01945nas a2200241   4500008004100000245010100041210006900142260000900211300001400220490000700234520124700241653001201488653001901500653001401519653001701533653001301550653001801563653001601581100002201597700002101619700002301640856004001663       2006                        eng d00aLethality of essential oil constituents towards the human louse, Pediculus humanus, and its eggs0 aLethality of essential oil constituents towards the human louse   c2006  a303 - 3090 v773 aEssential oils have been widely used in traditional medicine for the  eradication of lice, including head lice, but due to the variability of  their constitution the effects may not be reproducible. In an attempt  to assess the contribution of their component monoterpenoids, a range  of common individual compounds were tested in in vitro toxicity model  against both human lice (Pediculus humanus, an accepted model of  head lice lethality) and their eggs, at different concentrations. No  detailed study into the relative potencies of their constituent  terpenoids has so far been published. Adult lice were observed for lack  of response to stimuli over 3 h and the LT50 calculated, and  the percentage of eggs failing to hatch was used to generate ovicidal  activity data. A ranking was compiled for adult lice and partially for  eggs, enabling structure–activity relationships to be assessed for  lethality to both, and showed that, for activity in both life-cycle  stages, different structural criteria were required. (+)-Terpinen-4-ol  was the most effective compound against adult lice, followed by other  mono-oxygenated monocyclic compounds, whereas nerolidol was  particularly lethal to eggs, but ineffective against adult lice.10acontrol10aEssential oils10ahead lice10aMonoterpenes10aOvicidal10aPediculicidal10apediculosis1 aPriestley, C., M.1 aBurgess, Ian, F.1 aWilliamson, E., M.  uhttps://cats.myspecies.info/node/37