Note: Michigan State University (MSU) has posted the following whitefly alert on its Extension website:
Recently, reports from the University of Florida indicate that there are now established populations of insecticide-resistant sweet potato whitefly (Bemisia tabaci) in Palm Beach County, FL.
There are two major biotypes (identical genetic strains) of whitefly: B and Q. The B biotype of whitefly has been in the U.S. for more than 30 years, while the Q biotype only became a problem within the last 10 years. The Q biotype is much more resistant to conventional control compared to the B biotype. The Q biotype has been found in cotton fields for many years, though, and their presence in the whitefly population has come and gone over the years.
A very high level of insecticide use is needed for the Q biotype to become dominant. The B biotype usually outcompetes the Q biotype and it still remains the dominant pest whitefly of greenhouse plants.
Greenhouse growers in Florida and other parts of the country should be vigilant when scouting their plant material to monitor whitefly populations. For growers opting to use insecticides to control whitefly, MSU Extension recommends several options.
Growers can also use biological control to manage whitefly populations. There are two commercially available parasitoids in the U.S.: Encarsia formosa and Eretmocerus eremicus. Eretmocerus eremicus will parasitize both sweet potato and greenhouse (Trialeurodes vaporariorum) whiteflies, while Encarsia formosa will only parasitize greenhouse whiteflies. For production during these warmer months, Eretmocerus eremicus is more effective at higher temperatures than Encarsia formosa. There are also two commercially available predators that feed on whiteflies: Amblyseius swirskii and Delphastus catalinae. A. swirskii feeds on the eggs and nymphs of whiteflies while D. catalinae feeds on whitefly eggs.
Check out the MSU story for more information.