Florida growers and researchers are keeping a wary eye on chilli thrips, an invasive pest with potential to spread and damage a wide array of crops.
Florida’s landscape plant industry so far is ground zero for the pest since its discovery in the United States, but it’s been spotted as far away as Texas. Scattered Florida outbreaks also have occurred in blueberry, strawberry and pepper fields.
Around the world, chilli thrips attack crops ranging from cucumbers to tomatoes, mangoes, citrus and strawberries.
“It’s got the potential to go clear across the Sun Belt,” says Galen Frantz, senior crop management specialist with Glades Crop Care Inc. in Jupiter. “There’s enough traffic in foliage between Florida and California and all points in between.”
Rotate modes of action
Many transplant producers mingle ornamentals and vegetables, increasing movement opportunities, says Lance Osborne, entomology professor at the University of Florida’s Apopka research center.
Chilli thrips could spread even farther, says Dakshina Seal, assistant research scientist at the university’s Homestead research center. Based on its global range, crops as far north as Canada may be threatened.
But for now, growers have several insecticides, including neonicotinoids, available to keep chilli thrips in check.
Transplanted material seems to be the main source of new infestations. Vegetable growers’ practice of applying an initial insecticide spray immediately after putting in transplants appears to prevent chilli thrips from getting a foothold there.
But, Seal says, “It’s only a matter of time before they develop resistance and they will become a serious problem.”
A similar resistance pattern is showing up with melon thrips, which first appeared in Florida in the 1990s, he says.
Frigid weather last winter help cut chilli thrips’ Florida populations, but their rapid reproductive cycle means numbers rebound when temperatures rise, Osborne says. “They’re just not starting at the levels of previous years.”
A new generation every two weeks during summer makes scouting crucial, says Scott Ludwig, integrated pest management specialist Texas AgriLife Extension Service in Overton. Without immediate attention, pest populations may shoot out of control.
Chilli thrips feed on tender new growth, primarily foliage, often sheltering in the centers of plants where that growth is concentrated. Outer layers can make them hard to spot.
“Anything that grows and is flushing in June and the rest of the summer months is at risk,” Ludwig says.