Acquisition of Candidatus Liberibacter asiaticus by psyllid species transiently landing and feeding on Citrus sinensis

‘Candidatus Liberibacter asiaticus’ (CLas), the prevalent agent associated with Huanglongbing (HLB), poses a severe threat to global citrus production. This study aimed to investigate the occurrence of psyllid species (other than Diaphorina citri) landing on citrus trees, evaluate their survival on citrus over optimal acquisition access periods (AAP), assess their ability to acquire CLas, and infer their potential role in pathogen transmission. Field surveys were conducted in Citrus sinensis plants located in backyards and poorly managed groves in two locations of São Paulo State, Brazil. Psyllids from twelve genera were identified, with Isogonoceraia divergipennis and Heteropsylla cubana being among the most constant species, showing greater abundance particularly in late winter and early spring. Controlled acquisition assays demonstrated that I. divergipennis, H. cubana, and Triozoida limbata could acquire CLas following a 72-h AAP, post-acquisition latency of 14 days and a subsequent 72-h post-latency period, with acquisition rates of 8.1%, 3.2%, and 2.4%, respectively, compared to 85.7% in D. citri. Notably, CLas was detected in the 'head-mesothorax' region only in T. limbata and D. citri, suggesting potential bacterial presence in the salivary glands and possible transmission competence. CLas titers were consistently higher in the 'metathorax-abdomen' than in the 'head-mesothorax'. While the data indicate occasional CLas acquisition by psyllids other than D. citri, there is currently no evidence supporting their role as natural vectors. Nonetheless, these species may serve as valuable models for elucidating transmission barriers in non-competent psyllids and highlight the need for further investigation into their epidemiological relevance.