TY - JOUR
AU - Peterson, Robert K D
AB - The old expression “chance favors the prepared mind” and the word “serendipity” perfectly fit this case. In the summer of 2006, my former major professor, Leon Higley, traveled to Bozeman, Montana, to attend a surprise party to celebrate my tenure at Montana State University. Like any self-respecting person who finds himself in the Bozeman area, he made the 90-minute drive south to Yellowstone National Park. What he observed there by chance would ultimately lead to some amazing discoveries. While shuffling along the boardwalk trails with thousands of other tourists at Mammoth Hot Springs, he saw something surprising. No, surprising doesn’t do it justice; it was amazing. The tiger beetle Cicindelidia haemorrhagica (LeConte) (Coleoptera: Carabidae) was hunting on a hot, wet bacterial mat (Fig. 1). The beetle remained for long periods, not only under the hot sun, but also lingering on the bacterial mat, which was at least 42ºC. This was incredible because unlike what is known for other tiger beetles, it made no attempt to behaviorally cool itself by seeking shade, dipping its body in water for evaporative cooling, or stilting its body to reduce insolation. Leon knew this was not normal because of his experiences studying other tiger beetle species (Brosius and Higley 2013). Other tiger beetles—especially those that are warm-adapted and hunt and forage in open, sparsely vegetated areas—can spend more than 50% of each diurnal period behaviorally cooling themselves or completely avoiding activity during the midday. They simply don’t linger in hot areas. Fig. 1. Open in new tabDownload slide Cicindelidia haemorrhagica hunting on a hot cyanobacterial mat in Yellowstone National Park. (Photo by R.K.D. Peterson.). The behavior of C. haemorrhagica seen that day became an intriguing biological mystery. What is happening in Yellowstone, and why is it different than anywhere else? As is his nature, Leon excitedly talked about it with me, and we agreed that it would be fantastic to research this fascinating phenomenon. A little background: Cicindelidia haemorrhagica was first recorded actively hunting and scavenging on the surface of thermal soil immediately adjacent to active hot springs in Mammoth Hot Springs during an ecological survey more than 130 years ago (Hubbard 1891). At that time, Hubbard (1891) noted that the environment these beetles inhabited seemed to exceed the thermal limits for other known insect species. This was all that was known about C. haemorrhagica until we began our research. As is typical in research, it wasn’t until several years later—2016, in this case—that the stars aligned and we were finally able to begin the work. Kelly Willemssens, a Ph.D. student at the University of Nebraska–Lincoln, wanted to explore fundamental ecological questions about the beetle, especially its relative distribution in Yellowstone National Park and its behavior on the hot springs. The research was our initial foray to begin to answer our questions: How do these beetles survive? Are they adapted to these extreme conditions, which include exposure to high levels of metal toxins, very high temperatures, and water ranging from very acidic to very alkaline? Is C. haemorrhagica a metazoan extremophile? Our research team geared up and set off to investigate this unusual beetle—well, not so fast. Conducting entomological research in a U.S. national park is very different than nearly anywhere else. This is especially so for Yellowstone National Park, the nation’s first and the crown jewel of U.S. national parks. The research to be conducted had to be vetted via a lengthy permitting process that included a detailed proposal, reviews by a panel, revisions, and approval. As entomologists, we are used to collecting as many insects as needed for our research. For ecological and physiological research, this often means dozens to hundreds of insects. In Yellowstone and other national parks, insects and all other living and non-living things are considered a natural resource (a national resource, really). Consequently, requests to collect insects are scrutinized and the numbers allowed to be collected are often much lower than the initial request by the researchers. But that was only the beginning for our project. We had to track each and every specimen we were approved to collect. The required labeling of preserved specimens exceeded what we entomologists typically do when we label insects. Insects destroyed as a consequence of experiments still needed to be tracked and reported. In other words, we had to provide a paper trail for each insect. For many of us, when we need to go to the field, we simply go. That was not the case when doing field research in Yellowstone National Park. Much of the habitat within Yellowstone pushes the limits of what organic life can survive, so strict field-safety precautions were required. We had to check in online the week before we intended to be there. We also had to check out online when we returned. At the end of our field research season, we were required to check out and submit a report of what we did and what was the fate of every specimen we collected before applying for a renewal of our research permit for the next year. To protect the fragile environments (especially the hot springs), we could not have more than six people at a location at any one time—but we had to have at least three people to provide safety from encounters with grizzly and black bears! That’s right; if we had three people, two would do the research work and one would spot bears. While traveling to the locations and while working there, with each of us carrying bear spray, we shouted “Hey bear!” every few minutes so we didn’t surprise the ursines that might not see, smell, or hear us. We were required to practice Leave No Trace principles by not leaving equipment behind and by brushing away footprints before we left research sites (NPS 2018). Although we didn’t have required uniforms when doing field work in Yellowstone, we had to wear required accoutrements (Fig. 2) in addition to the aforementioned bear spray that each team member carried. We wore long pants and gaiters above our boots to repel hot acidic or alkaline water if we broke through the delicate, crusty soil (Fig. 3). We used hiking poles to test the soil ahead of us and make sure it was safe to step on. Finally, we wore brightly colored vests to ensure that the tourists knew that we were doing something official and that they shouldn’t follow us off-trail or off-boardwalk as we trekked to our research locations (Fig. 4). In addition, a team member was assigned to hang back for a while and make sure tourists didn’t follow us into these pristine, fragile areas. Fig. 2. Open in new tabDownload slide Kelly Willemssens observing the behavior of adult Cicindelidia haemorrhagica at an acid-sulfate hot spring. Note the brightly colored vest and gaiters. (Photo by R.K.D. Peterson.). Fig. 3. Open in new tabDownload slide One of the many reasons why tourists must stay on marked boardwalks and trails. The hot acidic water of the hot springs dissolved the sole of this hiking boot. (Photo by R.K.D. Peterson.). Fig. 4. Open in new tabDownload slide A research crew observing adult Cicindelidia haemorrhagica at a sulfide carbonate hot spring. (Photo by R.K.D. Peterson.). Speaking of tourists, Yellowstone officials encouraged us to engage with them and answer their questions about the research we were doing. This is part of our responsibility as science communicators, and we enjoyed doing it—even after a long, exhausting day at the research locations. What better way to get people fired up about the environment, ecology, biology, and insects than talking to those who were visiting a national park as we began and ended our research for the day? I think it’s fair to say that only entomologists who visit Yellowstone pay any real attention to its insects. Nearly everyone who visits the park wants to see the thermal features and the charismatic megafauna. That’s why it is so gratifying to talk with visitors to the park and advocate for insects, entomology, and science. We’ve heard it all, from “Are those the beetles that are destroying the pine trees?” to “When they bite you, does it hurt?” to “Is the Yellowstone volcano going to blow soon?” Despite these funny asides, the visitors were curious and appreciative to know about the insects (and spiders and mites) that are adapted to live in the thermal areas of Yellowstone. Open in new tabDownload slide In Yellowstone and other national parks, insects and all other living and non-living things are considered a natural resource (a national resource, really). Consequently, requests to collect insects are scrutinized and the numbers allowed to be collected are often much lower than the initial request by the researchers. With research permit in hand and dodging bears, bison, and—the most dangerous of all—tourists, we searched Yellowstone for the beetles. In the entire park, we only found them on hot springs, regardless of whether the pH of the water was 2 or 11. The beetles hunt other insects that are stunned by the heat of the springs. As mentioned, they don’t seem bothered by the heat and make no attempt to cool themselves while hunting and mating in the hot sun from 10 a.m. to 6 p.m. (Fig. 5). They seem to be adapted to these conditions, but we couldn’t be sure until we studied the same beetle species outside of Yellowstone, where they do not live on hot springs. Fig. 5. Open in new tabDownload slide An alkaline siliceous hot spring with several adult Cicindelidia haemorrhagica. Surface temperatures of the water, soil, and cyanobacterial mats are shown in text and a few beetles are circled in yellow. (Photo by R.K.D. Peterson.). So, off we went to southern Idaho, where we found a population that lives on salt flats near the Snake River. And we struck gold. Although they are the same species, these beetles did not behave at all like those in Yellowstone. In Idaho, the beetles hunted in the open during the day, but constantly tried to cool themselves by retreating to the shade of plants, dipping their abdomens in water for convective cooling, and stilting their bodies to avoid the hot surfaces (Willemssens 2019). This discovery was nothing short of astonishing: a population of a species of tiger beetle in a specialized, extreme habitat behaves very differently than a population of the same species in another habitat. What is even more intriguing is that the geologic history of Yellowstone means that the beetles have only been present there for at most 14,000 years, because the glacial Pinedale Icecap, which was as thick as 1,600 m, covered the entire area (Marcus et al. 2012). In other words, there has been relatively little time for these behaviors to diverge between these populations. The beetles behave very differently, but is it only behavioral? Why do beetles in the Idaho population try to cool themselves during the day, but the Yellowstone beetles do not, even though their geothermal substrate is much hotter? Are there physiological or morphological differences in the Yellowstone beetles that allow them to tolerate the intense heat? Graduate students Bray Adams, John Bowley, and Monica Gotschall have continued the research, and we now know a lot more about the beetles’ adaptations and ecophysiology (Willemssens 2019, Bowley 2021, Gotschall 2021). We conducted numerous experiments that revealed that C. haemorrhagica in Yellowstone has adapted to resist internal heating; its ventral abdomen has developed enhanced reflectivity to infrared radiation, increasing heat resistance (Bowley 2021; Fig. 6). Fig. 6. Open in new tabDownload slide John Bowley (extreme upper left) using a thermal camcorder to record beetle (lower right) and surface temperatures at a siliceous alkaline hot spring. (Photo by R.K.D. Peterson.). As much as we have learned, we don’t know anything about the immature stage of the beetle. The areas where the larvae live are warm enough that snow instantly melts on them. The larvae may live one to two full years before becoming adults. How do they tolerate the hot, moist soil that also may be highly acidic or alkaline? I often joke that C. haemorrhagica is the beetle that keeps on giving, and we’ve only scratched the surface in our understanding of its ecology in Yellowstone. And, of course, it is not the only Yellowstone insect that is a thermophile or extremophile. Brine flies, soldier flies, and shore bugs also exhibit adaptations to the extreme conditions of the hot springs, but we know next to nothing about them (Fig. 7). Fig. 7. Open in new tabDownload slide Thermophilic brine flies (Diptera: Ephydridae) at an acid-sulfate hot spring. The larvae and adults feed on thermophilic Zygogonium spp. algal mats. (Photo by R.K.D. Peterson.). Being able to do research in Yellowstone National Park and the Greater Yellowstone Ecosystem is a great privilege. The requirements we must adhere to are nothing compared to the opportunity to study insects in this pristine, fragile, and unique environment. We look forward to doing much more research and spending more time studying these insects. The extremophile insects in Yellowstone have so much to teach us. Not only are they important for fundamental understandings of physiology, ecology, and evolution, but they relate directly to conservation and adaptations to global warming. Furthermore, these extremophile insects can inspire advances in design, engineering, and materials. And it all stems from a chance observation and a prepared mind. Serendipity, indeed. Acknowledgments I thank L. Higley, whose initial observation and brilliant mind began this journey. I thank the graduate students on the project: K. Willemssens, J. Bowley, M. Gotschall, and B. Adams. I thank numerous Montana State University faculty and staff who have helped with this project, and E. Oberg and A. Carlson at Yellowstone National Park. Finally, I thank the numerous undergraduate students who have helped with this research. All research was conducted under Yellowstone Research Permits #7092 and #8100. Bob Peterson is a professor of entomology and department head in the Department of Land Resources & Environmental Sciences at Montana State University. His research focuses on environmental risk assessment, insect ecology, and integrated pest management. He is also a past president of ESA. References Cited Bowley , J.L. 2021 . Thermoregulatory adaptations of the wetsalts tiger beetle, Cicindelidia haemorrhagica, in Yellowstone National Park . M.S. thesis. Montana State University , Bozeman, Montana . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Brosius , T.R. , and L.G. Higley. 2013 . Behavioral niche partitioning in a sympatric tiger beetle assemblage and implications for the endangered Salt Creek tiger beetle. PeerJ . 1 : e169 . Google Scholar Crossref Search ADS PubMed WorldCat Gotschall , M.M. 2021 . Bioaccumulation and partitioning of heavy metals in Cicindelidia haemorrhagica in Yellowstone National Park. M.S. thesis. University of Nebraska , Lincoln, Nebraska . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Hubbard , H.G. 1891 . Insect life in the hot springs of the Yellowstone National Park. The Canadian Entomologist 23 : 226 – 235 . Google Scholar Crossref Search ADS WorldCat Marcus , W.A. , J.E. Meacham, A.W. Rodman, S. Allan, and R. West. 2012 . Atlas of Yellowstone . University of California Press, Berkeley, California and University of Oregon Press , Eugene, Oregon . ISBN: 978-0-520-27155-5. Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC NPS (National Park Service). 2018 . Leave No Trace Seven Principles . U.S. National Park Service . www.nps.gov/articles/leave-no-trace-seven-principles.htm. Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Willemssens , K.A. 2019 . Ecology of Cicindela haemorrhagica haemorrhagica in the extreme environments of thermal pools in Yellowstone National Park . Ph.D. dissertation. University of Nebraska , Lincoln, Nebraska . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC © The Author(s) 2022. Published by Oxford University Press on behalf of the Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/pages/standard-publication-reuse-rights) © The Author(s) 2022. Published by Oxford University Press on behalf of the Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
TI - Hot Springs, Tigers, and Bears … Oh My!
JF - American Entomologist
DO - 10.1093/ae/tmac055
DA - 2022-09-10
UR - https://www.deepdyve.com/lp/oxford-university-press/hot-springs-tigers-and-bears-oh-my-pqXEKVbMR9
SP - 30
EP - 33
VL - 68
IS - 3
DP - DeepDyve
ER -