While bats often get a bad rep in movies and literature, experts have long argued that they’re misunderstood and are bigger allies to humanity than we give them credit for. A new study published in the journal Science on Thursday demonstrates this in explicit detail. It found that the death of bats in the U.S. due to fungal disease has also led to the death of some of society’s most vulnerable: children.
The rise of White-nose Syndrome. Spear-headed by Eyal Frank, an environmental economist at the University of Chicago, the study analyzed what happened after bat colonies were plagued by a new species of fungus, Pseudogymnoascus destructans, hailing from Europe. The disease was first documented in New York state in 2006.
Pseudogymnoascus destructans causes bats to develop a fatal disease called white-nose syndrome, or WNS. The disease gets its name from the effect it produces in bats, which develop visible white fungus on their muzzles and wings. According to the National Park Service, the cold-loving fungus infects bats during hibernation, a period when they slow their metabolic rate and lower their body temperature to save energy throughout winter.
“Hibernating bats affected by WNS wake up to warm temperatures more frequently, which results in using up fat reserves and then starvation before spring arrives,” the agency explains.
The link between White-nose Syndrome and crops. How is a disease in bats related to infant deaths? The key is in crops.
Crops around the world have a problem with insects, which damage produce. In fact, Frank states that about 13% of crops in the U.S. are destroyed by insects each year. This represents a loss of $27.6 billion annually.
Bats are blessing to farmers in this area, as bats that eat insects consume more than 40% of their body weight every night. Their effect on crops is well-documented, with research showing that bats limit the growth of insect populations in forests and agricultural plots. The pest control services provided by bats to farmers have a value that ranges between $3.7 billion and $56 billion per year.
However, when the bats in counties affected by WNS started dying from the disease, farmers had to do something. According to Frank, farmers in these areas started to increase their use of insecticides. The decision would end up having dire consequences they could have never imagined.
The results. In his study, Frank found that farmers in counties with bat die-offs increased their use of insecticides by 31.1% on average. He also noticed something else, though: The same counties where farmers had increased their use of insecticides also saw a 7.9% increase in infant deaths from internal causes.
Frank investigated other possible reasons for the deaths, such as unemployment, the opioid epidemic, the weather, and more, but he found nothing else that could explain the situation.
“This result highlights that real-world use levels of insecticides have a detrimental impact on health, even when used within regulatory limits, which highlights the difficulties of assessing the public health impacts of pesticides when regulating them individually,” Frank wrote in the study
Eli Fenichel, an environmental economist at Yale University who was not involved in the study, praised Frank’s work in an interview with The New York Times.
“He uses simple statistical methods to the most cutting-edge techniques, and the takeaway is the same,” Fenichel said. “Fungal disease killed bats, bats stopped eating enough insects, farmers applied more pesticide to maximize profit and keep food plentiful and cheap, the extra pesticide use led to more babies dying. It is a sobering result.”
Greater impact. In Frank’s view, the implications of his research go far beyond this specific case. It highlights the importance of well-functioning ecosystems, he writes, where interactions between natural enemies (bats and insects) help farmers use less toxic substances for pest control.
“We often pay a lot of attention to global extinctions, where species completely disappear,” Frank told the Times. “But we start experiencing loss and damages well before that.”
This isn’t the first time Frank has investigated how animal deaths affect humans. In June, he co-authored a study about the collapse of the vulture population in India. Frank found that the loss of vultures, which are also not held in high esteem but perform a critical service by feeding on carcasses, had caused disastrous consequences. Their absence caused rotting carcasses to pollute waterways and contributed to an increase in dogs infected with rabies. Overall, this led to more than half a million human deaths in five years.
Image | Michael Pennay | Jennifer Krauel
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