SALON

Wednesday, Oct 28, 2009 9:05 PM UTC

Transgenic squash super-weeds gone wild

Genetically modified squash will contaminate their wild cousins, delighting cucumber beetles everywhere

By

Topics: How the World Works, Biotechnology,

Genetically modified corn and soybeans get all the press, but since as far back as 1996, transgenic squash, engineered to include resistance to three of the most deadly squash viruses, has been farmed in both the U.S. and Mexico. Since gene flow from GM crops into their wild counterparts is inevitable, some scientists worry that farmers may be inadvertently creating a race of super squash weeds. This would be a problem, because some varieties of wild squash — specifically, Texana gourds — are considered serious weed threats in cotton and soybean fields. This is what happens when you mess with Mother Nature — your transgenic squash genetically contaminates wild squash which then proliferates through your genetically modified corn and soybean fields.

Or at least that’s one theory. Some researchers at Penn State, led by biologist Andrew Stephenson, set out to find out exactly what we can expect to happen as transgenic squash genes migrate into the wild. They planted mixed populations of transgenic and wild squash and recorded their susceptibility to various viral and bacterial pathogens over a three-year period. (Abstract of paper in the Proceedings of the National Academy of Science here. Layman-friendly summary of research here.)

As expected, the GM squash did a good job of resisting the viral pathogens, which instead hit the wild squash hard, resulting in stunted, slower growth and fewer flowers. But then an interesting thing happened. Squash have evolved in conjunction with their own specialist herbivores, cucumber beetles. Most herbivores are repelled by bitter compounds produced in squash leaves called cucurbitacins. But not tcucumber beetles; they just can’t get enough of the stuff. Unfortunately for the squash, the cucumber beetles are a transmission agent for a bacterial squash killer — wilt disease — which spreads via beetle poop that falls into the “open wounds” of chewed-upon squash leaves.

Cucumber beetles, quite understandably, don’t enjoy feasting on stunted, droopy squash plants that have been hammered by viruses. Instead, they seek out the biggest, healthiest, most abundantly flowering squash plants they can find. Which means the Penn State researchers discovered that the genetically modified squash that had most successfully resisted viral infection perversely attracted hordes of beetles, and thus were more likely to contract the deadly wilt disease than their wild counterparts. Built-in resistance to one set of mortal threats unexpectedly set them up to be vulnerable to an entirely different doom.

The moral of the story? In this case, the dangers of viral resistance from genetically modified squash escaping to the wild and creating a race of super-squash weeds that would rampage through the corn fields might be a little overblown. That does not mean, however, that Mother Nature will automatically maintain the status quo no matter how dramatically humans tinker with the structure of living things. It just tells us that figuring out how ecosystems will react to the introduction of new species with new traits is a complex business, with a host of unexpected variables lying in wait to trip us up.

Andrew Leonard

Andrew Leonard is a staff writer at Salon. On Twitter, @koxinga21. More Andrew Leonard.

Next Article

Related Stories

More Related Stories

Featured Slide Shows

The week in 10 pics

close X
  • Share on Twitter
  • Share on Facebook
  • Thumbnails
  • Fullscreen
  • 1 of 11
  • Lisa Montgomery embraces her nephew Thursday after a tornado tore apart her home in Cleburne, Texas. The twister killed six people and destroyed entire swaths of the North Texas town.
    Credit: AP/LM Otero

  • Jack McMahon, the defense attorney for abortion doctor Kermit Gosnell, speaks outside the Criminal Justice Center Philadelphia Tuesday. His client was convicted of killing three babies in his clinic, and will serve multiple life sentences.
    Credit: AP/Matt Rourke

  • A photo taken Monday captures Vice President Joe Biden's response to a Milwaukee second-grader's innovative proposal to end America's epidemic of gun violence. This guy!
    Credit: AP/Jenny Aicher

  • Sen. Rand Paul, R-Ky., flanked by a grouper-eyed Michele Bachmann, addresses the IRS' admission that it targeted Tea Party groups in advance of the 2012 election. In an op-ed for CNN Thursday, the Kentucky senator slammed the president for his faux outrage.
    Credit: AP/Molly Riley

  • Ousted IRS chief Steven Miller is sworn in on Capitol Hill Friday. Miller testified before the House Ways and Means Committee on the extra scrutiny the agency gave conservative groups applying for tax-exempt status.
    Credit: AP/J. Scott Applewhite

  • Attorney General Eric Holder pauses as he testifies on Capitol Hill before the House Judiciary Committee Wednesday. Holder is under fire, among other things, for the Justice Department's gathering of phone records at the Associated Press.
    Credit: AP/Carolyn Kaster

  • O.J. Simpson sits during an evidentiary hearing at Clark County District Court in Las Vegas, Nev., Thursday. Simpson, who is currently serving a nine-to-33-year sentence in state prison for armed robbery and kidnapping, is using a writ of habeas corpus to seek a new trial.
    Credit: AP/Las Vegas Review-Journal/Jeff Scheid

  • Major Tom to ground control: On Sunday astronaut Chris Hadfield recorded the first music video from space, a cover of David Bowie's "Space Oddity."
    Credit: AP/NASA/Chris Hadfield

  • When it rains it pours. President Barack Obama speaks during a news conference Thursday with Turkish Prime Minister Recep Tayyip Erdogan, inexplicably inspiring an #umbrellagate Twitter meme.
    Credit: AP/Jacquelyn Martin

  • A smoke plume rises high above a road block at the intersection of County A and Ross Road east of Solon Springs, Wis., Tuesday. No injuries were reported, but the the wildfire caused evacuations across northwestern Wisconsin.
    Credit: AP/The Duluth News-Tribune/Clint Austin

  • Recent Slide Shows

  • Share on Twitter
  • Share on Facebook
  • Thumbnails
  • Fullscreen
  • 1 of 11

Related Videos

Comments

 16 Comments

Comment Preview

Your name will appear as username

You may use these HTML tags and attributes: <a href=""> <b> <em> <strong> <i> <blockquote>

A conversation about globalization.

follow salon

Most Read

Popular on Reddit

links from salon.com

vote
New Yorker launches tool by Aaron Swartz to protect leaks: Strongbox, co-created by the late technologist, is an open-source drop box for leaked documents
156 points157 points | 4 comments
vote
New Yorker launches tool by Aaron Swartz to protect leaks: Strongbox, co-created by the persecuted late technologist, is an open-source drop box for leaked documents
116 points117 points | comment
vote
Obstruction will ruin the GOP: Playing politics and abusing the system can excite the extremes, but it's a recipe for long-term political disaster
37 points38 points | 8 comments
vote
With the help of Photoshop, artist Yao Lu has made shanshui — traditional ink paintings — of China's landfills
12 points13 points | comment
vote
Revenge editing on Wikipedia: The unmasking of a writer who took advantage of online anonymity to pursue vendettas with other writers
12 points13 points | 3 comments

From Around the Web

Presented by Scribol
listener_new_rect The Listener: So long, Sookie Stackhouse

Recommendations