Continued foliar herbivory by the red spider mite Tetranychus macfarlenei on Plumbago zeylanica severely reduces the levels of a medicinally important metabolite in the roots

Red spider mite, Tetranychus macfarlanei, was identified as a causative parasite for Plumbago zeylanica in India. Present study was undertaken to evaluate the detrimental role of T. macfarlanei on P. zeylanica. The relative change in biomass, stem length, stem diameter, and leaf number was significantly reduced by mite infestation as compared with uninfected plants. A significant reduction of chlorophyll a, chlorophyll b, and total chlorophyll was observed in mite-infested plants. Mite infestation significantly hampered the normal physiological process of the plant, namely, CO₂ assimilation, stomatal conductance, electrolyte leakage, cell membrane injury, and carboxylation efficiency. A significant increase in tissue H₂O₂ and lipid peroxidation coupled with depletion of antioxidant enzymes, namely superoxide dismutase and catalase indicated augmented oxidative stress associated with biotic interaction. Finally, a significant reduction of root-specific secondary metabolite, plumbagin, production highlighted the potential damage of T. macfarlanei in P. zeylanica. The experimental outcome could conclude that the aboveground symptoms due to mite infestation could also exert profound detrimental effect in the belowground tissues.