Corix Plains Institute Research Used Radar to Show Effects of Artificial Lights on Grasshoppers

March 30, 2021

Corix Plains Institute Research Used Radar to Show Effects of Artificial Lights on Grasshoppers

Elske Tielens

The expansion of artificial night lights globally has had important impacts on animal behavior and health, recent studies have shown. A study led by a research team at the University of Oklahoma on the effects of bright city lighting on grasshoppers will appear in the next issue of the journal Biology Letters.

Elske Tielens, a postdoctoral research fellow conducting research at the Corix Plains Institute at OU, is lead author on the study, “Nocturnal city lighting elicits a macroscale response from an insect outbreak population,” which represents the first analysis of lights at night on insect movement at regional scales. The study was supported by a grant from the National Science Foundation (EF-1840230).

Analyzing weather surveillance radar in June and July 2019, Tielens found that some 45 million grasshoppers – a “biblical plague” – took flight during the outbreak peak, concentrating over city lighting such as the Las Vegas strip. The group also found daily movement cycles of dusk ascent from vegetated habitat toward lit urban areas after dark.

This study is novel, Tielens said, because the effects of artificial lights at night on the behavior of insects at large scales have not previously been documented in a quantitative way. It shows how insects are interacting with the landscape, including human made environments. Given that humans are, and continue to, influence the environment, it is important to understand the effects this has on insect populations. This knowledge can help researchers both conserve our diverse world of insects, as well as manage important pest species.

Another reason this study is interesting, Tielens added, is because using weather radar to follow how insects respond to artificial night lights hasn't been done before.

Radar surveillance and landscape associations of an outbreak population of grasshoppers for the night of July 25-26, 2019. The Las Vegas weather surveillance radar (red circle) provides continuous nightly coverage of the abundance and distribution of grasshoppers aloft (blue-green-yellow colormap) and enables delineation from weather signals (grayscale colormap). As the sun sets over the domain, habitat cues shift from vegetation greenness to light intensity, corresponding with mass ascent of grasshoppers into the airspace. The inset region highlights a 60 × 60 km area over the Las Vegas metro. The upper time series shows the variation in habitat associations (Pearson correlation coefficients) between grasshopper abundance and vegetation greenness (green) and light intensity (blue) across the night. The lower time series shows the number of grasshoppers detected aloft. Yellow dotted lines indicate the times of local sunset and sunrise.

“We used weather radar to track the swarm of grasshoppers. Instead of filtering out the biological signal to get a good picture of weather, we filtered out the weather signal to be able to see movement of insects,” she explained. “Using this approach, we were able to analyze insect response to bright city lights at a larger scale than previously done.

“I am interested in insect biodiversity, and how local and macro-ecological processes interact to create the communities of insects that we encounter in a forest or in our yards,” Tielens said. “Our research group as a whole is interested in animal movement in the air – insects, but also birds. This research project was really a learning tool to develop skills in using radar to follow animal movement. It's great when a learning tool also manages to produce novel research and helps some of our graduate students add scientific papers to their name!”

In her current position, Tielen said it’s “a privilege to work on novel and exciting research questions in ecology,” stating that she is also “passionate about applying my data analysis skills to broader societal issues.”

Tielens’ post-doc adviser, Jeffrey Kelly, Corix Chair in Water and Sustainability and director of the Corix Plains Institute, commented, “We know that the airspace just above us is an essential habitat for most animals, but we don’t know much about how our activities are impacting life in the air. This study reveals that effects of artificial light at night on grasshopper behavior are pervasive at large scale.” Kelly also is a professor of biology and is associated with the Oklahoma Biological Survey.

About the Corix Plains Institute

The Corix Plains Institute was established in 2018 to focus on transdisciplinary research and training in environmental sustainability. The CPI is envisioned as a catalyst for engaging OU faculty, students and staff with external partners to use team science approaches to solve complex problems in environmental sustainability. CPI builds on experience with interdisciplinary graduate student training programs and interdisciplinary research efforts to incubate new, creative, and convergent approaches to solving complex environmental problems and creating positive community impact.