Composition of volatiles of citrus varieties and their effects on the behavior of Diaphorina citri.

Huanglongbing (HLB) is the most devastating citrus disease worldwide, with no resistant varieties currently available. Effective management of HLB relies heavily on controlling its primary vector, the Asian citrus psyllid (Diaphorina citri, ACP). This study aimed to evaluate the attractiveness of different citrus varieties to ACP using a four-arm olfactometer and to characterize the volatile organic compounds (VOCs) extracted from these plants. The varieties tested included three sweet orange scions ('Valencia', 'Westin', and 'Pera') and three rootstocks ('Rangpur' lime, 'Sunki Tropical', and 'BRS Bravo'). VOCs were extracted using HS-SPME and identified via GC-MS. Results indicated that 'Sunki Tropical', 'Rangpur' lime, and 'Valencia' were significantly more attractive to ACP compared to other varieties. The reduced attractiveness of rootstock genotypes, such as 'BRS Bravo' and the control 'Flying Dragon', was correlated with higher levels of germacrene D and γ-elemene. Conversely, the increased attractiveness of 'Rangpur' lime and 'Sunki Tropical' was associated with abundant D-limonene. In grafted scions on 'Rangpur' lime, linalool was identified as a key compound linked to the attractiveness of 'Westin' and 'Valencia'. These findings suggest that the differential attractiveness of citrus varieties to ACP is influenced by specific VOC profiles.