An invasive tree known as the tallow tree, considered by some to be a “super invader” with toxic leaves and no natural enemies in the United States is taking over the south.
This tree is overtaking forests from Florida to Texas, and grows three times faster than most native hardwood tree, and each one casts off about a hundred thousand seeds per year.
Controlled burns haven’t stopped their spread, nor have herbicide sprays from helicopters. Cutting them down works only when each stump is immediately doused with chemicals. Harvesting them for biofuel remains more a promise than a practical solution.
Some scientists say introducing a flea beetle from the tallow’s native habitat in eastern China may be the best alternative.
Yes, they’re aware of “nightmare scenarios” with other non-native plants and bugs, environmental scientist Michael Massimi said.
But he also points to success stories, such as the aquatic weevil that munches on giant salvinia, a floating fern from Brazil that had been clogging waterways in Florida and Texas until its insect enemy was brought in. The weevil underwent a similar line of testing through the U.S. Department of Agriculture, and like the flea beetle, the weevil spends its entire life-cycle on one plant, he said.
“Importing an organism to help control another organism right off the bat doesn’t sound very intuitively smart to do, but it turns out that especially with insects and plants, they’ve co-evolved over many millions of years, and in a lot of cases, the insect is very host-specific,” said Massimi, the invasive species coordinator for the Barataria-Terrebonne National Estuary Program along the Louisiana Gulf Coast.
In this case, the flea beetle (Bikasha collaris) generally ignores other plants as it eats the roots and leaves of the tallow (Triadica sebifera), a host-specific tendency tested on about 150 other plant species in a decade of laboratory work in the U.S. and China, researchers said.
The USDA’s Animal and Plant Health Inspection Service has been working on an environmental impact assessment, which will include a public comment period. If approved, the bugs could be released sometime in 2018. Meanwhile, researchers in Louisiana are studying tallows to gain a better understanding of the beetle’s effectiveness once they are let loose.