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SUPERFLY - Biologists Hope Insect Will Rescue The Lovely Bromeliad

DOROTHY L. HARRIS/Courtesy photo

Mike Burton, a University of Florida Institute of Food and Agricultural Sciences biologist, releases 100 lixadmonti franki flies. Their larva eats Mexican bromeliad weevil larva.

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By Gary Pinnell | Highlands Today

Published: October 24, 2007

If you're in Highlands Hammock State Park and a fly lands on your nose, don't swat it. That might be Franki, who's flying to the rescue of bromeliads everywhere.

One hundred lixadmonti franki flies were released in the hammock and thousands more across south Florida to combat the evil Mexican weevil, whose nests destroy bromeliads.

What are bromelaids? They're epiphytes, meaning they grow on trees. Most have long thin leaves and some have a brilliant flower, which sprout from a rain-filled core or cup.

There are 20 varieties of bromelaids in Florida, not just in state parks, but on private property as well.
The pineapple bromeliad is related to the pineapple family, with its long mint-green leaves. Another looks like pine needles stuck in the side of a tree. The best known bromeliad is Spanish moss.

"Some people think Spanish moss is a parasite, but it's not, it's an airplant," said Dorothy Harris, park services specialist.

The real parasites in this story are weevils, which shred the inside of the bromeliad to make a cocoon.
"The larvae," said Harris, "destroy the host plant as they tunnel and feed within its interior. You don't see the weevil itself. You see it when the plant falls to the ground like leaf litter."

The weevils were first discovered in 1989 in imported nursery plants, then in Highlands County in March 1999, said Howard Frank, a University of Florida professor. They've spread through 21 counties in southern Florida, from the Keys north to Orange County.

"Once we were aware they were in Florida, we started doing surveys in the park," said Harris. At first, they saw an abundance of healthy bromeliads. These days, not so many.

"Our plants got eaten," Harris said. "After the hurricanes in '04, it seems like the fallout has gotten less. But we have far fewer plants than we had. The wind blew a lot out of the trees. Some plants are
surviving. But I'm not sure if the little plants are going to make it, or if they grow to a certain size and then the weevil moves in."

"They are still moving north," Frank said, speaking passionately. "The bromeliads are dropping dead out of the trees, and I don't like that. Which makes this a horrible problem. People go on and on about the manatee and the scrub jay. We're talking about 20 species being wiped out."

Why We Fight

When the weevils hitched a ride from Mexico, they left behind all their natural predators, said Harris.
So how should botanists fight the weevil?

"Well, we can't do anything with chemicals," Frank said. "You can't spray all of central Florida by air with pesticides. It would cause untold environmental harm." Meaning it would kill beneficial insects, animals, maybe even people.

Which brings us back to franki, the fly. Like the weevil, the fly is also a parasite, but that's what biologists are counting on.

As part of the Comprehensive Everglades Restoration Plan, the South Florida Water Management District invested $17,000 on fly research.

"They're a little bigger than a housefly, and our hope is they will eventually reproduce enough," Burton said.

But why should we care about the bromeliad? Good question, Harris conceded, but the answer isn't so clear.

"They are what make the Florida environment different from that of North Carolina," Frank said.
And they are little ecosystems in themselves. They provide homes to other tiny organisms, intricate species which have never been closely studied, Harris said. "We don't know what they do."

What is certain is that if bromelaids are wiped out by the weevil, a fraction of the earth's ecology could disappear.

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