I am finally getting to some of those trade magazines that pileup on my desk throughout the year. I came across an article from The Grower in the November/December 2009 issue. The article is entitled Efficacy on the Decline by Vicky Boyd. The article summarizes some examples of pest resistance in whitefly. Specifically, the article talks about imidicloprid and how whiteflies are gaining resistance to this compound. The article states two researchers, one from the University of Arizona in Yuma and one at the University of Florida Gulf Coast Research and Education Center that have been seeing trials of whitefly resistance. John Palumbo states that he's seen a steady increase in imidicloprid resistance in the past 5 to 6 years. At the University of Florida, David Schuster has seen an increase of whitefly resistance to imidicloprid increase eight-fold from the years 2000 to 2006. I'm sure that many growers can probably say the same thing of their crops from the use of this chemical. When the chemistry came out it worked great, but now it seems that the pests don't respond in the same way. This is why it is recommended to rotate with different modes of action in remedying specific pests. As always make sure that you have correctly identified the past in which you want to control. A good publication from the University of Florida is http:edis.ifas.ufl.edu/pi121. This publication classifies insecticides based on mode of action from that Insecticide Resistance Action Committee. You can use this publication to help you rotate through different types of motive action when dealing with specific pests. Rotating through different types of motive action is a Best Management Practice in the nursery industry. It will also help keep certain chemistries available longer to control pests.