Effects Of Electron Beam Irradiation On Acaricide-Resistant And Susceptible Strains Of Tetranychus Urticae (Acari: Tetranychidae)

Simple Summary A lab-selected strain of the two-spotted spider mite, Tetranychus urticae Koch, exhibited strong resistance to acequinocyl, bifenazate, and etoxazole in comparison with a susceptible strain. This study compared the development and reproduction in acaricide-resistant and -susceptible strains of T. urticae by electron beam irradiation. Both T. urticae strains had similar radiosensitivities and 400 Gy could be used as a phytosanitary treatment for both strains of this species. 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 F-1 hatchability in newly emerged adults were completely suppressed. The F-1 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.