dc.contributor.author | Karatolos, Nikolaos | en_GB |
dc.date.accessioned | 2011-12-21T12:05:24Z | en_GB |
dc.date.accessioned | 2013-03-21T10:25:30Z | |
dc.date.issued | 2011-10-18 | en_GB |
dc.description.abstract | The whitefly Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) is a
serious pest of protected vegetable and ornamental crops in most temperate regions of
the world. Neonicotinoids, pymetrozine (a feeding blocker), spiromesifen (a tetronic
acid derivative), bifenthrin (a pyrethroid), and pyriproxyfen (a juvenile hormone
mimic) are among the most important insecticides used to control this species.
Bioassays were used to quantify responses of recently-collected strains of T.
vaporariorum to three neonicotinoids (imidacloprid, thiamethoxam, and acetamiprid),
pymetrozine, spiromesifen, bifenthrin, and pyriproxyfen. 454 pyrosequencing was
exploited to generate the first transcriptome for this species. PCR-sequencing was
used to identify mutations in the target proteins of spiromesifen and bifenthrin
potentially associated with resistance to these compounds. Microarray sequencing
technology was employed to investigate differences in gene expression associated
with pyriproxyfen resistance.
Resistance to neonicotinoids was age-specific in expression and consistently
associated with resistance to pymetrozine, supporting a hypothesis of metabolic
resistance analogous to that in the tobacco whitefly, Bemisia tabaci. Bioassays also
showed moderate to high level resistance to spiromesifen, bifenthrin and
pyriproxyfen in some strains. Analysis of the transcriptome identified genes encoding
enzymes involved in the detoxification of xenobiotics (cytochrome P450s,
carboxyl/cholinesterases, and glutathione-s transferases) and ones encoding
insecticide targets: acetyl-coA carboxylase (ACCase), the target of spiromesifen and
the voltage-gated sodium channel protein targeted by pyrethroids. PCR-sequencing
revealed a single nucleotide polymorphism in the ACCase gene, which was
consistently associated with spiromesifen resistance. Three amino-acid substitutions
in the sodium channel of pyrethroid-resistant T. vaporariorum were found in
positions previously implicated in pyrethroid resistance in B. tabaci. Microarray
sequencing disclosed that a cytochrome P450 gene (CYP4G61) was overexpressed in
a strain selected for increased pyriproxyfen resistance. The implications of these
results and opportunities for further work are discussed. | en_GB |
dc.description.sponsorship | BBSRC | en_GB |
dc.description.sponsorship | Bayer CropScience | en_GB |
dc.identifier.citation | Karatolos et al., 2010 Pest Management Science 66: 1304-1307 | en_GB |
dc.identifier.citation | Karatolos et al., 2011 BMC Genomics 12: 56 | en_GB |
dc.identifier.citation | Karatolos et al., 2011 Pest management Science In Press | en_GB |
dc.identifier.citation | Karatolos et al., 2011 Insect Molecular Biology Under Review | en_GB |
dc.identifier.citation | Karatolos et al., 2011 PLoS ONE Under Review | en_GB |
dc.identifier.uri | http://hdl.handle.net/10036/3350 | en_GB |
dc.language.iso | en | en_GB |
dc.publisher | University of Exeter | en_GB |
dc.rights | This thesis is available for Library use on the understanding that it is copyright
material and that no quotation from the thesis may be published without proper
acknowledgement.
I certify that all material in this thesis which is not my own work has been identified
and that no material has previously been submitted and approved for the award of a
degree by this or any other University. | en_GB |
dc.subject | Trialeurodes vaporariorum | en_GB |
dc.subject | whitefly | en_GB |
dc.subject | Insecticide resistance | en_GB |
dc.subject | neonicotinoids | en_GB |
dc.subject | pyrethroids | en_GB |
dc.subject | spiromesifen | en_GB |
dc.subject | pyriproxyfen | en_GB |
dc.subject | transcriptome | en_GB |
dc.subject | microarray | en_GB |
dc.subject | molecular mechanisms | en_GB |
dc.title | Molecular mechanisms of insecticide resistance in the glasshouse whitefly, Trialeurodes vaporariorum | en_GB |
dc.type | Thesis or dissertation | en_GB |
dc.date.available | 2011-12-21T12:05:24Z | en_GB |
dc.date.available | 2013-03-21T10:25:30Z | |
dc.contributor.advisor | Ffrench-Constant, Richard | en_GB |
dc.contributor.advisor | Denholm, Ian | en_GB |
dc.publisher.department | Biological Sciences | en_GB |
dc.type.degreetitle | PhD in Biological Sciences | en_GB |
dc.type.qualificationlevel | Doctoral | en_GB |
dc.type.qualificationname | PhD | en_GB |