LIBRO-CONGRESO-CITRUS

S13
S13O03
Multiple insecticide resistance traits in a field derived population of the Mediterranean fruit fly,
Ceratitis capitata.
Ortego F., Couso-Ferrer F., Arouri R., Huertas-Rosales O., Beroiz B., Perera N., Cervera A., Hernández-Crespo P., and
Castañera P.
Centro de Investigaciones Biológicas (CIB - CSIC), Departamento de Biología Medioambiental, Spain. ortego@cib.csic.es
Resistance to malathion is widely spread in Spanish field populations of the Mediterranean fruit fly, Ceratitis
capitata (Wiedemann) (Diptera: Tephritidae). A malathion resistant strain (W-4Km), derived from a field
population collected in Castellón in 2004, was obtained by laboratory selection. The W-4Km strain was 176fold
more resistant to malathion than a susceptible C strain, established from wild C. capitata collected at
non-treated experimental fields in Valencia in 2001, and maintained in our laboratory without exposure to
insecticides. The resistance mechanism of the W-4Km strain was found to be associated with a single point
mutation in the target acetylcholinesterase (AChE). Further laboratory selection of this strain with malathion
or other insecticides led to a highly malathion resistant strain (W-10Km, about 500-fold resistance), a lambdacyhalothrin-resistant
strain (W-1Kl, 205-fold), and a spinosad resistant strain (Xabia-W-100s, resulting from
the cross of the W-4Km strain with a field derived population, over 200-fold). A novel resistance mechanism
associated with the AChE gene has been discovered in the W-10Km strain. The synergistic activity of PBO
and DEF in the W-1Kl strain suggests that metabolic resistance mediated by both P450s and esterases may
be involved in the development of resistance to lambda-cyhalothrin. However, none of the mechanisms
previously described appear to be implicated in the resistance to spinosad. These results indicate that multiple
resistance traits are present in the field derived population. Moreover, we have shown that resistance to
lambda-cyhalothrin and spinosad can rapidly evolve to levels that may compromise their effectiveness in the
field.
S13O04
Citrus fruits and the Mediterranean fruit fly.
Papadopoulos N.T. 1 , Papachristos D.P. 2 , and Ioannou C.S. 1
1 University of Thessaly, Laboratory of Entomology and Agricultural Zoology, Greece; and 2 Benaki Phytopathological Institute,
Entomology and Agricultural Zoology, Greece. nikopap@uth.gr
The Mediterranean fruit fly (medfly), Ceratitis capitata (Diptera: Tephritidae) is considered one of the most
important pests of citrus fruits. Recent and older studies demonstrate a variable degree of susceptibility
among different citrus species to medfly infestations. They indicate that the chemical properties of the citrus
fruit rind are the most important barrier prohibiting survival and development of medfly immature stages.
The toxic properties of rind vary considerable among different citrus species as a result of quantitative and
qualitative (composition) aspects of citrus essential oils. Effects of fruit flesh on biological traits of larvae do not
vary much among different citrus species. On the other hand, citrus essential oils affect, in a variable manner
among different fruit species, a range of adult behavioral traits. For example, male medflies are attracted
to citrus essential oils while exposure to them increases mating competitiveness over non-exposed males.
Likewise, citrus oils regulate female ovipositional decisions. The current paper provides a comprehensive
account of the complex interactions between medfly and citrus plants. Practical and theoretical implications
are discussed.
S13O05
Looking inside the chemosensory system of the medfly Ceratitis capitata
Malacrida A.R., Gomulski L.M., Scolari F., Falchetto M., Siciliano P., Manni M., and Gasperi G.
University of Pavia (UNIPV), Department of Biology and Biotechnology, Italy. malacrid@unipv.it
The Mediterranean fruit fly, Ceratitis capitata is an important pest of citrus crops and this has led to the
development of extensive control programmes. Apart from traditional insecticide-based control methods
that are often associated with mass-trapping, it has become a model organism in Sterile Insect Technique
222 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012