WHITEFLY BIOTYPE Q IN THE US? WHAT DOES IT MEAN AND HOW TO BE PREPARED By Dr. Luis Caņas The Ohio State University Department of Entomology OARDC Wooster, OH BACKGROUND Whiteflies from the genus Bemisia have caused problems in different systems for more than a decade. In greenhouses the most common whitefly nowadays is known as Bemisia argentifolii, or silverleaf whitefly. In the past there has been some confusion as to the different common names this species receives. Here I am including some information: Bemisia argentifolii = Bemisia tabaci (biotype B) Common names: silverleaf whitefly, sweetpotato whitefly The important thing to remember is that whiteflies from the genus Bemisia form a complex of species and/or biotypes. During the decade of the 90s the most common biotype was biotype A, but it was replaced by biotype B because it was more reproductively aggressive but also because biotype B was able to develop resistance to organophosphates, carbamates and pyrethroids very rapidly. Thus, most scientists argue that the reason biotype B became established was a combination of its natural reproductive ability and its ability to develop resistance to the most compounds it was exposed to. However, the implementation of IPM system that combined new more targeted chemistries such as neonicotinoids (imidacloprid, etc), insect growth regulators, natural enemies, among others, allowed for the successful control of biotype B. Even in industries that rely a lot on the neonicotinoids, the control of biotype B has been for the most part successful. In addition, in recent years other neonicotinoids have been introduced that have different effects against whiteflies and can have significant control over the different instars (i.e. TriStar, Flagship, Safari, Celero). Now, all this is relevant because there is a new biotype that is causing major problems throughout the world and it appears that it has been introduced into the US. This is the biotype Q. PRESENT  STATUS During the past couple of months there have been reports about the presence of the whitefly biotype Q in the US. These reports come from surveys conducted by Drs. Tim Dennehy, Judy Brown, (University of Arizona) and Dr. Frank Byrne (University of California), that suggest the biotype Q was found on poinsettias in California (see links below for additional information). The recent finding of this new whitefly biotype has triggered a fast response from various groups and organizations and has apparently resulted in the State of Arizona declaring and administrative quarantine to diminish the risk of entrance of biotype Q to this state (see links below for more information). The reality is that because of the possibility of the spread of this new biotype and because of the threat that it posses to major US industries, all the different groups, including floriculture growers, need to be increase efforts to prevent receiving and/or shipping whitefly contaminated material. IMPORTANCE The whitefly Q biotype was original found in the Iberian peninsula. The Q biotype has shown high levels of resistance to neonicotinoids and the insect growth regulator pyriproxyfen. Because of the wide array of hosts the different biotypes of whiteflies can attack (more than 500 species) the damage inflicted to different industries can be counted in the millions of dollars. The fact that this insect complex can inflict severe losses to different industries stresses the importance of preventive efforts led by different groups and should include academia, the government and the different industries potentially affected as pointed out by The Society of American Florists (SAF), and the American Nursery & Landscape Association (ANLA, see press release below). WHAT TO DO IF YOU ARE HAVING TROUBLE CONTROLLING WHITEFLIES As with any major pest infestation you need to contact your extension agent, but also please document all steps taken to control the problem. In addition, if you notice that whitefly populations are becoming a lot more difficult to control you might need to collect samples to diagnose if it is biotype Q. You can contact me for advice on how to collect the samples. Unfortunately, the only way to diagnose this new biotype is by DNA and/or serological analysis. Because of the high resistance of biotype Q to neonicotinoids and some of the insect growth regulators currently being used for whitefly control it would be very important to implement management programs that include a good sanitation program to prevent entrance of whiteflies. This includes close inspection of incoming shipments with material that can be contaminated with these insects. Pay special attention to the poinsettia shipments being received as whiteflies can be present even when no adults are observed. Remember that the eggs and nymphs are very small and can only be observed with the aid of a hand lens. Properly placed and monitored sticky cards are also key to detect early whitefly infestations. A good management program needs to include a good pesticide rotation program where pesticides with different mode of action are included. In addition, it is probably a good idea to begin adding natural enemies to the management programs as this would reduce the need of repeated pesticide applications. A list of some examples of chemistries used against whiteflies is included here: Soaps and oil extracts M-Pede - potassium salts of fatty acids Triact 70 - extract of neem oil Organophosphates (Mode of Action Group 1) Orthene Turf Tree and Ornamental Spray - acephate Pyrethroids (Mode of Action Group 3) Decathlon - cyfluthrin Talstar - bifenthrin Neonicotinoids (Mode of Action Group 4) Flagship - thiamethoxam Celero - clothianidin Marathon - imidacloprid Safari - dinotefuran Tristar - acetamiprid Insect growth regulators (Mode of Action Group 7) Enstar II - S-Kinoprene Distance - pyriproxyfen Benzoylurea insect growth regulators (Mode of Action Group 15) Adept - diflubenzuron Inhibitor of chitin (Mode of Action Group 16) Talus - buprofezin Biopesticide insect growth regulator Azatin - azadirachtin See Table 1 for biological control options. OTHER LINKS Florida Department of Agriculture http://www.doacs.state.fl.us/pi/enpp/ento/b.tabaci.html Arizona Department of Agriculture Quarantine http://agriculture.state.az.us/Main/DAO%20Bemisia%204%2013%2005.pdf ANLA press release http://www.anla.org/applications/PressReleases/releases/0201.htm Oregon State University, Pacific Northwest Nursery IPM http://oregonstate.edu/Dept/nurspest/Alert/Alert.cfm Ecke Ranch Information and press releases http://eckeranchtechhelp.com/eve/ubb.x/a/tpc/f/9516013/m/209109008/inc/1 Greenhouse product news http://www.gpnmag.com/gpn/index.cfm/powergrid/rfah=%7Ccfap=/CFID/1953461/CFTOKEN/11266837/fuseaction/showNewsItem/newsItemID/9099 http://www.gpnmag.com/gpn/index.cfm?fuseaction=showNewsItem&newsItemId=9138 GMpro http://www.greenbeam.com/features/weG032105.stm http://www.greenbeam.com/email/archives/gm04-26-05.htm OTHER SOURCES Horowitz, A. R., Denholm, I., Gorman, K., Cenis, J. L., Kontsedalov, S., Ishaaya, I. 2003. Biotype Q of Bemisia Tabaci Identified in Israel. Phytoparasitica 31, 94-98. Horowitz, A. R., Kontsedalov, S., Khasdan, V., Ishaaya, I. 2005. Biotypes B and Q of Bemisia Tabaci and Their Relevance to Neonicotinoid and Pyriproxyfen Resistance. Archives of Insect Biochemistry and Physiology 58, 216-225. Muniz, M., Nombela, G. 2001. Differential Variation in Development of the B- and Q-Biotypes of Bemisia Tabaci (Homoptera : Aleyrodidae) on Sweet Pepper at Constant Temperatures. Environmental Entomology 30, 720-727. Pascual, S., Callejas, C. 2004. Intra- and Interspecific Competition Between Biotypes B and Q of Bemisia Tabaci (Hemiptera : Aleyrodidae) From Spain. Bulletin of Entomological Research 94, 369-375.