“I’m more interested in the questions... I’m also very interested in getting the attention of people who don’t care about the science to just say, “Wow, this is weird!” In that case, I hope I have gotten them to think about something.”
Hans Klompen is a Professor in the Department of Evolution, Ecology, and Organismal Biology and Director of the Acarology Collection at The Ohio State University. He studied Animal Ecology at the Catholic University in The Netherlands and received his PhD in Biology from the University of Michigan working with Barry O’Connor on systematics and host associations of sarcoptic mange mites. This was followed by two postdocs working on tick systematics, using morphology (with Jim Oliver at Georgia Southern University) and molecules (with Bill Black at Colorado State University). In 1996, Hans was hired at Ohio State University where he is the Director of the Acarology Collection and main organizer of the annual Acarology Summer Program, a 1-3 week set of intensive workshops teaching identification of mites.
Dr. Klompen spoke with Darren Lee Miller via Zoom on Thursday, August 23, 2022.
Dee Miller: I’m curious about your background, where you're from and how it influenced the direction of your career as a research scientist.
Hans Klompen: I was born and grew up in the Netherlands, did my Master's there in biology and then I met my future advisor from the University of Michigan. He was interested in mentoring students, and I wanted to do a PhD, so that worked out nicely. I did my thesis on mange mites, then switched to ticks for a postdoc at Georgia Southern University, which happens to be the home of the United States National tick collection. Yes, there is such a thing! And after that, I did molecular work during a postdoc at Colorado State, and finally got hired here at Ohio State in 1996. I retired a year ago.
Miller: It sounds like for the whole of your career, from the time that you were a PhD student until now you’ve studied – I don't know what to call them – parasitic insects?
Klompen: I've been studying mites the whole time. People ask, can you make a whole career out of doing only that? Well, as of now there are about 60,000 known species, and I'm interested in species descriptions. And our estimate of diversity for mites is somewhere between one and five million, so there’s still a lot of work left to do. I like them because they do unexpected things, and they look interesting.
Miller: So, mites aren’t insects?
HK: No, they are arthropods like insects but they are much closer to spiders. Officially arachnids have four pairs of walking legs while insects have only three pairs.
DM: And these are so tiny that we normally can't see them with the naked eye?
Klompen: Most of them are tiny, less than a millimeter, but others are six or seven millimeters, and you can easily see those. The ones I work with are as small as half a millimeter to almost a millimeter and a half. It's all microscope work.
Miller: So, what is Acarology? How would you describe it to a non-scientist?
Klompen: If you say, “entomology,” you're talking about the science of insects, entomon. When you're talking about “arachnology,” you're talking mostly about spiders, arachnids. Acarology is the study of acari, which is the Greek word for mite. The Greeks did describe a few mites, not very well, but they did.
Miller: I imagine that’s because they didn’t have the technology to look so closely at something that small. Have you been working with powerful microscopes since the beginning? And how has that technology changed over time?
Klompen: Imaging has been an eternal problem, because we always want more. It's perfectly simple to look at a mouse or a bird, they're big enough, no problem. But to see mites, you need magnification. I started working with relatively simple microscopes. In the 90’s, we mostly used phase contrast illumination, which is a fairly standard way of looking at things at 400x - 1,000x magnification. But to clearly see the kinds of details visible in the exhibition videos, we use another technique, differential interference contrast. It has also been around for a long time, but I didn't have access to it until later in my career. It is really nice when imaging thicker mites – the ones I'm working with are relatively round and dense. A colleague of mine is really into scanning electron microscopy (SEM), which works well on hard mites but is absolutely awful on soft ones. So things like dust mites that most people recognize, when you put those under a standard SEM treatment, you get an image of a shriveled, ugly thing because you have to dehydrate specimens for SEM. The USDA developed a technique for imaging specimens at the temperature of liquid nitrogen. That’s super cold but you don't dry it out, so you get gorgeous images of soft bodied mites. Unfortunately, it requires a low temperature scanning electron microscope (LT-SEM), which on average costs somewhere above half a million, and my lab doesn’t have a budget like that. So my students started using confocal microscopy because they got interested, for whatever reason, in the functions of mite body parts, learning how things work.
Miller: Confocal? What is that?
Klompen: Confocal laser scanning microscopy (CLSM) is an imaging technique that increases resolution and contrast by using a pinhole to block out-of-focus light as the image is recorded. We capture multiple flat images at different depths to eventually reconstruct images of three-dimensional structures. One of my students spent a year working on understanding how the mouthparts of these little guys work. He was particularly obsessed with extremely small mites, and got fantastic results. And then another student heard about some outfit in Germany. The German government gave them Micro-CT scanners, and then prompted them to find different ways to use them. And we were like, we will definitely put these to use. Micro-CT is a 3D imaging technique using X-rays to see inside an object, slice by slice. They can do what a confocal can do. We now have Micro-CTs for about 50 species, and I am trying to figure out what to do with all of it because my students have more skill with this equipment than I do.
Miller: In the films you shared with us for the exhibition, we can see that cross sectioning view, we’re going slice by slice through the organism. What are some of the difficulties and benefits of working that way to image the mites?
Klompen: Confocal and Micro-CT allow us to look at the inside, and the tradition has been for us to look only at the outside. In fact we used to use chemicals to clear all internal structures away. However, there are structures on the inside that we know very little about and that we couldn’t study after those structures were cleared. Things like mouthparts that I already mentioned, and structures on the inside of the genital chamber of females that are quite variable. Now, after we scan we use the computer to slowly remove anything that is not the structure we want, to eventually build a 3-D image of the structures we are focused on. We know how to do it, but it's a hell of a lot of work!
Miller: When you talk about removing the parts that you don't want so that you can focus on the thing that you're paying attention to, are you doing that clearing away with the actual physical organism, or are you doing that as a form of image editing?
Klompen: This is post-production work. We don't actually look at the specimens directly anymore, only the images that we have on the computer. We have to remove the bits we don't want to be in the image, much like retouching a photograph. But, we do this in 3-D, and sometimes there are little things sticking out that we don't even know are there. It's very easy to knock it out before you realize, oh, I really wanted that.
Miller: Photographers do a lot of post production retouching, and I'm trying to imagine what it would be like to work not just with an x and y, but also with a z axis!
Klompen: You constantly have to rotate the image to see, okay, well, that is not connected to anything else, so I can remove it bit by bit, work my way deeper inside.
Miller: It sounds tedious.
Klompen: Very tedious. The thing is, we seem to have no problem attracting students to our program who want to be on a computer twirling things around.
Miller: The images themselves are really beautiful, kind of seductive. They look like aliens from outer space, which is, I think, part of the reason that Tim and I got excited about them. They fit well with the theme of recording the world, both at the macro and micro-levels. Learning more about how things work – and creating beautiful images – are certainly goals that I admire and share as a scholar; but, this very expensive equipment, and the time to pay the research assistants to do this work comes at a cost. What is the cost benefit analysis that the university or the grant funders are looking at here? Besides just getting to know the biodiversity of mites, what are the imagined applications of the work you're doing?
Klompen: I'm more interested in the questions; but, one example of a pragmatic application is that there is a huge, very diverse lineage of four-legged mites that feed on plants. They transmit quite a number of plant diseases, so dealing with these is important for food security and the economy. On the other hand, some of our research can seem esoteric. For example, one student dug a hole on campus to look at mites in deep soil. They are worm-like with barely any legs and have absolutely no economic importance. Yet, we found that they are the closest relatives to these things attacking plants. The two different groups of species share a lot of the same structures, but they function in different ways. We can use this research to figure out how the plant mites operate, and I think that is of value in itself. One of the movies that you have is a genus of mite that most people did not care about until we discovered that in their immature state they are parasites of ants. They attack ant pupae, feeding on them and effectively sucking them dry. When they do this on their original host with whom they co-evolved, there's not a lot of loss. However, there are very damaging invasive ants out there, and these mites effectively eradicated an invasive species of ants from a large area in Columbia. So biocontrol is a possible application of our research. I thought it was totally cool to discover parasitic mite babies. So I think in answer to your question, do I look for things that have importance to society? Not necessarily. But it happens.
Miller: It sounds like this could be of real value to agricultural systems or forest conservation. Has any of this work been patented for this purpose?
Klompen: Not that I know of. We generally think the overall interest in mites is so low that it's not worth it. It's hard to get people excited. I mean, these videos look good. And I think we are finally getting to the point where the images are interesting. We really want to print them as photos or 3-D, but it’s still difficult to get enough resolution. If I can't see the hairs, then I don't want to print it. We're working to set up a small program on how to identify species for high schools, making the 3-D images available to them as research specimens, and as the starting material for taxonomic keys. Everything can be done online, and the images are hopefully going to be good enough and interesting enough that a highschool student will want to spend time with them.
Miller: I feel like the idea underneath your answer here is you feel strongly about creating aesthetically pleasing images that are interesting to spark people's curiosity. Like you want to seduce them into science. We are showing these in the context of a contemporary art gallery. How do you feel about having your research displayed in an art exhibition?
Klompen: It's great. The way I'm looking at it, a pretty picture with an interesting story might hook people and get them interested in science. I'm also very interested in getting the attention of people who don't care about the science to just say, “Wow, this is weird!” In that case, I hope I have gotten them to think about something. We may not be saving the last tiger, which of course should be done, but this is something different.
Miller: Saving last tiger, conserving biodiversity, or making people more cognizant of the ways our industrial economy and settlements impact other living things, are these what you hope to direct our attention to?. Is there a kind of advocacy going on here?
Klompen: I can see that argument but I don't really want to push threats to biodiversity using mites. Using my research to raise awareness about threats to biodiversity would be difficult. But if I get someone to think, “Wow! There are so many different kinds of weird things,” then absolutely.
Miller: Getting people to express wonder?
Klompen: Yeah. And I hope they start thinking about all these strange things that are really small and beautiful, or at least interesting. Even if they don't think the mites are pretty, then at least I can help people to be aware of things.
Miller: Learning never stops. There's always something new.
Klompen: There are so many options just for entertainment or whatever. Now we are getting something that we can show people. And in my view, if you can show pretty pictures, you have won half the battle. Without photos, communication with the broader public just doesn't work.
Miller: You retired last year, but it looks like you’re in your lab, working. So, what’s next for you?
Klompen: I love this work. I love these little critters. I want to spend time working on them. One of my former advisors said, “I get to do what I want to do, and get paid for it, too!” So that's, in large part, my motivation to just keep on going. There are a number of things that I want to finish that I find too interesting to drop.