ACTIVITY OF PYRIDABEN ON RESISTANT GLASSHOUSE POPULATION OF TETRANYCHUS URTICAE KOCH

Ovicidal-ovolarvicidal activity of pyridaben on glasshouse population of polyphytophagous mite Tetranychus urticae Koch (Acari: Tetranychidae), resistant to clofentezine and dicofol, was investigated during 70 – 75 generation development (January 1994 – May 1996). In 1994, dicofol and clofentezine resistance was moderate: dicofol resistance ratios varied between 13 and 60, and clofentezine resistance ratios varied between 4 and 23. Pyridaben resistance was low: resistance ratios varied between 2 and 6. Since last measurement in 1994, constant and significant increase of resistance has been recorded, especially to clofentezine.
The ratios of resistance to clofentezine reached maximum in December 1995 (891 – 19005). The ratios of resistance to pyridine were highest in January 1996 (138 – 372). Last measurement of clofentezine activity (April 1996) and pyridaben activity (May 1996) showed substantial decrease of resistance.
The ratios of resistance to dicofol ovolarvicidal activity reached maximum in December 1995 (214 – 249) while the ratios of resistance to dicofol ovicidal activity were highest in May 1996 (191 – 215). This increase of resistance was probably due to the co-adaptation process.
Pyridaben concentration with 90% ovolarvicidal effect, calculated from regression lines obtained in 1995 and 1996, were far above the concentration recommended for use in Yugoslavia.
Synergized activity of piperonyl butoxide and clofentezine, and piperonyl butoxide and pyridaben, confirmed importance of multifunctional oxidases from T. urticae eggs for expression of resistance to these two compounds.
Acaricidal effect of combination of piperonyl butoxide and dicofol was synergized at LC₅₀ level, but not at LC₉₀ level.

I Balkan Symposium On Vegetables and Potatoes

D. Marcic

Tetranychus urticae, two-spotted spider mite, pyridaben, clofentezine, dicofol, resistance

https://doi.org/10.17660/ActaHortic.1997.462.72