Spatial Distribution of Paysandisia archon (Burmeister) (Lepidoptera: Castniidae) Infestation on Palms in the City of Pesaro

ABSTRACT

Paysandisia archon is a South American castniid moth unintentionally introduced in Europe through the international plant trade and first reported there in the early 2000s. Its larvae cause severe damage to palms (Arecaceae) by feeding on the apical meristem and excavating inside the trunk, leading to structural instability and eventual plant death. Despite its high invasiveness, information on its distribution and host palms remains limited. This study analysed the spatial occurrence and severity of P. archon infestations in the urban area of Pesaro using an interpolation deterministic approach called Inverse Distance Weighting (IDW). Data were collected through visual inspections of infested palms during summer 2024, assessing damage to trunks and foliage. Damage severity was related to palm species and previous control treatments. The obtained results allowed mapping infestation severity and revealed a statistically significant relationship between damage severity and treatment: previously treated palms showed lower damage levels, while untreated palms suffered more severe damage. However, no significant differences emerged between treated and untreated palms when considering only the presence or absence of symptoms, suggesting that control measures affect damage progression rather than infestation onset. These findings improve understanding of the effectiveness of defence strategies and support the development of more efficient monitoring and prevention measures for protecting urban ornamental palms.