Effects of Electron Beam Irradiation on Acaricide-Resistant and Susceptible Strains of Tetranychusurticae (Acari: Tetranychidae)

The objective of our study was to compare the effects of electron beam irradiation on the development and reproduction of Tetranychus urticae strains that were susceptible or resistant to acequinocyl, bifenazate, and etoxazole. Electron beam irradiation (50–400 Gy) was applied to T. urticae eggs, nymphs, and adults, after which the hatching rate, the emergence rate, longevity, and fecundity were analyzed. Eggs of all the T. urticae strains were irradiated with 150 Gy, and none of them hatched. When protonymphs were irradiated with 300 Gy, oviposition and thus F1 hatchability in newly emerged adults were completely suppressed. The F1 hatching rate of irradiated adults began to markedly decrease with a dose of 200 Gy, and all strains experienced 100% inhibition at a dose of 400 Gy. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (Sodium dodecyl sulfate polyacrylamide gel electrophoresis) showed substantial reductions in the levels of a 50 kDa protein in the susceptible and three resistant strains of T. urticae after irradiation with 400 Gy. These results indicate that a dose of 400 Gy was required to inhibit the normal development and reproduction of T. urticae, and susceptible and acaricide-resistant strains of T. urticae had identical radiosensitivities.