Beetle helps control Florida's tropical soda apple problem

Over the past two decades, Florida cattle ranchers have spent as much as $16 million a year doing battle with an invasive weed called tropical soda apple, known as TSA, that takes over pastures, elbowing out the forage grasses ranchers need for their cattle.

But a beetle released by the University of Florida’s Institute of Food and Agricultural Sciences is taking a bite out of the problem by feeding on the weed and reducing its competitiveness. UF researchers describe the beetle’s success as a biological control agent in the current issue of the journal Florida Entomologist.

Gratiana boliviana, as the beetle is known to scientists, is a native of South America and the first biological control agent in North America to be used against TSA. The beetles are highly specific feeders whose voracious appetite is focused only on TSA but not on related plants such as eggplant, peppers or potatoes.

Julio Medal, the UF entomologist who led the research team that released the beetle, said TSA has not only been a problem on cattle ranches, but also in citrus groves and vegetable fields.

“It causes a lot of economic problems, and to prevent its spread, you can’t move cattle from Florida to other states without holding them at least six days in a TSA-free area,” he said. This is enough time to destroy the viability of any TSA seeds that may be in their digestive tracts.

Nearly 200,000 beetles have been released in the state since 2003, and the insect is now established throughout central and south Florida. In the journal, Medal reported that the beetles caused the invasive weed to suffer significant defoliation as well as decreased fruit, and thus seed production, in Polk and Okeechobee counties.