Bat-killing fungus linked to increase in infant mortality rate, loss of farming revenue

(CN) — When a fungus ripped through bat populations in the U.S. it didn’t just affect bats — through a series of knock-on effects, it also hampered farmers' ability to grow crops and manage pests and has led to a devastating increase in infant mortality rates.     

As maligned and feared as they are, bats actually are helpful partners to farmers because they eat around 40% of their body weight every night, mainly insect pests on farms, according to the study published in Science on Thursday. 

“Bats have gained a bad reputation as being something to fear, especially after reports of a possible linkage with the origins Covid-19,” environmental economist Eyal Frank, an assistant professor at the University of Chicago’s Harris School of Public Policy, said in a statement accompanying the study. “But bats do add value to society in their role as natural pesticides, and this study shows that their decline can be harmful to humans.”

Farmers save somewhere between $3.7 to $53 billion because of the free labor bats provide as natural pesticides, Frank wrote in the study, so when a fungus called white-nose syndrome spread throughout bat populations in the U.S. in 2006 and 2007, killing 70% of the country’s bat population — and the result was disastrous. 

To replace the bats, farmers started using on average 31.1% more chemical pesticides. Crop yields decreased because the chemical pesticides didn’t work as well as the bats did to keep insects off of crops, so farmers lost both revenue and the money spent on pesticides. From 2006 to 2007, Frank estimated that farmers lost $26.9 billion.

Because wind and water erosion can carry pesticides off farms, even to communities not immediately surrounding agriculture, Frank studied county level infant mortality data and found that the infant mortality rate increased 7.9% in affected counties. For every 1% increase in insecticide use, there’s a corresponding 0.25% increase in the infant mortality rate, Frank wrote in the study.

“When bats are no longer there to do their job in controlling insects, the costs to society are very large — but the cost of conserving bat populations is likely smaller,” Frank said in the statement. “More broadly, this study shows that wildlife adds value to society, and we need to better understand that value in order to inform policies to protect them.”

To better understand the value of wildlife’s value and how threats animals face affect humans — especially for bats, whose habitats are being threatened across the country by both humans and climate change — experts point to things like more funding for wildlife monitoring efforts and better monitoring of chemical pollutants. Both can help better inform conservation policies, like the Biden administration's plan to place 30% of land marine areas in the U.S. under federal protection by 2030.   

“In the absence of rigorous quantitative evidence on the social costs of biodiversity loses, we risk making ill-informed policy decisions regarding the tension between preserving nature or allowing additional economic development at its expense,” Frank wrote in the study.  

Subscribe to Closing Arguments

Sign up for new weekly newsletter Closing Arguments to get the latest about ongoing trials, major litigation and hot cases and rulings in courthouses around the U.S. and the world.

Email *

Submit