Bat die-off linked to increased insecticide use and infant mortality

The diminution of bat populations in the United States as a consequence of the proliferation of a fungal ailment has resulted in decreased incomes for farmers and an additional 1300 fatalities in infants under the age of one, a recent study has revealed.

In regions afflicted by the bat disease, farmers augmented their utilization of insecticides by 31 percent to offset the decrease in insect predation by bats, as discovered by Eyal Frank at the University of Chicago in Illinois. Frank estimates that between 2006 and 2017, farmers in impacted areas incurred a $27 billion loss due to reduced crop sales and elevated insecticide expenses.

Additionally, in the affected regions, there was an 8 percent surge in the number of infant mortalities before the age of one, which Frank attributes to the heightened use of insecticides. “Insecticides are inherently toxic,” he remarks. “Even when employed at prescribed levels, there seems to be a health toll.”

White-nose syndrome, which was first observed in 2006 in hibernating bats with a white fungal growth on their muzzles in a cave in New York state, has been propagating throughout North America, resulting in the demise of myriad bats.

Upon learning about white-nose syndrome, Frank recognized it as an opportunity to directly evaluate the advantages that bats confer upon farmers. “This serves as a rather exemplary approximation for an ideal experiment where populations are arbitrarily manipulated,” he explicates.

Through the utilization of data from agricultural censuses, Frank compared counties where white-nose syndrome had been identified with those where it had not yet manifested until 2017 – ceasing at that point due to the periodic release of census data.

In the stricken counties, insecticide usage surged annually subsequent to the detection of the disease, while remaining relatively stable in unaffected areas.

It is noteworthy that white-nose syndrome impacts solely 11 of the approximately 50 bat species in the U.S. and has exterminated around 70 percent of those species, on average, in afflicted regions, underscoring that the overall value of bats to farmers in the U.S. considerably surpasses the figures Frank has tabulated.

Subsequently, Frank delved into data regarding infant mortality, excluding fatalities stemming from accidents and homicides. The 8 percent escalation in afflicted counties would have culminated in an additional 1300 infant deaths by 2017, according to his calculations.

Frank posits that his findings transcend mere correlation, illustrating that the die-off of bats precipitates both heightened insecticide utilization and increased infant mortality. He contends that the most compelling aspect is the parallel trajectory observed in counties upon the arrival of the disease, irrespective of the year of its onset.

Nonetheless, the precise mechanism through which heightened insecticide utilization translates into increased infant mortality remains nebulous. “I am unable to provide insights into the direct exposure mechanism; my findings only suggest that the notion of exposure via food is untenable,” states Frank.

Therefore, inhalation of insecticides or consumption of contaminated water sources emerges as the most plausible routes of exposure.

“Frank persuasively demonstrates that in counties affected by white-nose syndrome, there is a surge in insecticide utilization compared to unaffected counties,” asserts Roel Vermeulen at Utrecht University in the Netherlands.

Vermeulen, however, posits that the financial repercussions could engender heightened stress in agricultural communities, which might also contribute to escalated infant mortality. “Hence, it remains debatable whether the observed effects on infant mortality can be solely ascribed to heightened insecticide use,” he contends.

“This study underscores the capacity of bats to safeguard human lives simply by fulfilling their natural role of consuming insects,” remarks Jennifer Raynor at the University of Wisconsin-Madison.

Raynor further emphasizes the importance of diverse wildlife for human health and well-being, underscoring that technological advancements cannot invariably supplant these benefits post their loss.

Vermeulen believes the study advocates for a broader perspective on human health, asserting the necessity to transition from a human-centric health impact evaluation, solely considering the direct impacts of pollution on human health, to a planetary health impact assessment.