LIBRO-CONGRESO-CITRUS

S12
not indicate effect of the previous presence of CTV in Las infection and HLB symptoms, with similar proportion
in treatment with viruses (68%) and without viruses infection (60%). On the other hand, mild (“PIAC”) or of
medium severity (“CV 154”) isolates of CTV, showed the lowest rate of occurrence of HLB (30-40%), which
reached 70-80% when plants were pre-inoculated with the severe CTV isolates “Capao Bonito” “CV 93” and
“Barao B”. The pre-inoculation of isolates of medium severity of CTV: “CV 104”, “CV 155” and “CV 27”, also
carrying respectively CCaVd, Psorosis and CEVd, induced 70, 80 and 100% of HLB symptoms.
Financial support: Fundag, FAPESP and CNPq.
S12P13
The efficient transmission of “Candidatus Liberibacter americanus” from periwinkle
(Catharanthus roseus) to different citrus genotypes by dodder
Francisco C.S., Locali E.C., Machado M.A., and Coletta-Filho H.D.
Centro APTA Citros Sylvio Moreira (IAC), Laboratório Biotecnologia, Brazil. carolinaf@centrodecitricultura.br
In Sao Paulo State, Brazil, both bacteria “Candidatus Liberibacter asiaticus” (Las) and “Ca. L. americanus” (Lam)
are associated with Huanglongbing - HLB or Greening disease in citrus. Nowadays Lam has been observed in
low prevalence in HLB-disease plants, contrary to its high prevalence in the first 2 years of disease outbreak,
2005 and 2006. But despite of this drastic swift on prevalence of “Ca. Liberibacter” species scientific interests
remain on Lam bacteria. Based on our experience and supported by the Lopes & Frare (2008) data, Lam grafting
transmission is randomly and not efficient for most citrus species, which increases difficulties in experiments
under controlled conditions aiming to study plant-pathogen interaction. But, similarly to Asiatic species of Ca.
Liberibacter, Lam reached high titers in periwinkle plants (Cataranthus roseus). The main objective of this study
is to analyze the transmission of Lam from periwinkle to citrus by dodder (Cuscuta spp.) as an alternative to
improve the transmission efficiency of that pathogen. Periwinkle seedlings infected with Lam were used as
source for bacterial acquisition by dodder. After a period of 15 days parasitizing periwinkle plants, the dodder
were keep connected to citrus plants by 30 days for the transmission. The citrus plant tests were analyzed by
end-point PCR and qPCR. The results show that ‘Ponkan’ mandarin (Citrus reticulata) and ‘Dourada’ lime (Citrus
limettioides) were infected at rate of 100%, while ‘Hamlin’ sweet orange (Citrus sinensis) of 75%, and ‘Key’ lime
(Citrus aurantifolia) of 50%. However, the back transmission of Lam from periwinkle to citrus by dodder is an
efficient strategy to be used for overcoming the low rate of transmission of this pathogen by grafting.
S12P14
Population dynamics of Diaphorina citri (Hemiptera: Psyllidae) in orchards of ‘Valencia’ sweet
orange, ‘Ponkan’ mandarin and ‘Murcott’ tangor trees
Beloti V.H. 1 , Felippe M.R. 2 , Rugno G.R. 1 , do Carmo-Uehara A. 2 , Garbim L.F. 2 , Godoy W.A.C. 1 , and Yamamoto P.T. 1
1 Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Entomologia e Acarologia, Brazil; and 2 Fundo de Defesa da Citricultura
(Fundecitrus), Científico, Brazil. pedro.yamamoto@usp.br
Huanglongbing (HLB), a destructive disease of citrus, is caused by endogenous, sieve tube-restricted bacteria,
named Candidatus Liberibacter species. Diaphorina citri (Hemiptera: Psyllidae) is a vector of the bacteria in
Asia and America. The purpose of this work was to study the population dynamics of D. citri in orchards of
‘Valencia’ sweet orange, ‘Ponkan’ mandarin, and ‘Murcott’ tangor trees located at the São José farm in the
municipality of Taquaritinga, SP, Brazil. Yellow sticky traps were used to monitor the vector. The largest number
of D. citri was captured on the ‘Ponkan’ trees followed by the ‘Murcott’ and ‘Valencia’ sweet orange. Chemical
pest control and environmental factors are likely to be responsible for this result. Pearson’s correlation analysis
indicated that there is a weak correlation between the abundance of D. citri and the environmental factors
of temperature and precipitation. An analysis of variance suggested that there was a significant difference
in the abundance of D. citri among the three citrus tree varieties, and the autocorrelation was significant for
the ‘Valencia’ orange orchard. Spectral analysis indicated that there were greater frequencies of peaks in
the ‘Ponkan’ mandarin and ‘Murcott’ tangor trees, and the simulations performed using a stochastic logistic
model suggested that the psyllid populations on orange trees are the most susceptible to local extinction; this
result likely occurred because of the high levels of chemical control applied to orange trees.
204 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012