Cuticular permeability

Hurst (19) discusses the similarity in action of the pyrethrins and of DDT as indicated by a dispersant action on the lipids of insect cuticle and internal tissue. He has developed an elaborate theory of contact insecticidal action but provides no experimental data. Hurst believes that the susceptibility to insecticides depends partially on the cuticular permeability, but more fundamentally on the effects on internal tissue receptors which control oxidative metabolism or oxidative enzyme systems. The access of pyrethrins to insects, for example, is facilitated by adsorption and storage in the lipophilic layers of the epicuticle. The epicuticle is to be regarded as a lipoprotein mosaic consisting of alternating patches of lipid and protein receptors which are sites of oxidase activity. Such a condition exists in both the hydrophilic type of cuticle found in larvae of Calliphora and Phormia and in the waxy cuticle of Tenebrio larvae. Hurst explains pyrethrinization as a preliminary narcosis or knockdown phase in which oxidase action is blocked by adsorption of the insecticide on the lipoprotein tissue components, followed by death when further dispersant action of the insecticide results in an irreversible increase in the phenoloxidase activity as a result of the displacement of protective lipids. This increase in phenoloxidase activity is accompanied by the accumulation of toxic quinoid metabolites in the blood and tissues—for example, O-quinones which would block substrate access to normal enzyme systems. The varying degrees of susceptibility shown by different insect species to an insecticide may be explainable not only in terms of differences in cuticle make-up but also as internal factors associated with the stability of oxidase systems. 

Gibbs, A. G. (2002). Lipid melting and cuticular permeability new insights into an old problem../. Insect Physiol., 48, 391 400. 

Is cuticular permeability important Cuticular and respiratory water-loss... 

Consideration of the waterproofing function of cuticular lipids first requires an assessment of cuticular transpiration relative to the overall water budget. The fact that organismal water-loss rates increase greatly when surface lipids are removed does not necessarily mean that increased cuticular permeability is responsible. Insects can lose water by transpiration through the cuticle, by evaporation from the tracheal system through open spiracles, and by... 

Finally, even when HC composition and cuticular transpiration are correlated, causation cannot be assumed. For example, higher cuticular water-loss rates in the desert ant, Pogonomyrmex barbatus, are correlated with a decrease in abundance of an n-alkane and an increase in a methylalkane (Figure 6.2 Johnson and Gibbs, 2004). This is exactly what one would expect if lipid melting points affect cuticular permeability, but this increase is also accompanied by a change in mating status. Mated, de-alate queens that have founded... 

Hadley, N.F. (1978). Cuticular permeability of desert tenebrionid beetles correlations with epicuticular lipid composition. Insect Biochem., 8, 17-22. 

Noble-Nesbitt, J. (1991). Cuticular permeability and its control. In The Physiology of the Insect Epidermis, ed. K. Binnington and A. Retnakaran. East Melbourne, Victoria, Australia CSIRO Publications, pp. 252-283. 

Rourke, B.C. and Gibbs, A.G. (1999). Effects of lipid phase transitions on cuticular permeability model-membrane and in situ studies. J. Experim. Biol., 202, 3255-3262. 

Toolson, E.C. and Hadley, N.F. (1979). Seasonal effects on cuticular permeability and epicuticular lipid composition in Centruroides sculpturatus Ewing 1928 (Scorpiones Buthidae)../. Comp. Physiol. B, 129, 319-325. 

Toolson, E.C. and Kuper-Simbron, R. (1989). Laboratory evolution of epicuticular hydrocarbon composition and cuticular permeability in Drosophila... 

Toolson, E.C., White, T. R. and Glaunsinger, W. S. (1979). Electron paramagnetic resonance spectroscopy of spin-labelled cuticle of Centruroides sculpturatus (Scorpiones Buthidae) correlation with thermal effects on cuticular permeability. 

Yoder, J.A., Benoit, J.B., Rellinger, E.J. and Ark, J.T. (2005b). Critical transition temperature and activation energy with implications for arthropod cuticular permeability. J. Insect Physiol., 51, 1063-1065. 

Kerstiens, G. 2006. Parameterization, comparison, and validation of models quantifying relative change of cuticular permeability with physicochemical properties of diffusants. Journal... 

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