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Ongoing climate change has increased temperatures and the frequency of droughts in many parts of the world, potentially intensifying the desiccation risk for insects. Because resisting desiccation becomes more difficult at higher temperatures and lower humidity, avoiding water loss is a key challenge facing terrestrial insects. However, few studies have examined the interactive effects of temperature and environmental humidity on desiccation resistance in insects. Such studies on bees (Hymenoptera: Apoidea: Anthophila) are especially rare, despite their ecological and economic importance. Here, we crossed temperature (20, 25, and 30 °C) with humidity (<5, 50, >95 % RH) manipulations and measured time to mortality, water loss rates, and the water content at mortality of bumble bees (Bombus impatiens). We found that both higher temperature and lower humidity increased water loss rates, while warmer temperatures reduced survival time and lower humidity decreased water content at mortality. Additionally, we observed large intraspecific variation in water balance traits between colonies, and larger individuals survived longer and could tolerate more water loss before mortality. This study raises important questions about the mechanisms underpinning water loss in bumble bees and suggests that frequent access to nectar may be especially important for bumble bees' water balance and survival in a warming and drying climate., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

High relative air humidity (RH ≥ 85%) is frequent in controlled environments, and not uncommon in nature. In this review, we examine the high RH effects on plants with a special focus on stomatal characters. All aspects of stomatal physiology are attenuated by elevated RH during leaf expansion (long-term) in C 3 species. These include impaired opening and closing response, as well as weak diel oscillations. Consequently, the high RH-grown plants are not only vulnerable to biotic and abiotic stress, but also undergo a deregulation between CO 2 uptake and water loss. Stomatal behavior of a single leaf is determined by the local microclimate during expansion, and may be different than the remaining leaves of the same plant. No effect of high RH is apparent in C 4 and CAM species, while the same is expected for species with hydropassive stomatal closure. Formation of bigger stomata with larger pores is a universal response to high RH during leaf expansion, whereas the effect on stomatal density appears to be species- and leaf side-specific. Compelling evidence suggests that ABA mediates the high RH-induced stomatal malfunction, as well as the stomatal size increase. Although high RH stimulates leaf ethylene evolution, it remains elusive whether or not this contributes to stomatal malfunction. Most species lose stomatal function following mid-term (4-7 d) exposure to high RH following leaf expansion. Consequently, the regulatory role of ambient humidity on stomatal functionality is not limited to the period of leaf expansion, but holds throughout the leaf life span., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

High relative air humidity (RH≥85%) during growth disturbs stomatal functioning, resulting in excessive water loss in conditions of high evaporative demand. We investigated the expression of nine abscisic acid (ABA)-related genes (involved in ABA biosynthesis, oxidation and conjugation) and two non-ABA related genes (involved in the water stress response) aiming to better understand the mechanisms underlying contrasting stomatal functioning in plants grown at high RH. Four rose genotypes with contrasting sensitivity to high RH (one sensitive, one tolerant and two intermediate) were grown at moderate (62±3%) or high (89±4%) RH. The sensitive genotype grown at high RH showed a significantly higher stomatal conductance (g s ) and water loss in response to closing stimuli as compared to the other genotypes. Moreover, high RH reduced the leaf ABA concentration and its metabolites to a greater extent in the sensitive genotype as compared to the tolerant one. The large majority of the studied genes had a relevant role on stomatal functioning (NCED1, UGT75B2, BG2, OST1, ABF3 and Rh-APX) while two others showed a minor contribution (CYP707A3 and BG1) and AAO3, CYP707A1 and DREB1B did not contribute to the tolerance trait. These results show that multiple genes form a highly complex regulatory network acting together towards the genotypic tolerance to high RH., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Plants grown at high relative air humidity (RH≥85%) are prone to lethal wilting upon transfer to conditions of high evaporative demand. The reduced survival of these plants is related to (i) increased cuticular permeability, (ii) changed anatomical features (i.e., longer pore length and higher stomatal density), (iii) reduced rehydration ability, (iv) impaired water potential sensitivity to leaf dehydration and, most importantly, (v) compromised stomatal closing ability. This review presents a critical analysis of the strategies which stimulate stomatal functioning during plant development at high RH. These include (a) breeding for tolerant cultivars, (b) interventions with respect to the belowground environment (i.e., water deficit, increased salinity, nutrient culture and grafting) as well as (c) manipulation of the aerial environment [i.e., increased proportion of blue light, increased air movement, temporal temperature rise, and spraying with abscisic acid (ABA)]. Root hypoxia, mechanical disturbance, as well as spraying with compounds mimicking ABA, lessening its inactivation or stimulating its within-leaf redistribution are also expected to improve stomatal functioning of leaves expanded in humid air. Available evidence leaves little doubt that genotypic and phenotypic differences in stomatal functioning following cultivation at high RH are realized through the intermediacy of ABA., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

High temperatures that prevail at sun-exposed sites such as heaths, depressions, or on slopes, increase the risk of desiccation for rove beetles (Staphylinidae). Therefore, atmospheric and sub-atmospheric humidity determine the microclimates and thus habitat preference and activity of xerothermophilous species. In the nature reserve Marienfließ, a heathland in the south of Mecklenburg-Western Pomerania, Northeast German Lowlands, air temperature and humidity were recorded year-round along a transect at 10 sites, i.e. where the vegetation was more dense and more humid than where the vegetation was sparse and it was drier, using data loggers placed in the litter layer that recorded the conditions every 30 min in 2021. Monthly visits were made to determine the biomass of vegetation, soil and litter properties, edaphic rove beetle fauna and total abundance and and that of individual species at 1 m2 sites. Statistical analysis of 365 diurnal cycles per site, with pronounced amplitude in air temperature and humidity, clearly delineated the cooler and more humid sites from warmer and drier ones. Between 10 and 22 of the 30 xerothermophilous species (73.3%), such as, e.g. Quedius persimilis Mulsant & Rey, 1876, Xantholinus gallicus Coiffait, 1956, Cousya longitarsis (Thomson, 1867) and Euaesthetus superlatus Peyerimhoff, 1937, were recorded only at the cooler and moist sites on the heath. Comparison of the abundances and distribution of species revealed that the xerothermophilous heath-dwelling and desiccation-prone species prefer rather constant environmental conditions, i.e. niches in cool and moist habitats on warm and dry heathland.

High temperatures that prevail at sun-exposed sites such as heaths, depressions, or on slopes, increase the risk of desiccation for rove beetles (Staphylinidae). Therefore, atmospheric and sub-atmospheric humidity determine the microclimates and thus habitat preference and activity of xerothermophilous species. In the nature reserve Marienfl ieß, a heathland in the south of Mecklenburg-Western Pomerania, Northeast German Lowlands, air temperature and humidity were recorded year-round along a transect at 10 sites, i.e. where the vegetation was more dense and more humid than where the vegetation was sparse and it was drier, using data loggers placed in the litter layer that recorded the conditions every 30 min in 2021. Monthly visits were made to determine the biomass of vegetation, soil and litter properties, edaphic rove beetle fauna and total abundance and and that of individual species at 1 m2 sites. Statistical analysis of 365 diurnal cycles per site, with pronounced amplitude in air temperature and humidity, clearly delineated the cooler and more humid sites from warmer and drier ones. Between 10 and 22 of the 30 xerothermophilous species (73.3%), such as, e.g. Quedius persimilis Mulsant & Rey, 1876, Xantholinus gallicus Coiff ait, 1956, Cousya longitarsis (Thomson, 1867) and Euaesthetus superlatus Peyerimhoff, 1937, were recorded only at the cooler and moist sites on the heath. Comparison of the abundances and distribution of species revealed that the xerothermophilous heath-dwelling and desiccation-prone species prefer rather constant environmental conditions, i.e. niches in cool and moist habitats on warm and dry heathland. [ABSTRACT FROM AUTHOR]

White asparagus is a highly appreciated, high-value crop with a distinguished economic relevance among vegetables. Freshly harvested asparagus is available only during a short part of the year and the demand varies. The produce is perishable and only proper handling can ensure its quality after a reasonable shelf life. In this study, we investigated a new method to reduce one of the most important reasons for quality decline: fresh matter losses. The potential benefits or disadvantages of moist asparagus packaging for unpeeled white asparagus (cv. 'Gijnlim') was tested. We used polythene sleeves or bags, lined with cellulose fleece to hold added water for moisturizing. 500 g bunches of spears were filled in the bags. Spears were partly covered by the sleeves or totally covered by the bags. All spears were stored for 3 to 11 days at the temperature of 2°C, 8°C and a combination of 2°C/22°C.The last temperatures were to simulate retail conditions. In wet bags spear fresh weight increased, losses in bags with dry fleece were low. Maintaining of fresh weight in wet bags coincided significantly with higher bending firmness, and lower shear force, which points to less fibrousness. Wet storage also reduced the incidence of dried cut surfaces but promoted the incidence of lengthwise fractures and, in combination with higher temperature, grey-brown discolouration and colour saturation. Wet packaging may be beneficial primarily under low temperature and low air humidity storage conditions.

Background and Aims In addition to preventing water loss, plant cuticles must also regulate nutrient loss via leaching. The eceriferum mutants in Hordeum vulgare (barley) potentially influence these functions by altering epicuticular wax structure and composition. Methods Cultivar 'Bonus' and five of its cer mutants were grown under optimal conditions for vegetative growth and maturation, and nine traits were measured. Nutrient and water amounts going through the soil and the amount of simulated rain as deionized water, affecting phyllosphere humidity, delivered during either the vegetative or maturation phase, were varied. Cer leaf genes and three wilty (wlt) mutations were characterized for reaction to toluidine blue and the rate of non-stomatal water loss. Key Results Vegetative phase rain on 'Bonus' significantly decreased kernel weight and numbers by 15–30 %, while in cer.j59 and.c36 decreases of up to 42 % occurred. Maturation phase findings corroborated those from the vegetative phase. Significant pleiotropic effects were identified: cer.j59 decreased culm and spike length and 1000-kernel weight,.c36 decreased kernel number and weight,.i16 decreased spike length and.e8 increased culm height. Excepting Cer.zv and.ym mutations, none of the other 27 Cer leaf genes or wlt mutations played significant roles, if any, in preventing water loss. Cer.zv and.ym mutants lost non-stomatal water 13.5 times faster than those of Cer.j ,.yi ,.ys and.zp and 18.3 times faster than those of four cultivars and the mutants tested here. Conclusions Using yield to measure the net effect of phyllosphere humidity and wax crystal structure revealed that the former is far more important than the latter. The amenable experimental setup described here can be used to delve deeper. Significant pleiotropic effects were identified for mutations in four Cer genes, of which one is known to participate in wax biosynthesis. Twenty-seven Cer leaf genes and three wlt mutations have little if any effect on water loss. [ABSTRACT FROM AUTHOR]

With a high surface to volume ratio, small organisms must carefully regulate their internal water status. Spotted-wing drosophila, Drosophila suzukii (Matsumura), is an invasive frugivorous insect distributed across a wide range of geographical regions that can have periods of dry and hot weather, suggesting that this species has strategies to avoid stressful environments and reduce water loss. It also survives winter as an adult fly, indicating that it has adaptations to the low air humidity of this season. To determine the importance of water stress to D. suzukii, we studied their survival in environments of low humidity, which was manipulated using Drierite, and their survival and water loss in response to desiccation. Survival of both sexes was lower in drier conditions, and while female winter morph D. suzukii had higher mortality early on, remaining flies were able to survive longer in the drier conditions than the summer morphs. A bioassay method was adapted from Enjin et al. (2016) using 48-well plates to videotape the location of flies and quantify their behavioral responses to humidity. Male and female D. suzukii avoided dry conditions within the bioassay system, but only when there was at least 25% differential between humidity extremes. This response was observed for both summer and winter morphs of D. suzukii and our results provide guidance for attempts to manipulate crop environments to reduce the economic impact of this pest. [ABSTRACT FROM AUTHOR]

White asparagus is a highly appreciated, high-value crop with a distinguished economic relevance among vegetables. Freshly harvested asparagus is available only during a short part of the year and the demand varies. The produce is perishable and only proper handling can ensure its quality after a reasonable shelf life. In this study, we investigated a new method to reduce one of the most important reasons for quality decline: fresh matter losses. The potential benefits or disadvantages of moist asparagus packaging for unpeeled white asparagus (cv. 'Gijnlim') was tested. We used polythene sleeves or bags, lined with cellulose fleece to hold added water for moisturizing. 500 g bunches of spears were filled in the bags. Spears were partly covered by the sleeves or totally covered by the bags. All spears were stored for 3 to 11 days at the temperature of 2°C, 8°C and a combination of 2°C/22°C.The last temperatures were to simulate retail conditions. In wet bags spear fresh weight increased, losses in bags with dry fleece were low. Maintaining of fresh weight in wet bags coincided significantly with higher bending firmness, and lower shear force, which points to less fibrousness. Wet storage also reduced the incidence of dried cut surfaces but promoted the incidence of lengthwise fractures and, in combination with higher temperature, grey-brown discolouration and colour saturation. Wet packaging may be beneficial primarily under low temperature and low air humidity storage conditions. [ABSTRACT FROM AUTHOR]

Hand-feel touch firmness is a sensory method reported to be used by the blueberry industry to characterise individual fruit firmness quality. A 'soft' blueberry may be considered unmarketable. However, firmness assessed by a hand touch is questionable due to being highly influenced by the assessor's subjective judgment. Objective instrumental methods are preferred to measure firmness and create a reliable and consistent dataset. This research aimed to study the relationship between sensory hand-feel touch firmness measured by a trained sensory panel and instrumental mechanical parameters of blueberry 'Centurion'. To our knowledge, this is the first attempt to relate instrumental mechanical parameters to hand firmness using a sensory panel setting and reference samples to exemplify hand-feel intensity differences. Seven assessors were trained to evaluate hand touch firmness in a sensory panel setting. References samples resembling a blueberry were made of silicone and used to calibrate assessors' performance by exemplifying four blueberry firmness scores ('very soft', 'soft', 'firm' and 'very firm'). Six sensory sessions were conducted, where each session represented a harvest date and storage time combination (3 harvest dates X 2 storage times). Each sensory session considered blueberries exposed to five storage relative humidity (71 %, 88 %, 95 %, 97 % and 100 % RH). As a result, assessors were able to discriminate differences in hand touch firmness as influenced by storage relative humidity (water loss differences). In addition, mechanical parameters measured by the slope of force-deformation curve using a plate probe on a compression test (hardness slope) or a needle probe on a penetration test (skin break slope) were best related to sensory hand-feel firmness. Average hardness slope and skin break slope higher than 1.7 kN m−1 and 0.42 kN m−1, respectively, were associated with a very low (≤5 %) likelihood of observing unmarketable ('soft' + 'very soft') 'Centurion' blueberries in a batch. Our study provides a basis for the standardisation of mechanical methods that can be used to assess blueberry quality based on its ability to represent consumer sensation preferences of texture. • A sensory panel was used to evaluate hand-feel touch firmness. • Water loss induces textural changes perceived by hand-feel firmness. • Chord stiffness correlates to hand-feel firmness. • Instrumental values were linked to unmarketable blueberries. [ABSTRACT FROM AUTHOR]

Terrestrial isopods, as successful colonizers of land habitats, show a great variety in species distribution patterns on a global, continental, or regional scale. On a local, within-habitat level these patterns reflect the species' tolerance limits and the presence of suitable hiding places (shelter sites, refugia). Humidity preference reflects a species' capability for water retention which, in turn, depends on the integumental barrier. Desiccation resistance is a key feature in isopod survival under different environmental conditions. The present study shows a correlation between cuticle thickness and desiccation resistance under three relative humidity (RH) ranges (about 30, 75 and 100% RH) in nine species, relating these to the species' differences in meso- and microhabitat choices. Habitat preferences are also associated with differences in cuticle surface morphology. The results support our hypothesis that species distribution and desiccation resistance are associated with particular cuticular morphological traits. Phylogenetic relations seem to be less important in desiccation resistance than cuticle thickness and external morphology. [ABSTRACT FROM AUTHOR]

Abstract: Desiccation resistance, that is, the ability to reduce water loss, is an ecologically important trait relevant to all terrestrial organisms, which may constrain species distributions. Nevertheless, relatively few studies have investigated plastic capacities in desiccation resistance. We here investigate plastic responses in body mass change, used as a proxy of desiccation resistance, to variation in temperature and relative humidity in the tropical butterfly Bicyclus anynana (Butler) (Lepidoptera: Nymphalidae). Our results indicate that butterflies acclimated to a higher (27 °C) compared with a lower temperature (18 °C) and a lower (50%) compared with a higher (90%) relative humidity displayed a decreased loss of body mass, and therefore likely a loss of body water (27 °C: 11%, 18 °C: 15%; 50% r.h.: 14%, 90% r.h.: 18%). Thus, mass loss was reduced under conditions indicating increased desiccation risk, suggesting adaptive phenotypic plasticity. Effects were most pronounced during the first 24 h after acclimation, indicating quick and transient responses to environmental conditions. As anthropogenic climate change is predicted to increase the magnitude and frequency of heat and drought periods, we argue that more studies on plastic capacities in traits relating to desiccation resistance are needed to better understand species responses. [ABSTRACT FROM AUTHOR]

Hibernation is a period of water deficit for some small mammals, and humidity strongly influences hibernation patterns. Dry conditions reduce length of torpor bouts, stimulate arousals, and decrease overwinter survival. To mitigate these effects, many small mammals hibernate in near saturated (100% RH) conditions. However, big brown bats ( Eptesicus fuscus) hibernate in a wider variety of conditions and tolerate lower humidity than most other bats. To assess arid tolerance in this species, we compared torpid metabolic rates (TMR) and rates of total evaporative water loss (TEWL) between two populations of E. fuscus with differing winter ecologies: one that hibernates in humid karst caves and one that hibernates in relatively dry rock crevices. We used flow-through respirometry to measure TMR and TEWL of bats in humid and dry conditions. Torpid metabolic rates did not differ between populations or with humidity treatments. Rates of TEWL were similar between populations in humid conditions, but higher for cave-hibernating bats than crevice-hibernating bats in dry conditions. Our results suggest that E. fuscus hibernating in arid environments have mechanisms to decrease evaporative water loss that are not evident at more humid sites. Drought tolerance may facilitate the sedentary nature of the species, allowing them to tolerate more variable microclimates during hibernation and thus increasing the availability of overwintering habitat. The ability to survive arid conditions may also lessen the susceptibility of E. fuscus to diseases that affect water balance. [ABSTRACT FROM AUTHOR]

Postharvest peel splitting in banana impairs visual quality and exacerbates mass loss, fruit fly infestation and microbial infection. The aim was to determine the mechanistic basis of peel splitting. We therefore monitored the change in physical and mechanical properties of the peel as affected by different storage conditions. Peel splitting occurred axially, in the fruit corners. It began 4 d after ripening induction. Splitting was preceded by radial cracks in the inner peel, that propagated towards the outside. In fruit stored at 98 % relative humidity (RH), splitting occurred in 38 % of fruit; there was no splitting in fruit stored at 14 or 60 % RH. The percentages of fruit with radial cracks in the inner peel were 63 %, 100 %, and 100 % at 14 %, 60 % and 98 % RH, respectively. The fracture force (F max) of the peel decreased rapidly from 53.0 ± 1.6 N to 2.1 ± 0.2 N during ripening. Simulated radial cracks (cuts) in the inner peel decreased F max from 22.8 ± 2.2 N to 15.9 ± 0.9 N Paring off the outer peel decreased F max from 18.9 ± 1.7 to 4.4 ± 0.8 N, but paring off the inner peel had no effect. Osmotic water uptake by peel discs incubated in glucose solutions decreased with increasing concentration. Water was lost to hypertonic glucose solutions causing discs to shrink. Epidermal and hypodermal cell wall thickness both increased due to cell wall swelling. Our results show: (1) the outer peel layers represent the mechanical backbone of the peel, (2) radial cracks in the inner peel are the first stage of peel splitting and (3) peel splitting is caused by local stress concentrations due to radial cracking and is exacerbated by cell wall swelling. Key to reducing peel splitting at retail is prompt removal of fruit from the high RH environment of the plastic-lined cartons. • The outer peel layers represent the mechanical backbone of the peel. • Peel splitting is caused by local stress concentrations due to internal radial cracking. • High RH promotes banana fruit peel splitting. [ABSTRACT FROM AUTHOR]

Aeroterrestrial green algae are exposed to desiccation in their natural habitat, but their actual volume changes have not been investigated. Here, we measure the relative volume reduction (RVRED) in Klebsormidium crenulatum and Zygnema sp. under different preset relative air humidities (RH). A new chamber allows monitoring RH during light microscopic observation of the desiccation process. The RHs were set in the range of ∼4 % to ∼95% in 10 steps. RVRED caused by the desiccation process was determined after full acclimation to the respective RHs. In K. crenulatum, RVRED (mean ± SE) was 46.4 ± 1.9%, in Zygnema sp. RVRED was only 34.3 ± 2.4% at the highest RH (∼95%) tested. This indicates a more pronounced water loss at higher RHs in K. crenulatum versus Zygnema sp. By contrast, at the lowest RH (∼4%) tested, RVRED ranged from 75.9 ± 2.7% in K. crenulatum to 83.9 ± 2.2% in Zygnema sp. The final volume reduction is therefore more drastic in Zygnema sp. These data contribute to our understanding of the desiccation process in streptophytic green algae, which are considered the closest ancestors of land plants. [ABSTRACT FROM AUTHOR]

The effects of temperature and moisture content on the linear viscoelastic behavior of extruded amorphous potato starch were studied using dynamic mechanical analysis (DMA) from the glassy to the rubbery state. Sinusoidal tensile tests were carried out in multifrequency mode in the range of 0.1-40 Hz, with a temperature ramp of 20 to 135 °C. The water loss during DMA thermal scanning was evaluated by gravimetric analysis of batch sampling in parallel experiments that simulated temperature evolution. Loss and storage moduli were then corrected on real moisture content. Using the time-temperature superposition principle, master curves were obtained for loss and storage moduli over 18 decades in frequency. The generalized Maxwell model, in the form of a Prony series obtained from master curve fitting, was used to predict the relaxation modulus. Results showed that the relaxation modulus varied over a wide range, from 2650 MPa ( t = 10 s, 20 °C, 8 % w.b.) to 0.16 MPa ( t = 10 s, 95 °C, 16 % w.b.). The obtained constitutive equation was effective to predict the linear viscoelasticity behavior of potato starch in a wide range of thermomechanical conditions, as shown by the results of simulations of tensile experiments using finite elements. [ABSTRACT FROM AUTHOR]

To keep fresh and quality of postharvest fruit & vegetable, it is the most important to provide storage environments with high relative humidity(RH). Currently in China, the two mainly used humidification methods are packaging with plastic membrane/bag and installing ultrasonic humidifier in the storage room. All these methods have different degree of disadvantages. In order to provide steady high RH and keep fresh for unpackaged fruits & vegetable under storage, a kind of dry-fog controlled humidifier system was designed and built. Main parts of the system are humidity sensor, Israeli made atomizer with orifice size of 5 mm, water purification system, air compress system, purified water storage tank, pressure regulation and controlling device, water and air transportation tubes, and micro-computer controlling terminal. Mists generated through the fogger had average particle diameters of 2-10 μm, which can rapidly spread and integrate into surrounding environment air, providing RH as high as 90%-98%. The humidity sensor in the storage room can continually sense changes of humidity and transmit the signal to the micro-computer controlling terminal, then the controlling unit can automatically control on or off of the atomizer. So that RH in the storage room can keep at the setting point level, and this was demonstrated by RH monitor within 24 hours after system and responding efficiency tests. Application test and evaluation on fruit & vegetable fresh keeping was conducted, and the results showed that tested fruit & vegetable stored under dry-fog controlled humidifier had much less weight loss than those stored under natural RH condition, but at the same water content level as those packaged with plastic bag. In addition, storage time and shelf life of the tested fruit and vegetable exposed to the dry fog was doubled as compared to those stored in the natural RH condition. Overall sensory quality index of dry-fog exposed fruit and vegetable was also improved. Moreover, attributes of controlling decay incidence and delaying decay development were also found with dry-fog controlled humidity system during postharvest storage period(data not shown). Finally, evaluation and analysis of installation and usage cost of dry-fog controlled humidity system was done. In conclusion, advantages of dry-fog controlled humidity system are no water condensation under low temperature, keeping the cooling storage room ‘dry’ with high humidity, saving energy and labor work, and protecting environment. These findings suggest that the application of dry-fog controlled humidity system has major benefits on postharvest storage of fresh fruit and vegetables. [ABSTRACT FROM AUTHOR]

High relative air humidity (RH ≥85%) during leaf expansion hampers stomatal responsiveness to closing stimuli, a genotype-dependent effect. Genotypes with reduced stomatal closure in response to closing stimuli (i.e., sensitive genotypes) show low bulk leaf abscisic acid concentration ([ABA]). We hypothesized that the amount of ABA produced in the roots and delivered with the transpiration stream to the leaves is a critical step for a proper stomatal functioning in high RH-grown plants. Ten genotypes from a cut rose tetraploid population were grown at moderate (62%) or high (89%) RH. Stomatal anatomy and responsiveness to desiccation or ABA feeding were evaluated. Root and leaf petiole xylem sap [ABA] were quantified, and ABA delivery rate from root-to-shoot was estimated. High RH reduced stomatal responsiveness to both closing stimuli in the sensitive genotypes, whereas it had a non-significant effect in the tolerant ones. Estimates of [ABA] in root xylem sap at transpirational flow rate were not related to the genotypic differences in the sensitivity to high RH. However, high RH increased this concentration irrespective of the genotype, probably due to a reduced dilution of the [ABA] in the xylem sap as a result of a lower transpiration rate compared to moderate RH-grown plants. Leaf petiole xylem sap [ABA] was neither related to the genotypic differences in the sensitivity to high RH nor it was affected by RH. We concluded that genotypic differences in the stomatal sensitivity to high RH cannot be explained by changes in the [ABA] delivered with the transpiration stream from the roots to the leaves. [ABSTRACT FROM AUTHOR]

The impact of desiccation on habitat selection, foraging and survival has been characterized for many insects. However, limited information is available for parasitic wasps. In this study, water balance, relative humidity (RH) preference, and effect of humidity on survival of solitary Evania appendigaster (L.) (Hymenoptera: Evaniidae) and gregarious Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae) were examined. These species are both oothecal parasitoids of the American cockroach Periplaneta americana (L.) (Dictyoptera: Blattidae). E. appendigaster had significantly higher cuticular permeability (CP) and a lower surface area to volume ratio but a similar percentage of total body water content compared to A. hagenowii . No differences in these attributes were found between sexes of each parasitoid species. The percentage of total body water loss rates among E. appendigaster males and females and A. hagenowii females were similar but significantly lower than that of A. hagenowii males. All parasitoids except E. appendigaster males exhibited reduced survival times as the RH of their enclosure decreased from 87% to 38%, but this phenomenon did not occur when parasitoids were given a sugar solution. In environmental chambers with a 44–87% RH gradient, both sexes of E. appendigaster resided significantly more often in the 87% RH chamber than in the 44% RH chamber. For A. hagenowii , females preferred both the driest and the wettest chambers and males preferred the driest ones. These results demonstrate the water balance profile and its relationship to life history traits and differential responses to RH in these competing parasitoid wasps, suggesting the role of physiological and behavioral adaptations in shaping their ecological niche. [ABSTRACT FROM AUTHOR]

Animals typically respond to environmental variation by adjusting their physiology, behavior, or both. Ectothermic animals are particularly sensitive to microclimatic conditions and behaviorally thermoregulate to optimize physiological performance. Yet, thermoregulation can be costly and may obligate a physiological tradeoff with water loss. Presumably, this tradeoff intensifies when animals undergo necessary life-history events (e.g., pregnancy or digestion) that impose significant behavioral and physiological changes, including shifts in behavioral thermoregulation and increased metabolic rate. Thus, behavioral responses, such as modified microclimatic preferences, may help mitigate the physiological tradeoff between thermoregulation and water loss. Herein, we examined the influence of major physiological states (specifically, pregnancy, ecdysis, and digestion) on evaporative water loss and on behavioral adjustments in a viviparous snake, Vipera aspis . First, we used open-flow respirometry to measure the effects of physiological states and microclimatic conditions (temperature and humidity) on the rate of total evaporative water loss (TEWL) and metabolic rate (rate of O 2 consumption, V ˙ O 2 ). Then, we experimentally tested the influence of physiological state on microclimate selection. We found that energy-demanding physiological states were associated with i) an increased rate of TEWL and V ˙ O 2 compared to control states and ii) a slight preference (statistically marginal) for both warm and humid conditions compared to controls, suggesting a state-specificity in behavioral response. Overall our results underline the impact of physiological state on water loss and demonstrate the potential for behavior to mitigate the physiological tradeoff between thermoregulation and water balance. [ABSTRACT FROM AUTHOR]

This study investigated the standard metabolic rate (SMR) and evaporative water loss (EWL) responses of three Australian trapdoor-constructing mygalomorph spider species, two undescribed arid-zone species ( Aganippe 'Tropicana A' and A. 'Tropicana B') and a mesic-dwelling species ( A. rhaphiduca) to acute environmental regimes of temperature and relative humidity. There were significant effects of species, temperature, and relative humidity on SMR. SMR was lower for A. raphiduca than both A. 'Tropicana' spp. with no difference between the two A. 'Tropicana' spp. Metabolic rate increased at higher temperature and relative humidity for all three species. There were significant effects of species, temperature, and relative humidity on EWL. The mesic Aganippe species had a significantly higher EWL than either arid Tropicana species. EWL was significantly higher at lower relative humidity. Our results suggest an environmental effect on EWL but not SMR, and that mygalomorphs are so vulnerable to desiccation that the burrow provides a crucial refuge to ameliorate the effects of low environmental humidity. We conclude that mygalomorphs are highly susceptible to disturbance, and are of high conservation value as many are short-range endemics. [ABSTRACT FROM AUTHOR]

The article discusses extracorporeal membrane oxygenation (ECMO) therapy which is given to the patient after the failure of medical and surgical options who are exposed to the effects of uncompensated insensible water loss which results in hypernatraemia. The focus of the study is to explore the degree of water loss that occurs from the Hilite 2400LT oxygenator and to determine the amount of heat or humidity that alleviates water loss.

Abstract: The system proposed in this paper consists of humidity and temperature control during the food maturation process by using a dehumidifier equipped with a desiccant rotor containing silicagel. In this system the condensation/drainage stage is omitted since the humid room air is directed out of the cold store (process air) and the dried air is introduced via the dehumidifier inside the cold store. It allows separate control of the humidity and temperature inside the cold store. The experimental results are obtained in real conditions; the weight loss of the products was determined and it was, also, proved that dried products such as cheeses treated by this method retain their fresh color, texture and other organoleptic properties to ensure their final quality. [ABSTRACT FROM AUTHOR]

Abstract: In the context of global environmental change much of the focus has been on changing temperatures. However, patterns of rainfall and water availability have also been changing and are expected to continue doing so. In consequence, understanding the responses of insects to water availability is important, especially because it has a pronounced influence on insect activity, distribution patterns, and species richness. Here we therefore provide a critical review of key questions that either are being or need to be addressed in this field. First, an overview of insect behavioural responses to changing humidity conditions and the mechanisms underlying sensing of humidity variation is provided. The primary sensors in insects belong to the temperature receptor protein superfamily of cation channels. Temperature-activated transient receptor potential ion channels, or thermoTRPs, respond to a diverse range of stimuli and may be a primary integrator of sensory information, such as environmental temperature and moisture. Next we touch briefly on the components of water loss, drawing attention to a new, universal model of the water costs of gas exchange and its implications for responses to a warming, and in places drying, world. We also provide an overview of new understanding of the role of the sub-elytral chamber for water conservation, and developments in understanding of the role of cuticular hydrocarbons in preventing water loss. Because of an increasing focus on the molecular basis of responses to dehydration stress we touch briefly on this area, drawing attention to the role of sugars, heat shock proteins, aquaporins, and LEA proteins. Next we consider phenotypic plasticity or acclimation responses in insect water balance after initial exposures to altered humidity, temperature or nutrition. Although beneficial acclimation has been demonstrated in several instances, this is not always the case. Laboratory studies show that responses to selection for enhanced ability to survive water stress do evolve and that genetic variation for traits underlying such responses does exist in many species. However, in others, especially tropical, typically narrowly distributed species, this appears not to be the case. Using the above information we then demonstrate that habitat alteration, climate change, biological invasions, pollution and overexploitation are likely to be having considerable effects on insect populations mediated through physiological responses (or the lack thereof) to water stress, and that these effects may often be non-intuitive. [Copyright &y& Elsevier]

Migratory birds deposit fat and protein before passing ecological barriers and must economize these during such crossings. Birds crossing the western Sahara during autumn face a trade-off between cold and humid air along with head winds at high altitudes versus warm and dry air along with tail winds at low altitudes. Since water loss rate increases with temperature, migrants should avoid warm and dry air to save water and hence fly at high altitudes. By quantifying nocturnal songbird migration across the western Sahara with radar, we found that more than 60% of the songbirds migrated below 1000m above ground level. Thus, the majority of songbirds performed sustained migratory flights in much warmer and drier conditions than predicted (weighted means: 30°C; relative humidity: 27%; water vapour density: 7.8g/m3). Based on the metabolically available water from fat and protein catabolism, we estimated the maximum possible overall water loss rate of a flying model bird, the garden warbler, Sylvia borin, for the entire Sahara crossing at 0.29g/h. This is considerably lower than water loss rates for the same model bird passing our study site, 0.62g/h at 30°C, based on applied calculations of physiological studies. Our results clearly show that migrating songbirds can fly at much higher temperatures, and have considerably lower water loss rates, than predicted. This new insight based on observations under natural conditions will have substantial impact on the development of new physiological models for birds and other animals with restricted access to water. [Copyright &y& Elsevier]

The paper presents the results of measurements and calculations concerning the influence of weather conditions on the operation of wet cooling towers of 905 MWe units of the Opole Power Plant (Poland). The research concerned the influence of temperature and relative humidity of air, wind and power unit load on the water temperature at the outlet from the cooling tower, the level of water cooling, cooling efficiency and cooling water losses. In the cooling water loss, the evaporation loss stream and the drift loss stream were distinguished. In the analyzed operating conditions of the power unit, for example, an increase in T a m b air by 5 °C (from 20 – 22   ° C to 25 – 27   ° C ) causes an increase in temperature at the outlet of the cooling tower by 3 – 4   ° C . The influence of air temperature and humidity on the level of water cooling Δ T w and cooling efficiency ε were also found. In the case of Δ T w , the effect is in the order of 0.1 – 0.2   ° C and results from the change in cooling water temperature and the heat exchange in the condenser. The ε value is influenced by air temperature and humidity, which determine the wet bulb temperature value. Within the range of power changes of the unit from 400 to 900   MWe , the evaporated water stream m ˙ e v , depending on the environmental conditions, increases from 400 – 600   tons / h to the value of 1000 – 1400   tons / h . It was determined that in the case of the average power of the unit at the level of 576.6   MWe , the average values of the evaporation and drift streams were respectively 0.78 % and 0.15 % of the cooling water stream. Using statistical methods, it was found that the influence of wind on the level of water cooling, cooling efficiency and cooling water losses was statistically significant. [ABSTRACT FROM AUTHOR]

• Water loss induced earlier ethylene production and faster softening late in storage. • Water loss and ethylene production associated loosely with tissue ABA content. • ABA content was strongly associated with fruit firmness, irrespective of water loss. • Accelerated softening caused by dehydration may be ethylene, but not ABA, mediated. • The role of ABA in kiwifruit dehydration is unclear. Kiwifruit may be stored for prolonged periods at low temperatures during which time the fruit continue to ripen slowly and dehydration occurs. Abscisic acid (ABA) plays important roles in both fruit ripening and environmental stress response, including dehydration. To investigate the inter-relationships among postharvest dehydration, ethylene production, ABA and fruit ripening, two independent experiments were undertaken with 'Hayward' kiwifruit. Water loss was manipulated by holding fruit in three environments of different humidities at 20 °C for up to 6 d, and at 0 °C for up to 16 weeks. The impacts of the treatments over time after harvest were investigated on fruit softening, ABA content and ethylene production, and on the expression of genes of the ABA biosynthetic pathway and ethylene metabolism. Water loss induced earlier ethylene production and accelerated softening late in storage. However, these changes were not directly related to increased ABA content. The strongest association seen was between tissue ABA content and fruit firmness, irrespective of the degree of water loss. In conclusion, it is suggested that the accelerated softening of 'Hayward' kiwifruit caused by dehydration may be mediated via ethylene, but that the precise role for ABA, either directly or indirectly, is as yet difficult to ascribe. [ABSTRACT FROM AUTHOR]

Weight loss and decay are common physiological disorders during postharvest handling and storage of pomegranates. The study focused on relating the ability of plastic liners as internal packaging to modify both gaseous and moisture atmosphere around the fruit to moisture dynamics and physical and physiological quality of pomegranate fruit (cv. Wonderful) during storage. Fruit were packed with no-liner, non-perforated 'Decco', non-perforated 'Zoe', micro-perforated Xtend®, 2 mm macro-perforated high density polyethylene (HDPE), and 4 mm macro-perforated HDPE plastic liners. After 84 days of storage at 5 °C and 90–95% relative humidity (RH), fruit packed with no-liner lost 15.6 ± 0.3% of initial weight. Non-perforated (Decco and Zoe) liners minimised losses to 0.79 and 0.82% compared to Xtend® micro-perforated (4.17%) and 2 mm HDPE (2.44%) and 4 mm macro-perforated HDPE (4.17%) liners, respectively. Clearly, micro- and macro-perforation of liners minimised moisture condensation, fruit decay, and shrivel severity. Micro-perforated Xtend® and macro-perforated 4 mm HDPE were the best treatments in minimising postharvest losses that are often associated with inadequate environment control inside packaging compared to the use of non-perforated liners. [ABSTRACT FROM AUTHOR]

• Contribution of transpiration and respiration to fruit mass loss was investigated. • Respiratory water production, carbon loss and dissipated heat were also investigated. • Contribution of respiration was significant, especially at high RH. • Temperature had greatest influence on mass loss, followed by storage time and RH. Mass loss from fresh produce is associated with quality degradation during storage. Though transpiration is the main process, respiration can significantly contribute to mass loss, especially at higher than normal humidity conditions where the transpiration rate is negligible. In this paper, the relative contribution of the transpiration and respiration processes to the total mass loss of fresh pomegranate fruit were investigated. The study quantified the effects of storage temperature, relative humidity (RH) and time on these processes. Fruit were stored at 278.15, 288.15 and 298.15 K and 77, 82 and 93% RH for 43 d. Total rate of mass loss ranged from 0.036 to 0.886 mg m−2 s−1 (0.002 to 0.060 mg kg−1 s−1). Net transpiration rate ranged from 0.002 to 0.055 mg kg−1 s−1 at vapour pressure deficit (VPD) between 0.010–0.544 kPa. Water loss and carbon losses due to the respiratory process contributed up to 35% and 23% at high RH (93%) and 4% and 3% at lower RH (77%) of the total mass loss, respectively, and the rest was due to VPD. For the range of temperature and RH tested in this study, RH had the greatest influence on the transpiration rate and respiratory mass loss compared to temperature. The relative contribution of the two processes to the total mass loss under different storage conditions is an important step towards improvement and design of effective control strategies. [ABSTRACT FROM AUTHOR]