Silicon-Induced Suppression of the Two-Spotted Spider Mite Tetranychus urticae Populations and Physiological Responses of Sugar Beet Under Greenhouse Conditions

Silicon-containing formulations have been investigated as potential complementary tools for managing arthropod pests, including the two-spotted spider mite (Tetranychus urticae Koch). The present study evaluated the effects of different silicon application regimes on spider mite population development and physiological status of sugar beet (Beta vulgaris L. cv. Kujavia) under controlled greenhouse conditions. Plants were treated with one or two foliar applications of a commercial silicon formulation at two dosage levels and artificially infested with adult female spider mites. The population density of developmental stages, leaf infestation level, egg production, and chlorophyll content (SPAD index) were determined. Silicon treatments significantly affected leaf infestation, larval abundance, total motile stages, non-motile stages, and total spider mite population. The most effective treatments reduced the abundance of mobile developmental stages and overall population density compared with untreated controls. Although differences in SPAD values were not statistically significant, no significant effect of the tested silicon-containing formulation on leaf chlorophyll status was detected under the experimental conditions. Multivariate analyses demonstrated differentiation among the experimental treatment combinations, based on the combined set of measured variables, indicating that the treatment combinations differed in their overall plant–mite response. The results indicate that the tested silicon-containing formulation may have potential as a complementary component of integrated pest management programs targeting T. urticae, although its efficacy requires further validation under field conditions.