Water Relations in an Insect, Thermobia Domestica

1972 ◽  
Vol 57 (2) ◽  
pp. 285-296
Author(s):  
A. Y. K. OKASHA
Keyword(s):  
Water Content ◽  
Water Relations ◽  
Water Loss ◽  
Uptake Mechanism ◽  
Dry Air ◽  
Thermobia Domestica ◽  
General Terms ◽  
Moulting Cycle ◽  
Percentage Water Content

1. The percentage water content of Thermobia can be increased by starvation. 2. After desiccation (3 days in dry air) the water content of starved insects is still above normal; yet such insects will take up water from a infsaturated atmosphere (83% R.H.). 3. The rate of water loss into dry air from starved insects is not dependent upon water content. 4. Both water content and rate of water loss remain constant throughout the moulting cycle. 5. In general terms the uptake mechanism is not dependent upon water content. 6. Severe starvation before desiccation seems to impair or inhibit the uptake mechanism.

Water Relations in an Insect, Thermobia Domestica

1971 ◽  
Vol 55 (2) ◽  
pp. 435-448
Author(s):  
A. Y. K. OKASHA
Keyword(s):  
Water Content ◽  
Water Uptake ◽  
Volume Regulation ◽  
Dry Matter ◽  
High Water ◽  
High Water Content ◽  
Uptake Mechanism ◽  
Thermobia Domestica ◽  
Moulting Cycle ◽  
Very High

1. Water uptake is not inhibited by centrifugation, exposure to 45 °C, burning of the integument or by submergence in water for 1 h. 2. Repeated desiccation followed by rehydration does not inhibit water uptake. This, however, results in insects with an extremely high water content. 3. Starvation also results in insects with a very high water content, the latter depending on the length of starvation, and also results in the depletion of dry matter. 4. Desiccation followed by rehydration does not result in any loss in dry matter additional to that caused by starvation. 5. The ability to rehydrate of insects desiccated at various stages of the moulting cycle is described. It is concluded that at the later stages of the moulting cycle water uptake ceases. 6. The results are discussed in the light of current theories of the uptake mechanism. It is suggested that the uptake mechanism is primarily concerned with volume regulation. 7. It is also suggested that anal blockage, which is known to arrest uptake, results in a nervous inhibition bringing about such an effect, rather than the rectum being the site of uptake.

The leaf miner Phyllocnistis populiella negatively impacts water relations in aspen

2019 ◽  
Vol 40 (5) ◽  
pp. 580-590 ◽  
Author(s):  
Diane Wagner ◽  
Jenifer M Wheeler ◽  
Stephen J Burr
Keyword(s):  
Water Vapor ◽  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Water Loss ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Leaf Miner ◽  
Phyllocnistis Populiella

Abstract Within the North American boreal forest, a widespread outbreak of the epidermal leaf miner Phyllocnistis populiella Cham. has damaged quaking aspen (Populus tremuloides Michx.) for nearly 20 years. In a series of experiments, we tested the effects of feeding damage by P. populiella on leaf water relations and gas exchange. Relative to insecticide-treated trees, the leaves of naturally mined trees had lower photosynthesis, stomatal conductance to water vapor, transpiration, water-use efficiency, predawn water potential and water content, as well as more enriched foliar δ13C. The magnitude of the difference between naturally mined and insecticide-treated trees did not change significantly throughout the growing season, suggesting that the effect is not caused by accumulation of incidental damage to mined portions of the epidermis over time. The contributions of mining-related stomatal malfunction and cuticular transpiration to these overall effects were investigated by restricting mining damage to stomatous abaxial and astomatous adaxial leaf surfaces. Mining of the abaxial epidermis decreased photosynthesis and enriched leaf δ13C, while increasing leaf water potential and water content relative to unmined leaves, effects consistent with stomatal closure due to disfunction of mined guard cells. Mining of the adaxial epidermis also reduced photosynthesis but had different effects on water relations, reducing midday leaf water potential and water content relative to unmined leaves, and did not affect δ13C. In the laboratory, extent of mining damage to the adaxial surface was positively related to the rate of water loss by leaves treated to prevent water loss through stomata. We conclude that overall, despite water savings due to closure of mined stomata, natural levels of damage by P. populiella negatively impact water relations due to increased cuticular permeability to water vapor across the mined portions of the epidermis. Leaf mining by P. populiella could exacerbate the negative effects of climate warming and water deficit in interior Alaska.

The Evaporation of Water from Helix Aspersa

1964 ◽  
Vol 41 (4) ◽  
pp. 759-769
Author(s):  
JOHN MACHIN
Keyword(s):  
Water Content ◽  
Water Loss ◽  
Vapour Pressure ◽  
Freezing Point ◽  
Muscular Activity ◽  
Helix Aspersa ◽  
Distilled Water ◽  
Atmospheric Conditions ◽  
Evaporative Water ◽  
Dry Air

1. Observations of intact specimens of Helix aspersa together with experiments with isolated skin preparations are described. 2. Under normal atmospheric conditions increases in haemocoelic pressure, probably due to general muscular activity, are sufficient to maintain the superficial mucous coating of the skin. 3. Under conditions of rapid water loss more intense muscular undulations serve to spread mucus which collects in the grooves to more exposed areas of the skin. 4. The water content, the rate of water loss in dry air, the equilibrium in saturated air and depression of freezing point of isolated mucus samples have been measured. 5. The vapour pressure of mucus has been shown to be within 0.4% of that of distilled water under the same conditions. 6. The significance of the above findings is discussed in relation to evaporative water loss and water uptake of an intact snail.

Water Relations in an Insect, Thermobia Domestica

1973 ◽  
Vol 58 (2) ◽  
pp. 385-400
Author(s):  
A. Y. K. OKASHA
Keyword(s):  
Amino Acids ◽  
Water Relations ◽  
Free Amino Acids ◽  
Free Amino ◽  
The Body ◽  
Thermobia Domestica ◽  
Moulting Cycle

1. The concentrations of Na+ and K+ in the haemolymph remain relatively constant during the moulting cycle. 2. Desiccation, desiccation followed by rehydration and starvation exert little or no effect on the concentrations of Na+ and K+ in the haemolymph. 3. The volume of haemolymph decreases during desiccation and increases after rehydration. 4. More Na+ is voided in the excreta during desiccation. 5. Repeated desiccation and rehydration causes the loss of both Na+ and K+ from the body. 6. The effects of desiccation and rehydration on the concentrations of chlorides and free amino acids in the haemolymph are described.

WATER RELATIONS OF ASEXUAL SPORES OF SPHAEROTHECA MACULARIS (WALLR. EX. FR.) COOKE AND ERYSIPHE POLYGONI DC.

1965 ◽  
Vol 11 (3) ◽  
pp. 531-538 ◽  
Author(s):  
J. S. Jhooty ◽  
W. E. McKeen
Keyword(s):  
Relative Humidity ◽  
Water Content ◽  
Osmotic Pressure ◽  
Water Relations ◽  
Erysiphe Polygoni ◽  
Significant Change ◽  
Sphaerotheca Macularis ◽  
Glass Surfaces

The conidia of Sphaerotheca macularis germinate best at a relative humidity (R.H.) of 99 and 100% on glass surfaces, and germination does not occur if the R.H. is below 93%. Conidia of Erysiphe polygoni DC. germinate at 3% R.H. The water content of conidia of S. macularis and E. polygoni is 53 and 69% respectively. The osmotic pressure of S. macularis conidia is about 18 atm and their density varies from 1.10 to 1.11 g/ml. There is no significant change in the diameter and length of the conidia during germination.

Adaptation to Water Stress of the Leaf Water Relations of Four Tropical Forage Species

1980 ◽  
Vol 7 (2) ◽  
pp. 207 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow ◽  
MJ Fisher ◽  
E Schulze
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Water Relations ◽  
Bound Water ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Panicum Maximum ◽  
Soil Drying ◽  
Buffel Grass ◽  
Heteropogon Contortus

Three tropical grasses, green panic (Panicum maximum var, trichoglume), spear grass (Heteropogon contortus) and buffel grass (Cenchrus ciliaris) and the tropical legume siratro (Macroptilium atropurpureum), were grown in plots in a semi-arid field environment. The water relations characteristics of leaves from plants subjected to a soil drying cycle were compared with those of unstressed leaves from plants in irrigated plots. Minimum water potentials attained in the stressed leaves were c. -44, - 38, - 33 and - 13 bar for the four species, respectively. The grass leaves adjusted osmotically to water stress, apparently through accumulation of solutes, so that there was a decrease in osmotic potential at full turgor (Ψπ100) of 5.5, 3.9 and 7.1 bar, and in water potential at zero turgor (Ψ0) of 8.6, 6.5 and 8.6 bar for green panic, spear grass and buffel respectively. Water stress appeared to increase slightly the proportion of bound water (B) and the bulk modulus of elasticity (ε) of the grass leaves, but it did not alter the relative water content at zero turgor (RWC0) or the ratio of turgid water content to dry weight of the tissue. The Ψπ100 and Ψ0 of stressed siratro leaves decreased by 2.5-4 bar and 3-5 bar respectively when subjected to soil drying cycles. These changes could be explained by the marked decrease in the ratio of turgid water content to dry weight of the leaf tissue rather than by accumulation of solutes. The values of RWC0 and ε for siratro leaves were not altered by stress but, in contrast to the grasses, B was apparently decreased although the data exhibited high variability. Adjustments in Ψπ100 and Ψ0 of stressed leaves of buffel grass and siratro were largely lost within 10 days of rewatering.

scholarly journals Theoretical Analysis of the Entrainment–Mixing Process at Cloud Boundaries. Part I: Droplet Size Distributions and Humidity within the Interface Zone

2018 ◽  
Vol 75 (6) ◽  
pp. 2049-2064 ◽  
Author(s):  
Mark Pinsky ◽  
Alexander Khain
Keyword(s):  
Water Content ◽  
Droplet Size ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Mixing Process ◽  
Governing Parameter ◽  
Interface Zone ◽  
Dry Air ◽  
Air Interface ◽  
Entrainment Mixing

Abstract The problem of a complex entrainment–mixing process is analyzed by solving a diffusion–evaporation equation for an open region in the vicinity of the cloud–dry air interface. Upon normalization the problem is reduced to a one-parametric one, the governing parameter being the potential evaporation parameter R proportional to the ratio of saturation deficit in the dry air to the available liquid water content in the cloud air. As distinct from previous multiple studies analyzing mixing within closed adiabatic volumes, we consider a principally nonstationary problem that never leads to a homogeneous equilibrium state. It is shown that at R < −1 the cloud edge shifts toward the cloud; that is, the cloud dissipates due to mixing with dry air, and the cloud volume decreases. If R > −1, the cloud edge shifts outside; that is, the mixing leads to an increase in the cloud volume. The time evolution of droplet size distribution and its moments, as well as the relative humidity within the expanding cloud–dry air interface, are calculated and analyzed. It is shown that the values of the mean volume radii rapidly decrease within the interface zone in the direction away from the cloud, indicating significant changes in the cloud edge microstructure. Scattering diagrams plotted for the cloud edge agree well with high-frequency in situ measurements, corroborating the reliability of the proposed approach. It is shown that the humidity front moves toward dry air faster than the front of liquid water content. As a result, the mixing leads to formation of a humid air shell around the cloud. The widths of the interface zone and humid shell are evaluated.

The Water Relations of Earthworms

1956 ◽  
Vol 33 (1) ◽  
pp. 29-44 ◽  
Author(s):  
BETTY I. ROOTS
Keyword(s):  
Body Weight ◽  
Water Content ◽  
Water Relations ◽  
Filter Paper ◽  
Tap Water ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Glass Tubes ◽  
Allolobophora Chlorotica

1. The water content of Lumbricus terrestris, after keeping on moist filter-paper for 3 or 4 days, is 84.8% of its body weight. That of Allolobophora chlorotica is 80% of its body weight. Both species can survive a loss of 60% of the body weight, but not much more. 2. Earthworms of the species A. chlorotica, A. terrestris f. longa, Dendrobaena subrubicunda, L. rubellus and L. terrestris are all able to survive from 31 to 50 weeks in soil totally submerged beneath aerated water. The same species, and A. caliginosa can survive for 72-137 days in aerated tap water without food. 3. Garden specimens of A. chlorotica make U-shaped burrows in soil beneath water. They do not irrigate either the burrows or glass tubes. Egg-cocoons of A. chlorotica, taken from culture pots of soil, will hatch under water and the young worms will feed and grow though totally immersed.

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