Effect of Various Plant Extracts and Organic Emulsifiers on Acaricidal Activity of Two-spotted Spider Mite (Tetranychus urticae)

The objective of this research was to determine acaricidal activity (AA) on the two-spotted spider mite (Tetranychus urticae; TSSM) in persimmon trees by (1) using plant extracts (PEs) and different extraction methods (water, boiling water, fermentation, and ethanol) from various plant parts (leaves, stems, fruits, and roots) in 46 species from 28 families, (2) using mixers of various PEs and organic emulsifiers (OEs), and (3) using selected PEs and OEs. Boiling water extracts of Chrysanthemum zawadskii and Mentha arvensis all parts above ground, and Rehmannia glutinosa and Coptis japonica roots among 46 plant species from 28 families were found to be more effective on AA of TSSM, and TSSM was 57-75% controlled by 10% of the PEs in a laboratory test. The order of AA on TSSM by OEs at 5% concentration was powder soap (100%; PS) > natural emulsifier-B (98%; NEB) > loess sulphur (89%; LS) > natural emulsifier-A (51%; NEA) > brown rice vinegar (45%; BRV). In the treatment by PEs alone, TSSM was 60.4% and 44.0% controlled by 5% extracts of Chrysanthemum zawadskii and Rehmannia glutinosa, respectively, in an organically produced persimmon tree field. However, in the combination treatments by PEs and OEs, TSSM was 55.5-77.9% controlled by Chrysanthemum zawadskii extract (5%) + NEB (1%), Rehmannia glutinosa extract (5%) + NEB (1%), Chrysanthemum zawadskii extract (5%) + PS (1%), and Rehmannia glutinosa extract (5%) + PS (1%) when compared with non-treated controls. Persimmon leaf injuries did not show after treatments by 10% Chrysanthemum zawadskii and Rehmannia glutinosa extracts, and 5% NEB and PS. Thus, the PEs and OEs may be used for controlling TSSM in organically produced crop fields.