Declining bat population is increasing infant mortality in US, says new study; Here's the strange connection

A decline in bat populations across the United States from 2006 to 2017 has resulted in increased pesticide use by farmers, leading to a rise in infant mortality, according to a new study. Published in the journal Science, the research by Eyal Frank from the University of Chicago highlights the significant impact on human health and agricultural costs.

The study found that the reduction in insectivorous bats, vital for pest control, caused a 31% rise in pesticide use. This increase has been linked to a nearly 8% rise in infant mortality in the affected areas, totaling approximately 1,334 additional deaths over the study period.

The decline in bat populations, caused by white-nose syndrome (WNS), led to substantial agricultural losses and increased expenses, amounting to $26.9 billion in affected counties between 2006 and 2017. WNS, caused by the fungus Pseudogymnoascus destructans, leads to high mortality rates in bats, ranging from 33% to 99%, and has the potential to result in local extinctions within six years.


Frank stated, "The gradual expansion of the disease provides a setting that approximates random manipulation of bat population levels, which allowed me to estimate how farm operations and human health change differentially before and after a location experiences a negative shock to biological pest control."

Previous research has shown that bats play a crucial role in controlling agricultural pests by consuming large quantities of insects. Frank’s study used county-level data on insecticide usage and infant mortality to assess the impact of increased pesticide use due to the decline in bat populations. The results underscored the harmful effects of insecticides on human health, even when used within regulatory limits.

In addition to his research on bats, Frank, along with researcher Anant Sudarshan, highlighted the impact of declining vulture populations in India, which they estimate contributed to the deaths of 500,000 people due to the spread of infectious diseases like rabies.