News / Science & Technology

Plants Weaken Without Insects Bugging Them

During each growing season for five years, eight of the 16 experimental primrose plots (yellow flowers) were treated biweekly with an insecticide; the other eight were not. (Credit: Anurag Agrawal)
During each growing season for five years, eight of the 16 experimental primrose plots (yellow flowers) were treated biweekly with an insecticide; the other eight were not. (Credit: Anurag Agrawal)
Rosanne Skirble
Farmers' efforts to keep their fields free of insect pests could actually be weakening their crops, according to a new study.

Plants and insects have always had a complex relationship, and over millions of years, they have changed each other in significant ways.

Even as insect pollinators encouraged plants to produce colorful flowers, many plants also developed traits, such as powerful toxins, to protect themselves from hungry bugs.

Evolutionary pressures

The new study examines how insects and plants are still co-evolving.

Plant-Pest-Evolution
Plant-Pest-Evolutioni
|| 0:00:00
...
 
🔇
X


Anurag Agrawal studies evolution in real-time. The Cornell University professor of ecology and evolutionary biology set up experimental plots of evening primrose to observe the evolutionary pressures that insects continue to put on the wildflower.

“We took insects out of the picture for half of the plots, using an insecticide, and we then watched the evolutionary change that happened in those plant populations,” said Agrawal.
Seed predation on evening primrose fruit by Monpha brevivitella moth larva. (Credit: Marc Johnson)Seed predation on evening primrose fruit by Monpha brevivitella moth larva. (Credit: Marc Johnson)
x
Seed predation on evening primrose fruit by Monpha brevivitella moth larva. (Credit: Marc Johnson)
Seed predation on evening primrose fruit by Monpha brevivitella moth larva. (Credit: Marc Johnson)

Agrawal and colleagues were surprised by what they saw. In their five-generation, five-year study reported in Science, evidence for evolutionary change began showing up quickly, after just two or three years.  

“When we take insects out of the picture, essentially the plants were less resistant. In other words, they evolved in the direction we expected them to," Agrawal explained. "If they are not experiencing the pressure of insect pests, they were flowering earlier and producing less toxins so they become essentially less resistant.”

Losing their resistance

In other words, plants that enjoyed chemical pest protection lost some of their natural bug resistance, compared to plants that were not sprayed. 

Agrawal says he and his team were also surprised to discover that the speedy adaptation of the primrose to a bug-free environment triggered other changes in the local ecology.  “And that had to do with the other species that were competing with our evening primroses,” he said.

Such as dandelions, whose population doubled over the five years, reducing the number of primroses.

“The suppressing of the insects favored the dandelions,” Agrawal added.

Most plants naturally produce defensive toxins to ward off insect attacks. But in today’s high-yield farming systems, growers have strong incentives to use powerful chemical sprays to keep pest populations under control. 

Natural balance

Agrawal's study suggests farmers should consider ways to strike a more natural balance between crops and bugs.

“I think that what it tells us is that insects are really important, that over the millennia plants have figured out ways to co-exist with their pests and that when we perturb that system in any way, there are likely to be a set of consequences, some of which we can predict and others we can’t,” he says.

The researchers plan to maintain their experiment as a living, learning laboratory to track evolutionary changes over the coming decades.

You May Like

Karzai's Legacy: Missed Opportunities?

Afghanistan's president leaves behind a much different nation than the one he inherited, yet his legacy from 13 years in power is getting mixed reviews More

Video Secret Service Chief Under Fire for White House Security Breach

Julia Pierson faces tough questions from lawmakers after recent intrusion at White House, says: 'It is clear that our security plan was not executed properly' More

Frustrated, Liberian Students Want Ebola Fight Role

Thousands have volunteered to go to counties, rural villages to talk to people in their language about deadly virus More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Malaysia Struggles to Stop People Joining Jihadi
X
Mahi Ramakrishnan
September 30, 2014 2:16 PM
Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Malaysia Struggles to Stop People Joining Jihad

Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Could US Have Done More to Stop Rise of Islamic State?

President Obama says airstrikes against Islamic State militants in Syria will likely continue for some time because, in his words, "there is a cancer that has grown for too long." So what if President Obama had acted sooner in Syria to arm more-moderate opponents of both the Islamic State and the Syrian government? VOA State Department Correspondent Scott Stearns reports from the United Nations.
Video

Video Treasure Hunters Seek 'Hidden Treasure' in Central Kenya

Could a cave in a small village in central Kenya be the site of buried treasure? A rumor of riches, left behind by colonialists, has some residents dreaming of wealth, while others see it as a dangerous hoax. VOA's Gabe Joselow has the story.
Video

Video Iran's Rouhani Skeptical on Syria Strikes

Iranian President Hassan Rouhani expressed skepticism Friday that U.S.-led airstrikes in Iraq and Syria could crush Islamic State militants. From New York, VOA’s Margaret Besheer reports the president was also hopeful that questions about Iran’s nuclear program could be resolved soon.
Video

Video US House Speaker: Congress Should Debate Authorization Against IS

As wave after wave of U.S. airstrikes target Islamic State militants, the speaker of the Republican-controlled House of Representatives says he would be willing to call Congress back into session to debate a formal, broad authorization for the use of military force. VOA’s Michael Bowman reports from Washington, where legislators left town 10 days ago for a seven-week recess.
Video

Video Ebola Patients Find No Treatment at Sierra Leone Holding Center

At a holding facility in Makeni, central Sierra Leone, dozens of sick people sit on the floor in an empty university building. They wait in filthy conditions. It's a 16-hour drive by ambulance to Kailahun Ebola treatment center. Adam Bailes was there and reports on what he says are some of the worst situations he has seen since the beginning of this Ebola outbreak. And he says it appears case numbers may already be far worse than authorities acknowledge.
Video

Video Identifying Bodies Found in Texas Border Region

Thousands of immigrants have died after crossing the border from Mexico into remote areas of the southwestern United States in recent years. Local officials in south Texas alone have found hundreds of unidentified bodies and buried them in mass graves in local cemeteries. Now an anthropologist and her students at Baylor University have been exhuming bodies and looking for clues to identify them. VOA’s Greg Flakus has more from Waco, Texas.
Video

Video Ebola Robs Liberians of Chance to Say Good-Bye to Loved Ones

In Liberia, where Ebola has killed more than 1,500 people, authorities have worked hard to convince people to allow specialized burial teams to take away dead bodies. But these safety measures, while necessary, make it hard for people to say good bye to their loved ones. VOA's Anne Look reports on the tragedy from Liberia.
Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.

AppleAndroid