Toxicity of Flufenoxuron Alone and in Mixture with Alphacypermethrin or Fenbutatin Oxide to Tetranychus urticae and Panonychus ulmi (Acari: Tetranychidae)

Acaricidal activity of flufenoxuron alone and mixed with alphacypermethrin or fenbutatin oxide was evaluated in laboratory and field studies. In a laboratory study with the twospotted spider mite, Tetranychus urticae Koch, flufenoxuron alone and mixed with alphacypermethrin was highly effective against immature stages, but ineffective against eggs and nontoxic to adults. A mixture of flufenoxuron and fenbutatin oxide was effective against all stages of T. urticae. Flufenoxuron had no repellent activity, but flufenoxuron + alphacypermethrin exhibited strong repellency. In females treated as deutonymphs with flufenoxuron alone and mixed with alphacypermethrin, we observed substantial reduction in egg viability but there was no obvious effect on number of eggs laid. In a field study of a population of European red mite, Panonychus ulmi (Koch), and a population of T. urticae, efficacy of flufenoxuron and its mixtures, expressed as a protective value at 30 d in each treated plot relative to an untreated plot, was similar to that of the commonly used azocyclotin or hexythiazox. Based upon laboratory and field data, flufenoxuron or mixtures described may be used to prevent damage by P. ulmi and T. urticae.