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Tiny bug deployed as weapon against invasive Brazilian pepper tree

By
Paul Brinkmann
The Brazilian pepper tree has invaded 700,000 acres in Florida, but it now has a new enemy -- the tiny thrip, a bug being released by University of Florida researchers that will eat new growth. Photo courtesy of Vic Ramey/University of Florida
The Brazilian pepper tree has invaded 700,000 acres in Florida, but it now has a new enemy -- the tiny thrip, a bug being released by University of Florida researchers that will eat new growth. Photo courtesy of Vic Ramey/University of Florida

ORLANDO, Fla., Nov. 5 (UPI) -- A tiny bug from South America could help landowners in Florida and other states start winning a decades-long, multimillion-dollar war against invasive Brazilian pepper trees.

Since June, investigators have opened containers with Brazilian pepper thrips at many sites around the state that contain the weedy tree. The insects eat new shoots on the invasive plants, keeping their growth in check, but they do not eat other plants, said Carey Minteer, assistant professor of biology at the University of Florida.

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If they do what is expected, the bugs could help reduce the cost to ranchers and state and federal governments who spend millions of dollars annually trying to control or eradicate Brazilian pepper trees.

As a relative of poison ivy and poison sumac, the trees are is not edible for livestock, but birds eat the berries and spread the seeds. The plants are a menace in Everglades National Park, which protects unique species like the Florida panther and American crocodile in 1.5 million acres of subtropical marshland and wilderness at the southern end of Florida.

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"This insect is a much more environmentally friendly way to manage" Brazilian pepper, Minteer said. "They only thrive and reproduce on Brazilian pepper itself."

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Minteer's teams are focusing on Florida ranches first. Disturbed land, like pastures or fallow farmland, is where Brazilian pepper takes root the easiest.

In Florida alone, this non-native plant imported from South America in the 1800s now covers 700,000 acres, which is almost as large an area as Rhode Island. It originally was prized as an ornamental shrub with bright red berries and given new local names like Florida Holly or Christmas Berry.

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But it's listed as a noxious weed or invasive problem in Florida, Hawaii and Texas and in parts of California because it crowds out native plants and takes over large areas of pasture, coastline and fallow farmland.

"I have a crew that rears these thrips in high numbers so we can get them out into the state where they're needed," Minteer said. The bugs come from the University of Florida's Norman C. Hayslip Biological Control Research and Containment Laboratory, at the Indian River Research and Education Center in Fort Pierce.

Rancher Mike Adams near Fort Pierce estimates he spends $250,000 a year trying to control or eliminate the trees by cutting them back or using herbicides.

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"It's going to be a win-win for us and the environment," Adams said. "The university's biocontrol program will help us to protect our natural areas, help our cattle to have more grass, and we won't have to apply chemicals to trees anymore."

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Hawaii is gearing up to release thrips, as well, said Tracy Johnson, an entomologist with the U.S. Forest Service in Hawaii. He said he and other researchers in Texas and California are watching Florida's project closely.

He called Brazilian pepper a major problem in Hawaii, "probably in the top 20 invasive plants."

"It invades the drier side of the islands, especially ranches. It's spread over tens of thousands of acres," Johnson told UPI.

Releasing a natural enemy, also called biocontrol, is the only way to win a battle against an invasive species that has become firmly established, said Bethany Bradley, associate professor at University of Massachusetts.

Bradley has authored books on invasive species in the United States and helped organize a catalog of them. She noted that Brazilian pepper has been spreading north into Georgia and was even reported in South Carolina.

"With climate change, people do plant things farther north -- subtropical plants especially," she said. "In general, we do a very poor job of tracking plants like this and alerting other states. Usually it's not declared illegal until it's a widespread problem, and by then it's too late."

Despite the major problems, Brazilian pepper is not identified as a problem in many states. It's illegal to sell it in Florida, but nurseries still carry it in other parts of the country. For example, Brazilian pepper is for sale on the Lowe's website. Calls and emails to Lowe's were not immediately returned.

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Brazilian pepper thrips can survive cold temperatures and will eventually spread on their own, but so far they are confined to their release areas, Bradley said.

The public in general won't ever know the thrips are there, Minteer said, because they are so small. Impact on the Brazilian pepper itself would be noticeable by yellowing leaves or tips where the insect feeds.

Approved for release in June, the first distribution of Brazilian pepper thrips took place July 16 in Davie, Fla., just south of Fort Lauderdale. More of the thrips have been released in Miami-Dade, St. Lucie, Brevard, Collier, Hillsborough and Polk counties, Minteer said.

If Florida is successful in its efforts with biocontrol of Brazilian pepper, Hawaii and other states are likely to follow with their own release of Brazilian pepper thrips in the next year or two, Johnson said.

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