Listen to our podcast episode or read the transcript below featuring Dr. Will Beckerson, zombie insects researcher, as we talk about zombie ants, zombie snails, zombie movies, and body tattoos (of zombie insects).
Science is not just for the people at the top level of academia. It’s really meant to be for the world to share.
The fungus kills the host and then eats it from the inside out.
Tanya: Hi everyone, and welcome to Ask a Scientist, a Science Journal for Kids podcast, where we explore what it’s like to be a scientific researcher. I’m Tanya Dimitrova, and I’m here with my co-host, Dr. Miranda Wilson.
Miranda: Hey there.
T: Our guest today is Dr. William Beckerson. He’s a Molecular Biology and Genetics postdoctoral research fellow at Utrecht University in the Netherlands. Here at Science Journal for Kids, we just adapted one of Will’s papers about fungi that turn ants and other insects into zombies. The adapted article is available in two reading levels for school students as young as 4th grade up to 12 graders. Its title is, “How Do Some Fungi Turn Insects Into Zombies?“
Today, we will talk with him about his work, but we will also get to know, at least a little bit, the person behind the professional scientist. Hello, Will, and welcome to the podcast.
Will: Hi, happy to be here. Thanks so much for inviting me. I’m excited to talk about a little science with you today.
M: Perfect. So let’s start by talking a little bit about your educational background for our student listeners out there. So first of all, let’s talk a little bit about your high school experience. Were you always interested in science or were you kind of a everything-is-interesting and focused later?
W: Back then, science was probably one of my poorest subjects, actually. So one thing to note, I grew up in a really rural town in Kentucky. So our science and education program was not the best. They didn’t have the top-of-the-line tools for us to play with. And I can say, at least in my high school career, I never had the opportunity to look in a microscope or anything like that during our class. So during my high school career, I actually didn’t focus on science at all.
And I went to college to become an accountant. And it wasn’t until my third year of college that I took an introductory biology course that was required as part of this general education curriculum that I really discovered the wonders of the microscopic world and fell in love with biology.
And I can remember the specific class because we were doing an exercise where we went and collected pond water, and we were taking a look at this under the microscope. And I knew what bacteria were. We looked at cell models in high school, but I had never actually seen what they look like under a high-power microscope. So during this class, we took what appeared to the naked eye as clear water and put this underneath the microscope.
And what I saw was amazing. It was brimming with life. Lots of little, tiny, different-shaped microorganisms swimming around, doing their thing. And I remember I was particularly enamored by amoebas. So for those of you out there who aren’t familiar, amoebas are these very globular microorganisms that move around with these things called pseudopoda, which stands for false feet. So they kind of extend their cell membrane and they push themselves around on the surface, like crawling around.
And I remember seeing this particular amoeba crawl towards another small spinning life form that I later learned was a paramecium and it began to do something peculiar. It started to wrap its pseudopoda around the paramecium like a big hug and then it engulfed the paramecium inside the cell.
And this is a process that I now know is called phagocytosis. And this is how amoebas find food and eat food. And I remember just being dumbfounded by the whole process. Like, here is this tiny microscopic thing with no brain, no skeleton, and no muscles, yet it’s smart enough to not only be able to recognize what is food and what’s not food, but to move towards it and do so without any of these complex structures that we as humans have.
T: All the while being invisible to us.
W: Yeah, completely unaware to passers-by, right?
So life is going on all around us. We can’t even see it happening. And from this point forward, I was really interested in how do these tiny microscopic organisms do the things they do? And in particular, how do they interact with each other? How do they know what’s going on around them?
M: So did you graduate with a business degree or did you switch majors?
W: I switched majors in my third year, which was kind of a feat, but I did graduate with a minor in business administration because by that point I’d already had all the classes that you need for this minor.
M: So are there any teachings or lessons from your time as a business student that you think helped you as a scientist?
W: Absolutely. So one of the most bizarre things that I learned very quickly in my introductory biology class is that some of the ways in which we operate as a society mirror very closely what happens at the cellular level. So in business, we talk about this idea of people coming up with a product, making blueprints for this product, producing said product, shipping it out to distribution centers, the distribution centers ship it out, you know, globally to people’s mailboxes. And this is basically how, you know, consumers receive goods on their end.
Well, if you compare that to what’s happening inside a cell, it’s very similar. So you have genetic material, that is the blueprints. This genetic material is being made into products or proteins. These proteins are being shipped out to distribution centers, like the Golgi apparatus, and then they’re being sent to the various components of the cell, the globe, if you will.
So I found it remarkable how easy it was to learn biology with some of these business backgrounds.
M: That’s awesome. So you’re a first-generation college graduate, we learned.
W: I am, yes.
M: But obviously you didn’t stop after a bachelor’s. You continued on to get a master’s and a PhD, and now you are doing a postdoctoral fellowship. It’s a long process to become a researcher. What has motivated you through all of your educational journeys?
W: As a business major, I wasn’t the best of students, maybe B or C average. And a big part of that was because I wasn’t passionate about what I was doing. But I found when I switched over to biology and I had this genuine drive of curiosity, my grades improved. And it’s because I was doing the homework. I was reading outside of the material that was called for in class. And it’s because I was genuinely interested in the topic.
So looking back on it, yes, there’s been a long road to get to where I have been today. But at no point was it ever really a process of, okay, now I gotta get my masters; okay, now I gotta get my PhD. So basically, you become completely engrossed in a topic that you’re passionate about. And I think you’ll find a lot of people who teach or do research or outreach at these levels kind of have that same spark that drove them through the madness of academia.
M: That driving force of curiosity has taken you to a lot of different places. You currently live in the Netherlands, which is really far away from Kentucky.
M: Can you briefly describe what a day in your life in the Netherlands is like? Is it different from the U.S. lifestyle? Tell us a little bit about it.
W: Some of the biggest culture shocks, as you would call them, are things that you experience for the first time when you go to different places, in reference to traveling to the Netherlands, is just how much vacation that people have here.
So in the United States, we kind of have a two-week window, you know, more or less for most people. But in Europe, it’s much larger than that. It’s closer to two months. And this is spread out a little bit throughout the year. So a typical vacation might be two or three weeks for a Dutch citizen and I got to say it at first, you know with my very “work work work” American brain, I thought that this was somewhat of a waste of time. But what I’ve come to realize is taking breaks and Exploring things not only allows you to broaden your perspective, but it also allows you to reset.
T: We have a question for you from a listener.
N: Hi, my name is Natalia and I am a volunteer at Science Journal for Kids. In science, pretty much as in life, you often have to overcome challenges or hurdles. Could you share a particularly challenging experience in your research or in your life and how you overcame it?
W: In research, one of the first things that the professors in my department told me is, you’re going to fail at a majority of things you do. And that’s just based on the fact that you’re really at the frontier of what we know. And I can remember the first time that I asked my professor as a PhD student a question that he didn’t know the answer to. And that was shocking to me, because growing up, going through education, it’s really treated as this inventory of knowledge, and we’re supposed to memorize it all, and that’s how education has traditionally been taught.
So to get to this point where I asked questions and there was no answer was kind of shocking. And that really was a transition into my research career.
But most of the things that we work on, particularly with zombie ants, a lot of what we do fails. So really, a big portion of my job is to think critically about what’s going wrong, what are other ways that we can approach the problem, and what are some creative solutions that we can come up with to try to figure out what’s actually going on with this biological system.
So we do a lot of outreach events with the communities, with science centers, with zombie ants for example, we did it with the Parks and Wildlife Services, you know, doing summer camps and going out and showing people these really cool organisms. And we’re really passionate about sharing this with the world.
T: While working on your paper’s adaptation, we actually found out that you have extensive body tattoos showing different insects as a way to demonstrate your commitment to the field, maybe. So tell us about your tattoos. Did you come up with the art yourself based on your work or…?
W: I must say, I had tattoos long before I started studying zombie ants. So, as a statement of my commitment to research, I don’t know if that’s fair to say, but it’s definitely an expression of my love for what I do.
So, for those of you out there, I’ll give you sort of a mental picture of what’s going on. So, this tattoo starts at my wrist and goes all the way up to my shoulder blade. And at the bottom is a graveyard. And on top of that graveyard is this kind of branching tree. And on this tree are tons of insects that are infected with different fungi that cause behavioral manipulation. So these are all examples of behavior-manipulating parasites that we know of in nature. And we’re finding more and more every year. It’s quite amazing.
So on this tattoo sleeve, we call it, there’s the zombie ant, which if you read the adaptation, you’ll be very familiar with. There’s also the zombie fly. Now, what’s interesting about the zombie fly is rather than causing this death-grip behavior that we see from biting in ants, the fungus is actually able to make the saliva of the fly very sticky. So it actually winds up gluing its mouthparts (eusthestrates) before the fungus comes out.
There’s also the zombie wasp, the zombie…
T: Actually, let’s clarify this. What are zombie insects? How do you recognize them?
W: So, a zombie insect is an insect that is being behaviorally manipulated by a parasite. And this usually results in behaviors that are advantageous for the parasite itself and its reproduction.
T: And lethal to the insect.
W: Yes. That is just a small subset of the many different behavioral manipulating parasites out there. And not all of them are fungi.
There’s a great example of a snail that is infected by a worm. And this is actually what we call a dual-host system. So the worm reproduces and has offspring only in the guts of birds. And so these birds poop out the worms all over the place. It helps them spread. But in order to get back from the bird poop to the birds, they infect a secondary host, a snail. And when they infect this snail, they cause a couple of behavior changes that we see in a lot of behavioral manipulating pathogens, primarily the “summit disease” or the desire for the snail to climb up on top of things.
Now, you might ask, like, well, you know, why, if you were a worm, would you care if your snail climbed up on top of things? Well, once the snail is on top of things, the worm then grows into the eyestalk of the snail, and it’s a very fluorescent color. And this basically acts as neon lights for birds to come down, eat the snail that’s sitting on a dinner plate at the top of these plant structures, and then it completes its life cycle back in the digestive tract of birds.
So we see examples of worms doing this, crustaceans doing this, some viruses you could even consider to be behavior manipulating, like rabies, for example. There are protists, like Toxoplasma gondii, that can cause behavior changes in mice. So it’s really a wild world out there, and there’s many examples of these symbiotic relationships that cause weird and very cool phenotypes.
T: Will they be called symbiotic if one of the participants in them dies a gruesome death at the end?
W: I’m glad you asked this question because as part of our outreach, one of the questions we get asked a lot is this question, like, why do you call this symbiotic? And I think this is because a lot of people think the term symbiosis means good for both organisms. But actually, symbiosis is an umbrella term. Symbiosis just means interaction between two species.
So there are three main flavors of this. There are mutualism. Mutualism is the win-win relationship. So an example of this is pollinators. Pollinators land on flowers, they eat the nectar for food, and then in exchange, they pick up pollen and take it to new hosts or new flowers in order to reproduce.
There are parasites, so Ophiocordyceps, in zombie and other behavior-manipulating parasites would definitely fall into the parasite group. Everybody listening to this has probably experienced parasites in the past either through the form of mosquito bites, or maybe some ticks if you’ve ever gone camping in the woods.
And then the third one is a more interesting category called commensalism, and this is defined as one organism benefiting and another one neither being benefit nor hurt. And there’s some debate on whether or not true commensalism exists, if you think of things over the entire course of evolution, but I think one good example of a potential commensalist is a tree frog. So tree frogs like to hang out in trees. It gives them some camouflage, some height, and protection from predators so they benefit. I don’t think the tree really cares that the frog is there. Some may, some might not. It’s hard to say.
T: So one of my favorite parasites that also manipulates the behavior of its host is the one you mentioned, Toxoplasma gondii, which is surprisingly common, not only in cats, but also importantly in people. And as far as I’ve read, according to some estimates, something like 20% to up to almost 50% of all people on the planet carry these parasites lodged in our neural circuits. Which is just one example of a parasite from another species that impacts us as much. So as you work with these zombie-making parasites, do you sometimes worry about your own health or about people’s health in general?
W: Yeah, so let me get you some background on Toxoplasma gondii. We’re using some fancy Latin words that maybe the viewers don’t understand. So this is a tiny microorganism. It’s a protist, meaning it’s eukaryotic, but it’s a single-celled eukaryote. And normally, or the normal host for this is also a dual-host system. So this infects cats and reproduces in the cat’s body, but it can also exit through fecal matter, just like in the bird example we talked about, or urine and it can be picked up by mice.
Now, in order to get back to its original host, it causes behavioral changes in the mice that make them less afraid of cats and less adverse to cat urine. So they’ll hang out in areas where cats prowl and inevitably are more likely to be eaten than mice that do not have toxoplasma.
Now, toxoplasma is an example of a generalist pathogen, or you might refer to it as pseudo-generalist, meaning it can infect multiple hosts. So you’ve already given the example that it can infect not only cats and mice, but also humans. And there’s been studies that have shown it in wolves. So mammals seem to be the domain of this protist.
Other organisms, like ophiocordyceps, are highly host-specific, meaning they only have one host. So when I work with ophiocordyceps, for example, I’m never really afraid of getting infected by this organism because it’s so tied together with the behaviors that it manipulates in its ant host that it can’t even infect or cause behavioral manipulations in other species of ants, let alone other species of insects, let alone mammals, which are very different.
Now, if you want some more background on toxoplasma, there have been some interesting studies trying to figure out, well, does it cause any behavioral change in other mammals? The studies in humans have found that it seems like car crash victims may have higher incident rates of infection with toxoplasma, which could indicate that there may be a slight increase in risk-taking behavior while driving. And it has also been linked correlatively to incidence rates of schizophrenia, which is a neurological disorder that happens late in life.
So these are two examples of how this kind of generalist might be affecting animal behavior. But in these cases, we wouldn’t refer to this as behavioral manipulation, because behavior manipulation has two main components. One, the parasite has to be the causal agent. And two, the behavior that’s being exhibited in the host, sometimes referred to as an extended phenotype, must be beneficial to the parasite. So in the case of, you know, these humans, if this is a real effect, humans getting in car crashes does not benefit toxoplasma at all. So it would, it would not be considered a true behavior manipulation.
M: You and your team examined the relationship between fungi and insects, mainly ants, where the fungi basically takes over the insect and makes them do things to help the fungus spread. Is that a good summary?
W: That’s a fantastic summary.
M: So basically that turns the insect into a zombie.
W: Yes, so maybe here’s a good point to clarify what we mean when we say zombie because we’re not talking about dead things that are brought back to life, which is kind of this classical view of like the land of the dead and a lot of zombie-genre movies. But rather we’re talking about behavior manipulation. So there’s a subcategory of zombie movies where you see that the zombie phenotypes are actually living things acting very erratically and usually caused by a virus or some other organism. So great examples of movies that depict this real example of symbioses is The Girl with All the Gifts, which is another movie about what if ophiocordyceps could affect people. It also has fantastic biology in it. I Am Legend can be considered another zombie apocalypse movie where the hosts are still living.
And perhaps the best depiction is 28 Days Later, which is a fantastic old film about zombie outbreak caused by a virus. And I think it gets everything about biology fantastically correct with the exception of the rate at which things get infected. So in the movie, people get bitten and within seconds they’re zombies. That’s the only thing I think that’s incorrect.
One of the things I really like about that film that I haven’t seen in any other film, spoiler alert, so if you’re going to watch the film, this is going to spoil it. So here’s your countdown, your 3, 2, 1. In that movie, the way that the movie ends is all of the zombies die because their bodies are so hyperactive all the time that it’s consuming so much energy and without a food source and without eating, their body burns out and they die, which is a fantastic representation of kind of what happens in parasitic relationships.
M: Okay, well, I have new movies for my list when I’m up for zombie things. So in your research, it turns out that these behaviors in the ants are really similar regardless of what species of fungi are infecting them. Can you tell us a little bit about why these behaviors might be similar? How we get that kind of convergent evolution happening?
W: Yeah, I’d love to, and I’m so glad you used the word “convergent evolution” here because it’s not just the fungi that are causing a lot of these similar behaviors. So we talked about the example of the snail and how it causes summitting disease. Well, summitting disease is one of the most common behavior manipulations that we see in these systems. So in all of these zombie flies, zombie ants, zombie snails, you see this climbing behavior. Now for fungi, that’s because having your host climb to an elevated position allows you to spread spores further on wind. So it allows you to infect more ants than you otherwise would be able to on the floor.
Now what we’ve found in our research is even though these behaviors are similar, the way in which these fungi from different groupings cause this behavior in the host is different. So, you know, the summitting behavior that’s caused in zombie flies might be mechanistically different than those that we see in ants.
T: So we actually have some questions from readers specifically about the article.
Natalie: Hi Dr. Beckerson, my name is Natalie and I am a Grade 10 student in Canada. After reading your zombie ants article, I have a question for you. Does the physical appearance of infected insects change when the zombie fungi enter their body? Thank you so much.
W: The physical appearance does not change. However, ants are very social creatures and they communicate with the world around them through smell, through chemicals, right? So these antennae that you see coming off the ant’s head, these are used to smell the environment and this is how they communicate with one another. It’s how they know to follow these trails. If you’ve ever seen, you know, these ant trails going from like a piece of candy on the sidewalk back to the nest and everybody’s single file, what’s happening there is they’re laying pheromone trails that they can then smell with their antenna to follow.
So one of the defense mechanisms of ants for when other ants get sick is they can smell a change and they can smell the difference between healthy and sick ants. So once an ant becomes infected with ophiocordyceps, it’s only a matter of time before the ant begins to smell different and the rest of the ants in the nest kind of pick up on this. Now, the kind of brutal yet brilliant strategy of ants to deal with sickness is to simply kill that individual and take it away from the nest. So, you know, we call this social immunity.
T: Maybe they should take it away first and then kill it...
T: … as opposed to killing it in the nest. If they’re going to kill it anyways.
W: Well, like I said before, the ophiocordyceps cannot be transmitted during this kind of yeast-like growth phase, so killing it near the nest does not cause infection. So they’re able to do this. But when you kill the host, then there’s nothing for the fungus to manipulate, and then it really can’t complete its life cycle.
So one of the other behavioral manipulations that we see is very early on into infection, before the other ants can tell the difference, the fungus causes the ants to abandon their social roles and to leave the nest and increase what we call foraging behavior, which is basically this wandering, searching behavior.
And then we also see some disruption of the circadian rhythm or the daily rhythm that tells you when it’s time to sleep and when it’s time to be awake. The ants that we study from Florida are normally nocturnal, meaning they’re awake at night and asleep during the day. But when they’re infected by ophiocordyceps, just like the zombies in the movie, they’re awake all the time. They forage, their activity is increased. And one of the things that we’re really trying to piece together in our research is what chemicals are the fungi making that are causing this increase in activity and disruption of circadian rhythm?
T: So we have a few more questions that take you even further back to basic biology.
Aili: Hi, I’m Aili, and I’m in first grade, and I have some questions for you. I’ve noticed that ants are very small, and if they’re small, why do they build such big houses? And why do they live in groups?
W: Yes, that’s a very good observation that you made. Ants are comparatively very small. And it’s precisely the fact that they are small that they work together and they build such big houses. Because when you don’t have size, there’s power in numbers. So they make lots and lots of ants, and lots of ants need somewhere big to live. Because there’s so many of them, they need a big house to live in. By living in groups and working together, they are able to protect themselves from other really big insects that might otherwise harm them. So really, they work together as a big family to protect one another, and that gives them an advantage in nature.
T: Awesome. Okay, one more question. Here it is.
A: Why do some ants have wings and others don’t?
W: Some ants have wings and some don’t. It’s because they’re different species and some it’s just because of the roles that they play in the nest. So most of the ants that you’ve ever seen are female. So ants only produce female workers, they only produce female soldiers and the queens themselves are females. The only time that you see male ants is during mating season, when you have male ants. The reason they have wings is so they can fly off to new colonies and form new families with other ants. And then you’ll also see wings on queens when they’re new. And once they find a male, which is called a drone, to pair with, then they lose their wings as well. So wings can be based on your role that you play in your family and your society.
But also certain insects have wings all the time, like some of the beetles. And this has to do with lifestyle. So for certain organisms, being able to fly around, like for example bees, and to get to pollen and nectar more easily is advantageous. So in nature, the bees that evolve this ability to move around quicker are selected for, meaning they produce more often than bees that do not. And this is called natural selection.
So over time, you might have an adaptation that allows you to move more quickly. And then this can eventually turn into something like wings that allow you to move very quickly and up and down and left and right. And that happens very slowly over a long period of time, because these traits are advantageous.
M: Okay, so at the end of each of our episodes, we like to ask a fun question. Your research is really, really interesting, and it sounds like there are a lot of still unanswered questions. If you had a million dollars, what would your next big research question be? What would you want to do with that money?
W: I think with that amount of money, what I would really like to do is expand the research community that’s studying these questions. So right now there are only a few labs in the world that study the molecular genetic components of these. There are lots of labs out there that study the life cycles and the environment that these live in and how they impact the communities around them. But there are not so many that are studying how these parasites manipulate these hosts. So what I would do is set up some kind of consortium and have people give pockets of this money for people to study different things, like the zombie beetles, like the zombie snails, and collaboratively work together so that we can see how these convergently evolved traits are similar and how they’re different, and really expand the body of knowledge around zombifying parasites.
T: Wow, Will, thank you so much for teaching us so much, not only about zombie ants, but also about so many biological topics.
W: No problem. Thank you so much for having me. And I love talking about zombie ants to anybody who will listen.
M: Did you know that you can directly read one of Will’s scientific papers, stripped from its complex scientific jargon and made understandable to readers as young as 5th grade in school? The link is in the show notes. You can also just Google its title: How Do Some Fungi Turn Insects Into Zombies? Or go directly to www.sciencejournalforkids.org and search for zombie.
T: That’s all for today. This is our last episode in the season and this year. If you haven’t yet, we recommend that you go back and listen to our previous episodes. You’ll find nine other interviews with fascinating researchers from all sorts of disciplines, from robotics, earthquakes, and space science, to seals, beavers, and fossils. We really have something for every taste.
This podcast was produced with help from volunteers Natalia Torres-Bejar, Natalie Zhu and Ailia Mladenova, sound engineer Maria Mihailova and hosts Miranda Wilson and me, Tanya Dimitrova.
Thank you for listening. Subscribe to this podcast to receive notifications about future episodes of Science Journal for Kids Ask a Scientist. Till then!