For years, bats have gotten a bad rap as the creepy creatures lurking in the dark. But for just as long, agricultural producers have known that the winged wonder is actually the hero of the story, not the villain.
Now a plague is decimating bat colonies. The culprit: white-nose syndrome. And it’s costing U.S. agriculture up to $495 million each year, according to a paper recently published in the Journal of the Association of Environmental and Resource Economists from Colorado State University Associate Professor of Agricultural and Resource Economics Dale Manning.
“When bats get this disease, it’s deadly to them, and it’s highly contagious,” said Manning, who was lead author on the paper, which is co-authored by Professor of Agricultural and Consumer Economics at the University of Illinois Urbana-Champaign Amy Ando.
“Lost bat populations have harmful ripple effects on food and agriculture,” Ando said. “Crop yields fall, and input costs rise as farmers try to compensate for the services bats usually provide. That drives down the value of farmland and the number of acres planted, and the supply shock probably also hurts consumers as ag production becomes more costly.”
What is white-nose syndrome?
White-nose syndrome is caused by Pseudogymnoascus destructans, a fungus that thrives in cold, damp places – like the caves, mines and rock crevices that bats like to hang out in. The disease was named because the fungus looks like white fuzz on infected bats’ muzzles.
In 2006, the fungus was first found in a cave in New York – possibly after hitching a ride on a traveler’s clothes or gear, or via a stowaway bat in a shipping container. Previously, WNS has been found in bats in Europe and China, although the animals there appear to have adapted to it. Once the fungus made its way here, however, it quickly began a devastating plague that has spread across the U.S. and Canada, eradicating an average of 80% of infected bat colonies.
“If WNS is in a cave where the bats are hibernating, then it can easily spread throughout that cave and wipe out the entire population,” Manning said. “That can be devastating, especially as it affects so many different species, including those that are already endangered.”
The disease specifically attacks the skin of bats while they’re hibernating. As it spreads throughout the body, it causes the bats to be more active than usual, using up their winter fat reserves and starving before spring arrives.
Forget Batman, the bat is agriculture’s unsung hero
Bats provide many benefits to agriculture around the world.
“Some bats are important pollinators for high-value crops in tropical and desert climates, and guano is an important fertilizer in some parts of the world,” said Ando, who also co-directs the Center for the Economics of Sustainability at UIUC. “But the biggest benefit provided to people by the bats hurt by white-nose syndrome is pest control. The humble little brown bat can eat over half of its body weight in bugs every night.”
Certain insects have long been a costly enemy to agriculture. Like the chinch bug – this menace to sorghum and corn growers sucks out the plants’ vital fluids. Or the leafhopper – which secretes a toxin on alfalfa, stunting the plant and killing young seedlings. And don’t forget the voracious cutworm – a moth whose larvae feed on a plant’s leaves, buds and stems until it literally cuts it down.
But what’s that in the sky? Is it a bird? Is it a plane? No, it’s a bat. And it’s here to save the day.
The much-maligned mammal can eat about 3,000 insects a night. That makes bats a producer’s best (and cheapest) method of pest control. Not bad especially when you consider that a favorite meal of bats, the corn rootworm, costs U.S. producers approximately $1 billion a year all by itself.
The additional costs of white-nose syndrome
Because bats are so beneficial, their declines have consequences beyond the requirement for producers to buy pesticides, impacting both land price and viability.
The loss of bats due to white-nose syndrome in a county causes land rental rates to fall by $2.84 per acre, and $1.50 per acre in neighboring counties. Additionally, agricultural land falls by 1,102 acres in a county with an outbreak while neighboring counties lose 582 acres.
“If you no longer get that free pest control you’ve had on marginal land where yields may be lower than average and input costs are already high, then having to also deal with yield loss and/or purchase chemical pesticides to replace the bats’ service can be enough to make land no longer viable,” Manning said.
That cost hits even harder as current studies show that once bat populations are hit, they don’t necessarily recover.
“At least not yet,” Manning said. “Right now, these populations are crashing and staying low. Whether or not that’s permanent is still uncertain.”
In the paper, they reference another stark potential repercussion to this problem from a 2016 study by University of Chicago environmental economist Eyal Frank.
“Frank found that after white-nose syndrome outbreaks, the bat population collapsed and chemical pesticide use went way up, and he was able to detect an increase in infant mortality rates of 5%,” Manning said. “So, there are potentially large costs of losing these populations, even in the short run.”
While their focus was on identifying the cost of the problem, Manning said they did see some potential solutions.
“We worked fairly closely with the researcher as the U.S. Fish and Wildlife Service, and they provided us with cost estimates for two different solutions that they’re currently looking at,” he said.
One option is vaccination. While WNS is highly lethal, a vaccine against the disease is being developed, Manning said. The other possibility is using a fungicide preemptively in places where bats live. Both solutions would be less costly than losing the bat populations, he said.
Ando plans to present the work to wildlife scholars and government agency officials at the White-Nose Syndrome National Meeting next month.
“We hope direct communication and collaboration can help those who are working to advance effective management of WNS in the U.S.,” she said.
But this research has even broader implications.
“This started with one applied question,” Manning said. “It was supposed to inform a very specific case, but through that question we were able to develop an approach – a conceptual framework and an empirical method for valuing the services provided by society’s natural capital. So, in doing this really applied research, we were able to identify a gap in our academic understanding of how to estimate the value of natural capital to our society.”