A new species of whitefly has been detected in Florida. What this means for Florida growers remains unknown.
They look like tiny white dots specked along the green of leafy vegetables, but these minuscule, winged bugs — known as whiteflies — have some Florida growers concerned. In April, a species of the whitefly that is resistant to a number of insecticides was detected in Florida nurseries.
But concern may be premature, according to Dr. Hugh Smith, the assistant professor of vegetable entomology at the University of Florida’s Institute of Food and Agricultural Sciences at the school’s Gulf Coast Research and Education Center in Wimauma.
The B's and Q's Of It
Whiteflies have been in the Sunshine State since 1900. In the 1980s, the whitefly B-biotype species was detected — a pest that caused irregular ripening of tomatoes and other crops. The B-biotype also spread viruses in tomatoes, cucurbits and beans.
While growers have treated their crops to protect against the B-biotype with insecticides, the new species of the whitefly is thought to be more resistant. The Q-biotype was first detected in Arizona in 2004 and has elevated levels of resistance.
“In other countries, it’s been very difficult to control with some of the most important insecticides,” Smith said. “It was found in Florida in 2005.”
The Q- and B-biotypes are identical. The only way the species can be determined is through lab testing. With the Q-biotype detected in local nurseries this past year, growers who treat whiteflies could potentially be faced with a resistant biotype that dominates and kills plants.
The concern, Smith said, is about whether or not the Q-biotype will establish itself in field crops.
This year, the Q-biotype was detected in 19 retail nurseries and in nine wholesale nurseries, including some in Hillsborough County. The Q-biotype was commonly found among ornamental plants, such as poinsettias.
“Many people didn’t think we’d be able to keep it out of the field for more than a year, but we kept it out for more than 10 years,” Lance Osborne, a professor of biological control of insects and mites at the University of Florida, said. “The B-biotype is a significant pest worldwide and is very problematic for tomatoes. The big difference is that the Q-biotype is more tolerant of pesticides.”
The biggest tool growers can use, Osborne said, is proactivity.
“It’s not a disaster if we manage things appropriately,” Osborne said. “Pesticide resistance management is the top priority.”
Preparing for the Pest
Handling the treatment of the Q-biotype whiteflies will be one of the discussion topics at the Florida Ag Expo
Thursday, Nov. 2, at the University of Florida’s Gulf Coast Research and Education Center in Wimauma.
Smith will be one of the whitefly speakers.
“To the best of our knowledge, the Q-biotype has never caused any problems to agriculture in the United States of America,” he said. “There’s no reason for (Florida growers) at this point to think they’re dealing with the Q-biotype in the field. That’s the vegetable perspective.”
Like Osborne, he cited proactivity as a top concern.
“We need to be vigilant and keep testing,” he said. “We need to test the susceptibility to insecticides. What we need to do is actually take advantage of populations that have been detected, study them and come up with guidelines for Florida growers if the Q-biotype becomes established in the field. We’re making generalizations (about the Q-biotype). We can’t generalize about what is now considered to be its own species because species are probably made up of populations that may respond differently to insecticides.”
Detecting the pest and determining the proper response are the next steps for growers and researchers.
“How do the two compete on a given crop in Florida? We don’t know,” Smith said. “If a grower sprays something that kills one biotype but not the other, the resistant one becomes predominant. There are insecticides that work
against both. Growers shouldn’t really be doing anything different in their whitefly management, other than continuing to practice good resistance management.”
Growers with concerns are encouraged to attend the Florida Ag Expo or to contact their local University of Florida Institute of Food and Agricultural Sciences extension.
Contact Emily Topper at etopper@plantcityobserver.com.
