Transpiration in Podura Aquatica L. (Collembola, Isotomidae) and the Wetting Properties of its Cuticle

1. In the collembolan, Podura aquatica , transpiration through the cuticle is high at all relative humidities. Above 90% relative humidity, cuticular permeability is abnormally high but no adequate explanation of this can be given. 2. Transpiration through the cuticle is high at all temperatures and there is no evidence of a critical temperature over the range 17-29° C. 3. Abrasion increases the transpiration rate, and at least partial recovery occurs within the instar. Moulting fully restores the transpiration rate to the normal level. 4. The hydrofuge nature of the cuticle strongly suggests the presence of an orientated lipid monolayer on its surface. Strong wax solvents render the cuticle wettable, whereas treatment with water under reduced pressure does not. 5. Consideration of the fine structure suggests that the hydrofuge layer is discontinuous and that it occurs on the tips of the minor tubercles. This is compatible with an overall high transpiration rate. 6. The occurrence of hydrophil areas of cuticle is correlated with a smooth cuticular surface. 7. The biological effects of the hydrofuge and hydrophil areas in the life of the insect are discussed.

[1]  M. W. Holdgate,et al.  The Wetting of Insect Cuticles by Water , 1955 .

[2]  S. R. Nutman.  Function of the Ventral Tube in Onychiurus armatus (Collembola) , 1941, Nature.

[3]  J. Beament.  The Waterproofing Mechanism of Arthropods: I. The Effect of Temperature on Cuticle Permeability in Terrestrial Insects and Ticks , 1959 .

[4]  W. Thorpe.  PLASTRON RESPIRATION IN AQUATIC INSECTS , 1950, Biological reviews of the Cambridge Philosophical Society.

[5]  J. Beament.  The cuticular lipoids of insects , 1945 .

[6]  M. Locke.  The Formation of Tracheae and Tracheoles in Rhodnius prolixus , 1958 .

[7]  W. M. Davies.  The Effect of Variation in Relative Humidity on Certain Species of Collembola , 1928 .

[8]  J. A. Ramsay.  The Evaporation of Water from the Cockroach , 1935 .

[9]  M. Holdgate,et al.  The Epicuticular Wax Layers of the Pupa of Tenebrio Molitor L. , 1956 .

[10]  J. Beament.  THE WATERPROOFING MECHANISM OF ARTHROPODS II. THE PERMEABILITY OF THE CUTICLE OF SOME AQUATIC INSECTS , 1961 .

[11]  A. D. Lees,et al.  An egg-waxing organ in ticks. , 1948, The Quarterly journal of microscopical science.

[12]  J. Noble-Nesbitt.  The Fully Formed Intermoult Cuticle and Associated Structures of Podura Aquatica (Collembola) , 1963 .

[13]  V. Wigglesworth.  The Principles of Insect Physiology , 1940 .

[14]  B. Wheeler.  The Integument of Arthropods , 1952 .

[15]  J. A. Ramsay,et al.  Studies on the Onychophora: III. The Control of Water Loss in Peripatopsis , 1937 .

[16]  J. Noble-Nesbitt.  The Cuticle and Associated Structures of Podura Aquatica at the Moult , 1963 .

[17]  J. Beament.  Wetting Properties of Insect Cuticle , 1960, Nature.

[18]  J. Beament.  The Penetration of Insect Egg-shells , 1949 .

[19]  M. Locke.  The Structure of Insect Tracheae , 1957 .

[20]  M. Holdgate.  Transpiration Through the Cuticles of Some Aquatic Insects , 1956 .

[21]  J. Beament.  The penetration of the insect egg-shells; penetration of the chorion of Rhodnius prolixus, Stal. , 1948, Bulletin of entomological research.

[22]  J. Beament.  THE WATER RELATIONS OF INSECT CUTICLE , 1961, Biological reviews of the Cambridge Philosophical Society.

[23]  W. Thorpe,et al.  The water-protecting properties of insect hairs , 1948 .

[24]  M. Way.  The structure and development of the larval cuticle of Diataraxia oleracea (Lepidoptera). , 1950, The Quarterly journal of microscopical science.