2025 Volume 67 Pages 105-108
Generally, when testing acaricide susceptibility of spider mites on horticultural crops, populations collected from multiple sites and locations within the same greenhouse are mixed based on the assumption that no difference in genetic diversity and acaricide susceptibility between populations exists. However, the magnitude of the difference in acaricide susceptibility between spider mite populations in the same greenhouse has not been investigated. This study compared the susceptibility of two-spotted spider mite Tetranychus urticae Koch (green form) populations collected from three sites at each location in a single rose greenhouse to different acaricides. For all acaricides, the maximum LC50 values were obtained in populations collected from the northwest of the greenhouse and the base of rose plants. In addition, differences in LC50 values were observed for amitraz EC between collection sites, with maximum differences of 124.6-fold at 24 h post-treatment. These results suggest that local subpopulations develop acaricide resistance, even within a single greenhouse and rose plant. They also vary widely in acaricide susceptibility.
