title: Cuticle Thickening in a Pyrethroid-Resistant Strain of the Common Bed Bug, Cimex lectularius L. (Hemiptera: Cimicidae).
abstract: Thickening of the integument as a mechanism of resistance to insecticides is a well recognised phenomenon in the insect world and, in recent times, has been found in insects exhibiting pyrethroid-resistance. Resistance to pyrethroid insecticides in the common bed bug, Cimex lectularius L., is widespread and has been frequently inferred as a reason for the pest's resurgence. Overexpression of cuticle depositing proteins has been demonstrated in pyrethroid-resistant bed bugs although, to date, no morphological analysis of the cuticle has been undertaken in order to confirm a phenotypic link. This paper describes examination of the cuticle thickness of a highly pyrethroid-resistant field strain collected in Sydney, Australia, in response to time-to-knockdown upon forced exposure to a pyrethroid insecticide. Mean cuticle thickness was positively correlated to time-to-knockdown, with significant differences observed between bugs knocked-down at 2 hours, 4 hours, and those still unaffected at 24 hours. Further analysis also demonstrated that the 24 hours survivors possessed a statistically significantly thicker cuticle when compared to a pyrethroid-susceptible strain of C. lectularius. This study demonstrates that cuticle thickening is present within a pyrethroid-resistant strain of C. lectularius and that, even within a stable resistant strain, cuticle thickness will vary according to time-to-knockdown upon exposure to an insecticide. This response should thus be considered in future studies on the cuticle of insecticide-resistant bed bugs and, potentially, other insects.
authors.affiliation: Department of Medical Entomology, The University of Sydney and Pathology West-ICPMR Westmead, Westmead Hospital, Westmead, NSW, 2415, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Lilly
authors.affiliation: Australian Centre for Microscopy & Microanalysis, The University of Sydney, NSW, 2006, Australia.
authors.forename: Sharissa L
authors.initials: SL
authors.lastname: Latham
authors.affiliation: Department of Medical Entomology, The University of Sydney and Pathology West-ICPMR Westmead, Westmead Hospital, Westmead, NSW, 2415, Australia.
authors.forename: Cameron E
authors.initials: CE
authors.lastname: Webb
authors.affiliation: Department of Medical Entomology, The University of Sydney and Pathology West-ICPMR Westmead, Westmead Hospital, Westmead, NSW, 2415, Australia.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Doggett
mesh_terms: D000818:Animals; D001315:Australia; D001511:Bedbugs / Q000187:drug effects*; D007305:Insecticide Resistance / Q000187:drug effects*; D007306:Insecticides / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins