United States. Over a thousand children died because… there were no bats

White nose syndrome (WNS) is a disease caused by a cold-loving fungus that originates from Europe. Pseudogymnoascus destructanswhich kills bats during hibernation. The fungus primarily attacks bats inhabiting North America, and has caused the deaths of millions of them since 2006. The name comes from the characteristic white coating of mycelium hyphae on the snouts of diseased animals.

Bats living in this climate zone are insectivorous mammals that eat thousands of insects every night, an amount equivalent to 40 percent of their body weight, a large portion of which are crop pests and mosquitoes. Eyal Frank from the University of Chicago decided to analyze the impact of the loss of bats on the environment and local communities. The results of his research were published in the journal Science.

The WNS study met the criteria for a randomized controlled trial, Frank explained. The spread of the disease is closely monitored, so the researcher could compare counties where bats live with those where the disease has not yet reached.

Where there were no bats, farmers used significantly more pesticides, an average of 31.1 percent. The study’s author linked this increase to an increase in the average infant mortality rate by almost 8 percent, a parameter often used to assess the impact of environmental toxins. In counties where bats were sick, children died more often than in those where the animals were healthy. This translated into 1,334 additional infant deaths, although pesticide use standards were not exceeded.

Frank considered other factors that could plausibly explain the rise in deaths—unemployment, the opioid epidemic, weather, differences in mothers, or the introduction of genetically modified crops—but they did not explain the rise in pesticide use or the rise in infant deaths. He analyzed the data for an additional year, but the observed relationship persisted, so he considered the evidence compelling: farmers responded to a decline in insectivorous bats, and that response had a negative impact on the health of human infants.

This isn’t the only study linking the fates of human and animal populations. Earlier, Frank and another researcher estimated that the collapse of vulture populations in India could have killed 500,000 people, as the lack of scavenger birds spread rabies and other diseases.

Studies of cicadas, which appear in large numbers every 13 to 17 years in the United States, have shown that the increased use of pesticides during the “cicada years” may be related to the increased infant mortality rates during those years. People born in cicada years also had lower test scores and were more likely to drop out of school.

In 2021, the journal PNAS published a paper showing that the presence of wolves reduces the number of road accidents in a given area because fewer deer run onto the roads and collide with cars.