Jocelyn Holt, a doctorate candidate in the Department of Entomology of Texas A&M University’s College of Agriculture and Life Sciences, understands it is easier to win a battle when you know what weapons your enemies have in their arsenal.
Following that line of thinking, Holt envisions a future where agricultural producers will know key genetic traits of the pests on their crops so they may target them more precisely. But Holt wants to take that line of thinking a step further; she wants to make studies like this in the field of entomology more accessible for all.
“I hope in the future that we’ll be able to genetically screen an insect population to see if it will benefit from biocontrol or determine if whether using a biopesticide is a more effective approach,” said Holt.
Holt’s academic focus is the interplay between population genetics, microbial composition and beneficial interactions, or mutualisms, in invasive insect species. Her innovative thinking and approach to looking at pest-related agricultural problems has already garnered her many awards, grants and recognition.
“Ultimately with my work I want to broaden our understanding of genetics and microbiota and how we can use that info to be more successful at agriculture,” Holt stated. “When it comes to pest control, one-size-fits-all is not the most effective approach.”
Microbiota are defined as ecological communities of commensal, symbiotic and pathogenic microorganisms, which are found in and on all multicellular organisms, from plants to animals.
Holt said once a pest’s genetics and microbiota are better understood, it can influence the methods producers take to manage or control those pests.
“Jocelyn’s framing of invasive species as invasive communities, due to the microbiota they bring with them, provides a refreshing way to approach the study of invasive species and their interactions with the communities they encounter at the locations they invade,” said Raul Medina, Ph.D., Texas A&M Department of Entomology professor, Bryan-College Station.
Holt, who works in the Medina lab, counts him as a mentor and he in turn is one of her strongest supporters. Holt said she enjoys the process of interfacing with the Texas A&M AgriLife Extension Service specialists and collaborating with other scientists and researchers in academia and government institutions, such as the U.S. Department of Agriculture.
“Once we know the data, it is also important to me to make that content widely accessible in some form,” she said. “Not just having scientific papers published or having graphical abstracts. If something like an infographic poster makes the information more accessible to AgriLife Extension county agents and our stakeholders, then that is what we’ll need to do. I want to present content in multiple formats so it can reach the broadest audience that may benefit from it.”
NIFA grant to study sugarcane aphid
The USDA’s National Institute of Food and Agriculture, NIFA, recently awarded Holt a predoctoral fellowship grant for her work on Melanaphis sacchari, better known as the sugarcane aphid. Holt’s grant runs through 2023.
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“If a producer can one day easily identify the genetics of the sugarcane aphid in their fields, they will know how to better fight them, and there will be less economic loss,” she said.
Holt said her previous research shows that there are genetic and microbial composition differences between sugarcane aphids on sorghum and sugarcane.
“However, it is still unknown whether variation among Buchnera aphidicola strains in sugarcane aphids positively influence this insect’s pestiferous nature,” she explained.
SCAs have been a problem for sorghum producers in Texas since 2013, after the introduction of a new sorghum-adapted lineage. They produce large amounts of honeydew, which can clog combines. In 2013, some sorghum growers lost up to 50% of their crop due to sugarcane aphid-infested fields.
Holt is examining the genetic differences among populations of sugarcane aphids and is especially interested in determining if their differing microbiota correspond to genetically distinct aphid populations, which in turn could affect what damage different populations may do to crops.
In the genes
Holt’s grant, “Assessing Ecological Facilitation by the Symbiont Buchnera Aphidicolain Genetically Distinct Sugarcane Aphid Populations,” could prove to be a key tool in future efforts to combat the aphids and other pests.
SCAs rely on the obligate symbiont Buchnera aphidicola, a type of bacteria living in a specialized organ inside of the sugarcane aphid, which creates essential nutrients that aphids need to survive and cannot produce on their own.
Although Buchnera aphidicola is the most abundant bacteria inside the sugarcane aphid, it is not the only one. When invasive insects arrive to a new location, field or crop, they bring their team of microbial symbionts with them.
That means even same species insects can have distinct differences in their microbiota. Knowing these differences by identifying the genetic variants in sugarcane aphids and their symbionts holds the promise of producers one day being able to target pesticides more precisely — not just the type of insects in their fields but the genetic makeup of those pests and their symbionts.
“A great example of the role microbes can play in insects is that certain types of bacteria actually enable some aphids to survive attacks by their natural enemies more readily than others,” Holt said.
Passion becomes profession
Holt has early childhood memories of being fascinated by insects but did not realize early on that her passion could become her profession. She recalls as a child collecting insects from plants and putting them in jars to observe; something she continues to do to this day.
Holt earned a bachelor’s degree in biology from Cal Poly Pomona, with a minor in botany. While a student, she worked as a research assistant in the Entomology Department at the University of California Riverside. Holt went on to earn her master’s in biology at California State University Northridge. Soon after, she got a fulltime teaching job in Houston at San Jacinto College North.
“I haven’t had a traditional career path or been a traditional student in any way,” Holt said. “Deciding to go back to graduate school for entomology after working for five years was a thing I had to decide I was going to do, I could do, and then I had to make it happen.”
Friends and family pointed out that leaving a good fulltime teaching job to pursue a doctorate, especially in a different field of study, was a risky decision. But as much as Holt enjoyed teaching biology at the college level, she kept being drawn back to insects.
“I knew I had to have a doctorate in entomology if I was ever going to be able to fully pursue my passion professionally,” Holt explained. “I want to help make entomology more accessible to a broader range of students.”
Holt understands most people are raised and conditioned to think all insects are scary or creepy, a bias that can be hard to overcome. She hopes she can inspire the next generation of students to think insects are cool and to dispel fear and misinformation.
“I think if we show students enough amazing insect photos and explain how the benefits of many insects outweigh the negatives, we could help dispel a lot of fear and falsehoods. Teaching the connection insects have to our ecosystem and agriculture, and why the portrayal of wasps, hornets, spiders and the like are usually inaccurate, would go a long way.”
Holt also said explaining more about the importance of pollinators and which insects are a pest versus which are beneficial could help by increasing the general public’s understanding of bugs.
Transition to Texas A&M
“It was one of the best decisions I ever made to come to Texas A&M, but it wasn’t easy,” she said. Holt is the first person in her family to pursue a doctorate, so she felt like the path to achieve that wasn’t something obvious or that she had seen laid out before. But she knew her persistence and perseverance could lead her to that dream job in entomology.
Holt said Texas A&M kept coming up as the alma mater of many of her mentors. Once she was accepted into the doctoral program, she knew it was an opportunity she couldn’t pass up. She said going from being a teacher to being a student again gave her a unique perspective.
“It was scary and there are no guarantees with pursuing a Ph.D.; until you take prelims it feels really up in air if you’ll be deemed doctorate material,” she said. “But I treated my prelims like a job interview, which helped me deal with the stress.”
“Holt’s commitment to finding answers to her scientific questions is energizing,” Medina said. “When she asks a question, she learns whatever she needs to in order to answer that question, If she assesses that she may not be able to learn all she needs to within a reasonable time frame, she incorporates collaborators into her projects. She is great at networking, so there is enough expertise within her network to answer all sorts of scientific questions.”
“Sometimes in entomology, we come up with messy data,” Holt acknowledged. “But maybe that data is from plucking individual insects from different fields and subsequently genetically distinct populations all together. At first, we may think there is no pattern but maybe we can understand the messy data if we also include the individual’s genetic and microbial backgrounds. Maybe we can better control our control groups.”
Awards and accolades
In addition to her NIFA grant, Holt has received a Graduate Diversity Excellence Fellowship and a Lechner Excellence fellowship at Texas A&M. She has also been the recipient of the Entomological Society of America’s John Henry Comstock Award.
Holt is a founding member of Aggie Women in Entomology. She has participated in the Texas A&M University Women in Science and Engineering, TAMU WISE, and the LAUNCH Program, which stands for Learning Communities, Academic Excellence, Undergraduate Research, National Fellowships, Capstones and Honors.
“I’m proud of my awards and scholarships, it is nice to be recognized for hard work,” Holt said. “Much of the time accomplishments don’t get recognized, so it is important to celebrate achievements. And when accomplishments are recognized, it is great having the satisfaction of knowing this is something viewed as worthwhile to do and beneficial. That helps keep me going when things are stressful or difficult.”
STEM, paying it forward
“There weren’t many people who looked like me — multiracial and female — in my fields of study,” Holt explained. “I want people who don’t think they fit or belong in the STEM field to know that they can find the resources, strength and the resilience to do it.”
Holt said she feels lucky to have had so many strong and gifted mentors over the course of her academic career. It is extraordinarily important to her that she can also serve in that role for past, present and future students.
“No one does it singlehandedly; I am grateful for my mentors. It was up to me to make the decision to pursue my doctorate and put the steps in place to work toward achieving that goal but what the love and support of my partner, friends and family has meant to me can’t be underestimated.”
She also strives to shine a light on how different fields can work together to solve complex problems. Holt shares the example of the Human Microbiome Project as something that can shine a light for other fields and make microbiota better appreciated and understood.
Holt is also excited by the prospect of better understanding the function of microbes and how a group may function differently from individual to individual.
“In addition to what I can do to aid agriculture, at the end of my career I want to be able to say I made entomology more accessible,” Holt said. “My dad always said, ‘If you find something you like and then do that for a career, it won’t feel like work.’ I’d say entomology is a win for me.”