A recent study reveals that light pollution has far-reaching effects on the flight behavior of moths, even beyond the direct illumination of streetlights. Researchers used harmonic radar to track the movements of moths, and found that their flight paths were significantly more erratic, suggesting a ‘barrier effect’ from artificial lighting. This research highlights the complex and widespread impacts of light pollution on nocturnal insects, which play crucial roles in food webs and plant pollination.
Unveiling the Hidden Impacts of Artificial Lighting
Light pollution is often thought to primarily affect nocturnal animals by drawing them towards streetlights and causing them to become easy prey. However, a new study published in the Proceedings of the National Academy of Sciences reveals that the impact of artificial lighting on moths goes far beyond this direct attraction.
Researchers from the Julius-Maximilians-Universität (JMU) Würzburg in Germany, in collaboration with scientists from Berlin and Providence (U.S.), used radar tracking to study the flight behavior of several species of hawkmoths and lappet moths. Surprisingly, they found that the moths’ orientation was disturbed not only within the direct illumination of streetlights, but also in the surrounding, darker areas.
Moth Flight Paths Disrupted by Light Pollution
The experiments, conducted at a radar system in Großseelheim near Marburg, Germany, tracked the movements of 95 moths up to 1 kilometer away from their release point, which was surrounded by six streetlights at a distance of 85 meters. The researchers attached small transponders to the moths, which did not affect their flight behavior, and used the harmonic radar system to monitor their movements.
“Using radar tracking, we found that the orientation of moths is also disturbed outside the cone of light: the flight paths of the three species of hawkmoths and one species of lappet moths, for which we were even able to demonstrate a barrier effect from streetlights, were significantly more curvy than normal,” explains Dr. Jacqueline Degen, head of a junior research group at the JMU Biocentre.
Implications for Nocturnal Insect Populations
The study’s findings suggest that the effects of light pollution on moths are much more far-reaching and complex than previously assumed. Contrary to the researchers’ initial hypothesis, only 4% of the moths studied actually flew directly towards the streetlights. This indicates that the disturbance caused by artificial lighting extends well beyond the immediate illuminated area.
The implications of this research are significant, as moths play a vital role in food webs and plant pollination. The sharp decline in insect populations in recent years has been linked to various factors, including light pollution. This new study highlights the need for a deeper understanding of the complex interactions between nocturnal animals and the growing presence of artificial lighting in the environment. As the researchers note, “the increasing use of artificial light at night is one of the most dramatic man-made changes on earth,” and its impact on ecosystems is only beginning to be fully understood.
