LIBRO-CONGRESO-CITRUS

S16
design is RCB with 4 treatments and 4 replicates: no insecticide, calendar applications, insecticide applications
according to a threshold of 0.2 psyllids/stem tap sample, and applications according to a 0.7 threshold. Vector
populations are monitored biweekly by tap sampling. Differences in vector abundance among treatments
are being correlated to HLB infection levels estimated by Q-PCR and most importantly, to fruit yields.
Consequences of each vector control strategy on beneficial arthropod fauna are also being evaluated, as well
as potential negative impacts on biological control processes in the crop. After two years, a yield increase was
observed with the calendar treatment, but so far additional costs would require high juice prices scenarios to
be sustainable. Negative impacts of calendar sprays on biological control of mites and leafminers have also
been observed
S16P04
Development of the Huaglongbing (HLB) vector, Diaphorina citri Kuwayama, 1908 (Hemiptera:
Psyllidae), in different host plants.
Alves G.R., Diniz A.J.F., Lima A.A., Vieira J.M., and Parra J.R.P.
Escola Superior de Agricultura Luiz de Queiroz - Universidade de São Paulo (Esalq/USP), Entomologia e Acarologia, Brazil.
gustavo_ralves@yahoo.com.br
Huanglongbing (HLB) or greening is considered the most important Citrus disease in the world. In Brazil, it is
transmitted by the Asian citrus psyllid Diaphorina citri. Knowledge on the life cycle of D. citri in natural and
non-citrus hosts may help Integrated Pest Management in citrus. The objective of this work was to evaluate
the effect of the most common cultivars grown in the state of São Paulo (Hamlin, Pêra, Natal, Valencia and
Ponkan) and that of the orange Jessamine, Murraya paniculata, used in Brazil as hedgerow and considered
a very important non-citrus host for this psyllid. D. citri couples were individually confined in cages for egg
laying during 24 h, under laboratory conditions (temperature: 25±2°C; RH: 60±10%; photophase: 14h). Egg
hatching and nymph mortality were daily observed until adult emergence. The egg viability ranged from 83.3
% to 56.8% for Valencia and Hamlin cultivars, respectively. The nymphal viability was also the lowest in the
Hamlin cultivar (57.4%), with no differences among the other treatments. The highest viability was observed
in the Valencia cultivar (65.9%) with the lowest in the Hamlin cultivar (32.6%).The life cycle lasted from 18.4
(Natal) to 17.2 (orange Jessamine) days.
S16P05
Agreggation and sampling plans for Diaphorina citri (Hemiptera: Psyllidae) immature stages in
citrus.
Asplanato G. 1 , Amuedo S. 1 , and Franco J. 2
1Facutad de Agronomía - Universidad de la República (FAGRO-UDELAR), Protección Vegetal, Uruguay; and 2Facultad de Agronomía -
Universidad de la República (FAGRO-UDELAR), Biometría y Estadística, Uruguay. gasplana@fagro.edu.uy
The Asian Citrus Psyllid Diaphorina citri is an efficient vector of the associated bacteria to Huanglongbing,
considered the most destructive citrus disease in the world. In Uruguay, the psyllid was reported in 1991 but
the disease has not been discovered yet. Studies were conducted to determine the distribution pattern of D.
citri eggs and nymphs on flush shoots and to develop reliable sampling plans. The samplings were carried out
from 2006 to 2009 in five citrus orchards located in the main citrus growing region of Uruguay. Taylor´s power
law was appropriate and adequate to describe the variance-mean relationship of all D. citri development
stages on the five orchards. The dispersion index b from Taylor’s power law did not vary among orchards and
development stages. Data from all orchards were pooled and common regression slope for eggs and nymphs
were estimated. The distribution pattern of immature stages was aggregated among flush shoots as indicated
by the dispersion index b=1.42, that was significantly > 1. The minimum sample size to estimate densities
above five immature stages (eggs nymphs) per flush shoot was 175 flushes for a precision level of 0.25,
appropriate for management decisions. To provide a quick estimation of D. citri in citrus orchards, a presence
– absence sampling plan was evaluated.
284 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012