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TECHNICAL TIPS   Q Biotype Whiteflies- Fight the Hype! - BY RICK YATES, TECHNICAL SUPPORT MANAGER Rick Yates Technical Support Manager       Mark Twain once said, "The rumors of my death have been greatly exaggerated". In some circles the appearance of the Q biotype whitefly in the US has been blown up to similar proportions. While this is certainly not good news for growers we need to take a deep breath and review what we know so far.    For several years the B biotype whitefly has been the predominant strain in the US. In Europe the Q biotype whitefly has displaced the B biotype. To look at the two critters you could not tell them apart. In fact, molecular analysis is needed to distinguish between them. The differences only become apparent when you “pop the hood” and take a look at how they respond to certain insecticides. The Q biotype whitefly is reported to be highly resistant to the insect growth regulators Talus and Distance that work quite well on the B biotype. It isalso reported to be significantly less responsive to neonicitinoid insecticides. This includes Marathon, TriStar, Flagship, Celero, Safari and other products that share the same active ingredients. This does not mean that control of the “Q” cannot be achieved with these products, just that they are much less sensitive to this mode of action than the “B”. Safari provided excellent control of Q biotype whiteflies for Griffin customers during the 2005 poinsettia crop. The take home message is that although control is possible with this mode of action now, the countdown towards resistance is already well under way. We must utilize diligent scouting while making informed decisions on how to rotate insecticides by mode of action. Dr. Raymond Cloyd from the University of Illinois has published a guide to rotating greenhouse insecticides by mode of action that is very comprehensive.     Just how widespread is the Q biotype whitefly in the US? After first being identified in Arizona late in 2004 it has been identified in over 20 states as of this writing. Nearly every state in New England and the mid-Atlantic states have confirmed the presence of “Q” in their states. Some entomologists feel that the Q biotype whitefly is already widely distributed in the US and may have been here for some time before researchers in Arizona discovered its presence. If you haven’t already had a brush with this pest chances are you won’t have to wait long to get your first crack at them.    Researchers are already hard at work screening pesticides for effectiveness against the “Q”. The confusing aspect to this is that some treatments that work well in one trial sometimes fall flat in another and vice versa. This is to be expected since there are no doubt variations in pesticide sensitivity within the “Q” populations just like there is with the “B”. The good news is that many of our currently registered pesticides are showing good to excellent efficacy against this new pest. The work ahead is to continue to share research and grower experiences in order to help us refine our recommendations. Rotating modes of action to slow pesticide resistance is always imperative but our room for error with this best is likely to be slim indeed. At this point the best advice is to stay informed on what the experts are recommending as it is a little like hitting a moving target at this point. This web site is an excellent resource and is updated often: http://www.mrec.ifas.ufl.edu/LSO/bemisia/bemisia.htm    If you need help in getting your whiteflies tested or in developing a responsible pesticide program please contact Griffin’s Technical Department. Q Biotype Whitefly