Unfortunately, we have a developing whitefly issue in Florida. We are having major issues managing 2 biotypes in a number of areas in South Florida. Both biotypes are referred to as Bemisia tabaci. The Q biotype has been detected in a number of landscapes in Palm Beach County. This is the VERY FIRST TIME it has been found in a landscape or outside a greenhouse or nursery since it was found on an ornamental plant in a greenhouse many years ago (2004-2005). This is extremely troubling considering the issues we have with many of the tools we use to manage whiteflies.
Bemisia tabaci (Gennadius) feeds on more than 900 host plantsand vectors over 111 plant virus speciesand is considered to be a major invasive species worldwide.The taxonomic status of B. tabaci remains debated between 36 previously identified biotypes and the newly proposed 24 discrete species and they can only be identified by performing genetic analysis. Losses in agricultural production have increased owing to B. tabaci as new, more virulent and less pesticide-sensitive cryptic species have spread to all continents except Antarctica.Very few countries have escaped its cosmopolitan distribution and subsequent establishment of at least one of the B. tabaci cryptic species. The two most invasive members of the cryptic species complex posing the greatest threat to growers are Middle East –Asia Minor 1 (MEAM1) and Mediterranean (MED) (commonly known as biotypes B and Qrespectively).
After the introduction of MEAM1 into the United States around 1985, unprecedented losses began occurring on poinsettia in the late 1980s in Florida, followed by high infestations in field-grown tomato crops.MEAM1 rapidly spread across the southernUnitedStates toTexas,ArizonaandCalifornia, whereextreme field outbreaks occurred during the early 1990s on melons, cotton and vegetable crops. Losses exceeded more than 500 million dollars in one year.
Indistinguishable morphologically from MEAM1, MED is extremely problematic to agricultural production because populations are highly prone to develop resistance to insect growth regulators (IGRs)and neonicotinoid insecticides.Both classes of insecticides are widely used for controlling whiteflies in many cropping systems, includingcotton, and ornamentals.
Based on recent reports, we may be in for a challenging year for whitefly management. We are receiving reports from the keys to Palm Beach County that whitefly populations in landscapes are reaching unprecedented levels and they don’t seem to be responding to pesticide applications. At this point in time, the Q-biotype has been found in three areas: Boca Raton, Palm Beach and Palm Beach Gardens. Samples from all the other difficult to manage populations are the B-biotype. If you hear of whitefly problems please contact either Cindy McKenzie or Lance Osborne.
Cindy McKenzie, Ph.D. Lance S. Osborne, Ph.D.
Research Entomologist University of Florida, IFAS
USDA, ARS, US Horticultural Research Laboratory 2725 Binion Road
2001 South Rock Road Apopka, FL 32703
Fort Pierce, FL 34945 Phone: 407-410-6963
What do we know as of 5-27-2016?
Biotype-Q has been found in 5 different communities with
three properties in one neighborhood having infested plant material. These communities are: Palm Beach Gardens (4/25/16), Palm Beach
Island (5/10/2016, 5/25/2016), Boynton Beach (5/11/2016), and Boca Raton
(5/11/2016). There was also one
wholesale nursery in Boynton Beach. The primary host plant on which this
whitefly has been found is hibiscus. Dr. McKenzie has also determined that these
finds represent only one of the 3 haplotypes known to have been previously
introduced into the U.S. greenhouses and nurseries. The diagnostics used by Dr. McKenzie’s lab are
state of the art: Once a properly preserved dead insect is
received, a biotype determination can be made within 24-48 hours. This rapid diagnostic ability gives us the
ability to track the spread of this pest very quickly.
Unfortunately, sample submission has been somewhat confused
over the last week or so.
Agricultural concerns and ornamental Industry professionals
can send their samples directly to Dr. McKenzie.
If anyone would prefer to submit an insect to the Florida
Department of Agriculture and Consumer Services – Department of Plant
Industries or to the Diagnostic Laboratory in the Department of Entomology and
Nematology at the University of Florida in Gainesville they can do so, although
adding this step will take longer for the sample to reach Dr. McKenzie and thus
delay a biotype determination.
·
It is more difficult to manage with pesticides
that other whiteflies?
·
It has limited distribution in Florida and the
United States. This is the first time it
has ever been found on plants outside of a nursery or greenhouse. This whitefly attacks a significantly larger
number of plants than we have observed for the Ficus, Rugose spiraling or the
Bondar’s nesting whitefly in the last few years.
·
This whitefly produces honeydew and sooty mold but
the amount will probably be greatly reduced compared to the Rugose Spiraling
whitefly and will lack the white-waxy fluff.
Thus, the aesthetic damage won’t be as obvious as that caused by both
the Rugose and Ficus (leaf drop).
·
Biological controls exist that are sold
commercially and present naturally in the environment. We fully expect these natural enemies to
provide control of Biotype-Q as they have done for Biotype-B since the mid-90’s,
so long as they are not disrupted by pesticides applications.
·
The
real threat of Biotype-Q in Florida will
be to the commercial production of vegetables.
Biotyes Both Biotype-B and Biotype Q are efficient vectors of
viruses. We already know how difficult
it is to manage the spread of viruses in both cucurbit and tomato crops as a
result of Biotype-B feeding. The
presence of the more resistant Biotype-Q will make the production of crops more
challenging and expensive. Biotype-Q is
also perceived as a major threat to cotton and vegetable production in other
U.S. states.
Sample
submission specifics:
Infested leaves and dead insect specimens
should be brought to local Extension offices.
Wrap in a dry paper towel and place in a sealable plastic
bag and then in an envelope. Freezing the specimen overnight before
transport is highly recommended. Live insects should not be transported.
·
Samples can be prepared in the same fashion
and sent directly to Dr. McKenzie:
Cindy McKenzie, Ph.D.
Research Entomologist
US Horticultural Research Laboratory
ARS-USDA
2001 South Rock Road
Fort Pierce, FL 34945
772.462.5917 office
772.462.5911 lab
772.462.5986 fax
What should commercial growers be doing?
1. Scout – this is essential. Inspect your crops at least weekly to find infestations early. Do not let the whiteflies get ahead of you, or your treatment options will be more limited and expensive.
2. Exclude or isolate. If reasonably possible, try to exclude whiteflies from your growing structures with screening material, and if possible, isolate the facility so that workers have to enter through an anteroom.
3. Practice good sanitation – this is also essential. Keep weeds controlled because they serve as an alternate host for the whiteflies, and maintain other good growing practices.
4. Inspect incoming shipments, and isolate if necessary. All of the major propagators cooperated in this program, so you should not be receiving undue numbers of whiteflies on your planting material. Zero-tolerance is NOT a reasonable goal and you may see a whitefly or two when shipments arrive. That is ok, and means that your propagator (or rooting station) is probably following good management practices. However, if you see many whiteflies on incoming shipments, keep those shipments separate from your other crops until they have been treated and the whitefly cleaned up. Do not forget then to contact your propagator or rooting station to inform them about the situation. Ask whether they are biotyping their whiteflies, if they are monitoring resistance levels in their whitefly populations, and if they are following the Task Force’s recommended Management Program.
5. Watch your neighbors’ fields. If you’re near cotton or vegetable fields, you may see whiteflies migrate to your greenhouse at the end of their season, and you will then have to deal with them. If you know when those harvesting operations occur, you are better able to prepare.
6. Study and implement the “Management Program for Whiteflies on Propagated Ornamentals” recommended by the Whitefly Task Force. It is available at http://mrec.ifas.ufl.edu/lso/bemisia/DOCUMENTS/WhiteflyManagementProgram_1-15- 15.pdf. This program is based on the best and most current scientific data developed by the Whitefly Task Force scientists. Do not rely on just one or two effective products, but instead integrate products with different modes of action to decrease the potential for developing resistance. Rotate chemical classes after each life cycle length for that time of year (time from egg to adult).
7. If you have control problems: contact your propagator and your local extension agent or university expert. Follow our “Whitefly Management Program”, and get your whiteflies biotyped. The biotyping process is fast, and your specific information will be kept confidential. Knowing which biotype you are dealing with will help you choose the most effective control products. (The Management Plan provides a list of addresses where samples may be sent for biotyping.) In the United States the potentially impacted industries, federal and state governments, and scientists have cooperated in an aggressive, cooperative whitefly management effort to help growers produce a salable crop and minimize the likelihood of developing resistant whiteflies. You are an essential part of that effort. REMEMBER: Q-BIOTYPE WHITEFLIES ARE A DOCUMENTED THREAT, BUT THERE IS ALSO EVIDENCE THAT B-BIOTYPE ARE DEVELOPING RESISTANCE. Only by working cooperatively, wisely, and together can agriculture and ornamental growers solve this problem. PLEASE BE PART OF THE SOLUTION, NOT THE PROBLEM!
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