Controlling wireworms with neonicotinoid insecticides in wheat
Esser, Aaron D.
Pike, K. S.
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Wireworm (Limoniusspp.) populations and crop damage have been increasing in wheat (Triticum aestivum L.) production across eastern Washington. Today nearly all spring cereal crop acres throughout eastern Washington are treated for wireworms with neonicotinoid insecticides such as Cruiser® (thiamethoxam) or Gaucho® (imidacloprid) at rates between 0.190-0.315oz/cwt. At these rates, then eonicotinoids are toxic to wireworms but at sub-lethal doses, or in other words they repel or provide only seedling protection. Our objective is to find a labeled lethal dose of neonicotinoid insecticide to reduce wireworm populations. An on-farm test (OFT) was initiated in 2008 to examine spring wheat treated with 2.0oz/cwt of Gaucho vs. a non-Gaucho treated spring wheat check. At this location frost severely limited yield, however 2.0oz/cwt Gaucho had a trend for improved yield and economic return over costs, and it reduced wireworm populations by78%. A second OFT was repeated in 2010. Spring wheat treated with 2.0oz/cwt Gaucho significantly improved yield, economic return over costs and reduced wireworm populations 41%.