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Deep sequencing of pyrethroid-resistant bed bugs reveals multiple mechanisms of resistance within a single population.

Adelman ZN, Kilcullen KA, Koganemaru R, Anderson MA, Anderson TD, Miller DM - PLoS ONE (2011)

Bottom Line: Using LD(50) bioassays, we determined that resistance ratios for Richmond strain bed bugs were ∼5200-fold to the insecticide deltamethrin.Following assembly, analysis of newly identified gene transcripts in both Harlan (susceptible) and Richmond (resistant) bed bugs revealed several candidate cytochrome P450 and carboxylesterase genes which were significantly over-expressed in the resistant strain, consistent with the idea of increased metabolic resistance.These data will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs, and provide molecular markers to assist in the surveillance of metabolic resistance.

View Article: PubMed Central - PubMed

Affiliation: Fralin Life Science Institute and Department of Entomology, Virginia Tech, Blacksburg, Virginia, United States of America. zachadel@vt.edu

ABSTRACT
A frightening resurgence of bed bug infestations has occurred over the last 10 years in the U.S. and current chemical methods have been inadequate for controlling this pest due to widespread insecticide resistance. Little is known about the mechanisms of resistance present in U.S. bed bug populations, making it extremely difficult to develop intelligent strategies for their control. We have identified bed bugs collected in Richmond, VA which exhibit both kdr-type (L925I) and metabolic resistance to pyrethroid insecticides. Using LD(50) bioassays, we determined that resistance ratios for Richmond strain bed bugs were ∼5200-fold to the insecticide deltamethrin. To identify metabolic genes potentially involved in the detoxification of pyrethroids, we performed deep-sequencing of the adult bed bug transcriptome, obtaining more than 2.5 million reads on the 454 titanium platform. Following assembly, analysis of newly identified gene transcripts in both Harlan (susceptible) and Richmond (resistant) bed bugs revealed several candidate cytochrome P450 and carboxylesterase genes which were significantly over-expressed in the resistant strain, consistent with the idea of increased metabolic resistance. These data will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs, and provide molecular markers to assist in the surveillance of metabolic resistance.

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Relative abundance of metabolic genes.The product of the total number of reads from Harlan and Richmond 454 datasets used in the assembly of each P450, GST and CE contig was log10 transformed. GST, P450 and CE genes found to be significantly upregulated by qPCR in the resistant strain are highlighted in green.
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pone-0026228-g005: Relative abundance of metabolic genes.The product of the total number of reads from Harlan and Richmond 454 datasets used in the assembly of each P450, GST and CE contig was log10 transformed. GST, P450 and CE genes found to be significantly upregulated by qPCR in the resistant strain are highlighted in green.

Mentions: Due to the relative nature of these assays, such qPCR data alone do not necessarily provide information as to the absolute abundance of the targeted transcripts. In order to independently determine which P450, GST and CE contigs were the most abundantly expressed in bed bugs, we plotted log10 values for the product of the number of 454 reads which mapped to each contig from Harlan and Richmond strain datasets (Fig. 5). Of the P450 genes, we found that transcripts derived from cyp397a1 were by far the most abundant. As this gene also shows the greatest increase in transcriptional activity in Richmond strain bed bugs, these data imply that CYP397A1 may play the most prominent role in the cytochrome oxidase-mediated detoxification of pyrethroid insecticides. Likewise, cyp6dn1 is among the most abundantly expressed of the remaining CYP450 gene contigs. Similarly, esterase-encoding contigs CE3959 (>6 fold), CE21331 (>4 fold) represented two of the six most abundant esterase transcripts in bed bugs, with CE21331 being the most abundant (Fig. 5). Consistent with the lack of increased GST activity observed in the model substrate assays, the upregulated contig GSTs1 was among the lowest expressed of the GSTs. Taken together, these data implicate several candidate gene products as potentially involved in pyrethroid metabolism.


Deep sequencing of pyrethroid-resistant bed bugs reveals multiple mechanisms of resistance within a single population.

Adelman ZN, Kilcullen KA, Koganemaru R, Anderson MA, Anderson TD, Miller DM - PLoS ONE (2011)

Relative abundance of metabolic genes.The product of the total number of reads from Harlan and Richmond 454 datasets used in the assembly of each P450, GST and CE contig was log10 transformed. GST, P450 and CE genes found to be significantly upregulated by qPCR in the resistant strain are highlighted in green.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198472&req=5

pone-0026228-g005: Relative abundance of metabolic genes.The product of the total number of reads from Harlan and Richmond 454 datasets used in the assembly of each P450, GST and CE contig was log10 transformed. GST, P450 and CE genes found to be significantly upregulated by qPCR in the resistant strain are highlighted in green.
Mentions: Due to the relative nature of these assays, such qPCR data alone do not necessarily provide information as to the absolute abundance of the targeted transcripts. In order to independently determine which P450, GST and CE contigs were the most abundantly expressed in bed bugs, we plotted log10 values for the product of the number of 454 reads which mapped to each contig from Harlan and Richmond strain datasets (Fig. 5). Of the P450 genes, we found that transcripts derived from cyp397a1 were by far the most abundant. As this gene also shows the greatest increase in transcriptional activity in Richmond strain bed bugs, these data imply that CYP397A1 may play the most prominent role in the cytochrome oxidase-mediated detoxification of pyrethroid insecticides. Likewise, cyp6dn1 is among the most abundantly expressed of the remaining CYP450 gene contigs. Similarly, esterase-encoding contigs CE3959 (>6 fold), CE21331 (>4 fold) represented two of the six most abundant esterase transcripts in bed bugs, with CE21331 being the most abundant (Fig. 5). Consistent with the lack of increased GST activity observed in the model substrate assays, the upregulated contig GSTs1 was among the lowest expressed of the GSTs. Taken together, these data implicate several candidate gene products as potentially involved in pyrethroid metabolism.

Bottom Line: Using LD(50) bioassays, we determined that resistance ratios for Richmond strain bed bugs were ∼5200-fold to the insecticide deltamethrin.Following assembly, analysis of newly identified gene transcripts in both Harlan (susceptible) and Richmond (resistant) bed bugs revealed several candidate cytochrome P450 and carboxylesterase genes which were significantly over-expressed in the resistant strain, consistent with the idea of increased metabolic resistance.These data will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs, and provide molecular markers to assist in the surveillance of metabolic resistance.

View Article: PubMed Central - PubMed

Affiliation: Fralin Life Science Institute and Department of Entomology, Virginia Tech, Blacksburg, Virginia, United States of America. zachadel@vt.edu

ABSTRACT
A frightening resurgence of bed bug infestations has occurred over the last 10 years in the U.S. and current chemical methods have been inadequate for controlling this pest due to widespread insecticide resistance. Little is known about the mechanisms of resistance present in U.S. bed bug populations, making it extremely difficult to develop intelligent strategies for their control. We have identified bed bugs collected in Richmond, VA which exhibit both kdr-type (L925I) and metabolic resistance to pyrethroid insecticides. Using LD(50) bioassays, we determined that resistance ratios for Richmond strain bed bugs were ∼5200-fold to the insecticide deltamethrin. To identify metabolic genes potentially involved in the detoxification of pyrethroids, we performed deep-sequencing of the adult bed bug transcriptome, obtaining more than 2.5 million reads on the 454 titanium platform. Following assembly, analysis of newly identified gene transcripts in both Harlan (susceptible) and Richmond (resistant) bed bugs revealed several candidate cytochrome P450 and carboxylesterase genes which were significantly over-expressed in the resistant strain, consistent with the idea of increased metabolic resistance. These data will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs, and provide molecular markers to assist in the surveillance of metabolic resistance.

Show MeSH
Related in: MedlinePlus