scholarly journals Detection and Relative Titer of Candidatus Liberibacter asiaticus in the Salivary Glands and Alimentary Canal of Diaphorina citri (Hemiptera: Psyllidae) Vector of Citrus Huanglongbing Disease

2011 ◽  
Vol 104 (3) ◽  
pp. 526-533 ◽  
Author(s):  
El-Desouky Ammar ◽  
Robert G. Shatters ◽  
Christine Lynch ◽  
David G. Hall
Keyword(s):  
Salivary Glands ◽  
Alimentary Canal ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus

scholarly journals Latency and Persistence of ‘Candidatus Liberibacter asiaticus’ in Its Psyllid Vector, Diaphorina citri (Hemiptera: Liviidae)

2017 ◽  
Vol 107 (3) ◽  
pp. 264-272 ◽  
Author(s):  
Maria Cristina Canale ◽  
Arthur Fernando Tomaseto ◽  
Marineia de Lara Haddad ◽  
Helvécio Della Coletta-Filho ◽  
João Roberto Spotti Lopes
Keyword(s):  
Latent Period ◽  
Acquisition Time ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Old Adults ◽  
Sequential Inoculation ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Series Of Experiments

Although ‘Candidatus Liberibacter asiaticus’ (Las) is a major pathogen associated with citrus huanglongbing (HLB), some characteristics of transmission by the psyllid vector Diaphorina citri are not fully understood. We examined the latent period and persistence of transmission of Las by D. citri in a series of experiments at 25°C, in which third-instar psyllid nymphs and 1-week-old adults were confined on infected citrus for an acquisition access period (AAP), and submitted to sequential inoculation access periods (IAPs) on healthy citrus seedlings. The median latent period (LP50, i.e., acquisition time after which 50% of the individuals can inoculate) of 16.8 and 17.8 days for psyllids that acquired Las as nymphs and adults, respectively, was determined by transferring single individuals in 48-h IAPs. Inoculation events were intermittent and randomly distributed over the IAPs, but were more frequent after acquisition by nymphs. A minimum latent period of 7 to 10 days was observed by transferring groups of 10 psyllids in 48-h IAPs, after a 96-h AAP by nymphs. Psyllids transmitted for up to 5 weeks, when submitted to sequential 1-week IAPs after a 14-day AAP as nymphs. The long latent period and persistence of transmission are indirect evidences of circulative propagation of Las in D. citri.

scholarly journals Development on Infected Citrus over Generations Increases Vector Infection by ‘Candidatus Liberibacter Asiaticus in Diaphorina citri’

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 469
Author(s):  
Inaiara de Souza Pacheco ◽  
Diogo Manzano Galdeano ◽  
João Roberto Spotti Lopes ◽  
Marcos Antonio Machado
Keyword(s):  
Management Strategies ◽  
Fourth Generation ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Citrus Orchards ◽  
Vector Efficiency ◽  
Control And Eradication

‘Candidatus Liberibacter asiaticus’ (CLas) is a major causal agent of citrus Huanglongbing (HLB), which is transmitted by Asian citrus psyllid (ACP), Diaphorina citri, causing severe losses in various regions of the world. Vector efficiency is higher when acquisition occurs by ACP immature stages and over longer feeding periods. In this context, our goal was to evaluate the progression of CLas population and infection rate over four ACP generations that continuously developed on infected citrus plants. We showed that the frequency of CLas-positive adult samples increased from 42% in the parental generation to 100% in the fourth generation developing on CLas-infected citrus. The bacterial population in the vector also increased over generations. This information reinforces the importance of HLB management strategies, such as vector control and eradication of diseased citrus trees, to avoid the development of CLas-infected ACP generations with higher bacterial loads and, likely, a higher probability of spreading the pathogen in citrus orchards.

Prevalent transmission of 'Candidatus Liberibacter asiaticus’ over ‘Ca. Liberibacter americanus’ in a long-term controlled environment

2021 ◽  
Author(s):  
Maria Cândida de Godoy Gasparoto ◽  
Isabela Vescove Primiano ◽  
Renato Bassanezi ◽  
Silvia Afonseca Lourenço ◽  
Luiz Montesino ◽  
...  
Keyword(s):  
Sweet Orange ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Citrus Orchards ◽  
Test Plants

In Brazil, citrus huanglongbing (HLB) is associated with ‘Candidatus Liberibacter americanus’ (CLam) and ‘Ca. Liberibacter asiaticus’ (CLas). However, there are few studies about HLB epidemiology when both Liberibacter spp. and its insect vector, the Asian citrus psyllid (ACP, Diaphorina citri), are present. The objective of this work was to compare the transmission of HLB by ACP when both CLam and CLas are present as primary inoculum. Two experiments were performed under screenhouse conditions from April 2008 to January 2012 (experiment 1) and from February 2011 to December 2015 (experiment 2). The experiments were carried out with sweet orange plants infected with CLam or CLas as inoculum source surrounded by sweet orange healthy plants. One hundred Liberibacter-free adult psyllids were monthly confined to the source of inoculum plants for 7 days with subsequent free movement inside the screenhouse. Fortnightly, nymphs and adults of psyllids were monitored. Psyllid and leaf samples were collected periodically for Liberibacter detection by PCR or qPCR. CLas was detected more frequently than CLam in both psyllid and leaf samples. No mixed infections were detected in the psyllids. A clear prevalence of CLas over CLam was observed in both experiments. The final HLB incidences were 16.7 and 14.5% of Liberibacter-positive test plants, and CLas was detected in 92.3 and 93.1% of these infected plants. Mixed infection was observed only in 3.8% of infected test plants in experiment 1. These results endorse the shift in the prevalence of CLam to CLas observed in citrus orchards of São Paulo, Brazil.

scholarly journals Detection of ‘Candidatus Liberibacter asiaticus’ in Diaphorina citri and Its Importance in the Management of Citrus Huanglongbing in Florida

2008 ◽  
Vol 98 (4) ◽  
pp. 387-396 ◽  
Author(s):  
K. L. Manjunath ◽  
S. E. Halbert ◽  
C. Ramadugu ◽  
S. Webb ◽  
R. F. Lee
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Diagnostic Methods ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Polymerase Chain ◽  
Polymerase Chain Reaction Methodology

Citrus huanglongbing (HLB or citrus greening), is a highly destructive disease that has been spreading in both Florida and Brazil. Its psyllid vector, Diaphorina citri Kuwayama, has spread to Texas and Mexico, thus threatening the future of citrus production elsewhere in mainland North America. Even though sensitive diagnostic methods have been developed for detection of the causal organisms, Candidatus Liberibacter spp., the pathogen cannot be detected consistently in plants until symptoms develop, presumably because of low titer and uneven distribution of the causal bacteria in nonsymptomatic tissues. In the present study, TaqMan based real-time quantitative polymerase chain reaction methodology was developed for detection of ‘Ca. L. asiaticus’ in D. citri. Over 1,200 samples of psyllid adults and nymphs, collected from various locations in Florida, from visually healthy and HLB symptomatic trees at different times of the year were analyzed to monitor the incidence and spread of HLB. The results showed that spread of ‘Ca. L. asiaticus’ in an area may be detected one to several years before the development of HLB symptoms in plants. The study suggests that discount garden centers and retail nurseries may have played a significant role in the widespread distribution of psyllids and plants carrying HLB pathogens in Florida.

scholarly journals Resolution of the Identity of ‘Candidatus Liberibacter’ Species From Huanglongbing-Affected Citrus in East Africa

Plant Disease ◽  
2017 ◽  
Vol 101 (8) ◽  
pp. 1481-1488 ◽  
Author(s):  
Ronel Roberts ◽  
Glynnis Cook ◽  
Tim G. Grout ◽  
Fathiya Khamis ◽  
Ivan Rwomushana ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Housekeeping Genes ◽  
Diaphorina Citri ◽  
Candidatus Liberibacter Asiaticus ◽  
Citrus Production ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus ◽  
Resolution Of The Identity

‘Candidatus Liberibacter asiaticus’, the bacterium associated with citrus Huanglongbing (HLB), was reported from Uganda and tentatively from Tanzania, posing a threat to citriculture in Africa. Two surveys of citrus expressing typical HLB symptoms were conducted in Uganda, Kenya, and Tanzania to verify reports of ‘Ca. L. asiaticus’ and to assess the overall threat of HLB to eastern and southern African citrus production. Samples were analyzed for the presence of ‘Candidatus Liberibacter’ species by real-time PCR and partial sequencing of three housekeeping genes, 16S rDNA, rplJ, and omp. ‘Ca. L. africanus’, the bacterium historically associated with HLB symptoms in Africa, was detected in several samples. However, samples positive in real-time PCR for ‘Ca. L. asiaticus’ were shown not to contain ‘Ca. L. asiaticus’ by sequencing. Sequences obtained from these samples were analogous to ‘Ca. L. africanus subsp. clausenae’, identified from an indigenous Rutaceae species in South Africa, and not to ‘Ca. L. asiaticus’. Results indicate a nontarget amplification of the real-time assay and suggest that previous reports of ‘Ca. L. asiaticus’ from Uganda and Tanzania may be mis-identifications of ‘Ca. L. africanus subsp. clausenae’. This subspecies was additionally detected in individual Diaphorina citri and Trioza erytreae specimens recovered from collection sites. This is the first report of ‘Ca. L. africanus subsp. clausenae’ infecting citrus and being associated with HLB symptoms in this host.

Highly sensitive and rapid detection of citrus Huanglongbing pathogen (Candidatus Liberibacter asiaticus) using Cas12a-based methods

2021 ◽  
Author(s):  
Matthew Wheatley ◽  
Yong-Ping Duan ◽  
Yinong Yang
Keyword(s):  
Early Detection ◽  
Nucleic Acids ◽  
Detection Sensitivity ◽  
Sensitive Detection ◽  
Detection Methods ◽  
Candidatus Liberibacter Asiaticus ◽  
Fluorescent Reporter ◽  
Candidatus Liberibacter ◽  
Citrus Huanglongbing ◽  
Liberibacter Asiaticus

Citrus Huanglongbing (HLB) or greening is one of the most devastating diseases of citrus worldwide. Sensitive detection of its causal agent, Candidatus Liberibacter asiaticus (CLas), is critical for early diagnosis and successful management of HLB. However, current nucleic acid-based detection methods are often insufficient for the early detection of CLas from asymptomatic tissue, and unsuitable for high-throughput and field-deployable diagnosis of HLB. Here we report the development of the Cas12a-based DETECTR (DNA endonuclease-targeted CRISPR trans reporter) assay for highly specific and sensitive detection of CLas nucleic acids from infected samples. The DETECTR assay, which targets the five-copy nrdB gene specific to CLas, couples isothermal amplification with Cas12a trans-cleavage of fluorescent reporter oligos and enables detection of CLas nucleic acids at the attomolar level. The DETECTR assay was capable of specifically detecting the presence of CLas across different infected citrus, periwinkle and psyllid samples, and shown to be compatible with lateral flow assay technology for potential field-deployable diagnosis. The improvements in detection sensitivity and flexibility of the DETECTR technology position the assay as a potentially suitable tool for early detection of CLas in infected regions.

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