Project description:The common bed bug, Cimex lectularius, is an urban pest of global health significance, severely affecting the physical and mental health of humans. In contrast to most other blood-feeding arthropods, bed bugs are not major vectors of pathogens, but the underlying mechanisms for this phenomenon are largely unexplored. Here, we present the first transcriptomics study of bed bugs in response to immune challenges. To study transcriptional variations in bed begs following ingestion of bacteria, we extracted and processed mRNA from immune-related tissues of adult male bed bugs after ingestion of sterile blood or blood laced with the Gram-positive (Gr+) bacterium Bacillus subtilis or the Gram-negative (Gr–) bacterium Escherichia coli. We analyzed mRNA from the bed bugs’ midgut (the primary tissue involved in blood ingestion) and from the rest of their bodies (RoB; body minus head and midgut tissues).
Project description:A frightening resurgence of bed bug infestations has occurred over the last 10 years in the US. Current chemical methods have been inadequate for controlling bed bugs due to widespread insecticide resistance. Little is known about the mechanisms of resistance present in US bed bug populations, making it extremely difficult to develop intelligent strategies to control this pest. We have identified bed bugs collected in Richmond, VA which exhibit both kdr-type (L925I) and metabolic resistance to pyrethroid insecticides. LD50 bioassays determined resistance ratios of ~6000-fold to the insecticide deltamethrin, with contact bioassays confirming cross-resistance to several other labeled formulations. 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 carboxyesterase 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.
Project description:A frightening resurgence of bed bug infestations has occurred over the last 10 years in the US. Current chemical methods have been inadequate for controlling bed bugs due to widespread insecticide resistance. Little is known about the mechanisms of resistance present in US bed bug populations, making it extremely difficult to develop intelligent strategies to control this pest. We have identified bed bugs collected in Richmond, VA which exhibit both kdr-type (L925I) and metabolic resistance to pyrethroid insecticides. LD50 bioassays determined resistance ratios of ~6000-fold to the insecticide deltamethrin, with contact bioassays confirming cross-resistance to several other labeled formulations. 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 carboxyesterase 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. Deep sequencing was performed from total RNA isolated from adult male bed bugs using the Titanium 454 platform