Ears perked up in the Citrus Expo seminar hall last week when Lukasz Stelinski reported incidences of Asian citrus pysllid resistance to insecticides, “particularly the neonicotinoid group of insecticides in Florida.” The neonicotinoids have been a key weapon against the psyllids that have spread HLB to groves statewide.
Stelinski, an entomologist with the University of Florida’s Institute of Food and Agricultural Sciences, begins by explaining how insects develop resistance to insecticides. He says frequent use of insecticides can cause changes in insect populations over time. Remaining survivors have mutations “that make them more resistant to insecticides,” he says. When insects develop resistance, it takes more insecticide applications to kill them. “And so we reach a point where we can’t apply enough (insecticides),” he says.
“I think this is something that is alarming, the resistance that we’re seeing right now,” says Stelinski. “I think that it is alarming that we already are observing product failures and that growers are reporting them. So if we don’t work very diligently to reverse the problems that do exist and prevent them from further expanding, then it could be a significant problem when we talk about losing important tools that we rely upon.”
Fortunately, Stelinski offers a solution to resistance. “We’ve found that if we rotate (insecticides with) five modes of action, we can virtually prevent the problem,” he says. “And we have at our disposal that many modes of action registered for psyllid control. Not all of them are equally effective against every life stage” and not all are equally toxic to psyllids.
“Not cutting (insecticide application) rates is another strategy,” Stelinski adds.
Several other Citrus Expo speakers also addressed the control of Asian citrus psyllids in the battle against HLB. HLB has been the most devastating disease ever faced by Florida’s citrus industry.
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