Herbivory on Banker Plants Enhances Resistance-Related Responses of Neighboring Tomato Plants to the Two-Spotted Spider Mite

Banker plants are non-crop plants that sustain populations of biological control agents prior to pest outbreaks, offering a preventive strategy within integrated pest management (IPM). Their benefits have primarily been attributed to top-down regulation via natural enemy-mediated pest suppression; however, their potential bottom-up effects remain largely unexplored. Here, we show that airborne cues emitted from banker plants infested with the zoophytophagous mirid bug Nesidiocoris tenuis altered the performance of the two-spotted spider mite Tetranychus urticae on neighboring tomato plants Solanum lycopersicum. Exposure to airborne cues from infested sesame Sesamum indicum significantly reduced mite fecundity, whereas those from tomato and spider flower Cleome hassleriana had no detectable effect, indicating that the induction of crop resistance is dependent on banker plant species. Moreover, T. urticae infestation of banker plants consistently suppressed mite oviposition on neighboring tomato plants across all banker plant species tested. These findings suggest that banker plants can exert previously unrecognized bottom-up effects by modulating crop resistance-related responses through airborne cues. Therefore, selecting banker plant species that emit effective airborne cues may strengthen crop protection and stabilize biological control performance in sustainable IPM strategies.