Deep Sequencing of Pyrethroid-Resistant Bed Bugs Reveals Multiple Mechanisms of Resistance within a Single Population

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 LD50 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.

Mechanisms that contribute to the establishment and persistence of bed bug infestations

“…The observed reduction in survival in resistant strains is not surprising given their physiology. Pesticide resistant bed bug strains show increased detoxification gene expression (Adelman et al, 2011;Mamidala et al, 2012a;Mamidala et al, 2012b). Increased expression of these genes has been shown to decrease insect fitness, particularly longevity (Mamidala et al, 2012a and reference within).…”

“…There are multiple proposed mechanisms by which bed bugs resist pesticides including exposure prevention, increased metabolic breakdown and pesticide target mutation (Adelman et al, 2011;Bai et al, 2011;Mamidala et al, 2012b;Yoon et al, 2008;Zhu et al, 2010Zhu et al, , 2012Zhu et al, , 2013. The first mechanism of pesticide resistance identified in bed bugs was mutation of the voltage-sensitive sodium channel gene {kdr mutations) in bed bugs from New York.…”

“…This mutation results in significant insensitivity to deltamethrin exposure (Yoon et al, 2008). Recent studies have utilized RNA-seq technology to elucidate transcriptome differences between susceptible and resistant populations (Adelman et al, 2011;Bai et al, 2011;Mamidala et al, 2012b). These studies revealed that there are likely many factors responsible for pesticide resistance.…”

“…These studies revealed that there are likely many factors responsible for pesticide resistance. Multiple cytochrome P450, glutathione-5-transferase (GST) and carboxylesterase genes are expressed at higher levels in resistant populations (Adelman et al, 2011;Mamidala et al, 2012b). These genes are critical for metabolic resistance to pesticides (Enayati et al, 2005;Feyereisen, 1999;Li et al, 2007;Mamidala et al, 2012a;Mamidala et al, 2012b).…”

Prevention, identification, and treatment options for the management of bed bug infestations

“…Although approved insecticides from different chemical groups are often required for treatment, they are limited in availability and insecticide resistance is well known (Adelman et al 2011;Romero et al 2007). Pyrethroid insecticides are most prevalent, but there are increasing issues with resistance, lack of residual activity, and dispersion of bed bug populations when exposed to sub-lethal levels (Davies et al 2012;Mamidala et al 2012;Tawatsin et al 2011).…”