ConservationBytes.com

Night is the peak activity period for many animal species. In the Western Andes of Ecuador, the Chocó golden scarab flies between forest patches during the night, but urban lighting interferes with their paths and jeopardises populations already struggling to persist in fragmented native forests.

Urban development has created a network of illuminated infrastructure that allows our society to function day and night without interruption. It is no surprise that with so much artificial light, we increasingly have to move farther away from towns and cities to see a sky full of stars.

Light pollution poses a challenge for nocturnal species that have adapted to living in the dimness of night (1, 2) — see documentaries about the impacts of artificial light on wildlife and insects, and a related scientific talk. This problem might be one of the causes of the global decline in insects (3, 4), in turn negatively affecting their role in maintaining agricultural systems through pest control, pollination, and soil quality (5). These concepts are featured by the documentaries The Insect Apocalypse and The Great Death of Insects.

When flying, nocturnal insects orient their backs toward the sky, using the light of the moon and stars as a reference (6) (explained here and here). However, when they encounter artificial lights, they can no longer distinguish up from down, and so they can become disoriented, flying erratically, like a moth circling a streetlight.

It is estimated that a third of the insects attracted to artificial light die from collisions, burn injuries, exhaustion, and/or predation (7). In the tropics, finding countless dead insects at the base of urban lights is a common scene. Equally important is that artificial light also hinders migration, foraging, and the search for mates in many nocturnal species (1, 8, 9).

Nocturnal jewels

Camacho and collaborators evaluated the effect of artificial lighting at night on the Chocó golden scarab (Chrysina argenteola) (10). This species inhabits the tropical rainforests of the Western Andes from Ecuador to Colombia, and is a member of the group known as ‘jewel scarabs‘ due to their metallic body coloration (11). Because of its nocturnal habits and the larvae’s dependence on wood for food (12), the golden scarab has been increasingly affected by the loss of native forest in combination with light pollution from rural and urban expansion.