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Scientists release beetle in Hillsborough parks to attack invasive vine

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Published:   |   Updated: August 7, 2013 at 05:32 PM

LITHIA — Housing booms, big box stores and off-road vehicles aren’t the only threats facing Florida’s wild lands. A lovely green vine with heart-shaped leaves that can grow nearly a foot a day is making its move on natural areas throughout Florida, land that taxpayers have spent millions to purchase and preserve.

Left unchecked, the air potato, an aggressive Asian native now found in every Florida county, can blanket and smother hardwood hammocks, pine flatwoods and wetlands throughout the state. And if that happens, the gopher tortoises, red fox, bob cats and deer that live and forage on those lands will be left without habitat to sustain them. Rare plants found only in specific areas of Florida, could succumb, as well.

Scientists are banking on a tiny red beetle to stop the marching menace, one of an ever-growing list of extremely invasive plants, including Brazilian pepper, skunk vine, melaleuca trees and Asian climbing fern, that threaten to destroy Florida’s remaining native habitats.

The beetles, which also come from Asia, feed on the leaves of the air potato, which puts stress on the plant and reduces its ability to grow.

“We believe they will kill the air potatoes,” said state entomologist Eric Rohrig. “Right now, they are suppressing them. The beetles munch away and destroy all the leaves.”

Air potato is a member of the yam family and produces small, oblong potatoes about the size of a red potato. It was first introduced in Florida by a botanist in 1905 and it has been spreading ever since. The vines are capable of growing up to 9 inches a day and can grow up to 70 feet long.

In the areas where the beetles were introduced last year, the air potato vines are not reaching half the height they did previously, due to the stress the beetles have put on the plants, Rohrig said.

“We’re trying to be proactive,” said Brian Hughes, senior park ranger at Alderman’s Ford Park, which flanks the Alafia River in eastern Hillsborough County. Hughes worked with county environmental specialists Sheryl Bowman and Ken Bradshaw to sprinkle the red beetles on top of air potato in one of three county parks in recent weeks.

About 150 air potato beetles released in Alderman’s Ford are already showing their worth, leaving behind chewed-up leaves and larvae that will produce the next beetle regiment.

“I released about 400 beetles at Rocky Creek Trails Nature Preserve in Citrus Park. There is a lot of air potato out there,” Bowman said. “We’ve been... spraying out there for years” in an effort to eradicate the air potatoes, but some areas along the creek bank are difficult to reach.

“They are all over the cypress trees, all the way up to the crowns,” she said. “You can see the air potato right off of Upper Tampa Bay Trail. It drapes the trail for miles up and down.”

The vines are also smothering the native vegetation at Rhodine Scrub Preserve in Riverview, one of numerous areas purchased through the taxpayer-funded Environmental Lands Acquisition and Protection Program. It is one of the few places where the rare golden aster plant is still found.

Scientists want the beetles to eat themselves right out of business. The releases, the first in Hillsborough County and the first mass releases statewide, were funded through a federal-state partnership between the U.S. Department of Agricultural’s Animal and Plant Health Inspection Services and the Florida Department of Agriculture.

The issue of air potato invasion is not one to be taken lightly, Rohrig said.

“Once it is there, it just takes over,” he said. “It runs off everything, including reptiles and amphibians. So, you end up with a monoculture — a huge hunk of land with nothing living there but air potato.”

“This stuff is a major threat to the majority of plant life,” said Bowman, who applied to the state to get beetles for Hillsborough County parks and preserves. If she sees signs of success, she said, she’ll apply to get more.

The state studied the beetles for five years before agreeing to release them, to ensure they would not adversely affect other plants and animals, Rohrig said. The beetles do not have any known natural predator in Florida. However, they only eat air potato and scientist believe if their food supply ever runs out, they will die off, Rohrig said.

Rohrig is already seeing signs of success in areas where the beetles were released a year ago.

At Alderman’s Ford, even after just a few weeks, many of the vines’ leaves are taking on a lacy appearance.

“We’re hoping the little guys will have a great impact,” Hughes said. And because they can fly, he said, scientists are hoping they will successfully procreate and spread to other areas.

“Right now, the focus of the project is to release them at large infestations on public lands,” Rohrig said. “In city, county and state parks, even Everglades National Park. Anywhere there is a problem. As the project progresses, we will also distribute them in residential areas. After several years, we expect to see some great results.”

Meanwhile, county scientists are counting on the public to keep them posted, even provide photos, about where the beetles land and how well they are doing their job. Anyone who sees evidence of the beetles outside park boundaries can call (813) 672-7876.

“At our research site that’s over 100 acres, there is 90 to 100 percent damage (to the air potatoes) already,” Rohrig said. “The vine isn’t dead, per se, but it’s so chewed up that the vines can’t survive like that for long.

yhammett@tampatrib.com

(813) 259-7127

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