Influence of non-host aromatic plants on the survival and olfactory behavior of the African citrus psyllid, Trioza erytreae

Abstract Trioza erytreae Del Guercio, 1918, commonly known as the African citrus psyllid, is one of the main vectors of Huanglongbing (citrus greening), the most destructive citrus disease worldwide. Currently, there is no effective treatment for HLB; therefore, management efforts primarily focus on controlling the insect vectors. This often involves the use of insecticides, which raises concerns about environmental impact and the development of insecticide resistance. This study evaluates the potential of five aromatic non-host plants commonly found in the Mediterranean basin, which overlap with regions of citrus production ( Cistus ladanifer , Rosmarinus officinalis , Foeniculum vulgare , Lavandula stoechas , and Thymus mastichina ) to influence the survival and olfactory behavior of T. erytreae . Although the psyllids were able to survive for several days on these non-host plants, survival was significantly lower compared to the citrus host ( Citrus limon ), with C. ladanifer having the most detrimental effect. Olfactory assays revealed that, in females, C. limon , C. ladanifer , and L. stoechas elicited significantly higher probabilities of attraction compared with R. officinalis and T. mastichina . In males, C. limon elicited a significantly higher probability of attraction than R. officinalis , T. mastichina , and L. stoechas . A total of 123 volatile organic compounds (VOCs) were identified across all plant species, of which 48 were found to be important for the olfactory response of T. erytreae . Among these, 19 VOCs were positively correlated with psyllid attraction, while 15 showed negative correlations, indicating a potential repellent or disruptive effect. These results suggest that specific VOCs emitted by aromatic non-host plants can modulate host-seeking behavior in T. erytreae , highlighting their potential application in the development of semiochemical-based, environmentally sustainable strategies for citrus pest management.