work on this system, do you have big dreams for the future?

I started in 2016-17 and published a number of papers on this system. But a lot is still unknown. When studying understudied systems like this one, there are a lot of unknowns. You start with one question but then, as you are getting closer to the answer, 17 new questions pop up in your head. How does this happen? How are these associations evolved? Why are these other so weird? I think I will be working on this for quite a while but at the same time, I like to diverge.

And so I have taken an interest in other understudied groups of fungi. For example, I work on the Leotiomycetes, which is a class of fungi that are mostly cup fungi, but also plant parasites, and a bat parasitic species. Not many people work on this group and there is the problem of many undescribed species. Wherever we go, we find new species. We have described fungi for a little less of 300 years, and we are at 135,000 species that are described –that already is mindboggling. But the amount of estimated species is somewhere between 2 and 6 million species; there’s a lot out there that is not known yet.

Another thing is to study fungi in understudied geographic areas and habitats. For example, I recently applied for a project to study fungi in Siberia. Curiously enough, even lettuce leaves are can be an understudied habitat for fungi. I found that the most common species of fungi occurring on Romain lettuce (which is one the most commonly produced and consumed vegetable crops in the US) is an undescribed species. We do not know what it does, its ecology, its physiology. This gives us the opportunity to look at biodiversity from an agricultural point of view.

Understudied fungi on romain lettuce: I think this really encompasses the importance of studying biodiversity, and also the challenges associated with it. Talking of challenges, what challenges you had to overcome in your career and what lesson you would like to share?

One of the things I learned in my academic path is that not a single path is the same. I see many younger people and undergrads trying to mirror their path to these big names in research. They say, “Oh my god, I haven’t done this yet” or “I haven’t published a paper yet” or “My grades are too low”.
You know what: I had low grades when I was in college, and I ended up with a Ph.D. from Harvard. It is all about how you approach things, how passionate you are, and about craftsmanship. I think being successful in academia is hard work and a little bit of luck. But especially hard work. And also, be outgoing; have collaborations.

Especially with your path of self discovery, switching from veterinary medicine to mycology, you know first end how individual paths can be very diverse.

Having gone through that program of veterinary medicine in Belgium really helped me to be a successful academic. It still does. Because it was rough coming from where I came from in high school, I really learned how to learn. I laid a foundation for all future studies. I am really glad I did that: I don’t think I would be a successful academic if it wouldn’t have been for this weird side path. It looks like a weird side path now, but in my head, it feels really logical: I had to take that particular path to become the academic I am now.

And of course, there is passion. To be an academic you need to be passionate about your work. The demands are very high to be successful and stay in academia. I see many people, that I believe are really good academics, move outside of academia because it is too much. And part of the reason may be because they are missing this real internal passion about their field perhaps.

Read more about Danny

My chat with Danny was longer than the selected extract, and we discussed in more detail his research, his approaches to secure fundings for understudied species, and as a few suggestions for work-life balance. You can listen to the whole interview on Youtube, where the interview is paired with the making-of videos of the illustrations.

If you want to check out more of Danny’s work, visit his website on www.dannyhaelewaters.com or reach out to him on twitter @dhaelewa.

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