A few words about Whiteflies
Most growers probably have heard about a “new” whitefly that has appeared on poinsettia crops in many parts of the United States, called the Q Biotype. Depending on the source of information about the Q Biotype, growers might be overly concerned about this whitefly. The following section is an attempt to answer questions about this insect and its management.
1. What is the Q Biotype Whitefly?
It is a Bemisia tabaci biotype whitefly that – prior to December 2004 – was known to occur in northern European and several Mediterranean countries (mainly Spain), but not in the United States. We have been dealing with what is called the B biotype since 1986, and before that the A biotype – which was never a problem on ornamental plants.
Some scientists have called the B biotype the Silverleaf whitefly, Bemisia argentifolii – a separate species – but most now call it Bemisia tabaci – B Biotype. All the whitefly biotypes , A, B and Q, are identical in appearance and have virtually identical life cycles, host plants, etc, but differ in body chemistry. The only way they can be separated is by conducting laboratory tests.
2. Why should we worry about the Q whitefly?
The Q whitefly is potentially serious because it is often less susceptible to many of the commonly used whitefly insecticides. Although there is some variability among the Mediterranean Q strains, they generally show moderate to high resistance to one or more neonicotinoid insecticides (e.g. Celero, Flagship, Marathon, Safari, TriStar), and the insect growth regulators pyriproxyfen (Distance) and buprofezin (Talus). These pesticides are widely used in whitefly management programs on field and greenhouse crops.
3. Has the Q Biotype whitefly been detected in the United States?
Yes. The first official detection of a Q biotype whitefly in the U.S. was in March, 2005 when whiteflies collected from poinsettias in an Arizona retail outlet in December, 2004 were tested as part of a pesticide resistance monitoring program. This collection has been called the Poinsettia-04 strain. Since this detection the Q whitefly has been found in 23 states (as of September, 2006), including the major ornamentals-producing states of California, Florida, North Carolina, Texas, Georgia, Oregon, Michigan and New York. All Q biotype whiteflies were collected from ornamentals, and nearly all in greenhouses from poinsettias.
There are several populations of the Q biotype whitefly from different areas in the Mediterranean region, and these vary in susceptibility to the same insecticides. The same appears to be true in the U.S. Therefore, there is no “standard” Q biotype whitefly population.
4. Are the neonicotinoid insecticides useless against Q whitefly biotypes?
No. Even though laboratory and greenhouse tests on some Q biotype whiteflies have shown reduced susceptibility (65-85 % kill) to some of the neonicotinoid insecticides, trials on other Q whitefly biotypes have shown that the neonicotinoid insecticides are very effective (90%+ kill). Therefore, neonicotinoid insecticides can still be used – but not over used - as part of a whitefly management program. The key words here are management program. A good insect or disease control program will involve scouting, sanitation and exclusion in addition to pesticides. Rotation of a neonicotinoid insecticide with products that have different modes of action is the best approach. Information on pesticide mode of action can be found in the OHP Chemical Class Chart, available through an OHP Regional Sales Manager or on the OHP.com web site.
Regardless of the frightening scenarios that might be presented on the Q biotype, it remains a whitefly that can be managed. Growers in areas where the Q biotype has been present for many years still produce quality crops. Therefore we should consider the Q biotype whitefly as a serious – but manageable – problem. Some scientists believe that the B-biotype whitefly is potentially a more serious problem because it has a higher reproduction rate than the Q biotype. Bottom line: Whether B or Q biotype, a whitefly resistance management program is required.
5. Where can I locate the most current information on whitefly management?
Probably the best source of current information on whitefly management is maintained by Dr. Lance Osborne at the University of Florida. The web address is: http://mrec.ifas.ufl.edu/LSO/bemisia/bemisia.htm.
If you have questions about Judo or Marathon and Q-biotype control, or on any other OHP Inc. products, please contact your local rep or Dr. Richard Lindquist, OHP senior technical manager, at 406.388.2892 or click here to email him.
OHP Field Sales Representatives
Tobey Barr, SE, W.FL, 863-581-4617 (cell), E-mail Toby
Mike Beach, SE, E.FL, 407-620-8231 (cell), E-mail Mike
Don Hanson, NE, Mid-Atlantic, 757-373-8440, E-mail Don
Dennis Kern, SW, HI, 949-300-3468, E-mail Dennis
Ken Kuhajda, E. Great Lakes, 330-289-1279, E-mail Ken
Jason Miller, Pacific NW, 541-993-4647, E-mail Jason
Rich Mulder, Midwest, 402-740-8683, E-mail Rich
Andy Seckinger, S. Central, 314-422-3196, E-mail Andy
|
