AgriLife Research to study lice-mammal coevolution

A Texas A&M AgriLife Research project will take a deep look at the ages-long interaction between parasitic lice and mammal species, including humans.

Researchers will study the evolutionary relationship between sucking lice and a wide range of placental mammal hosts, including humans and other primates, rodents and seals. Researchers hope to answer why various louse species parasitize specific hosts and what makes these species good hosts.   

The three-year project received more than $197,000 from the National Science Foundation.

Principal investigator Jessica Light, Ph.D., AgriLife Research evolutionary biologist in the Department of Ecology and Conservation Biology, Bryan-College Station, said very little is known about Anoplura lice, or sucking lice. Researchers hope to shed light on the biological and physical characteristics in lice that have co-evolved with mammals over 90 million years.

Collaborators include scientists with the Natural History Museum of Los Angeles County, which is the lead institution for the project, the University of Nevada, Reno and the Florida Museum of Natural History. The research team will work closely with natural history collections such as the Biodiversity Research and Teaching Collections in Texas A&M’s College of Agriculture and Life Sciences.

Building the first evolutionary tree for lice

Understanding these blood-feeding parasites and disease vectors presents obvious potential public and animal health benefits, Light said. But the team’s initial goals are to produce foundational data regarding louse biology and build the first comprehensive species-level tree for sucking lice that parasitize mammalian hosts.

Light said the broader implications of the project include reducing parasite infestations. The study’s findings could offer insights into parasite host-choice and movement from host to host that help reduce or mitigate infestations and subsequent consequences.

“We hope to build an understanding of the relationship with genetic data and scientifically preserved samples,” she said. “We are going to build a hypothesis about the relationships with genetic data and compare what we find in lice to that of their hosts and try to understand what that evolutionary history or what that association has looked like over time.”

Identifying lice, mammal traits that lend to parasitism

The project will investigate how the evolutionary history, genetics and morphology of sucking lice determine associations with their mammal hosts and how those relationships may have changed over time, Light said. The research will also identify potential genetic and physical traits important among lice that may be used to study other parasite species.

The study will include genome sequencing and other high-throughput technology and techniques to follow louse ancestry and identify species divergences in the past. Fossil records will be used to determine times of divergences and allow researchers to cross-reference sucking louse divergences with their mammal hosts.

This will help scientists date sucking louse diversification events/timing, follow the evolution of characteristics of interest and assess their biogeographical histories and distributions relative to their hosts.

“Sucking lice are a model system in some respects because their life cycle constrains them to particular hosts,” she said. “They don’t have wings to fly like mosquitoes and do not jump like fleas. So, they almost solely rely on host-to-host contact to spread.”

Creating a public database, educational tools on lice

There are over 600 species of lice within the Anoplura group. Light said the species have similar shape and size but also have identifiable differences and preferred hosts.

Researchers want to know if lice associate with specific mammals based on characteristics like mouth parts that can pierce skin or hides, claws that can cling better to specific species or the ability to digest hosts’ blood, she said.

The research team will examine sucking louse morphology using community science initiatives and advanced micro-CT scanners, allowing them to categorize internal anatomy and explore how various organ systems may be responding to different hosts.

The team will create a database of morphological characteristics that is open to other researchers and for public use, she said.

The project will also include an educational element, Light said. Undergraduate and graduate students and post-doctoral researchers will train with cutting-edge methodologies and the data obtained will generate college-level curriculum for students and virtual reality educational tools for the public to learn about lice diversity and traits.

“In terms of morphology and genetics, we are really just scratching the surface regarding the features and functions found in lice,” she said. “Parasites are understudied organisms in general, so we hope gaining a better understanding of lice can enlighten us about the parasite-host relationships and ultimately lead to better ways to address problems they create.”