Monoculture farming is another way modern-day agriculture is killing bees, scientists say

While pesticides have long been blamed for the decline in pollinators, a study published in Proceedings of the Royal Society B on Tuesday has found that the mass-flowering of single plant species is increasing the prevalence of bee populations infected with parasites.

Monoculture farming -- which involves growing only one type of crop at a time on a specific field -- is a common agricultural practice, especially in the U.S., which has about 440 million acres being cultivated for monoculture. But one of the consequences of the practice is that landscapes without much natural habitat can suddenly experience mass-bloom events and have negative impacts on bees, according to the study.

Researchers at the University of Oregon surveyed 1,509 bees in sunflower fields and non-crop flowering habitats in California's Central Valley, finding that when the crops flowered for a short period of time across a large space, the events can aggregate pollinator species together, which then results in increased rates of bees becoming infected with parasites as they come in contact with each other.

Monoculture landscapes are attractive to bees because of the massive amounts of pollen and nectar provided by flowers that bloom at the same time, the researchers said. While mass-bloom events have the potential to provide immune and nutritional benefits to the bees, they instead were associated with higher rates of disease-causing parasites and pathogens in bees, Hamutahl Cohen, a researcher of the at the University of Oregon's Institute of Ecology and Evolution and one of the authors of the study, told ABC News.

"We have an incredible amount of biodiversity on this earth," Cohen said. "And we're seeing that wildlife is declining, and one of the primary drivers of decline is disease."

While in many ways the modification of landscapes is necessary to feed a growing population, Cohen described the mass-flowering crops as the "doorknobs of the bee world" as bees go from flower to flower to collect food amid their daily work.

"It's just the same thing as a human touching a doorknob," she said. "We all know this, because of the pandemic ... if you have a cold and you touch a doorknob, and someone else comes and touches that doorknob, they can get sick."

Scientists are suggesting that farmers stop the practice of monoculture farming, which are often in "highly degraded areas" such as California's Central Valley, which has seen an "incredible amount" of habitat loss in the past 100 years, Cohen said.

However, the fate of bees is not doomed, Cohen said. On fields where farmers who heeded the call to implement strips of perennial plants, bee aggregation was less likely to be associated with parasitism due to the increased diversity of flowers.

While Cohen was not surprised to see the enhanced rates of parasitism in bees and monoculture farming systems, she was surprised to find just how effective planting non-crop flowers were for conservation efforts.

"It didn't just dampen the effect of aggregating these," she said. "It actually reversed the effects."

The perennial plants are often selected for characteristics like drought tolerance and suitability for pollinators, Cohen said, adding that there can be "economic hurdles" to changing the landscape to implementing conservation practices.

These foods could disappear if pollinator populations continue to dwindle

Bees -- whether wild or managed --are integral to the production of the world's food supply. But as populations continue their steep decline, the crops that rely on pollination could become more scarce and even cease to exist in the future, according to scientists.

There are more than 4,000 species of bees in America, a large proportion of which are experiencing widespread decline, Scott McArt, assistant professor of pollinator health at Cornell University, told ABC News. In New York, 53 species, about 13%, are either experiencing population declines or range contractions over the past three or four decades, McArt said.

The honey bee population decreased 40% in the winter of 2018 to 2019 alone, and the annual rate loss for the 2019 to 2020 winter was also 40%, declines that experts described as "unsustainable."

The situation "isn't good," and most likely is even worse than researchers are estimating, he added.

"It's likely an underestimate of the true scope of population declines, simply because we don't have great historical records on a lot of these species," McArt said.

The production of crops that depend on pollinators generates more than $50 billion a year in the U.S., researchers say. Managed bee populations, which involve a beekeeper arriving to put down hives just as the crops are flowering, alone contribute to about $20 billion worth of U.S. agricultural production, Matthew Mulica, senior project manager at the Keystone Policy Center, a consulting company that works with the Honey Bee Health Coalition, told ABC News.

A "large proportion of what we eat" relies to some extent on pollinators, McArt said. An estimated 87% of angiosperms, or flowering plants, are reliant on pollinators, while around 75% of those are crops that rely on pollination, he added. The commercial production of more than 90 crops relies on about 3,600 bee species, according to the U.S. Food and Drug Administration.

Some of the crops that rely most on pollinators include almonds, blueberries, pears, apples, cherries, peppers, cucumbers and broccoli, Mulica said.

The bees also oil seeds in other crops, such as corn and soybean, Mulica said.

"It's an amazing service that honey bees and beekeepers provide for for agriculture," Mulica said.

Conservationists and scientists who study food security alike are concerned about how the downward trend of bee populations will affect food supply going forward, McArt said.

In the short term, food prices could rise if the number of bees pollinating crops continue to die off.

In the future, the crops could disappear forever, experts say.

How to mitigate pollinator declines

The top stressor on pollinators is the lack of habitat and floral resources, McArt said. Bees are actually thriving in agricultural and natural areas, McArt said, adding that it's the suburban and urban areas where they're not doing well.

"That happens to be where most of us live," he said.

McArt encouraged anyone with a plot of land or even an apartment balcony to plant a pollinator-friendly garden. He also suggested that homeowners hold off on mowing their lawns too often to encourage wildflowers to grow.

In addition, it will be necessary in the future to reduce the use of pesticides and mitigate climate change, which can cause plant pathogens to infect crops at higher rates, McArt said.

Lastly, beekeepers need to meticulously manage their hives, which can spread disease to wild bees if not monitored correctly, McArt said.

"That requires a lot of management by the beekeepers -- a lot more splitting of hives and re-cleaning," Mulica said.