Bed Bugs Under the Microscope.
Reports of bed bug activity have dramatically increased over the years, and each week we hear details of our customer’s experiences with these pests as we perform our bed bug treatment. Here at Best Pest Control, we are committed to staying current on the latest research and findings on how to effectively eradicate these pests from your home.
Over the past several months, Best Pest Control, Inc has been working with Cari Lewis, a University of Tulsa graduate student who has spent countless hours researching and testing the insecticide resistance of bed bugs. We believe her findings will further help us provide effective bed bug treatment to our customers. Her research is on the verge of publication, and in the meantime here’s an interview with our favorite entomologist.
- Cari, how did you first become interested in insects?
I became interested in insects early in life, partly because I spent the majority of my time outside after school. On multiple occasions I kept pet moths, lightning bugs, butterflies—anything I could catch—until I got caught and had to let them go. Needless to say, I was an insect nerd from the very beginning!
- The world is our classroom, and that’s wonderful you embrace the wonder of nature as a young child. How did your interest continue in the later years?
Later, in high school, I had an AP Environmental Science teacher (Mrs. Chatwin), who made science and learning a contagious passion, and she exposed me to the beautiful world of entomology. From there I studied at Oklahoma State University, where I worked with ticks, mosquitoes, and other disease vectors. After getting my B.S. in Entomology, I joined the Booth Lab at The University of Tulsa, and am now working on my Ph.D. with Dr. Warren Booth.
- Now as a graduate student you are studying bed bugs. Why?
Within the Booth Lab, we use model organisms to study biological questions that apply to a variety of similar organisms so that our research is applicable to a broad audience. Bed bugs, for example, are similar to cockroaches and lice, as they live in close contact with their hosts, and are considered urban pests. So, even though I study bed bugs, the patterns or discoveries I may find could be similar to other urban indoor pests, and may help in preventing further introductions and spread.
As my career progresses, I may become interested in a biological question that is better suited to a different organism, such as disease transmission. Bed bugs aren’t reliable vectors of disease (thankfully!), and so would not be a good model to study disease transmission. However, depending on the disease, mosquitoes and ticks, for example, are excellent vectors, and in that case, may potentially be better models.
So, although I use bed bugs as a model right now, my career interests are in studying urban insect pests and their relationship to humans. But, what’s really cool about bed bugs, is we actually know very little about their dispersal and patterns of infestations from the local to the global scale, so everything I’m studying is novel!
- We sent you samples of bed bugs from different homes we treated in the Northwest Suburbs of Chicago. Tell me a bit more what you did to these samples and what you wanted to learn from the testing?
The bed bugs from Chicago are being used for multiple projects, including insecticide resistance and fine-scale dispersal within a city. When I receive bed bugs, I identify them under the microscope because, believe it or not, there are actually two species of bed bugs! The common one that we, some more-so than others, are familiar with, and a tropical species, the aptly named Tropical bed bug.
I actually have a paper in press that describes this invasion of the Tropical Bed bug into a new region. This paper would not be possible without the collections efforts of the pest control professionals that work with us in providing samples. However, the finding will have potentially significant implications on how they will monitor bed bug populations. Following identification, I use a two-day process to extract their DNA. From there, depending on which project I am working on, I can amplify fragments of the DNA to gain information about things like pyrethroid resistance (or lack of), or to generate unique DNA profiles for each bed bug.
The genetic profile can tell us a lot about their infestations, such as how they are being moved within and between cities, by identifying individuals that are closely related or distantly related. It’s basically the equivalent of Ancestry.com for bed bugs, but we are the ones that want to know where they are from, as this will inform control efforts.
- Store bought materials can be very counter-productive and make a professional bed bug treatment process much more difficult because the bed bugs become resistant to certain insecticides. How do you identify insecticide resistance in your lab?
I use bed bugs as a model to study urban pest evolution and one way to do that is to study how their DNA has changed over time in response to our long-term use of insecticides. We know, based on prior research, using insecticides selects for individuals that have mutations in their DNA that reduces their sensitivity to certain insecticides. When exposed to insecticides, individuals without these mutations (which we call susceptible) are quickly killed and individuals with mutations (which we call resistant) survive to reproduce and pass these mutations on to the next generation.
We have laboratory techniques that we can use to identify and quantify these mutations in individual bed bugs, in order to then determine: 1) if resistance is present and 2) if resistance patterns have changed over time. While this model can help us understand how other urban pests may respond to long-term use of insecticides, it also provides insight into how we might control bed bugs in the future, such as using methods that don’t rely on insecticides alone.
- What are your future directions studying bed bugs?
While studying their insecticide resistance provides crucial information as to how we might better manage infestations, it only provides one piece to the puzzle on how bed bugs persist in urban areas. If we can prevent them from moving to new areas to begin with, we can prevent further resistance, and hopefully reduce the number of infestations drastically. So, to do that we have to identify how bed bugs are moved to new areas and where they come from.
While we know bed bugs are moved by humans, we don’t know much else. So, to study this, I’ve been working with pest management companies across the U.S. to get bed bugs from as many infestations as I can. This will allow me to decipher dispersal patterns. Once I have enough infestations, I will sequence each bed bug’s genome to generate a unique DNA profile for each infestation that I have received. I can then identify infestations that are related (because a large portion of their DNA profiles will be similar), and use that information to determine if there any patterns in where infestations are found. The goal with this project is to pinpoint common routes of dispersal and to inform pest management professionals of this, in order that they might develop strategies that may successfully mitigate introduction and further spread.
While insecticide resistance and patterns of dispersal contribute to our difficulty in controlling bed bugs, other factors likely play a role as well. One being the fact that we are only treating part of the total number of infestations within a given area, whether that’s because the infestation is unknown or is unable to be treated. My hypothesis is that bed bug reservoirs exist in cities that are not being treated, and these serve to re-infest public places. My goal with this project is to determine if reservoirs exist and identify areas reservoirs are found so that we can eliminate them and, in theory, reduce the overall number of infestations within a city. It’s going to be a lot of work, but I’m very excited to take it on!
- When you are not in the lab and thinking about bed bugs, what are your other interests?
Although I spend my days studying bed bugs, I like to be creative in my free time and work on home improvement projects. I recently installed a full wall of shelves to organize my “she shed” (the woman version of a man cave) which includes a sleuth of art supplies like oil paints, canvases, and other media. It’s a great outlet and stimulating my creativity outside of the lab has helped me come up with creative solutions to problems I’ve encountered in the lab. Such as, I couldn’t get good pictures of the bed bugs using a microscope, so I contacted Tulsa photographer Bob Sober and he helped me get high-resolution pictures to use in publications and presentations, a few of which are featured in the paper I previously mentioned. It was a really fun collaborative project! When I’m not indoors, I like to take inspiration from nature by exploring, camping and backpacking with my husband, Kyle, and our two dogs, Bert and Dahlia. And, of course, I have to try to identify every insect I see!