Weevils deployed in battle against fast-growing vine
Published 1:30 pm, Thursday, August 23, 2012
A group of scientists will soon spread out around the state to see whether countless tiny weevils have turned the tide against a fast-growing invasive vine first spotted in the state 12 years ago in northwest Greenwich.
University of Connecticut and Connecticut Agricultural Experiment Station scientists will check release sites, many of them in Fairfield and Litchfield counties, where weevils have been introduced for biological control of the mile-a-minute vine.
Researchers have been happy with what the weevils have accomplished since they were introduced in the state in 2009.
The scientists were scheduled to make some of their first stops in Westport and Stamford this week. Next week, they are scheduled to visit Fairfield, Greenwich, Norwalk and Wilton.
The vine gets its name from its rapid growth, with 6 inches on a hot summer day not unheard of. The vine wraps around and grows over other plants, drastically reducing sunlight to the plants and hindering their growth.
Greenwich Conservation Assistant Joseph Cassone, who participated when officials checked on the weevils in June, said the weevils appear to be doing their job.
"So far it looks like they are holding and spreading," he said about the weevils. "It looks like they are working. They are being found in areas where they weren't released."
One key aspect of the research was whether the weevils would be able to survive Connecticut's winters, said Carole Cheah, assistant agricultural scientist with the agricultural experiment station.
"One of the primary objectives was to see if the weevil can adapt to the southern New England climate," she said. "I think they have adapted quite well and we are quite pleased."
The monitoring in June revealed that the weevils had reproduced well after the mild winter, Cheah said.
Cheah's associate and a weed scientist at the agricultural experiment station, Todd Mervosh, said he was surprised by how much the vines had grown by that time of year and he attributed it to the early spring.
"I was a bit surprised they were as large and as long as they were on June 14," he said. "It will be interesting to see next week what it is like."
Scientists believe the vine arrived in the U.S. mixed in with a delivery of holly seeds from Japan to a now-defunct nursery outside of York, Pa., in the 1930s. The vines gradually spread outward from Pennsylvania into other mid-Atlantic states. Researchers believe the vine seeds were spread by birds or possibly inadvertently by humans.
That's where the weevil, which is no larger than an eighth of an inch, comes in.
Scientists were seeking a natural means to control the spread of mile-a-minute vine instead of using chemicals. Tests done in China and the U.S. determined the weevil would help control the spread of the vine without attacking other native plant species, Ellis said.
In Greenwich, the mile-a-minute vine was first spotted along King Street and Sherwood Avenue in the northwest corner in 2000. Many of the plants took root in Audubon Greenwich's Gimbel Sanctuary, an 80-acre site off Sherwood Avenue.
The working group has led the effort against the spread of the vine in the state. In 2009, a batch of 2,000 weevils were released in separate locations in Audubon Greenwich's Gimble sanctuary.
Last year, 1,000 weevils were introduced into Bruce Park to combat the vine that was found there.
Ellis said initial investigation of the Bruce Park site has been encouraging.
"That site has done amazingly well," she said. "There are fewer plants and the weevils established themselves very quickly."
Scientists will check to see the damage the weevils have done to the vines and also how far they have spread as they seek out new vines to use as a home.
The scientists, who are often joined by municipal environmental officials and sometimes volunteers, do a quick five-minute count at each site.
"The group disperses and in five minutes count how many weevils they find. It's almost like sneaking up on them," Cheah said. "They are very good at dispersing and finding vines in the vicinity. They can travel as far as a half-mile in one year."
Ellis said there is a slight irony in their work: as more people become aware of the vine, more vine-occupied locations are found.
"The more word we get out the more reports we have and we have a number of new towns, that included Madison, Prospect, Bristol and Middlefield."
The working group welcomes residents to report new locations and the vine can be easily identified now as it bears clusters of blue fruit, Ellis said.