Use of plasma-activated water to manipulate preference and performance of two-spotted spider mites [Tetranychus urticae (Acari: Tetranychidae)]

A key aspect of effective and sustainable pest management is to develop strategies which are rooted in intrinsic preference and performance responses of target pests. Meaning, a key research objective should be to quantify and characterize non-random feeding behaviors and pest population dynamics on different host plants and use such insight to manipulate target pests away from crops. Using a special jet, air can be heated to a very high temperature and blown into regular water to generate “plasma activated water” (PAW). Typically, PAW has lower pH, higher conductivity and salinity, and it is used to clean/sterilize surfaces. In crop production, PAW is also being promoted as an organic nitrogen fertilizer to boost seed germination and seedling vigor, and to control diseases and arthropod pests. Therefore, this study investigated effect of PAW-treated and untreated tomato plants on preference and performance of two-spotted spider mites (Tetranychus urticae). Ovipositional and attractiveness preference of two-spotted spider mite females were assessed through dual-choice tests in leaf discs from both PAW-treated and untreated tomato plants. We found that females exhibited a lower preference for settling and laid less eggs on leaf discs from PAW-treated plants compared to untreated plants. Population growth of spider mites was monitored over time. A significantly lower population of spider mites was observed on PAW-treated plants. The density of glandular trichomes was found to be significantly higher on PAW-treated plants. These findings suggest that PAW-treated plants have the potential to reduce their suitability as hosts of spider mites.