Invasive thrips in Florida

Photo courtesy of Lance Osborne

An invasive thrips species has been wreaking havoc in Florida. The insect was first detected in Florida in 2020 but has since spread significantly across the state. What once was isolated to greenhouses now has begun to harm a wide range of plants including those in residential landscapes.

The insect, Thrips parvispinus — commonly known as pepper thrips — is one of the smallest thrips species in Florida. Its size makes it challenging to detect. The tiny insects fly and hop from plant to plant, rasping the plant with their mouth parts and sucking the sap. Feeding on the plant restricts the plant’s growth and reduces crop yields. Researchers don’t know of any viruses this species transmits, but often, thrips can transmit viruses between plants, killing the plants.

“It isn’t that the sky is falling, but we have to pay attention to this and not ignore it,” says Lance Osborne, UF/IFAS entomologist at the Mid-Florida Research and Education Center. “Growers of any crop should be aware. This insect seems to have a fairly broad host range. This won’t just impact peppers and ornamental plant growers.”

Resources and research

A new website (bit.ly/thrips-ufl) developed in collaboration between UF/IFAS and USDA provides detailed information on the insect’s biology, early detection and damage symptoms with detailed videos and images. This website also includes a downloadable scouting sheet and means of contacting the proper professionals for any grower who detects the pest in their operation.

The pest has been detected on a wide variety of plants including 43 species from 19 plant families including ornamental plants, vegetables and fiber crops. Muhammad “Zee” Ahmed, USDA research entomologist, expects the list to grow.

“In order to minimize any kind of negative impacts, we started warning people right away that this pest had made its way to Florida,” says Osborne. “We better be careful. This insect is notorious for damaging peppers around the world but now it has moved from the greenhouse to the environment and has established itself in several areas around the state.”

“While damage symptoms are the most noticeable indicators of its infestations, they may not appear until after the plant has sustained considerable harm,” says Ahmed. “As they say, prevention is always better than cure, and this is particularly true when dealing with T. parvispinus.”

The research team including Ahmed, Cindy McKenzie of USDA, and UF/IFAS Extension agent John Roberts conducted a survey of garden centers in Palm Beach County to understand how widespread the pest is. Eight out of nine stores entomologists visited had the pest.

In November, a south Florida grower lost an entire pepper crop valued at more than $1.3 million to the pest.

“At first, the damage can mimic mites and can be misleading,” says Osborne. “The control methods are not the same and without proper treatment, these thrips can take out a whole crop.”

Entomologists encourage growers to scout often and inspect their plants carefully.

“Now that we know more about the insect, we need to do more research to know how to manage them,” says Osborne. “We want to help growers avoid wasting money and chemicals, so we are working to develop effective spraying strategies for controlling their populations.”

Researchers are conducting controlled experiments in quarantine facilities, including Alexandra Revynthi at the UF/IFAS Tropical Research and Education Center and Osborne at MREC. But scientists are eager to test their findings in real-word scenarios.

The regulations for research on controlled pests of this kind are strict. Scientists cannot move plant material or the live insects outside of infested areas, or work with them in university facilities accept in an approved quarantine room.

As such, research into how to manage the pest is still in its early stages, but researchers have made some progress.

When it comes to controlling thrips with insecticides, Piston, Conserve and Xxpire have the highest efficacy among contact insecticides tested in laboratory conditions, according to Alexandra Revynthi, assistant professor of ornamental entomology and acarology at UF/IFAS. Revynthi also notes there are good alternatives to consider for rotation, such as Kontos, Timectin, Hachi-Hachi SC and Sarisa.

Another option is Mainspring, which is a compound that stops thrips from feeding until they die from dehydration and starvation. Revynthi’s data also suggests that exposure to Mainspring, as well as the product Acephate, prevents significant feeding damage.

Unfortunately, laboratory conditions can only provide so much insight, so more research is still needed. “I may find something to be successful when testing it here in a small room with artificial lighting, but it might not work in a greenhouse, landscape or vegetable field,” says Osborne. “We’re interested in working with growers to help manage the pest so we can better understand how to treat these thrips in a commercial setting.”

Growers who detect T. parvispinus should immediately report their findings to the Florida Department of Agriculture and Consumer Services Division of Plant Industry. Then, researchers can work with growers to help manage the pest and develop the best treatment options available.

“This information will be critical in developing effective control strategies and preventing the further spread of this invasive species in the U.S.,” says Ahmed.