Can biological control involving predatory mites mitigate plant stress caused by phytophagous mites?

The biological control of phytophagous mites mediated by predatory mites promotes the maintenance of plant physiology by mitigating damage and preserving key traits related to photosynthesis and development. The immune system of plants, upon perceiving the presence of phytophagous mites, triggers signals mediated by reactive oxygen species (ROS). Under intense infestations, these redox signals can trigger oxidative stress, which compromises vital characteristics related to plant fitness. The use of pesticides as a management strategy is increasingly limited by resistance and collateral physiological impacts on plants. The release of predatory mites has emerged as an effective and sustainable biological approach. Predator-mediated foraging may suppress phytophagous mite infestations and mitigate the physiological stress of plants by limiting metabolic expenditures and physiological disturbances related to photosynthesis, growth, and reproduction. Thus, we review the benefits and risks of signals mediated by ROS in plants under attack by phytophagous mites. We conceptualize a stress state for plants under attack by these organisms and describe the benefits of foraging predatory mites reported in the literature from a meta-analytical perspective. Based on existing studies, we show that these natural enemies mitigate damage and the intensification of foliar chlorosis, limiting impacts on leaf area, the number of leaves, and the size of the plants. Furthermore, we speculate how the intensity of stress in the plant could act as a key point in the signals emitted to attract predatory mites. Finally, we emphasize the urgency of integrating this new perspective into future studies to improve the evaluation of the efficiency of natural enemies to benefit plant performance.