Israeli researchers have discovered that light pollution harms the ability of crickets to reproduce.
The study carried out by scientists from Tel Aviv University and Open University of Israel revealed that artificial light negatively impacts the the nocturnal chirping used by male crickets to attract female crickets for mating, reducing reproduction rates and potentially threatening the survival of the species.
In order to prove their hypothesis, the researchers used differing levels of artificial light at night and observed how the behavior of crickets changed in terms of chirping and locomotion.
Male crickets are nocturnal insects. Their chirping, which is heard during evenings and at nighttime in the summer, is a signal to females to mate. In natural environments, their chirping begins at sunset and continues until dawn. However, the study found that light pollution throws off the timing of the males’ mating calls, with chirping going on during the day.
“The distinction between day and night, light and darkness, is a major foundation of life on earth. But humans, as creatures of the day who fear the dark, disrupt this natural order: they produce artificial light that drives away the darkness,” said Keren Levy of Tel Aviv University, who co-led the study.
“Today more than 80 percent of the world population live under light pollution, and the overall extent of ALAN (artificial light at night) rises by 5 percent every year. ALAN negatively impacts the environment and affects natural behaviors that have developed over millions of years of evolution. ALAN affects the length and quality of sleep of many animals, leads to high mortality, and changes the activity cycles of many creatures. For example, dung beetles, that navigate using the Milky Way, lose their way when light pollution increases; sea turtles hatchlings seek the brightest surface in sight – supposedly the sea – and reach the nearby promenade instead."
The researchers studied dozens of crickets exposed to four different types of light during their life cycles. They found that crickets exposed to 12 hours of light followed by 12 hours of darkness exhibited normal behavior, while crickets exposed to partial lighting during dark periods lost their natural rhythm and become unsynchronized with their environment. Worse still, crickets exposed to constant light either developed their own cycles or lost all biological rhythm.
“Our results are in accord with many other studies demonstrating the severe impacts of low levels of artificial light at night on nature,” Levy said. “We ask, you, therefore, to help protect our environment and surroundings by turning off the lights in your backyards, on the terrace, in parking lots, and wherever possible. Help us bring the night and the Milky Way back into our lives and enable nightly coexistence with the creatures around us.”