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 <i>Nesidiocoris tenuis</i> altered the performance of the two-spotted spider mite <i>Tetranychus urticae</i> on neighboring tomato plants <i>Solanum lycopersicum</i>. Exposure to airborne cues from infested sesame <i>Sesamum indicum</i> significantly reduced mite fecundity, whereas those from tomato and spider flower <i>Cleome hassleriana</i> had no detectable effect, indicating that the induction of crop resistance is dependent on banker plant species. Moreover, <i>T. urticae</i> 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.