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.

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A susceptible, laboratory strain of bed bug, Cimex lectularius L., was used to determine the efficacy of insecticide products labeled or possessing a site label for bed bug control. Field strain bed bugs also were used to evaluate one insecticide product. The lethal time (LT),, values calculated for the laboratory strain bed bugs indicated that all of the pyrethroid products killed significantly faster than chlorfenapyr (0.5% [AIl; Phantom: BASF; LT50 = 10 d and 9 h). lamda-Cyhalothrin (0.03%; Demand CS; Syngenta) was the fastest acting insecticide (LT50 = 20 min), followed by bifenthrin (0.02% [AI]; Talstar One, FMC; LT50 = 53 min), deltamethrin (0.06% [AI]; Suspend SC; Bayer; LT50 = 61 min), and permethrin (0.05%; Dragnet SFR; FMC; LT50 = 88 min). The field strain bed bugs exposed to deltamethrin had an LT50 value of 14 day 8 h, indicating that the field strain was significantly less susceptible to deltamethrin than the laboratory strain. Chlorfenapyr exposure did not prevent the laboratory strain bed bugs from mating and laying eggs, nor did it prevent the eggs from hatching during the 2-wk exposure period. Surprisingly, none of the insecticides tested, including the pyrethroids, were repellent to laboratory strain bed bugs. Bed bugs rested on pyrethroid-treated panels and remained in contact with the panels until they died (2 h). Chlorfenapyr was also not repellent to bed bugs, but it caused no mortality during the 2-h test period. This study suggests that although pyrethroids were effective for controlling laboratory strain bed bugs, there is the potential for significant resistance in field strains. This study also determined that pyrethroid products were not repellent to bed bugs and would not cause bed bug aggregations to scatter or avoid treated surfaces.

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Social insects exhibit remarkable variation in their colony breeding structures, both within and among species. Ecological factors are believed to be important in shaping reproductive traits of social insect colonies, yet there is little information linking specific environmental variables with differences in breeding structure. Subterranean termites (Rhinotermitidae) show exceptional variation in colony breeding structure, differing in the number of reproductives and degree of inbreeding; colonies can be simple families headed by a single pair of monogamous reproductives (king and queen) or they can be extended families headed by multiple inbreeding neotenic reproductives (wingless individuals). Using microsatellite markers, we characterized colony breeding structure and levels of inbreeding in populations over large parts of the range of the subterranean termites Reticulitermes flavipes in the USA and R. grassei in Europe. Combining these new data with previous results on populations of both species, we found that latitude had a strong effect on the proportion of extended-family colonies in R. flavipes and on levels of inbreeding in both species. We examined the effect of several environmental variables that vary latitudinally; while the degree of inbreeding was greatest in cool, moist habitats in both species, seasonality affected the species differently. Inbreeding in R. flavipes was most strongly associated with climatic variables (mean annual temperature and seasonality), whereas nonclimatic variables, including the availability of wood substrate and soil composition, were important predictors of inbreeding in R. grassei. These results are the first showing that termite breeding structure is shaped by local environmental factors and that species can vary in their responses to these factors.

Although both treatment regimens reduced bedbug numbers, the fact that bedbugs were not eliminated after multiple applications suggests that the insecticides, applied at the current label rates, were inadequate. These results suggest that a more integrated approach to bedbug control is necessary in multi-unit housing situations.

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