USDA ARS participant probes parasites for population history insights

In the ORISE-administered USDA ARS program, Luke Hecht studied host-symbiont pairs—like pigs and parasitic roundworms—to better understand their historical occurrences and help predict future instances.


At the age of 17, history buff and Star Trek fan Luke Hecht developed a deep longing to explore the science that separates fact from fiction. Evolutionary biology, as he discovered, married his love of historical narrative with his fascination with philosophy and extraterrestrial life and inspired him to pursue a lifelong career.

“Evolutionary biology is the quintessential historical science, explaining why things are the way they are today in terms of past events,” said Hecht. “It is possible to estimate when humans first migrated out of Africa by analyzing the genome of a single individual.”

Hecht, now a biosciences doctoral student at Durham University in the United Kingdom, enjoys probing life’s smallest organisms, like parasites, to answer bigger questions about existence and evolution. Recently, he capitalized on an opportunity to do just that by participating in the ORISE-administered U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) Research Participation Program in Maryland. 

The USDA ARS Research Participation Program provides opportunities for students, postgraduates, established scientists and faculty to participate in programs, projects and activities at ARS-designated facilities to help ARS solve agricultural problems of high national priority.

As a participant at the Beltsville Agricultural Research Center (BARC), he applied his background in evolutionary biology to sequence the genomes of a parasitic roundworm, Trichinella spiralis. This parasite can infect a number of species, including humans, but most frequently it infects swine.

After downloading and assembling published genomes of pigs, Hecht used advanced algorithmic software to extract the historical changes in the size of the pig and parasite’s populations, dating back hundreds of thousands of years. 

Then, he devised his own algorithm to optimally align the two species’ demographic histories. Analyzing the relationship between the host and parasite’s population sizes can help scientists detect patterns, including the ecological circumstances that affect host and parasite abundance, and predict future occurrences.

“Our novel approach of comparative historical demography seems capable of easily generating well-founded hypotheses, if not conclusions, about the ecological drivers of parasite numbers and even aspects of parasite life history,” said Hecht. 

Hecht applied the process to other host-symbiont pairs, like mosquitoes and the malaria parasite, and drew inferences of malaria and mosquito generation times that were extremely close to published estimates. The more scientists understand about the relationship between mosquitos and malaria, the better prepared public health officials can be in managing the disease.

Hecht researched alongside his mentor Benjamin Rosenthal, S.D., the research leader of the Animal Parasitic Diseases Laboratory (APDL) and a former professor of his, and Pete Thompson, Ph.D., another ORISE participant. Their comradery was one of his favorite parts of the program.

The team’s results have been published here in the scientific journal Proceedings of The Royal Society B: Biological Sciences.

Hecht’s participation in the program significantly advanced his programming skills, specifically with the languages Python, R, and Unix, and strengthened his skills for the demands of his doctoral program, where he studies the effects of past climate change on the abundance and distribution of South American seals.

Hecht is yet unsure of his post-doctorate career path, but as a member of a local altruism group, he knows he wants to have a measurable, positive impact on others and the environment. He is confident the skills he gained as a scientific researcher in the USDA ARS Research Participation Program will benefit him regardless of a career choice in academia or public policy.

“The ORISE program is a great experience and one I would definitely recommend,” he said. “Thanks to my research team, I received the independence I would typically associate with working in an agile start-up while benefitting from the USDA as a large and diverse research organization.”

The USDA-ARS Research Participation Program is administered through the U.S. Department of Energy’s (DOE) Oak Ridge Institute for Science and Education (ORISE). ORISE is managed for DOE by ORAU.