The effect of insecticide synergists on the response of scabies mites to pyrethroid acaricides

Cielo Pasay, Larry Arlian, Marjorie Morgan, Robin Gunning, Louise Rossiter, Deborah Holt, Shelley Walton, Simone Alexandra Beckham, James McCarthy

Research output: Contribution to journalArticleResearchpeer-review

54 Citations (Scopus)

Abstract

BACKGROUND: Permethrin is the active component of topical creams widely used to treat human scabies. Recent evidence has demonstrated that scabies mites are becoming increasingly tolerant to topical permethrin and oral ivermectin. An effective approach to manage pesticide resistance is the addition of synergists to counteract metabolic resistance. Synergists are also useful for laboratory investigation of resistance mechanisms through their ability to inhibit specific metabolic pathways. METHODOLOGY/PRINCIPAL FINDINGS: To determine the role of metabolic degradation as a mechanism for acaricide resistance in scabies mites, PBO (piperonyl butoxide), DEF (S,S,S-tributyl phosphorotrithioate) and DEM (diethyl maleate) were first tested for synergistic activity with permethrin in a bioassay of mite killing. Then, to investigate the relative role of specific metabolic pathways inhibited by these synergists, enzyme assays were developed to measure esterase, glutathione S-transferase (GST) and cytochrome P450 monooxygenase (cytochrome P450) activity in mite extracts. A statistically significant difference in median survival time of permethrin-resistant Sarcoptes scabiei variety canis was noted when any of the three synergists were used in combination with permethrin compared to median survival time of mites exposed to permethrin alone (p
Original languageEnglish
Pages (from-to)1 - 8
Number of pages8
JournalPLoS Neglected Tropical Diseases
Volume3
Issue number1 (e354)
DOIs
Publication statusPublished - 2009

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