scholarly journals Intra-individual variation allows an explicit test of the hygric hypothesis for discontinuous gas exchange in insects

2009 ◽  
Vol 6 (2) ◽  
pp. 274-277 ◽  
Author(s):  
Caroline M. Williams ◽  
Shannon L. Pelini ◽  
Jessica J. Hellmann ◽  
Brent J. Sinclair
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Metabolic Rate ◽  
Water Loss ◽  
Individual Variation ◽  
Loss Reduction ◽  
Total Water ◽  
Explicit Test ◽  
Carbon Dioxide Release ◽  
Flow Through

The hygric hypothesis postulates that insect discontinuous gas exchange cycles (DGCs) are an adaptation that reduces respiratory water loss (RWL), but evidence is lacking for reduction of water loss by insects expressing DGCs under normal ecological conditions. Larvae of Erynnis propertius (Lepidoptera: Hesperiidae) naturally switch between DGCs and continuous gas exchange (CGE), allowing flow-through respirometry comparisons of water loss between the two modes. Water loss was lower during DGCs than CGE, both between individuals using different patterns and within individuals using both patterns. The hygric cost of gas exchange (water loss associated with carbon dioxide release) and the contribution of respiratory to total water loss were lower during DGCs. Metabolic rate did not differ between DGCs and CGE. Thus, DGCs reduce RWL in E. propertius , which is consistent with the suggestion that water loss reduction could account for the evolutionary origin and/or maintenance of DGCs in insects.

scholarly journals The scaling of carbon dioxide release and respiratory water loss in flying fruit flies (Drosophila spp.)

2000 ◽  
Vol 203 (10) ◽  
pp. 1613-1624 ◽  
Author(s):  
F.O. Lehmann ◽  
M.H. Dickinson ◽  
J. Staunton
Keyword(s):  
Carbon Dioxide ◽  
Body Size ◽  
Water Loss ◽  
Visual Motion ◽  
Bulk Water ◽  
Fruit Flies ◽  
Specific Rate ◽  
Allometric Exponent ◽  
Flying Insects ◽  
Carbon Dioxide Release

By simultaneously measuring carbon dioxide release, water loss and flight force in several species of fruit flies in the genus Drosophila, we have investigated respiration and respiratory transpiration during elevated locomotor activity. We presented tethered flying flies with moving visual stimuli in a virtual flight arena, which induced them to vary both flight force and energetic output. In response to the visual motion, the flies altered their energetic output as measured by changes in carbon dioxide release and concomitant changes in respiratory water loss. We examined the effect of absolute body size on respiration and transpiration by studying four different-sized species of fruit flies. In resting flies, body-mass-specific CO(2) release and water loss tend to decrease more rapidly with size than predicted according to simple allometric relationships. During flight, the mass-specific metabolic rate decreases with increasing body size with an allometric exponent of −0.22, which is slightly lower than the scaling exponents found in other flying insects. In contrast, the mass-specific rate of water loss appears to be proportionately greater in small animals than can be explained by a simple allometric model for spiracular transpiration. Because fractional water content does not change significantly with increasing body size, the smallest species face not only larger mass-specific energetic expenditures during flight but also a higher risk of desiccation than their larger relatives. Fruit flies lower their desiccation risk by replenishing up to 75 % of the lost bulk water by metabolic water production, which significantly lowers the risk of desiccation for animals flying under xeric environmental conditions.

scholarly journals Water Costs of Gas Exchange by a Speckled Cockroach and a Darkling Beetle

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 632
Author(s):  
Waseem Abbas ◽  
Philip C. Withers ◽  
Theodore A. Evans
Keyword(s):  
Body Size ◽  
Gas Exchange ◽  
Metabolic Rate ◽  
Water Loss ◽  
Evaporative Water ◽  
Factors Affecting ◽  
Darkling Beetle ◽  
Terrestrial Insects ◽  
Exchange Patterns ◽  
Respiratory Cost

Respiratory water loss during metabolic gas exchange is an unavoidable cost of living for terrestrial insects. It has been suggested to depend on several factors, such as the mode of gas exchange (convective vs. diffusive), species habitat (aridity), body size and measurement conditions (temperature). We measured this cost in terms of respiratory water loss relative to metabolic rate (respiratory water cost of gas exchange; RWL/V˙CO2) for adults of two insect species, the speckled cockroach (Nauphoeta cinerea) and the darkling beetle (Zophobas morio), which are similar in their mode of gas exchange (dominantly convective), habitat (mesic), body size and measurement conditions, by measuring gas exchange patterns using flow-through respirometry. The speckled cockroaches showed both continuous and discontinuous gas exchange patterns, which had significantly a different metabolic rate and respiratory water loss but the same respiratory water cost of gas exchange. The darkling beetles showed continuous gas exchange pattern only, and their metabolic rate, respiratory water loss and respiratory cost of gas exchange were equivalent to those cockroaches using continuous gas exchange. This outcome from our study highlights that the respiratory water cost of gas exchange is similar between species, regardless of gas exchange pattern used, when the confounding factors affecting this cost are controlled. However, the total evaporative water cost of gas exchange is much higher than the respiratory cost because cuticular water loss contributes considerably more to the overall evaporative water loss than respiratory water. We suggest that the total water cost of gas exchange is likely to be a more useful index of environmental adaptation (e.g., aridity) than just the respiratory water cost.

Metabolic rate and respiratory gas-exchange patterns in tenebrionid beetles from the Negev Highlands, Israel

2002 ◽  
Vol 205 (6) ◽  
pp. 791-798 ◽  
Author(s):  
Frances D. Duncan ◽  
Boris Krasnov ◽  
Megan McMaster
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
Water Loss ◽  
Activity Patterns ◽  
High Water ◽  
Standard Metabolic Rate ◽  
Active Species ◽  
Habitat Associations ◽  
Diel Activity ◽  
Water Vapour Pressure

SUMMARY This study correlates the pattern of external gas exchange with the diel activity of nine species of tenebrionid beetle from the Negev Desert, Israel. The study species are active throughout the summer months when daytime temperatures are high and no rain falls. There were no differences in standard metabolic rate, determined by flow-through respirometry, among the nine species. All the nocturnally active beetles exhibited a form of continuous respiration, whereas the two diurnally active and one crepuscular species exhibited a cyclic form of respiration referred to as the discontinuous gas-exchange cycle (DGC). The DGCs recorded have a long flutter period consisting of miniature ventilations, and 29–48 % of the total CO2 output occurred during this period. In this study, the flutter period played an important role in the modulation of metabolic rate, in contrast to other studies in which the burst period has been shown to be important. We suggest that the long flutter period is important in reducing respiratory water loss in arid-dwelling arthropods. This study lends support to the hypothesis that discontinuous gas exchange is important in reducing respiratory water loss from beetles that need to minimise dessication because of the high water vapour pressure gradient they experience. If the use of underground burrows were responsible for the evolution of discontinuous gas exchange, then we would expect all nine tenebrionid species to use DGCs since both the nocturnally and diurnally active species bury in the sand during periods of inactivity. We conclude that the activity patterns of the beetles are more important than their habitat associations in designating the type of respiration used.

Ant breathing: testing regulation and mechanism hypotheses with hypoxia

1995 ◽  
Vol 198 (7) ◽  
pp. 1613-1620 ◽  
Author(s):  
J Lighton ◽  
D Garrigan
Keyword(s):  
Gas Exchange ◽  
Water Loss ◽  
Negative Pressure ◽  
Co2 Emission ◽  
Nitrogen Accumulation ◽  
Phase Duration ◽  
O2 Concentration ◽  
Flow Through ◽  
Discontinuous Gas Exchange Cycle ◽  
And Function

Using normoxic and hypoxic flow-through respirometry, we investigated the regulation of the closed-spiracle (C) and the nature of the fluttering-spiracle (F) phases of the discontinuous gas-exchange cycle (DGC) of the ant Camponotus vicinus. We predicted that as ambient O2 concentrations declined, DGC frequency would increase, because C phase duration would decrease (reflecting earlier hypoxic initiation of the F phase) and F phase duration would shorten (reflecting nitrogen accumulation), if convective mass inflow caused by a negative pressure gradient across the spiracles, rather than by diffusion, is the dominant F phase gas-exchange mechanism. C phase duration decreased with declining ambient O2 concentrations, as predicted. In contrast, DGC frequency decreased and F phase duration increased with decreasing ambient O2 concentrations. This was opposite to the expected trend if gas exchange in the F phase was mediated by convection, as is generally hypothesized. We therefore cannot disprove that F phase gas exchange was largely or purely diffusion-based. In addition, our data show equivalent molar rates of H2O and CO2 emission during the F phase. In contrast, during the open-spiracle phase, the duration of which was not affected by ambient O2 concentration, far more H2O than CO2 was lost. We discuss these findings and suggest that current hypotheses of F phase gas-exchange mechanisms and function in reducing respiratory water loss in adult insects may require revision.

Responses to Humidity by Stomata of Nicotiana glauca L. And Corylus avellana L. Are Consistent With the Optimization of Carbon Dioxide Uptake With Respect to Water Loss

1980 ◽  
Vol 7 (3) ◽  
pp. 315 ◽  
Author(s):  
GD Farquhar ◽  
ED Schulze ◽  
M Kuppers
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Gas Exchange ◽  
Water Loss ◽  
Corylus Avellana ◽  
Carbon Gain ◽  
Nicotiana Glauca ◽  
Carbon Dioxide Uptake ◽  
Total Conductance ◽  
Corylus Avellana L

Intact leaves of N. glauca and C. avellana were exposed to a range of humidities and their gas exchange monitored. Rates of transpiration and assimilation of carbon dioxide, and their sensitivities to changes in total conductance (leaf and boundary layer) were determined. The ratio of these sensitivities, δE/δA, remained substantially constant over the range of humidities. The results represent the first experimental support for a recent hypothesis that stomata vary their apertures in such a manner as to keep δE/δA constant, which optimizes carbon gain with respect to water loss.

scholarly journals DISCONTINUOUS CARBON DIOXIDE RELEASE IN THE EASTERN LUBBER GRASSHOPPER ROMALEA GUTTATA AND ITS EFFECT ON RESPIRATORY TRANSPIRATION

1993 ◽  
Vol 177 (1) ◽  
pp. 169-180 ◽  
Author(s):  
N. F. Hadley ◽  
M. C. Quinlan
Keyword(s):  
Water Loss ◽  
Cycle Duration ◽  
Total Water ◽  
Lubber Grasshopper ◽  
Romalea Guttata ◽  
Adult Insect ◽  
Carbon Dioxide Release ◽  
Burst Phase ◽  
Increasing Temperature ◽  
Range Of Values

Ventilatory patterns were examined in the Eastern lubber grasshopper Romalea guttata and correlated with respiratory transpiration. Discontinuous release of CO2 was only observed in quiescent individuals during their scotophase. Interburst periods (spiracles closed) alternated with bouts of CO2 emission and O2 consumption (burst phase); no true ‘flutter’ phase was observed. Cycle duration decreased with increasing temperature in both hydrated and dehydrated individuals. Metabolic rates for this large, sluggish species are lower than those reported for smaller and/or more active grasshoppers. Water loss rates fell within an expected range of values for arthropods from mesic environments. Respiratory transpiration accounted for only 1.9-3.9 % of the total water loss between 15 and 30 sC and for only 7 % of the water loss during the burst phase of the cycle. These data indicate that the cyclic release of CO2 in this adult insect does not result in substantial savings of water.

scholarly journals Respiratory Strategies in Relation to Ecology and Behaviour in Three Diurnal Namib Desert Tenebrionid Beetles

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1036
Author(s):  
Frances D. Duncan
Keyword(s):  
Gas Exchange ◽  
Water Loss ◽  
Evaporative Cooling ◽  
Respiratory Physiology ◽  
Metabolic Rates ◽  
Beetle Species ◽  
Water Droplets ◽  
Namib Desert ◽  
Flow Through

The respiratory physiology of three diurnal ultraxerophilous tenebrionid beetles inhabiting either the dune slipface or gravel plain in the Namib Desert was investigated. The role of the mesothoracic spiracles and subelytral cavity in gas exchange was determined by flow-through respirometry. All three species exhibited the discontinuous gas exchange cycles with a distinct convection based flutter period and similar mass specific metabolic rates. There was variation in their respiration mechanics that related to the ecology of the species. The largest beetle species, Onymacris plana, living on the dune slipface, has a leaky subelytral cavity and used all its spiracles for gas exchange. Thus, it could use evaporative cooling from its respiratory surface. This species is a fog harvester as well as able to replenish water through metabolising fats while running rapidly. The two smaller species inhabiting the gravel plains, Metriopus depressus and Zophosis amabilis, used the mesothoracic spiracles almost exclusively for gas exchange as well as increasing the proportional length of the flutter period to reduce respiratory water loss. Neither species have been reported to drink water droplets, and thus conserving respiratory water would allow them to be active longer.

scholarly journals 717 PB 423 ETHYLENE DEGASSING OF GRAPEFRUIT

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 535g-536
Author(s):  
Peter D. Petracek
Keyword(s):  
Gas Exchange ◽  
Silicone Rubber ◽  
Water Loss ◽  
Fruit Color ◽  
Water Soluble ◽  
Chlorophyll Degradation ◽  
Initial Exposure ◽  
Early Season ◽  
Flow Through

Early-season fresh citrus are routinely exposed to ethylene to trigger chlorophyll degradation (degreening) in the peel and thus improve fruit color. Recent questions about whether ethylene is trapped in the fruit by subsequent waxing have sparked interest in characterizing ethylene exchange. Internal gas samples of mature, pesticide-free `White Marsh' grapefruit were taken through septa of silicone rubber on electrical tape affixed 10 the blossom end. Gassing of the fruit in a degreening room (10 ppm ethylene) required about four hours lo reach equilibrium while degassing was completed in less than two hours and was not affected by location of the fruit in a 0.680 m3 pallet bin. Waxing with a water-soluble wax immediately following ethylene exposure increased the time for complete degassing to over 48 h. Surface gas exchange protiles were prepared by sequentially analyzing the same fruit after: (1) harvest, (2) 22 h exposure to 10 ppm ethylene, (3) exposure to ethylene and washing with an ionic cleaning surfactant, and (4) exposure to ethylene and waxing. Glass cells with interfacing silicone rubber o-rings (23 mm diam.) were strapped to the fruit following each treatment. Ethylene emanation was measured by sampling the cells which were capped 15 m after removal from ethylene. Water and CO2 were measured by flow-through cells following ethylene analysis. Ethylene emanation following the initial exposure was the same for the stem end and midsection and two fold greater than the blossom end. Washing increased the rate of emanation five fold for the stem end and about 2.5 fold for the midsection and blossom end. Waxing reduced emanation by nearly four fold for the midsection and blossom end, but only 30% for the stem end. Water loss was increased about 40% by washing, reduced about 30% by waxing, and was primarily through the stem end. Stem-end CO2 exchange doubled upon waxing.

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