Bemisia tabaci biotype Q
From BugwoodWiki
Authors: Espinosa, A. and A.C. Hodges University of Florida
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Contents |
Introduction and Distribution
The whitefly, Bemisia tabaci, is one of the most prolific pests of vegetables and ornamentals throughout the world. There has been some confusion when referring to the different whitefly species and/or biotypes of Bemisia. Silverleaf whitefly, formerly known as Bemsia argentifolii, is now officially recognized as the ’B’ Biotype. The whitefly commonly referred to as sweet potato whitefly is B. tabaci,‘A’ biotype. Several other biotypes of B. tabaci exist, and various biotypes have shown substantial pesticide resistance. One of the biotypes that has been of particular concern to the U.S. in recent years has been B. tabaci biotype ‘Q’. Specific resistance issues have included: pyriproxyfen (Distance), neonicotinoids imidachloprid (Marathon or Merit), acetamiprid (TriStar), and thimethoxam (Flagship), and reduced susceptibility to IGR buprofezin (Talus). The ‘Q’ biotype originates from the Mediterranean and has been reported in the following countries: China, Egypt, France, Israel, Japan, Morocco, The Netherlands and Spain. The first report of the ‘Q’ biotype in the continental U.S. was during December 2004 at a poinsettia nursery in Arizona. As of January 2008, 25 states have been reported to have occurrences of Q-biotype, these are: Arizona, California, Georgia, Oregon, Michigan, Alabama, New York, Louisiana, Maryland, Kentucky, Pennsylvania, Florida, Connecticut, New Jersey, Maine, Vermont, Indiana, North Carolina, Illinois, Massachusetts, New Hampshire, South Carolina, Hawaii, Washington and Ohio. Note that some of these reports may have been isolated, and local specialists should be consulted to determine the extent of establishment for the ‘Q’ biotype. For distribution details please go to the following link: http://mrec.ifas.ufl.edu/lso/bemisia/bemisia.htm.
Hosts:
Bemisia whiteflies have a very wide host range, and are capable of feeding on over 500 plant species from 74 families. Among the most susceptible greenhouse ornamental plant species are: poinsettia, hibiscus, ivy, gerbera daisy, lantana, verbena, garden chrysanthemum, salvia and mandevilla. Among the vegetable crops and field crops, cucumber, melons, beans, eggplant, cabbage, peppers, squash, and tomatoes, cotton, potato, peanut, and soybean, are also very susceptible hosts.
Damage and Potential Economic Impact:
Whiteflies have piercing-sucking mouthparts and feed typically on the undersurface of leaves. They suck plant juices and excrete honeydew, which promotes the growth of sooty mold. Sooty mold interferes with photosynthesis and reduces the aesthetic value of the crop. During feeding, whiteflies reduce vigor and overall plant health by injecting enzymes and removing plant sap. Common damage symptoms for B. tabaci include: stem bleaching, chlorotic spots, stippling, leaf yellowing, leaf drop and plant death for severe infestations. In addition to directly damaging hosts, B. tabaci also vectors several devastating Gemini viruses such as tomato yellow leaf curl virus (TYLCV), tomato mottle virus (TMoV) and bean golden mosaic virus (BGMV). Determining that one of these viruses is present on your crop may be a good indicator that whiteflies are present. Some of the common virus symptoms are the following.
TYLCV
The most diagnostic symptoms appear in the leaves. Infected leaves remain small, curl upward, appear wrinkled, and interveinal and marginal yellowing or chlorosis occurs. Early stage infected plants show severe stunting, and hosts infected at later stages show stunting followed by an erect plant growth. Infected plants have shorter internodes and an overall bushy appearance.
TMoV
Younger leaves show chlorotic mottling, and older leaves are curled and chlorotic as well. Stunting is also common, but is more apparent when plants get infected in their younger stages.
BGMV
The most obvious symptom on the foliage is a bright, yellow or golden mosaic pattern. Plant stunting, distortion and leaf curling and rolling are also common. Infected pods may appear deformed, stunted and with mosaic spots. Seeds within are discolored, malformed and small. It is common to see individual diseased plants surrounded by healthy ones.
Identification Characteristics and Sampling Information:
Adults look very similar to tiny moths; they are covered with white waxy powder. Adult females measure about 1/16th of an inch in length. Eggs are whitish to light beige when recently laid, but get darker as they mature and before hatching they are dark blue or purple. Immature stages look like miniature scale insects. They are flat and oval, glassy to opaque light yellow or green and frequently have waxy filaments. As they mature, they turn cream or yellow. Although it can be difficult to differentiate between whitefly species either in the field or with advanced general microscopic screening, it is not possible to identify Bemisia tabaci biotype ‘Q’ through field or traditional morphological methods. Traditional methods for confirming species of whiteflies involve slide-mounting the pupal life stage. In contrast, biotypes must be identified by molecular methods. The adult stage of the whitefly is collected in 95% ethanol prior to testing. Rubbing alcohol may alter or otherwise denature the sample. At this time, most samples will not be tested for biotypes due to the expense, and lack of uniformly available protocols for testing. Some exceptions may apply. Testing may be possible through some existing research projects. If you’re not sure whether or not you have a whitefly infestation, collect or photograph the insects. For general species-level information, you may collect either adults or pupal stages of the insect. The adults are often noticed when the foliage is disturbed. The sessile pupal can be viewed by turning over host leaves. For species but not biotype level identification, you may place your samples in small vials or containers with 70% ethanol or rubbing alcohol. It is important to include the collection information that will include: location, type of plant infested, number of plants and collector’s name. If submitting your sample to a NPDN diagnostic lab, please use your local sample submission form. A link to all NPDN diagnostic labs is available at: http://www.npdn.org/ . The Florida Department of Agriculture & Consumer Services, Division of Plant Industry has produced a screening guide that may help you with your field identifications http://www.doacs.state.fl.us/pi/enpp/ento/aleyrodi.html.
Life History:
Did you know that recently hatched immatures crawl on the leaf for a couple of hours until they find a feeding spot where they insert their mouth parts to begin feeding? They remain immobile at their feeding location until they emerge into adults.
Whiteflies have the following life stages: egg, four immature or larval stages, a pupa, and adult The life cycle of whiteflies ranges from 2.5 to 3 weeks to up to 2 months under cooler conditions. Adult females deposit between 50 and 400 eggs, depending on temperature. Higher temperatures and favorable environmental conditions may result in very high whitefly populations after few generations. Females insert eggs on the end of short stalks located on the underside of leaves.
Control:
Your first line of questions for managing a pest should also be directed to your local cooperative extension service, link available at: http://www.csrees.usda.gov/Extension/. Local specialists will be familiar with the best integrated pest management (IPM) program in your area. If you are interested in chemical control options, remember to consider rotating modes of action for registered products in order to avoid the development of pesticide resistance. Also, it is important for you to understand the life cycle of the pest in your area in order to target applications to newly emerged 1st instars or adults. Later instar whiteflies as well as pupae have a waxy cover that can serve to protect them from pesticide applications. There are several biological control agents that have shown to be effective controlling this pest. Among them are predators (Orius, Delphastus, lacewing larvae), parasitoids (Eretmocerus, Encarsia) and pathogens (Beauveria bassiana). In Florida, B. tabaci is effectively managed on ornamentals and vegetables grown in greenhouses with Encaria transvena. More details about the USDA Bemisia tabaci ‘Q’ taskforce and a multi-state management program developed for the ‘Q’ biotype in ornamentals production is available at: http://mrec.ifas.ufl.edu/lso/bemisia/bemisia.htm
In the United States, the potentially impacted industries, federal and state governments, and scientists have cooperated in the 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.
Sooo… what can you do?
- Scout- Determine if you have whitefly problems. Understand that even though whiteflies might look similar, not all whiteflies are the same. It is very important to find out what type of whitefly you have. Studies have shown that in a population that has both Q and B biotypes, increasing pesticide applications will only increase Q biotype populations because the last ones have shown to be more resistant.
- Prevention- Examine new plant material before bringing it home, and consider isolating suspect host plants prior to planting in your yard. As whiteflies are attracted to both vegetables and ornamental hosts, it may be best to keep these planting separate from each other if at all possible. Exercise caution whenever you are introducing new plants to your gardens. Be aware that some ornamental plants may have been vegetatively propagated, and may become infested with INSV (Impatiens Necrotic Spot Virus) inadvertently through grafting. Once you have introduced a virus into your garden, it only takes a few whiteflies to spread unwanted disease.
- Sanitation- Remove known heavily infested plant material you have in your yard. Bag your infested plant material, and throw it away. Trimmed branches or other host material that is not bagged and discarded may contain live pupae waiting to emerge into adults and infest new plant material. Don’t use infested plant material in compost piles.
- Practice IPM-Familiarize yourself with the natural enemies present in your garden or landscape. Which insects or arthropods are beneficial? Conserving natural enemies in your landscape will help you achieve a balanced IPM program. Remember that the use of pesticides may harm natural enemies. Use pesticides only when necessary, and be sure to rotate modes of action to avoid the development of resistant populations. You may also selectively want to plant cultivars or varieties that seem to be more tolerant of low levels of infestation. Determinate tomato varieties with shorter grower seasons are preferred for areas with whitefly problems. Ultraviolet high reflection mulch will also reduce whitefly populations.
- Physical- Regular weeding of flowerbeds and vegetable gardens can reduce the alternative host options for whiteflies. Keep in mind that whiteflies are attracted to yellow. Yellow clothing, tools, or yard ornaments may be another factor in attracting whiteflies to your garden. As whiteflies are attracted to both vegetables and ornamental hosts, it may be best to keep these planting separate from each other if at all possible.
Image Gallery:
 Photo by David Riley, University of Georgia, Bugwood.org |
 Photo by Charles Olsen, USDA APHIS PPQ, Bugwood.org |
 Photo by W. Billen, Pflanzenbeschaustelle, Weil am Rhein, Bugwood.org |
 Photo by David Riley, University of Georgia, Bugwood.org |
 Photo by Pflanzenschutzamt Saarbrücken, Husken-Thimm Archive, Pflanzenschutzamt Saarbrücken, Husken-Thimm, Bugwood.org |
 Photo by Central Science Laboratory, Harpenden Archive, British Crown, Bugwood.org |
 Photo by W. Billen, Pflanzenbeschaustelle, Weil am Rhein, Bugwood.org |
 Photo by Pflanzenschutzamt Saarbrücken, Husken-Thimm Archive, Pflanzenschutzamt Saarbrücken, Husken-Thimm, Bugwood.org |
 Photo by Central Science Laboratory, Harpenden Archive, British Crown, Bugwood.org |
 Photo by David Riley, University of Georgia, Bugwood.org |
 Photo by Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org |
 Photo by Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services, Bugwood.org |
 Photo by Central Science Laboratory, Harpenden Archive, British Crown, Bugwood.org |
 Photo by Plant Protection Service Archive, Plant Protection Service, Bugwood.org |
 Photo by Howard F. Schwartz, Colorado State University, Bugwood.org |
 Photo by Howard F. Schwartz, Colorado State University, Bugwood.org |
 Photo by Howard F. Schwartz, Colorado State University, Bugwood.org |
 Photo by Howard F. Schwartz, Colorado State University, Bugwood.org |
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References:
- Bethke, J., L. Canas, J. Chamberlin, R. Cloyd, H. Counter, T. Dennehy, J. Dobbs, S. Ferguson, D. Gilrein, R. Lindquist, S. Ludwig, R. Oetting, L. Osborne, C. Palmer, J. Sanderson. Whiteflies. Found at: http://mrec.ifas.ufl.edu/lso/bemisia/bemisia.htm
- Bethke, J., L. Canas, J. Chamberlin, R. Cloyd, J. Dobbs, R. Fletcher, D. Fujino, D. Gilrein, R. Lindquist, S. Ludwig, C. McKenzie, R. Oetting, L. Osborne, C. Palmer, J. Sanderson. Q-Biotype Whitefly: Strategies for Prevention and Management. Found at: http://mrec.ifas.ufl.edu/LSO/DOCUMENTS/JOE-Q-Biotype%20Whitefly%20OFA%20Presentation.pdf
- Bethke, J., D. Gilrein, and S. Ludwig. 2006. The Q-biotype Whitefly. Found at: http://etipm.tamu.edu/publications/pdf/Whitefly%20GrowerTalks.pdf
- Brown, J.K., D.R. Frohlich, and R.C. Rosell. 1995. The Sweetpotato or Silverleaf Whiteflies: Biotypes of Bemisia tabaci or a Species Complex? Annu. Rev. Entomol. 40:511-534.
- Buchen-Osmond, C. Tomato Mottle Virus. ICTVdB Descriptions. Last Revised: 04-06. Found at: http://phene.cpmc.columbia.edu/ICTVdB/00.029.0.03.041.htm
- Dennehy, T.J., and J. Brown. The Poinsettia 04 Strain: A Biotype of Bemisia tabaci New to the Americas. Found at: http://mrec.ifas.ufl.edu/lso/BEMISIA/19%20April%20Arizona%20talk_TimDennehey%20(2).pdf.
- Gilbertson, R.L. UC IPM Pest Management Guidelines: Tomato. UC ANR Publication 3470 Diseases. Last Revised: 03-08. Found at: http://www.ipm.ucdavis.edu/PMG/r783103311.html#SYMPTOMS
- Hamon, A.B. 2001. Key to whitefly of citrus in Florida (Homoptera: Aleyrodidae). last Update: 03-06. http://www.doacs.state.fl.us/pi/enpp/ento/aleyrodi.html
- Hodges, G. Bemisia tabaci (Gennadius) (biotype ‘Q’): A potential new biotype for Florida’s vegetable and ornamental crops. (Hemiptera:Aleyrodidae) Found at: http://www.doacs.state.fl.us/pi/enpp/ento/b.tabaci.html
- Martin, N.A. 1999. Whitefly: Biology, identification and life cycle. Found at: http://www.crop.cri.nz/home/products-services/publications/broadsheets/91.pdf
- OFA. 2006. Q-Biotype Whitefly: Strategies for Prevention and Management. Found at: http://mrec.ifas.ufl.edu/LSO/DOCUMENTS/JOE-Q-Biotype%20Whitefly%20OFA%20Presentation.pdf
- Osborne, L.S. Whiteflies. Found at: http://www.mrec.ifas.ufl.edu/LSO/bemisia/bemisia.htm
- Osborne, L.S., and S. Ludwig. 2006. Whiteflies: ‘B’ or ‘Q’ Does it Make a Difference? Found at: http://mrec.ifas.ufl.edu/LSO/DOCUMENTS/lance-whiteflies-ohio.pdf
- Pernezny, K., R.T. McMillan Jr., E. Heibert and R. Lentini. SWFREC- Bean Golden Mosaic Disease in Florida. Found at: http://www.imok.ufl.edu/LIV/groups/IPM/path/bgmosaic.htm
- Perring, T.M. 2001. The Bemisia tabaci species complex. Crop Protection. 20:725-737.
- Recommendations for Management of Whiteflies, Begomovirus, and Insecticide Resistance for Florida Vegetable Production. Found at: http://manatee.ifas.ufl.edu/agriculture/vegetable_crops/pdfs/2006ResistanceMgmtRecs.pdf.
