Researching Pelecinids – Part 6

Last year I chronicled my experience researching Pelecinus polyturator in Dr. Norman Johnson’s lab. This research journey included learning the biology and behavior of P. polyturator, photographing specimens, collecting in town using Malaise traps, extracting DNA and amplifying it using polymerase chain reaction (PCR), learning the importance of literature reviews, and trying to collect live adults at Zaleski State Forest. Take a look at my previous blog posts to know more about these topics and catch up on my research so far.

author using laptop

The author analyzes DNA sequences using the Sequencher software

Over the last six months I continued working on my research, and now I have several exciting updates to share. While I took a hiatus from the lab in autumn semester to focus on my academic coursework, the research process did not stop. The DNA we extracted was sent out to be  commercially sequenced. Once I returned in spring semester, it was a matter of assembling those sequences and performing phylogenetic analysis before we could start drawing conclusions.

The focus of our study was the sex ratio variation between northern and southern populations of P. polyturator. Using molecular techniques we amplified sequences of the cox1 gene, which can be used as a genetic barcode to differentiate species. Additionally, we amplified the ftsZ gene in Wolbachia, an intracellular symbiotic bacterium that can effect sex ratio in insects. We suspected that if different strains of Wolbachia were present in the different P. polyturator populations, this could be a contributor of the observed sex ratio variation.

The Wolbachia turned out to be nearly identical from every locality sampled. On the other hand, the cox1 gene varied greatly between the northern and southern populations, and even between different localities of the southern population. From this information we concluded that the Wolbachia strain was not a direct cause of the sex ratio variation. The differences in the cox1 gene, however, suggested that there may be speciation occurring between the northern and southern populations.

Doing the research and analyzing the results was only a part of the process. Science is a collaborative endeavor, and it is important for a scientist to be able to communicate the results and ideas to others in a clear and concise way.

On March 1, I had the opportunity to present my research at the CFAES Undergraduate Research Forum. This is an event where students within the CFAES (that stands for College of Food, Agriculture, and Environmental Sciences) can showcase their research to other students and faculty, as well as a panel of judges. This forum attracts a wide audience of people from many different scientific disciplines and backgrounds. It is a great opportunity to interact with people who may not be familiar with entomology or molecular genetics. At first I was nervous to talk about my research, but it ended up being surprisingly fun to answer people’s questions. I even had a female P. polyturator specimen to show visitors, courtesy of Dr. Luciana Musetti and the Triplehorn Insect Collection.

Designing and presenting the poster was a great experience for me. I quickly learned that designing a poster is much different from writing a traditional scientific paper. Both formats are separated into similar sections such as an introduction, methods, results, and conclusions. A poster, however, has space constraints and must be attractive to a general audience. Large blocks of text typical of papers are unattractive and intimidating on posters. Overall, readability is the most important trait of a good research poster. The font should be large and easy to read, and everything should be spatially organized in a logical manner.

author and research advisor with poster

The author and her research advisor, Dr. Norman Johnson, stand in front of the research poster at the CFAES Research Forum.

author explaining research

The author explains her research to entomologist Dr. Megan Meuti

Presenting my poster at this research forum was a great preparatory experience for the upcoming Denman Undergraduate Research Forum. Because most of the research within CFAES was focused on agriculture and food science, I gained experience speaking to people unfamiliar with the topics of my research. The Denman will feature an even more diverse array of students and faculty, from business to chemistry to art, so I will need to be prepared to explain my research to those completely unfamiliar with entomology or molecular work. I will also be revising my poster using suggestions from the judges of the CFAES forum.

If you would like to learn more about my research project, as well as the research of other hardworking undergraduates, stop by the Denman in the Archie Griffin Grand Ballroom of the Ohio Union on Tuesday, April 3. I will be displaying my poster from 3:00 pm to 5:00 pm, and I would love to see you there!

About the Author: Hannah McKenzie is an undergraduate entomology major at the Ohio State University. She currently works as a curatorial assiatnt at the Triplehorn Insect Collection and is greatly enjoying her undergraduate research project on Pelecinus wasps.

Researching Pelecinids – Part 2

One of the most useful resources the Triplehorn Insect Collection has to offer is its extensive HOL database, an online taxonomic initiative that documents collected specimens of various insect groups. This database already contains records for over 845 thousand Hymenoptera specimens, and it continues to grow every week through the hard work of countless contributors.

One way to contribute to HOL is to photograph and upload images of collected specimens, further enriching the available data on specific taxa. Prior to the start of my research on pelecinids, there were zero images of the genus Pelecinus available in the database. To remedy this, I had the opportunity to work with Jordan Reynolds, an undergraduate student in Art & Technology who is currently working on specimen photography for the collection. Over the last several weeks, Jordan taught me about the technologies and techniques required for taking high-quality images for the database.

My goal in photographing a selection of the collection’s Pelecinus polyturator specimens is three-fold. First, I will obtain a more in-depth understanding of the external anatomy of these intriguing insects. Second, I can compare the morphologies of males and females of different sizes and localities. Third, I will contribute previously unavailable data to the HOL database.

Photographing collection specimens is not as simple as taking a picture with a camera. Because the specimens are relatively small, and because we require intricate detail in the images, we instead use a method known as focus stacking. With this method, the camera gradually moves along a track and takes multiple images at different distances. The focused areas of each image are then “stacked” together by a computer program so that the entirety of the final image is clear. Because the P. polyturator specimens required a large depth of field, we sometimes had to photograph and stack up to 100 images to create a sufficiently focused final image.

In addition to taking individual specimen images, we also took several comparison images. These provide a quick side-by-side comparison between two different specimens. Some of the images we took compare males and females of similar localities. Other images showcase females of similar localities and their dramatic variance in size.

comparison image of P. polyturator females

Comparison image illustrating the size variation in P. polyturator females

Of course, no system is perfect, and we faced many challenges along the way. Most of the parasitic wasps that get photographed by the collection are very small in size (no more than a few millimeters long). Therefore, the collection’s microscopic camera that is traditionally used for parasitoid photography is designed to take highly detailed images of very small specimens. P. polyturator females are unusual in that they are very large parasitoids that can exceed 40 mm in length. Because of this, many of the specimens we wanted to photograph could not fit under the microscopic camera. We instead opted to use a DSLR camera, which is used for macrophotography of larger specimens such as beetles and butterflies. Using this nontraditional method of parasitoid photography, we were able to produce high-quality images of the larger specimens by exploiting various imaging techniques.

Another challenge we faced was the handling of the specimens. All mounted insects in a collection must be handled with great care because they are dry and brittle. Pelecinids must be handled with extra caution because their long, string-like antennae and fragile abdomens will break with even the slightest bump.

We ended up with many beautiful images of these wasp specimens. The complete collection of images has been uploaded to HOL and is available on the page dedicated to P. polyturator. I would like to thank Jordan for all of his help with this photography endeavor. Without the countless hours he spent performing behind-the-scenes image processing, the final images could never have turned out so well.

About the Author: Hannah McKenzie is an undergraduate entomology major at the Ohio State University. She currently works at the Triplehorn Insect Collection and is participating in undergraduate research on Pelecinus wasps.

Researching Pelecinids – Part 1

image of a pelecinus wasp

Wasp in the genus Pelecinus, image by Cynthia L. McLaughlin and licensed under CC BY 2.0

Many years ago, arthropods were one of my greatest childhood fears. I was so petrified of bugs that I hardly ever went outside during the summer. Anyone who knew me as a child would never have guessed that I would someday develop a passion for entomology and a love for the insect world. I began to collect insects in little plastic jars, but my rudimentary “collection” might as well have been a dermestid buffet; this was long before I understood how to properly store, curate, and preserve specimens.

It wasn’t until my final year of high school that I realized that I could become an “entomologist” as a profession, a life-changing revelation. During the summer of 2016, I finally learned how to make a proper insect collection at the Ohio State University’s Stone Lab, where I enrolled in a week-long course on insect field biology. That autumn I started my first semester at Ohio State as an entomology major, commuting every day from my home in Westerville, Ohio.

I recently completed my first year in the entomology undergraduate program, and I couldn’t be more excited about my academic future. I have met so many great peers and faculty members within the entomology department, and I have had the chance to explore entomology in ways that my younger self could never have imagined. I joined my general entomology class on an all-day collecting trip in Hocking Hills. I visited the on-campus insectary and learned about rearing insects with Chrysalis Entomology Club. But perhaps the most enlightening experience I have had so far was my interaction with the Triplehorn Insect Collection. I participated in an internship at the collection during autumn semester, then continued to work there part-time during spring semester. This summer I plan to continue working at the collection, but now the collection has presented me with yet another exciting opportunity: working on my first undergraduate research project.

image of a June bug

Unidentified June bug (Phyllophaga) from central Ohio, image by author

I will work with Dr. Norman Johnson and Dr. Luciana Musetti over the summer to research wasps belonging to the genus Pelecinus. These beautiful insects may appear intimidating with their long, slender abdomens, but they are not aggressive toward humans and stings inflicted by their small ovipositors are rare. Their flexible abdomens are instead used to parasitize the larvae of Phyllophaga beetles, more commonly known as “June bugs”. The female wasp does this by thrusting its abdomen into the ground and ovipositing into the subterranean grubs.

My research will focus on Pelecinus polyturator, a species that can be found in areas of South America and in North America east of the Rocky Mountains, including here in central Ohio. One of the most interesting aspects of P. polyturator is that males are extremely uncommon north of Mexico but become much more common further south.

The goal of my research is to examine P. polyturator specimens from both northern localities and southern localities and determine if they are one species or if they are actually multiple distinct species. This can be determined using nondestructive DNA extraction and barcoding, which consists of using a species-specific genetic marker in a specimen’s DNA for species identification. I do not have any prior experience with DNA barcoding, or even molecular genetics in general, so I see this as an incredible opportunity to learn new skills that will benefit me throughout my entire scientific career. I will also get to learn first-hand how specimens such as Pelecinus wasps end up in an insect collection by going through the complete collecting process, from malaise trapping all the way to entering specimen data in the collection’s online Hymenoptera database.

At the conclusion of this research project, I plan to present my findings at both the Denman and the CFAES Undergraduate Research Forums. One of my main hopes for this project is that it can be used to illustrate the research experience for other students interested in undergraduate research, both entomological and otherwise.

As I continue to learn more about topics such as DNA barcoding, specimen collection, and Pelecinus wasps themselves, I will update this blog so that everyone reading can learn alongside me and watch the progress of my research in real-time. Keep watch for another post from me next week about taking photographs of P. polyturator specimens currently owned by the collection. I can hardly wait to share these images and the photography process behind them.

About the Author: Hannah McKenzie is an undergraduate entomology major at the Ohio State University. She currently works at the Triplehorn Insect Collection and is participating in undergraduate research on Pelecinus wasps.