Today, the United States’ agricultural landscape is 48 times more toxic to insects than it was 25 years ago. Per a new study published in the journal PLoS One, a single culprit—a class of pesticides known as neonicotinoids, or neonics—accounts for a staggering 92 percent of this fatal uptick, which arrives at a point when steep bug population declines have led some experts to warn of an impending “insect apocalypse.”

For the study, scientists from four North American research institutions analyzed data on the amount of pesticides used in the U.S.; the length of time pesticides remain in the environment; and levels of toxins found in honeybees, which serve as a proxy for all insects. The numbers show just how toxic U.S. agriculture has become, according to National Geographic’s Stephen Leahy, and appear to demonstrate a correlation between increasing toxicity levels and widespread neonics use.

“It’s stunning,” Steve Holmer, a researcher with the American Bird Conservancy who was not involved in the research, tells Leahy. “This study reveals the buildup of toxic neonics in the environment, which can explain why insect populations have declined.”

Kendra Klein, study co-author and senior staff scientist at Friends of the Earth U.S., says the team did not directly gauge what pesticides bees and other insects are exposed to. As a result, the research may overestimate actual insecticide doses; Klein adds, however, that the scientists’ decision to omit neonics’ many documented nonlethal effects, including impaired learning, memory and foraging skills, leads them to believe their study is still “a very conservative estimate.”

Speaking with the Guardian’s Lauren Aratani, Klein says, “We have not learned our lessons. We know neonics are one of the most toxic classes of pesticides to bees ever introduced into agriculture. There’s this fundamental recklessness and foolishness to introducing [neonics] and continuing down this path.”

As Aratani reports, farmers use nerve-targeting neonics on more than 140 kinds of crops, including apples, rice, corn and soybeans. The insecticides, introduced during the 1990s to combat insects’ heightened immunity to pesticides, were once praised for their supposed low toxicity. Now, they are known to be not only incredibly toxic, but persistent, remaining in soil, waterways and wetlands upward of 1,000 days.

Many of these lingering effects stem from the fact that neonics are systemic insecticides. When applied, the pesticides are dissolved and absorbed into crops, spreading toxins everywhere from stems to leaves, pollen, nectar and sap.

“I’ve documented and seen massive bee killings at the time of corn planting,” Minnesota commercial beekeeper Steve Ellis tells Aratani. “The dust comes off the corn seed and drifts on to flowers and flowering plants at corn seeding time and makes them toxic.”

Ellis continues, “It’s enough to kill them instantly. They come back and they’re suffering a lethal dose, lying on their backs dying from gathering the nectar and the pollen from the willow trees adjacent to the corn field.”

It’s worth noting that the European Union, acting in response to a report detailing the pesticides’ harmful effects on honeybees and wild bees, instituted a blanket ban on neonics at the end of 2018. Canada took similar regulatory steps earlier this year. The U.S.’ Environmental Protection Agency, meanwhile, banned 12 types of neonics in May but has yet to take more decisive action.

The most extreme predictions surrounding insects’ decline tend to be highly exaggerated: A study published earlier this year, for example, posited that 41 percent of insect species are declining and global numbers are dropping by 2.5 percent annually. But as Michelle Trautwein of the California Academy of Sciences tells the Atlantic’s Ed Yong, the researchers behind the findings are “trying to quantify things that we really can’t quantify at this point.”

Still, Yong writes, “What little information we have tends to point in the same worrying direction.”

The news isn’t all negative. “The good news is that we don’t need neonics,” Klein tells National Geographic’s Leahy. “We have four decades of research and evidence that agroecological farming methods can grow our food without decimating pollinators.”