Exploring the molecular basis of insecticide resistance in the dengue vector Aedes aegypti: a case study in Martinique Island (French West Indies)


The yellow fever mosquito Aedes aegypti is a major vector of dengue and hemorrhagic fevers, causing up to 100 million dengue infections every year. As there is still no medicine and efficient vaccine available, vector control largely based on insecticide treatments remains the only method to reduce dengue virus transmission.

Unfortunately, vector control programs are facing operational challenges with mosquitoes becoming resistant to commonly used insecticides. Resistance of Ae.

aegypti to chemical insecticides has been reported worldwide and the underlying molecular mechanisms, including the identification of enzymes involved in insecticide detoxification are not completely understood.

Results: The present paper investigates the molecular basis of insecticide resistance in a population of Ae. aegypti collected in Martinique (French West Indies).

Bioassays with insecticides on adults and larvae revealed high levels of resistance to organophosphate and pyrethroid insecticides. Molecular screening for common insecticide target-site mutations showed a high frequency (71%) of the sodium channel 'knock down resistance'(kdr) mutation.

Exposing mosquitoes to detoxification enzymes inhibitors prior to bioassays induced a significant increased susceptibility of mosquitoes to insecticides, revealing the presence of metabolic-based resistance mechanisms. This trend was biochemically confirmed by significant elevated activities of cytochrome P450 monooxygenases, glutathione S-transferases and carboxylesterases at both larval and adult stages.

Utilization of the microarray Aedes Detox Chip containing probes for all members of detoxification and other insecticide resistance-related enzymes revealed the significant constitutive over-transcription of multiple detoxification genes at both larval and adult stages. The over-transcription of detoxification genes in the resistant strain was confirmed by using real-time quantitative RT-PCR.

Conclusion: These results suggest that the high level of insecticide resistance found in Ae.

aegypti mosquitoes from Martinique island is the consequence of both target-site and metabolic based resistance mechanisms. Insecticide resistance levels and associated mechanisms are discussed in relation with the environmental context of Martinique Island.

These finding have important implications for dengue vector control in Martinique and emphasizes the need to develop new tools and strategies for maintaining an effective control of Aedes mosquito populations worldwide.

Author: Sebastien MarcombeRodolphe PoupardinFrederic DarrietStephane ReynaudJulien BonnetClare StrodeCecile BrenguesAndre YebakimaHilary RansonVincent CorbelJean-Philippe David
Credits/Source: BMC Genomics 2009, 10:494



Published on: 2009-10-26

Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please make sure to read our disclaimer prior to contacting 7thSpace Interactive. To contact our editors, visit our online helpdesk. If you wish submit your own press release, click here.

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Comments Page 1 of 1
M. Minchie Israel
Posted 106 days ago
Vector Control professionals like myself were so hopeful, especially in the earlier part of this decade, that the pyrethroid class of insecticides would be the perfect alternative to organophosphates such as Temephos in the control of Aedes aegypti mosquitoes. Now to see yet another study deflate those expectations places such a burden on the community to be more proactive in managing mosquito breeding at our homes and places of work. Unfortunately, this is a burden we homeowners and renters are not prepared to bear, preferring to leave it up to Government agencies whose main recourse are the very insecticides that we should be avoiding.
And so the struggle to empower private persons to become more active in the prevention of Aedes aegypti mosquitoes from colonising our premises continue. But I am afraid, this struggle will be a protracted one as it has always been.
M. Minchie Israel
http://woodshedenvironment.wordpress.com
 


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