A collapse in the North American bat population has led to increased pesticide use by farmers and increased infant mortality, a study found Thursday.
“Researchers are warning us that we are losing species on all sides (…) and that this could have catastrophic impacts for humanity,” Eyal Frank of the University of Chicago told AFP.
However, little research has been done to demonstrate these predictions, due to the difficulty of studying “an ecosystem on a very large scale,” the researcher says.
Published in the journal Science, this study provides tangible evidence of the current global decline in biodiversity and its consequences for humans.
– White nose syndrome –
For his research, Eyal Frank relied on a “natural experiment” – the sudden emergence of a deadly disease in bats – to quantify the benefits they provide in pest control.
Called white nose syndrome (WNS), the disease, caused by a fungus, began emerging in New York state in 2006 and has since spread across the United States.
Awakened prematurely from hibernation by illness, bats die from lack of insects to feed on and difficulty keeping warm.
For the study, the researcher tracked the spread of the disease in the eastern United States and compared pesticide use in affected counties and those that were not.
He found that in counties where bat populations had plummeted, farmers had increased pesticide use by 31 percent.
He then looked at whether this increased use was correlated with higher infant mortality rates, a measure that helps study the health effects of environmental pollution.
With more pesticides, the infant mortality rate increased by nearly 8%, which corresponds to 1,334 additional deaths, as contaminated water and air spread these chemicals from the fields to the human body.
The researcher emphasizes that the wide spread of the disease supports the result of his study and rules out a possible coincidence: any other explanation would have to align with the same trajectory of propagation and the same temporality.
– “Stem the crisis” –
“We need better data on the presence of pesticides in the environment,” the researcher says, adding that his study highlights the need to protect bats.
Vaccines are being developed against WNS, but the species is also threatened by habitat loss, climate change and the expansion of wind farms.
This research adds to the body of studies showing the cascading effects of wildlife loss on ecosystems.
For example, a recent study showed that the reintroduction of wolves in Wisconsin (north) has reduced collisions between vehicles and deer, with wolves positioning themselves along the roads.
In Central America, declining amphibian and snake populations have led to increased cases of malaria in humans.
“Stemming the biodiversity crisis is essential to maintaining the many benefits that ecosystems provide that technology will struggle to, or perhaps never, replace,” scientists from the University of California, Santa Barbara and the University of British Columbia wrote in a note.
“Studies like those of Eyal Frank are important to understand the interest of allocating resources for the preservation of biodiversity.”
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