Thanks to its famously cold weather, Vermont has so far escaped the effects of many invasive species that plague warmer parts of the globe. But that may be about to change as climate change leads to milder winters and some of those species begin to move farther north.
Joaquin Nunez, Assistant Professor of Biology in ¶¶Òõ̽̽’s College of Arts and Sciences, recently and how that may impact agriculture in Vermont and other states. The $1.5 million grant, awarded by the National Science Foundation, is being shared equally with two collaborating labs at the University of Kentucky and Northeastern University.
We sat down with Professor Nunez to talk about the grant, his work, and how this research may prove to be invaluable to some Vermont farmers.
What are you hoping to do with this grant?
For most of their history, the species of fruit fly I look at in my research, Drosophila suzukii (also called the spotted wing Drosophila), was only found in regions in Southeast Asia. Then, at some point during the turn of the century, the species began expanding rapidly toward the West; it reached Connecticut over a decade ago. So, we’re looking at a real-time example of an invasive species that shifted its habitat virtually overnight and caught most growers completely by surprise. We usually think of this kind of ecology as something that takes hundreds or thousands of years.
We don’t believe Drosophila suzukii is established in Vermont yet. So, every year they completely die out by the end of the winter and have to recolonize from somewhere in the South. However, as the climate continues to change, winters in regions like Vermont will become warmer and shorter. So, the first question is, where is the establishment barrier for this species and when can we expect these insects to become resident in Vermont? Then, how can we provide that information to folks so that they are not caught by surprise? Working to answer these questions is what exactly we're doing with the grant.
Tell us about your collaborators on this grant.
The grant has been given to researchers at three universities, and each of the principal investigators is attacking the question of what is allowing Drosophila suzukii to be such a successful invader through a different angle. Here in Vermont, we are tackling the question mostly through the lenses of genetics, doing analysis to understand what aspects of the genes, and mutations inside the genome, make them unique compared to other species.
At the University of Kentucky, Nick Teets and his team will be studying the physiological limits—like the maximum and minimum temperatures they can survive—of Drosophila suzukii, which is already established in Kentucky. Interestingly, this species can morph: If the larvae experience heat, they develop into a summer-specialized form. But if they experience colder conditions, they will develop into a different morph that’s better at surviving the winter. Nick’s lab is going to map out the specific traits that make these morphs seasonal specialists.
Katie Lotterhos, the researcher at Northeastern University in Boston, is an expert in both evolutionary modeling and climate change forecasting. So, she is going to use data from the other two labs to build an evolutionary model that she’ll then layer on top of different climate change forecast scenarios. Once that’s complete, we can begin to estimate when Drosophila suzukii might become established in Vermont.
How much of a threat does such a small creature pose?
Drosophila suzukii is a kind of fruit fly that is very destructive to crops, particularly soft-skinned fruit like blueberries, blackberries, grapes—foods that have an economic value to folks here in Vermont. They lay their eggs inside the fruit as it ripens, and when the eggs hatch, the larvae destroy the crops.
So yes, the individual fruit flies are tiny, but during the summer there is a lot of food available for them, and they reproduce really fast. Now imagine millions of those tiny things, which are difficult to catch or even see, attacking crops here in Vermont and laying their eggs. They have the ability to destroy entire fields very, very quickly. So, farmers need to be prepared.
Are there ways to fight this kind of fruit fly?
One way to attack the Drosophila suzukii problem is to spray, but that’s not an option if you’re an organic farmer. The other way is to cover the crops with nets to prevent the attacks. But there are a lot of questions about both methods.
If farmers decide to spray, these little fruit flies can develop insecticide resistance. And if even a small number of them survive because they have the right mutation, they're going to go into the forest and hide, and when they return, the descendants of those survivors will be more resistant to spraying.
With the nets, the questions are more about timing, such as how early to put them out. We want to allow beneficial pollinators to do their jobs but also want to exclude harmful incursions of Drosophila suzukii.
Will looking at solutions be part of your research?
Yes, studying this is one of the things that we want to do with the grant. We are working very closely with Vic Izzo and the folks at the ¶¶Òõ̽̽ Institute for Agroecology to do two things. The first is outreach. We want to take local students out to the farms to help us do collections and learn how to monitor this invasive species more effectively. The other thing we’re doing is talking to farmers, because they’re out there in the fields and have practical knowledge that scientists don’t have. The folks at Agroecology are going to facilitate those discussions so we can bring the farmers’ expertise into our models.
The Institute has fostered decades-long relationships with local farmers who are happy to participate in science and really want to be our allies. It’s a bridge between the scientific world and the more applied world, and it’s one of the beautiful things about Vermont.
Overall, what kind of value do you see coming from this grant?
I think this grant will give value at three levels. At the most basic level, Drosophila suzukii is a natural laboratory of the evolution of an invader in real time, giving us a more comprehensive understanding of the genetics, physiology, and overlap of climate change in these rapid invasions. At the intermediate level, it will give us a general sense as to what traits make an invader successful. And lastly, we hope to be able to provide farmers with a variety of models as the climate continues to change so they have a better idea of what to expect and how to handle it.
How does your work help support ¶¶Òõ̽̽’s focus on planetary health?
This project definitely aligns itself with the university’s bigger planetary health goals. It’s about the interaction between ecosystems and the effect of invasive species connected with climate change, and that’s related to the stuff that we grow and eat, right? So, there is a strong connection to human health. If healthy food is no longer available, we can’t survive.