Climate Change Is Helping One Weird Pest Destroy More Crops

The potato leafhopper is smaller than a grain of rice, but it can devastate crops if farmers aren't prepared.

Potato leafhopper. (Photo: Wikipedia)

Jun 11, 2015· 2 MIN READ
John R. Platt covers the environment, wildlife, and technology and for TakePart, Scientific American, Audubon, and other publications.

One of the worst agricultural pests in the United States is about to get a whole lot worse.

According to new research published in PLOS One, the effects of climate change have caused tiny but devastating migratory insects known as potato leafhoppers to arrive a full 10 days earlier than they did 60 years ago. Not only that, but the research shows that bug infestation levels are worse in warmer years, meaning they could pose a much greater threat than they have for decades.

In turn, the warmer weather may push the insects to travel farther north then they typically care to, meaning potato leafhoppers could soon move into regions where they currently aren’t posing much of a threat.

“How much farther north is it going to move, and for which crops do we need to start gearing up our management?” asked Dilip Venugopal, the study’s coauthor and a postdoctoral research associate at the University of Maryland. “Oregon has a very big hop industry. Leafhoppers like hops. It will be a real punch in the stomach if we are talking about our beer.”

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Potato leafhoppers migrate annually from Southern states all the way into the northernmost U.S. states and Canada. The bugs are only about an eighth of an inch long, but they cause millions of dollars’ worth of damage to agricultural crops every year, cutting into farmers’ potato, alfalfa, and hops profits.

They can feed on the sap of more than 100 plant species, but they don’t kill plants outright. The toxin in their saliva causes plants to dry and wither, lowering crop yields. Because of the bug’s minuscule size, farmers often don’t know when potato leafhoppers have invaded until they see the telltale crop damage.

The potential danger could blindside the industry. Farmers have turned to pesticides and leafhopper-resistant strains of alfalfa to control past infestations, but they may not be prepared if the insects continue to arrive earlier and infestation levels keep increasing.

“Agricultural systems have not been paying attention to migrating species,” Venugopal said.

He and his fellow researchers studied potato leafhopper sighting data from 1951 through 2012, as well as information on how the temperatures each year varied compared with the averages from the previous century. They found that warmer temperatures allow the leafhoppers to move north more quickly and reproduce faster. Venugopal likened it to a snowball rolling down a hill: “The effect is higher the farther it rolls on,” he said.

The researchers weren’t surprised when the analysis revealed that the insects were now arriving 10 days earlier in warmer years. Venugopal said climate change–induced early migration trends have been observed in mammals, birds, and other species, but the effect of climate change on migratory pests has not been widely studied until now.

While climate change could mean more pests for Canada, rising temperatures might also mean a wider range of growing days there. That’s according to another study in PLOS One published this week, which found that the high-latitude country is one of the few that would see more “suitable growing days” if climate change projections hold through 2100.

But right now, Venugopal said the agricultural industry needs to start planning for even worse insect invasions. Organic farmers, who do not use pesticides, may find themselves facing some of the greatest threats, he said. “If there are going to be more severe infestations, we need to start thinking and developing strategies now.”