Almond crop growers are faced with a predicament. Fungicides commonly used in almond orchards can harm the tree nut’s very own key pollinator: honey bees.

Researchers from Texas A&M University found that the fungicide iprodione, whether used alone or combined with other fungicides, can cause honey bees to die within about 10 days once they are exposed to amounts commonly used out in the field.

How Fungicides Affected The Bees

“[O]ur findings suggest that bees may face significant danger from chemical applications even when responsibly applied,” said study author and apiculture expert Dr. Juliana Rangel in a statement.

To test their effects on honey bees, researchers sprayed fungicides at varying doses and speeds through a wind tunnel. They were then assigned to different habitats and monitored for 10 days. A control group, on the other hand, received no chemical treatment.

The team found that the bees exposed to iprodione by itself or combined with fungicides boscalid, pyraclostrobin, and azoxytrobin perished at twice or thrice the rate of unexposed bees after the 10-day period. The effect was greater with a combination of fungicides.

It remains unclear how and why this specific fungicide is so destructive to honey bees. Previous research, however noted that some fungicides have greater persistence in residual amounts in honey bee wax in hives.

Consequences

In California alone, the almond production industry churns out around 80 percent of almonds consumed around the world, according to the Almond Board of California. Almost exclusively, almond growers depend on managed honey bees for pollination needs.

Honey bees alone contribute around $17 billion every year to the U.S. economy mainly through pollinating major agricultural crops, including almond.

Lead author and doctoral student Adrian Fisher II said that their findings could encourage alternatives such as changing spraying regimes or finding new chemical application methods that considers the pollinators’ biology and behavior.

“[W]e propose a more careful consideration of fungicide application in almond orchards or any agricultural crop during bloom, because it might negatively affect honey bee colony health in ways that are still poorly understood,” the authors recommended.

The findings were discussed in the Journal of Economic Entomology.

Grim Future Ahead

From the looks of it, bees worldwide are facing tough times.

The United States just declared the rusty patched bumblebee an endangered species, following delays in the Trump administration. Last September, the U.S. Fish and Wildlife Service (USFWS) already proposed the listing, but it had been delayed until March 21 as part of a bigger freeze imposed by the White House.

The rule formalizing the listing was in fact published in the Federal Register as early as Jan. 11 and was supposed to take effect in early February. This had even led to environmental group Natural Resources Defense Council filing a suit against Trump for delaying the bees’ protection.

Bumblebees are deemed crucial in many ecosystems for helping reproduce native wildflowers as well as creating seeds and fruits feeding wildlife as diverse as grizzly bears and songbirds, the federal agency said.

Disease and pesticide use are pinpointed as two of the biggest threats to bees’ existence, as compounded by their loss of habitat.