LIBRO-CONGRESO-CITRUS

S16
citrus flowers causing important economic losses due to fruit scarring. We studied different aspects of KCT´s
biology and ecology in order to improve its management. KCT populations were sampled throughout the
year in 14 citrus orchards in 2008 and in eight citrus orchards in 2009 and 2010 by sampling citrus flowers,
fruitlets and mature fruits, as well as employing ground and aerial sticky traps. Additionally, soil samples were
extracted using Berlese funnels in order to determine the presence and abundance of soil predatory mites.
KCT individuals were captured in the citrus groves all year round: for the three years of the study the highest
KCT population density was observed during the petal fall and the beginning of the fruit growing periods.
Differences in the population density and damage by KCT were observed among years, apparently related with
air temperature. With the data obtained, the aggregation pattern, sampling plans, and intervention threshold
for KCT were determined. With respect to soil predatory mites, 15 species from eight families were identified
being Parasitus americanus and Gaeolaelaps (Hypoaspis) aculeifer the most abundant. Higher populations of
some predatory mite species were associated with lower fruit damage caused by KCT suggesting potential for
biological control.
S16O19
Monitoring and management of Brevipalpus chilensis Baker (Acarina: Tenuipalpidae) in citrus
Olivares N. 1 , Vargas R. 1 , and Ripa R. 2
1 Instituto de Investigaciones Agropecuarias (INIA), CRI, La Cruz, Chile; and 2 Centro de Entomología Aplicada (CEA Ltda.), Chile.
nolivare@inia.cl
The mite Brevipalpus chilensis Baker is an endemic phytophagous pest in Chile. It has a wide host range
including citrus, grapes, custard apple and kiwi. The objective of this study was to evaluate B. chilensis
population fluctuation in Citrus sinensis, Citrus limon and Citrus reticulata. The studies were conducted
in three commercial orchards located in Valparaíso Region, Chile. Samples were taken every 15 days from
lignified and non-lignified branches, fruits, and leaves. The sampled structures that displayed the largest
abundance of mites were branches and fruits; the mites were not found on citrus leaves. In periods of fruit
absence, branch monitoring is the most suitable tool for determining the density of B. chilensis. The results
of this study show that B. chilensis is present all the season on lignified and non-lignified branches. This
would allow a more precise monitoring and control preventing the migration of the mites towards the fruits.
With these results we conclude that the optimal integrated management of B. chilensis in citrus orchards
must include practices such as opening tree canopy by selective pruning, removal of non-harvested fruit, and
chemical spray applications, one at the beginning of summer plus a second spraying post-harvest.
S16O20
Host adaptation of Tetranychus urticae populations in clementine orchards with a Festuca
arundinacea cover may contribute to its natural control.
Aguilar-Fenollosa E., Pina T., Gómez-Martínez M.A., Hurtado M.A., and Jacas J.A.
Universitat Jaume I (UJI), Ciències Agràries i del Medi Natural, Spain. aguilare@uji.es
Tetranychus urticae Koch (Acari: Tetranychidae) is a key pest of clementine mandarins, Citrus clementina
Tanaka (Rutaceae), in Spain. This mite is highly polyphagous and can be easily found in clementine orchards,
both in the trees and in the associated flora. In a previous study we found that the use of a cover of Festuca
arundinacea Schreber (Poaceae) offered a better regulation of T. urticae populations than either bare soil
or the traditional wild cover, which included a mix of weed species. We hypothesized that the selection of
two host races of T. urticae, specialized in F. arundinacea and C. clementina, could partly explain the results
obtained in field studies (bottom-up regulation). Reciprocal transplant experiments show that sympatric deme
× host combinations had higher mean fitness values than the allopatric combinations in clementine, but not
in F. arundinacea, for most of the fitness parameters evaluated in the present study. Because local adaptation
implies mean deme fitness to be systematically higher for the sympatric deme × habitat combinations than
for the allopatric ones, these results can be taken as indicative of occurrence of local adaptation in T. urticae.
Molecular genetics analyses with microsatellite markers support this conclusion and indicate that host
adaptation of T. urticae found in our system may indeed contribute to a better natural regulation of this mite.
282 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012