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How One Entomologist Followed a Passion to Understand Insect Interactions

Jocelyn Holt, Ph.D.

“One of my lines of research focuses on invasive sorghum aphids, which are a pest to grain sorghum crops,” says Jocelyn Holt, Ph.D. “These aphids also feed on invasive Johnson grass, a plant closely related to sorghum. By analyzing similarities and differences in insect traits, such as insect genetic and microbial composition and when they occur in agricultural crops versus on other host plants, we can better inform management practices. Here I am in my field clothes next to a patch of Johnson grass that is full of sorghum aphids. After the photo, I collected some aphids to keep as a colony for a future experiment.”

By Antonino Malacrinò, Ph.D.

Editor’s Note: This is the next post in the “Standout ECPs” series contributed by the Entomological Society of America’s Early Career Professionals (ECP) Committee, highlighting outstanding ECPs that are doing great work in the profession. (An ECP is defined as anyone within the first five years of obtaining their terminal degree in their field.) Learn more about the work ECPs are doing within ESA, and read past posts in the Standout ECPs series.

Jocelyn Holt, Ph.D.

Jocelyn Holt, Ph.D.

Jocelyn R. Holt, Ph.D., is currently a faculty fellow in ecology and evolutionary biology in the Department of BioSciences at Rice University. Her work focuses on how population genetic and microbial composition modulate pest insect traits and their symbiotic interactions.

She received a B.S. degree in biology from California State Polytechnic University Pomona, an M.S. in biology from California State University, Northridge, and a Ph.D. in entomology from Texas A&M University. While at Texas A&M she was awarded a Diversity Excellence Fellowship, identified bacteria not previously known in aphids, served as chair of ESA’s Student Affairs Committee, and was awarded a USDA-NIFA Predoctoral Fellowship to examine potential ecological facilitation of Buchnera aphidicola in sorghum aphids.

Malacrinò: Tell us about you.

Holt: I grew up in Riverside, California, which is one of the world’s biodiversity hotspots. It was here that I first became fascinated by insects and their interactions with other organisms. At the time, I did not know that one could pursue a career in entomology. It was not until a series of serendipitous events during high school that I realized I could turn my passion into a career. The experiences that I gained working as a research assistant in entomology at the University of California, Riverside, helped me find my path.

Despite knowing that I loved insects, my journey to research in entomology has been circuitous. I have worked for the Forest Service, Bureau of Land Management, and at the Luquillo Long Term Ecological Research (LTER) station, all focused on botany (plants are my second favorite group of organisms). I brought insight from these experiences to my teaching in biology at the two-year college level. Sharing interesting examples of how genetics and microbes influence organism health during my courses, along with some inspiration from a tenacious friend, led me to decide it was the right time to pursue a Ph.D.

Everyone’s journey to their life goals is different, and it was beneficial for me to live in different places and have unique experiences before committing to a doctoral program. I have great mentors who remind me that what we learn along our journey and how we apply that knowledge is the important part. I agree and plan to continue enjoying this adventure!

What is your research about?

Many factors can influence symbiotic interactions. I am interested in understanding how those factors modulate pest and invasive insect traits, especially when it applies to agro-ecosystems. To better understand symbiotic interactions, I analyze the population genetic and microbial composition of insects. I want to know how traits such as host preference, reproductive output, or behavior may be different among populations that are genetically or microbially different. How does the evolutionary ecology of insect populations that have different genetic or microbial compositions vary? And what roles do a microbial symbiont or collection of microbial symbionts play in an insect’s ability to adapt to its environment or to novel environments?

I always wonder, when there are negative results, if it is truly because there is no signal or pattern. Or, instead, it is because the organisms used had a particular genetic or microbial composition, and using individuals from a population with a different composition might yield different results. Thus far my work has focused on six-legged critters, their host plants, and the microbes they harbor, but I’m certainly open to investigating other arthropods in the future.

What is the most interesting research challenge that you have encountered? How did you solve it?

Working with live insects and plants always presents an interesting challenge. When you think of invasive organisms, you generally think of them being super resilient to different environmental conditions. But when you bring them into the lab or the greenhouse, you need to figure out what conditions allow these organisms to thrive or, at the very least, survive. Ideally, you start with environmental parameters from closely related organisms and modify them along the way until something works.

In one experiment, I was looking at how the presence of invasive ants influenced invasive aphid biomass. Before I set anything up, I grew lots of extra sorghum plants in the greenhouse, collected ant colonies from the field, and increased aphid numbers in clonal colonies. So, similar to prepping all your ingredients before cooking a meal, all of these things had to converge before I started experiments. When I first attempted this in a rearing room, with aphids on plants and ants on a soil substrate, nothing happened. I updated the experimental design and moved it to the greenhouse. After this I observed invasive ants tending invasive aphids, which allowed me to collect biomass data. While it took a while to understand the critters I worked with, this was valuable information that I have used in other experiments and on unrelated projects. So, for everyone out there planning to rear their own critters, be resourceful and persistent; eventually you will find a way to make it work.

You recently graduated from Texas A&M. Do you have any advice for students that are just starting a Ph.D.?

Before starting a Ph.D., I would highly recommend learning more about the principal investigators (PIs) that you are interested in working with. Make sure the person is a good fit for your career goals and personality by talking with them and the people that work in their lab. This can make a huge difference in your graduate experience.

Jocelyn Holt, Ph.D.

“I love a good adventure, especially when it comes to scouting for critters and taking in spectacular views,” says Jocelyn Holt, Ph.D. “During an ESA meeting in New Mexico, my colleagues and I hiked around the Sandia Mountains near La Luz Trail. I was taking in the spectacular desert views and capturing the moment when someone in our group snapped this photo. I think this photo represents my personality well.”

Once you get to graduate school, expand your support system of friends, peers, and mentors. All of these people have different skillsets and, depending on the scenario, can give insight or help through tough times. Having great mentors and a support system allowed me to acknowledge that striving for perfectionism can be counterproductive, while striving for excellence and having a growth mindset can allow you to shine. These positive experiences have shown me the value of mentorship and led me to mentor students in programs such as TAMU’s LAUNCH (undergraduate mentorship) and ESA’s EntoMentos.

Use the resources available at your college or university to promote your success. This could include participating in writing or bioinformatics workshops, applying for professional development programs such as ESA’s EntoMentos or Professional Advancement Career Training (PACT), or scheduling time to boost your mental health and physical well-being (something everyone absolutely should do). You’ll be more productive and clear-headed if you make time to sleep, move, and decompress—although how much time is needed varies for each person.

Another is prioritizing tasks and scheduling them in a calendar. This allows me to tackle tasks in multiple chunks of time, which generally keeps things from feeling overwhelming. In those instances where my calendar is full, I can still choose to take on an additional task in the short term with the knowledge that something else has to go.

Last, make sure to celebrate your accomplishments; yes, even the “small” ones like submitting an abstract, successfully troubleshooting the methodology for an upcoming project, putting together a presentation, or writing the intro for a manuscript or grant proposal. Celebrating serves as a reminder of how much you have gotten done!

What is the best thing you love about your job?

I love that I get to study insects and their interactions. So many interesting questions are out there to ask about insect-plant-microbe interactions that there are currently no answers to! In addition, I enjoy sharing my enthusiasm and knowledge with others. Just recently I was talking with a friend about how many insects are beneficial to people and ecosystems and that most arthropods do their own thing and leave us alone. (Unless you poke at them, in which case what happens next is on you.) Knowing that I can enhance other people’s lives, and that they go on to share this knowledge with others, brings a smile to my face. For me, it really is amazing that I was able to turn a passion for insects into a career.

Finally, if you could be any arthropod, which would you pick and why?

This is a tough one, and my answer changes with my mood. Sometimes I think it would be cool to be a dragonfly; as a nymph I could swim through the water and as an adult I would fly through the air with exacting precision. Other times I wonder what it would be like to have the sensory perception of a parasitoid wasp or a spider. Whatever the arthropod, it should have a gregarious phase and be up for an adventure, to match my extroverted and spontaneous personality.

Antonino Malacrinò, Ph.D., is a junior group leader at the University of Münster and is the International Branch Representative to the ESA Early Career Professionals committee. Email: antonino.malacrino@gmail.com.

Thanks to Priyadarshini Chakrabarti Basu, Ph.D., for providing feedback on this article.

All photos courtesy of Jocelyn Holt, Ph.D.

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