Phenomenal Phenology
Written by Emily Holsinger, OneHealth REU program 2022 participant
Hello! My name is Emily Holsinger and I am a rising senior from Northern Michigan University majoring in Biology. Growing up in the state of Michigan, I was never concerned about going in my backyard, sitting on a park bench, or playing in the woods. The worst that could happen was that I could get bitten by a mosquito or stung by a bee. However, in Maine there is a much worse beast that can cause rashes upon contact and can become airborne.
The browntail moth, native to Eurasia, was first introduced to New England in 1897. This species is a human health concern due to the larvae’s toxic hairs that leave a poison-ivy-like rash when exposed to skin. These hairs can spread many ways and can become airborne – leading to increased exposure as well as respiratory issues. Along with this, the larvae feed on the leaves of over 50 different types of hardwood trees and some species of shrubs. Defoliation caused by browntail can weaken infested trees and, in cases where repeated defoliation occurs multiple years in a row, tree deaths are common. In recent years browntail populations continue to rise and pose a significant hazard for people living in Maine as well as tourists who are visiting the state.
This summer, my lab and I are working hard to understand the behavior of the browntail in order to help inform management efforts. Originally I planned to study pheromone attraction; however, because we are working with live animals, not everything turns out how we would have hoped. Because we were unable to collect data on this, I shifted my focus and began looking at population dynamics of the moth during outbreaks such as the one we are currently in. Browntail pupate in late spring and form pupal nests (containing anywhere from 1 to around 90 pupae) that consist of leaves that are rolled up using silk produced by the caterpillars. Unfortunately, these nests contain thousands of toxic hairs and need to be collected and dissected safely (displayed in the attached image). We collected pupal nests from infested areas and obtained 2,605 potentially viable pupae. Each pupa was housed in individual containers as we waited for them to emerge. I am able to use this emergence data to determine parasitism rates and female versus male emergence rates which can help us to understand the conditions that are present during an outbreak and inform management efforts.
Because the adult moths are nocturnal, so is our research. This means that I not only get to explore Maine like everyone else in the daytime, but I also get to see what it is like here during the night. Although we are only a few nights into the experiment, I have already seen many lightning beetles, lots of deer, a juvenile eastern newt, and plenty of other moth species. I came here to gain experience with scientific research and I have already learned so much more. Furthermore, I am able to contribute to research that can help both the environment and the people that are affected by browntail.