Thrips parvispinus adult female feeding on bean leaf. PHOTO COURTESY L.S. Osborne, UF/IFAS MREC
When a new invasive pest appears on the radar, researchers and Extension faculty at UF/IFAS measure their progress not in years, but in weeks and months.
Last August, John Roberts, Ph.D., was settling into his new role as a UF/IFAS Extension horticulture agent in Palm Beach County when he got a call from Lance Osborne, Ph.D., entomology professor at the UF/IFAS Mid-Florida Research and Education Center in Apopka. Osborne told him Thrips parvispinus had been found in landscapes on Palm Beach Island. This was something new to add to Roberts’ list of invasive pests threatening Southeast Florida’s carefully maintained residential landscapes. He’d already been developing workshops to help landscapers and residents deal with phantasma scale, ficus whitefly and lethal viral necrosis on St. Augustinegrass, to name a few.
But T. parvispinus was a different beast entirely.
For one thing, the thrips is tiny—1 mm or less in length, making it hard to detect. In spite of its small size, it can do substantial damage to plant leaves and buds with its rasping and sucking mouthparts. The results can look like mite damage, which can lead to misdiagnosis and ineffective treatments. At this time, it’s too early to tell whether this species transmits any viral diseases, but other thrips do.
Although it’s commonly known as pepper thrips, it feeds on a wide range of plants, including popular landscape ornamentals like gardenia, mandevilla, and pinwheel jasmine, as well as peppers and other edibles.
A native of southeast Asia, T. parvispinus was first detected in Florida in 2020. At first the thrips was confined to greenhouses and nurseries, but then it started turning up in residential landscapes and vegetable fields. Knowing they had to act fast to get ahead of the pest, Osborne and other entomologists at the USDA and FDACS immediately issued alerts.
Osborne took Roberts and fellow horticulture agent Anna Meszaros out to Palm Beach Island and showed them how to identify T. parvispinus. Shortly after that, Roberts and Osborne applied for a grant from the National Horticulture Foundation to conduct a scouting study at big-box garden stores in Palm Beach County. Along with Cindy McKenzie, Ph.D., and Muhammad Ahmed, Ph.D., Roberts found the thrips on plants in 13 out of 14 stores. By January, researchers from UF/IFAS, FDACS and USDA-ARS had found the pest in 23 Florida counties.
Since last summer, Roberts has been in regular communication with researchers who are working on solutions for managing T. parvispinus. Experimenting with insect cultures in the laboratory is painstaking work, especially when results have to be tested in the field under different conditions. That’s why there’s not one, but two T. parvispinus task forces at work. Alexandra Revynthi, Ph.D., and her research team at the UF/IFAS Tropical Research Center in Homestead are studying the efficacy of various pesticide treatments. Osborne at Mid-Florida REC and McKenzie at the USDA-ARS lab in Fort Pierce are in the process of evaluating chemical and biological control agents. An amazing amount of information has been generated in a short space of time, but there are still many more questions that remain to be answered.
In May, Roberts hosted a two-hour webinar with Osborne, Revynthi and other specialists to provide the latest updates on T. parvispinus. This September 19-20, there will be a workshop tour about the thrips in Palm Beach, Broward and Miami-Dade counties. Visit these sites to register: Palm Beach County, Broward County, Miami-Dade County.
Like their Extension counterparts throughout the state, Roberts and Meszaros work closely with greenhouse managers, nursery owners, landscaping companies and local growers to share information about how to recognize the thrips and slow its spread. At the same time, these stakeholders share their observations from the field, which are relayed back to the specialists.
It's a constant feedback loop between researchers, specialists, extension agents and stakeholders that leads to solutions for invasive pests and other vexing issues for Florida’s commercial horticulture.
So what can green industry professionals do about T. parvispinus? Roberts recommends getting in touch with your county’s commercial horticulture Extension agent and bookmarking these two websites at MREC and TREC. If you have potential host plants, scout them often for thrips and avoid moving infested plants or plant material. The good news for greenhouses and nurseries is the pest has been detected early and there are a number of treatments which have so far shown to be effective against T. parvispinus. However, landscapers and vegetable growers have more limited options. Early detection is the key while effective Integrated Pest Management solutions are being produced.
Andra Johnson, Ph.D., is the Dean for UF/IFAS Extension and the Director of the Florida Cooperative Extension Service.