BEMISIA (Whitefly)

Biotype-Q or BIOTYPE-B?

This could be either one. They look identical.

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 plants and vectors over 111 plant virus species and 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 Q respectively).

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 southern United States to Texas, Arizona and California, where extreme 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, including cotton, 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. Bemisia feeds on a large number of hosts to Florida plants on which this whitefly has been found.

AN IMPORT MESSAGE ABOUT INSECTS IN THE LANDSCAPE

None of us wants to be overrun by insect pests, nor do we want to be exposed unnecessarily to the insecticides used to manage them. The most difficult problem we face with many of the pests that attack our landscape plants (whiteflies, mites, thrips, aphids), invade our homes (termites, cockroaches, bed bugs) or attack us or our pets (mosquitoes, flies, fleas) is that they have developed a tolerance to pesticides. In some cases, many pesticides have resistance issues even before they receive label expansions for legal use in the landscape. Resistance has developed broadly in commercial agriculture and spread to our landscapes on infested plant materials. Sometimes it can work in the opposite direction. Pesticides are a valuable commodity that must be protected so we can count on them when needed. This implies that pesticides are sometimes used in unnecessary ways. Unfortunately, this happens enough to cause some real problems. They may be applied to plants when no pests are present, or the wrong products are used, or they are applied without regard to preserving beneficial insects or non-target insects. We are currently seeing an invasion of a group of whiteflies that are significantly more damaging than the rugose spiraling or ficus whiteflies in the big picture. We collectively refer to them as Bemisia, or silverleaf whitefly B-biotype and Q-biotype. These “biotypes” look identical, but are genetically different in important ways. These whiteflies are arguably the most damaging pest to agriculture world-wide. People are starving in Africa because of them. In Florida, they are a major limiting factor in the production of tomatoes and other vegetables. Bemisia attacks more than 900 host plants and vectors at least 111 plant virus specie. . Worldwide agricultural production losses have grown because new, more virulent and less pesticide-sensitive Bemisia strains have spread to all continents except Antarctica. Very few countries have escaped its establishment.We are receiving calls and emails from many professional pest control operators and landscapers from the Keys to Palm Beach County that report difficult to control whiteflies are in landscapes. This is a serious and very concerning situation because the reports indicate that pesticides are not working. The quality of our landscapes is being impacted and the production of many vegetable crops is threatened. In the early 1990’s in the United States, crop failures, displacement of farm workers, and the costs associated with managing this pest surpassed $500 million dollars. These new strains present a potentially similar threat and the University of Florida, USDA, the Florida Department of Agriculture and Consumer Services, city governments and our industry colleagues are working to manage the threat. We cannot do it alone! WE NEED THE HELP OF THE GENERAL PUBLIC AND ALL POTENTIALLY IMPACTED INDUSTRIES.

WHAT CAN THE PUBLIC AND LANDSCAPERS DO?

• Report any whitefly populations that seem to be excessively high and difficult to control (contacts below).

• For whitefly control recommendations, contact your local County Extension office for help.

If you need help regarding your landscaping, we at Garden Services are fully licensed & insured to handle all your irrigation, landscaping, lawn maintenance and tree service needs whether it’s a residential, commercial landscaping or homeowner association property. If you ever have any comments or questions, please don’t hesitate to call or email me and I’ll be happy to answer any questions that you might have. Special thanks to UF/IFAS extension for some helpful information provided in this post. Until next month Happy Gardening!