Wasp Kills Pines

  • The Sirex woodwasp is killing pinetrees in New York, Pennsylvania and parts of Ontario and seems to be spreading. (Photo by Lester Graham)

Foresters are worried about a wasp that’s killing pine trees. The insect is
spreading through pine forests in northern states. Steve Carmody reports:

Transcript

Foresters are worried about a wasp that’s killing pine trees. The insect is
spreading through pine forests in northern states. Steve Carmody reports:


The female Sirex woodwasp injects a combination of a toxic mucus and a
fungus while laying her eggs in pine trees. The mixture feeds the eggs, but
kills tree cells, often further weakening stressed pines.


In the three years since it first appeared in upstate New York, the Sirex
woodwasp has spread to 25 New York counties, and two counties in
Pennsylvania and part of Ontario.


Bob Heyd, with the Michigan Department of Natural Resources, says the Sirex
woodwasp is spreading:


“The wasp is actually very strong fliers. They can fly 70 or 100 miles, so what it
is here… it will disperse very quickly.”


In other countries, forestry officials have found an imported predatory
nematode from the wasp’s home range in Europe has been an effective
biological control. It’s unclear if officials in the US will try the same
tactic.


For the Environment Report, I’m Steve Carmody.

Related Links

Hunt for Slug-Eating Nematodes

A $5,000 reward is being offered to anyone who finds a tiny, parasitic worm in the U.S. that kills leaf-eating slugs. The gray garden slug is notorious for destroying crops and ornamental plants in the Midwest. Researchers at Ohio State University have been looking for the worm that eats the slugs. So far, they’ve examined thousands of slugs sent to them in the mail … but they haven’t been able to find the worm. The Great Lakes Radio Consortium’s Natalie Walston reports:

Transcript

A five thousand dollar reward is being offered to anyone who finds a tiny, parasitic worm in the United States that kills leaf-eating slugs. The gray garden slug is notorious for destroying crops and ornamental plants in the Midwest. Researchers at Ohio State University have been looking for the worm that eats the slugs. So far, they’ve examined thousands of slugs sent to them in the mail, but they haven’t been able to find the worm. The Great Lakes Radio Consortium’s Natalie Walston reports.


(Natural sound of guinea hens)


The Kingwood Center in Mansfield, Ohio is made up of 50 acres of well-tended English gardens. Paved trails lead through rows of perennials and peonies, around fountains and a duck pond. Hundreds of hostas grow beneath shade trees, but the plants leaves have holes chewed through them. John Makely is Kingwood’s head gardener. He says the conventional methods to kill the slugs eating his hostas are out of the question here.


“The problem that we have here with slug bait is that we do have birds roaming around, peacocks and guinea hens that roam around freely. They sort of grouse, browse I should say, the grounds and we would be afraid that they would pick up some of those pellets and poison them.”


Slug bait consists of a poison that can harm more than its intended target. But right now, it’s the only commercial method available to control slugs. So, now there’s a big push by large, commercial nurseries to find a chemical-free way to kill the gray garden slugs that eat ornamental plants. Ohio State University researcher, Pavinder Grewal says there’s a major economic reason to find a good control method.


“Last year we had a lot of rain here when the corn was emerging. And there have been several fields in Ohio that were totally wiped out by the slugs. Basically zero corn production in some fields.”


Grewal has found a natural slug killer. It’s a tiny parasitic worm, known as a nematode. It is native to England and parts of several countries in South America. Farmers and gardeners in those countries buy them in bulk in powder form and sprinkle the worms on their fields. Scientists think the worm will work in this country as well. But if the worm is imported, it must first undergo years of testing to make sure it will not harm native plants and animals.


“We don’t see any problem because some of the tests that we have performed with the nematode…we find it to be pretty safe to non-target organisms. And, we find that this nematode does not infect all slugs.”


To prove this to the federal government could be difficult. Grewal is looking for the worm, in the United States he took out an ad in various publications. He studies more than twenty thousand slugs, but has yet to find the worm he’s looking for. Now he’s sending people off to remote areas of the country to find it. He hopes to be successful because it could take years of testing before the worms can be brought into this country. For the Great Lakes Radio Consortium, I’m Natalie Walston.