The white peach scale, Pseudaulacaspis pentagona (Targioni), is one of the most important pests infesting tea trees in Japan. We investigated the susceptibility of populations of the insect collected from tea fields in Shizuoka and Miyazaki prefectures against five insecticides, methidathion, isoxathion, buprofezin, fenpyroximate alone and a fenpyroximate- buprofezin mixture. The susceptibility was evaluated by spraying the pesticides on first instar larvae on tea branches. The corrected mortality of Shizuoka populations after treatment with 200 ppm buprofezin was less than 21.7%, indicating a high resistance to buprofezin. The LC50 of methidathion varied from 26.8 ppm (Miyazaki population) to 773.0 ppm (Yui population in Shizuoka), and thus resistance to methidathion was also suggested; however, Shizuoka populations were susceptible to both fenpyroximate treatments, as were the Miyazaki populations.
The seasonal occurrence of Neoseiulus womersleyi and Tetranychus urticae in apple orchards that received pyrethroid applications was investigated from 2006 to 2007 in Akita Prefecture, northern Japan. The density of N. womersleyi increased continuously during the summer in response to the density of T. urticae, even in pyrethroidtreated plots. The susceptibility of six strains of N. womersleyi was examined against nine pyrethroid insecticides. The mortality of females of the six strains of N. womersleyi was less than 30% in most insecticides tested. These results suggested that pesticide-resistant N. womersleyi occurred in commercial apple orchards, which is promising for the control of T. urticae in the apple IPM program.