Sudden bed bug resurgence across the developed countries in the world within the past few decades has been strongly associated with the high levels of insecticide resistance. Up-regulation of the detoxification enzymes and mutation of the sodium channel genes have been found across many of the field population of bed bugs, however, only one direct physiological evidence of the cuticular thickening of one population linked with the time to knocked-down has been reported. Here in this paper we determined and compared the cuticular thickness across five field-collected pyrethroid-resistant and two pyrethroid-susceptible populations of bed bugs. We used scanning electron microscopy (SEM) images of dorsoventrally sectioned adult male bed bugs of 7-day old after molting. Each bed bug were measured four cuticular segments (2nd and 3rd sternites and tergites), a segment divided into three measurement points (P1, P2, P3) from anterior to posterior ends. The statistical analysis of Wilcoxon Signed Rank Test revealed that the cuticular thickness of one of the two susceptible strains were statistically different from that of resistant strains in most of the measured positions. However, another pyrethroid-susceptible strain did not have statistically significant differences to that of other strains, except for RO strains. In conclusion, we observed population-level differences in cuticular thickness, one of which was associated with higher levels of pyrethroid-resistance. Thicker cuticle may give an advantage after insecticidal treatments, and the constant exposure to the residual insecticides may accelerate the natural selection of the thicker cuticle individuals in the field environment.

Determination and comparison of the cuticular thickness across several insecticide resistant and susceptible populations of the common bed bug, Cimex lectularius L., using scanning electron microscopy (SEM)

254th National Meeting (2017)

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