Susceptibility of female populations of Panonychus ulmi (Koch) (Acari : Tetranychidae) to some acaricides in apple orchards

Abstract

The levels of susceptibility of adult female European red mite, Panonychus ulmi (Koch) populations collected from apple orchards in Bursa region of Turkey, to acaricides, dicofol, bromopropylate and fenpyroximate belong to two different groups and an acaricide-insecticide, amitraz, were determined by a petri leaf disk-Potter spray tower method. When compared with the susceptible population, resistance ratios, as indicated by LC50 values, ranged from 2.2 to 11.9, 0.8 to 3.6, 1.0 to 22.5 and 0.9 to 7.9, while LC90 values varied from 1.6 to 9.8, 1.0 to 5.4, 1.0 to 47.4, 1.4 to 36.6, respectively, for amitraz, dicofol, bromopropylate and fenpyroximate. An examination of bioassay responses showed that susceptibility was lower for fenpyroximate and bromopropylate than for the other two compounds in the order of amitraz < dicofol. In conclusion, P. ulmi susceptibility to tested compounds varied widely from location to location.