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Irene Castellan
Bachelor student (2011-12)
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Title "Drosophila suzukii orientation
behaviour: detection and characterization of
interspecific and intraspecific volatile compounds"
Drosophila suzukii (also called Spotted Wing
Drosophila or SWD) has recently become one of the most
serious pest in Europe and North America, damaging soft
fruits like strawberry, blueberry, raspberry, red currant
and cherry. Females have very prominent ovipositors and are
able to lay eggs inside of both ripe and unripe fruits.
Hatching larvae feed inside fruits, causing them to collapse
and often resulting in fungus invasion. In 2010 and 2011 a
huge production loss of soft fruits was registered in
several regions, as for instance in the Italian region
Trentino-South Tyrol. At present there is a rising concern
for the berry production of 2012. This pest is a
multivoltine species, in summer season one generation can
take few weeks to complete, although animals kept in
captivity survived for more than 300 days. Therefore, it is
difficult to control its populations, considering also its
high reproduction rate and the fast dispersal capacity.
Moreover, fruits are infested very close to the ripping
process and therefore close to the time of harvesting. This
situation hampers the control of D. suzukii with
proper insecticides. In this thesis we aim to study the
orientation behaviour of D. suzukii and to
characterise the cuticular hydrocarbons of males and females
at different ages. To address the first objective we will
collect the volatile compounds released by selected fruits
and later we will try to find out which ones attract females
to lay their eggs. This will be achieved by the use of a
gas-chromatographer coupled with electroantennographic
detection (GC-EAD and EAG). The second goal will be to
extract the cuticular hydrocarbons of single-reared adults
at different ages and to characterise the chemical
composition of each extract with a gas chromatographer
coupled with a mass spectrometer (GC-MS). With these
experiments we should be able to find differences between
the two sexes, in particularly when insects reach their
sexual maturity. These compounds could have a pheromonal
activity, likely involved in courtship behaviour and sexual
recognition.
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