Impacts of the Invasive Moth Cydalima perspectalis on the Native Shrub Buxus balearica in Mallorca (Spain)

The box tree moth (Cydalima perspectalis) is an invasive lepidopteran that has rapidly spread across Europe, causing severe defoliation of the Buxus species. In the Balearic Islands, the endemic Buxus balearica is vulnerable due to its restricted distribution and protected status. This study assessed the physiological response of B. balearica to C. perspectalis herbivory by measuring oxidative stress markers and antioxidant defenses. Leaf samples were collected in Mallorca from unaffected plants, mildly defoliated individuals (<25% leaf area loss), and severely defoliated individuals (>70%). Biochemical assays revealed that mildly affected plants exhibited an increase in superoxide dismutase (SOD), glutathione peroxidase (GPx) activities, and total glutathione (tGSH), indicating a compensatory antioxidant response. Conversely, severely defoliated plants showed marked declines in SOD, GPx, and tGSH, accompanied by elevated malondialdehyde concentrations and reduced polyphenol content, reflecting lipid peroxidation and metabolic exhaustion. A field survey conducted in May 2025 confirmed that all adult B. balearica specimens were dead, with only juvenile shoots under 1 m surviving. These findings demonstrate that while B. balearica can initially mount biochemical defenses against C. perspectalis, but continuous herbivory overwhelms its capacity. Urgent monitoring and control strategies are necessary to protect this species, especially in vulnerable habitats.