Abstract
Huanglongbing (HLB) disease in Brazilian citrus orchards is historically associated with ‘Candidatus Liberibacter americanus’ (CLam), which occurs exclusively in Brazil, and the cosmopolitan ‘Ca. L. asiaticus’ (CLas), both vectored by Diaphorina citri. When HLB was first reported in 2004, both species were detected, with CLam predominating and of wider spatial distribution. However, from 2008 onward, CLas became dominant, and CLam was barely detected after 2013. To investigate this shift and decline on CLam incidence, we examined the acquisition by D. citri of CLam, CLas, or both, from single-infected or co-infected symptomatic citrus plants, as well as during the incubation period. Acquisition incidence of CLas reached 100% from the fifth nymphal stage onward, whereas CLam acquisition plateau of 80% was achieved at 40 days after adult emergence, suggesting delayed psyllid infection. During the incubation period, CLas was acquired in 86% of D. citri individuals, compared with 10% average for CLam. CLas titer in D. citri was up to two and half-fold higher than CLam titer. Consistently, CLam was also associated with later infection of citrus flushes compared to CLas. Altogether, our findings provide experimental evidence that the shift in CLas over CLam in Brazilian citrus belt results from faster infection of sweet orange flushes and higher infection rates and higher bacterium titer in D. citri.
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Acknowledgements
We thank André Sanches and his team for their support in maintaining the plants in the greenhouse during the trials. We also thank the entomology team at Fundecitrus for providing the insects from the stock colonies used during the trials, as well as for their assistance throughout the experimental procedures. We thank Daniela A. B. Coletti, Deividson F. Rodrigues, Jean M. Martins, and Sidnei F. Alkimin for their support in DNA extractions and PCR analysis. We thank Sidnei F. Alkimin for drawing the figures used in the schematic representations in the supplementary material.
Funding
Financial support was provided by the Fund for Citrus Protection (Fundecitrus 04 3069), This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), grant 2015/07011–3, and the National Council of Technological and Scientific Development (CNPq/Brazil) for providing a fellowship for the first author (306365/2024–3).
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Darolt, J.C., Cifuentes-Arenas, J.C., Martins, E.C. et al. Acquisition dynamics of ‘Candidatus Liberibacter asiaticus’ and ‘Ca. L. americanus’ by Diaphorina citri highlights the epidemiological decline of ‘Ca. L. americanus’.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-60740-2
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DOI: https://doi.org/10.1038/s41598-026-60740-2
Keywords
- Asian citrus psyllid
- Citrus greening
- Prokaryote-vector relationship
- Huanglongbing
- Citrus
Source: Ecology - nature.com
