Effects of Acaricides on Tetranychus urticae Koch (Green Form) collected from strawberry greenhouses in Okayama Prefecture, Japan

Abstract

We investigated the effects of ten acaricides on adult females and eleven acaricides on eggs of the two-spotted spider mite (Tetranychus urticae Koch (green form)) collected from eight strawberry greenhouses in Okayama Prefecture, Japan, using a rotary distributing sprayer. Additionally, we investigated the LC₅₀ and resistance ratio of adult females to acynonapyr and bifenazate. The acaricidal effect of emamectin benzoate, milbemectin, chlorfenapyr, acequinocyl, tebufenpyrad, cyenopyrafen, cyflumetofen, and pyflubumide on adult females was low in many populations. The effects of acynonapyr and bifenazate were high. Acynonapyr had a resistance ratio of 1 or less in all populations. Alternatively, the bifenazate had a maximum resistance ratio of 42.04, suggesting decreased sensitivity. The acaricidal effects of emamectin benzoate, milbemectin, etoxazole, chlorfenapyr, tebufenpyrad, cyenopyrafen, cyflumetofen, and pyflubumide on eggs were low in many populations. The effects of acequinocyl, acynonapyr, and bifenazate were highest in most populations.