The University of Delaware’s College of Agriculture and Natural Resources (CANR) has announced that the winners of the 2016 William J. Benton Graduate Student Awards are Solny Adalsteinsson and Amanda Rosier.

The awards were established in honor of William J. Benton, former CANR associate dean of research and professor in the Department of Animal and Food Sciences (ANFS), in recognition of his dedication to graduate education.

Solny Adalsteinsson

Adalsteinsson recently received her doctorate from UD’s Department of Entomology and Wildlife Ecology and will step into a post-doctoral position at Washington University in St. Louis.

While at UD, Adalsteinsson worked with her advisers Jeff Buler, assistant professor of wildlife ecology, and Greg Shriver, associate professor of wildlife ecology, researching Lyme disease and other pathogens that cause different tick borne diseases.

“The overall theme was looking at how urbanization changes local forest fragments, how those changes affect the disease transmission cycle in the environment, and what that means for human risk of Lyme,” said Adalsteinsson.

Adalsteinsson is looking at how invasive plants, specifically multiflora rose, affect tick populations and the populations of host animals that are important carriers of these pathogens. She said that in terms of tick abundance, forests with a lot of multiflora rose tend to have ticks concentrated in large numbers within those invasive plants. Forests without invasive plants, however, tend to have a larger number of ticks overall than the rose-invaded forests.

“It was a surprising and really interesting result. We did some modeling to figure out what was driving that relationship and we identified other changes to the habitat associated with these invasive plants,” Adalsteinsson said. “The most important one is the loss of leaf litter — all the dead leaves that accumulate on the forest floor. That makes up really important habitat for ticks because they need it to be humid and they evolved naturally to live in that litter layer.”

In the forests that have many invasive plants, the litter is gone, and Adalsteinsson thinks that results in a poor quality habitat for ticks to survive on the ground. Conditions are improved in the invasive plants themselves, and ticks are found aggregated within the plants in those sites.

Forests that have a thick litter layer intact and no invasion support more ticks overall.

When Adalsteinsson looked at the prevalence of the pathogen that causes Lyme disease, specifically looking at the presence of a bacterium in the ticks themselves, the ticks collected from forests with lots of multiflora rose had almost twice as much of the Lyme disease pathogen compared to the ticks from the uninvaded site.

In addition, Adalsteinsson studied mice and fledgling birds in urban landscapes to see how many ticks they were carrying. In some cases, she got tissue samples from the mice to look at what pathogens they were carrying and transmitting to the ticks and looking at which features of the urban landscape might influence the abundance of important disease reservoirs and their interactions with the ticks.

As to her favorite thing about studying at UD, Adalsteinsson said it was the “sense of community within the department and the support among the faculty and students. My advisers and my whole committee have just been fantastic to work with and have helped me and given me a lot of guidance shaping these ideas and figuring out what the important questions are. And I’ve had the opportunity to work with a lot of talented undergraduate students and technicians, and that’s really all thanks to my advisers and my committee.”

In addition to Buler and Shriver, Adalsteinsson wanted to thank her committee members Vince D’Amico, a research scientist with the U.S. Department of Agriculture (USDA) Forest Service and an adjunct faculty member in CANR, Jake Bowman, chair of the Department of Entomology and Wildlife Ecology, and Dustin Brisson, associate professor of biology at the University of Pennsylvania, for all the training and support they’ve provided her.

Amanda Rosier

Of receiving the Benton Award, Rosier said she was “profoundly honored to have received this acknowledgement of my accomplishments while a student here at UD.”

Rosier, who received her master’s degree from the Department of Plant and Soil Sciences, has been advised by Harsh Bais, associate professor of plant and soil sciences, and her research entailed studying beneficial bacteria that associate with plants – essentially the plant’s “microbiome.”

“We know about, and even use, bacteria to improve plant health. However, we know very little about how a majority of these ‘beneficials’ work. My research focuses on how different bacteria may work together in the environment to protect plants from pests and increase yield,” said Rosier.

With agriculture companies looking towards more natural ways to protect crops and garden plants by using micro-organisms, one current idea is to mix many different types of beneficial bacteria together to enhance their overall benefits to the plants even though bacteria don’t always get along.

“My work is looking into how two common, but very different plant beneficial bacteria interact with each other and how those interactions may impact the plant,” said Rosier. “One of the bacteria I work with, rhizobia, are commercially very important. These are bacteria that live symbiotically inside the roots of certain plants like peas and clover that can take the nitrogen from the air and make it so the plant can use the nitrogen as an essential nutrient.”

Rosier said that the other bacteria she works with, Bacillus subtilis, are very common in soil, but they also live on the plant root and can protect the plant from pathogens. She is looking at whether these two bacteria are better at helping the plant when they are together or if they cancel out each other’s plant benefits.

“My research is showing that there are subtle ways that these two bacteria are interacting with each other that might influence how well they function to help the plant. The Bacillus is capable of disrupting the ability of the rhizobia to ‘talk’ to each other. This is important, since the rhizobia need to communicate to each other in order to start the process of symbiosis with the plant. Considering that the whole point of using these bacteria together is to enhance plant growth, interactions such as those I have found could have an impact on developing better plant beneficial products,” said Rosier.

As an undergraduate studying for her degree in microbiology, Rosier said she was “fascinated by the concept that these incredible small organisms can have such a profoundly large and positive influence on the environment. We are surrounded by a greater number of helpful and beneficial bacteria than by those that may cause harm. If there is any one message, I’d like to emphasize is that microbes are awesome, not bad.”

Rosier said she would love to continue to pursue research either academically or in an industry position that combines the areas of microbiology and plant health or environmental restoration.

In addition to Bais, Rosier also wanted to thank Janine Sherrier, interim chair in the Department of Plant and Soil Sciences, for supporting her work and being a cheerleader along the way.

With regards to her favorite memories from UD, Rosier said that it is the little things that have made her experience memorable.

“My colleagues and fellow students in the department, those moments of achievement when an experiment works or getting really interesting results, and engaging in intellectual and challenging discussions with my mentors about my research. I’ve been incredibly fortunate to have found myself in the Department of Plant and Soil Sciences, and to have had the opportunity to engage in a research project that I really love and care about,” said Rosier.