Rate Of CO2 Release Research Articles

Improving representation of leaf respiration in large‐scale predictive climate–vegetation models

Improving representation of leaf respiration in large‐scale predictive climate–vegetation models

CO2 hydrate formation and dissociation rates: Application to Mars

CO2 clathrate hydrate is a crystalline material composed of water cages around a CO2 molecule. CO2 gas hydrates are naturally occurring on Earth and are a likely phase on Mars as well as other cold planetary bodies. CO2 hydrates have minor effects on terrestrial atmospheric composition, but may be a major reservoir for greenhouse gases on Mars. In this study, CO2 hydrate formation and dissociation rates were measured experimentally on ultrapure and CO2 infused water ice (ice containing previously trapped CO2 gas bubbles). Overall, increasing pressure and temperature increased CO2 consumption rates, indicating enhanced hydrate formation rates. CO2 consumption and release rates both increased significantly in infused ice experiments as did the overall amount of CO2 consumed. CO2 bubbles formed during freezing of the infused ice likely provided more surface area for hydrate nucleation, increasing the rate of formation. Higher dissociation rates in infused ice experiments compared to ultrapure ice may be due to the higher concentration of hydrate originally formed in the bubble-filled samples. These results suggest that CO2 hydrate formation in natural, gas-rich ice occurs significantly faster than previously assumed. In addition, formation rates would be maximized and dissociation rates minimized at Mars equatorial conditions, perhaps leading to long-term storage of atmospheric CO2 in localized clathrate reservoirs.

Examination of lysine requirement of healthy young male adults on a Chinese habitual diet by the modified indicator amino acid oxidation method

There is currently no reference for intake of lysine for Chinese people; therefore, the present study was conducted to determine the lysine requirement of Chinese young male adults on a habitual Chinese mixed diet based on the modified indicator amino acid oxidation method. Seven young men with a mean age of 23.7 ± 2.2 years that were healthy based on questionnaire, physical examinations and screening tests were evaluated. Subjects were evaluated over five consecutive 7 day periods, during which time they were administered decreasing amounts of lysine via the diet (65, 55, 45, 35, 25 mg·kg-1·d-1). Subjects were allowed to adapt from day 1 to 6 and the isotopes were measured on day 7 in each period. The subjects' body weights, body compositions and plasma proteins were also examined during the study. Amino acid kinetics were measured based on the indicator amino acid oxidation technique using the 13CO2 release rate and phenylalanine oxidation rate to estimate lysine requirements. Body weights, body compositions, and plasma proteins of subjects did not change significantly relative to those at baseline. The mean and the upper 95% CI of lysine requirements of Chinese habitual diets were determined to be 58.41 and 70.09 mg·kg-1·d-1, respectively, based on the 13CO2 release rate and 54.28 and 65.14 mg·kg-1·d-1, respectively, based on the phenylalanine oxidation rate.

Covalent functionalization of graphene oxide with flame retardant and its effect on thermal stability and flame retardancy of epoxy composites

In order to improve the dispersion and fire retardant property in epoxy resin (EP), graphene oxide (GO) was functionalized via surface modification by a flame retardant which was synthesized by the reaction of methyl dichlorophosphate and 10-(2,5-dihydroxyl-phenyl)-9,10-dihydro-9-oxa-10-phosphaphenan-threne-10-oxide (DOPO-BQ). The property of functionalized GO (FGO) was characterized by fourier transform infrared spectroscopy, H- and P- nuclear magnetic resonance, X-Ray photoelectron spectroscopy and thermogravimetric analysis (TGA). Series different ratios of GO- and FGO- epoxy nanocomposites were obtained by in situ polymerization. The incorporation of FGO enhanced the thermal stability and flame retardancy of epoxy nanocomposites effectively. The thermal properties of the nanocomposites were investigated by TGA test in nitrogen atmosphere, indicating that FGO can improve the char residues. The flame retardancy of the nanocomposites was characterized by cone calorimeter test. The results showed that the incorporation of 2 wt.% FGO into EP decreased the value of peak heat release rate, total heat release, average effective heat of combustion, peak values of the CO release rate and CO2 release rate by 25%, 28%, 29.5%, 27% and 29%, respectively. This work confirms that the FGO is an effective solution for improving the thermal stability and flame retardancy of epoxy resins.

Causes of decreasing mitochondrial respiration under light in four crops

Aims Despite the increasing attention given to the rate of mitochondrial respiration under light (Rd), considerable confusion persists over whether mitochondrial respiration in the dark (Rn) is inhibited by light and whether Rd is affected by light intensity. The objective of this study is to test the hypotheses: 1) Rn is not inhibited by light; 2) the rate of Rd changes with light intensity; and 3) the photosynthetic refixation of CO2 produced by Rn accounts for the apparent disparity between Rd and Rn. Methods In the present study, 0.02 mol·mol O2 (i.e. 2% O2) was used to saturate Rn and to inhibit photorespiration (Rp). By using combined gas exchange measurements and a low O2 (2% O2) method, the post-illumination CO2 release rate of Rn, photosynthetic rate (Pn) in response to photosynthetically active radiation (PAR) in 2% O2 at either 380 or 0 μmol·mol CO2, of C3 (Triticum aestivum and Glycine max) and C4 (Zea mays and Amaranthus hypochondriacus) plants, were measured. Important finding Rn was not inhibited by light. At 2% O2 and 0 μmol·mol CO2, the measured parameters could be used to accurately estimate Rd when CO2 concentration was set for 0 μmol·mol. Rd decreased with increasing light intensity. Although Rd was lower in the dark, this could be accounted for by photosynthetic re-fixing of respiratory CO2. For all plants tested, CO2 recovery rates increased with increasing light intensity (from 50 and 2 000 μmol·m·s).

Effect of experimental and seasonal warming on litter decomposition in a temperate stream

Litter decomposition, a fundamental ecosystem process in woodland streams, is potentially affected by the predicted increase in water temperature. Here, we assessed the effects of experimental and seasonal warming on oak litter decomposition and on the relative contributions of microbes and invertebrates to this process. Experimental warming (~3 °C) stimulated litter decomposition in the coldest, but not in the warmest, months. This may be attributed to (1) higher temperature sensitivity of decomposition at lower ambient temperature due to temperature limitation of enzymatic activity, (2) higher relative temperature increase in winter than in warmer months, (3) existence of a previous warming period in winter, and (4) stronger stimulation of the activity of detritivores by warming in winter due to the prevalence of earlier (smaller) instars than in warmer months. The low response of litter decomposition to warming may have been due to the low nutrient availability in the study stream. The 30-day litter decomposition was stimulated over the seasonal gradient (monthly mean temperature: 6–16 °C), which may be attributed to a stimulation of metabolic activities by warming and to changes in detritivore life history over the seasons. The stimulation of litter decomposition with temperature suggests that the rate of CO2 release from freshwaters will increase under global warming. However, invertebrate-driven litter decomposition was more responsive to warming than microbial-driven litter decomposition, suggesting that a larger fraction of litter carbon may be converted into secondary production and stored in the system for longer periods.

What controls the variability of wood-decay rates?

Decaying wood provides essential habitats for forest biota, and its CO2 return to the atmosphere is comparable to that from fossil-fuel combustion. Decomposition rates for wood debris (WD) from three tree species were measured by CO2 release in a subtropical forest over two years. Wood temperature and moisture were measured along with CO2, and each WD piece (n=320) was characterized by its initial weight, density, volume, surface area, and decay class. For individual pieces of WD in each wood-species and decay-class group, predictions of release rates based on temperature and moisture together had R2 values ranging from 0.25 to 0.57, predictions based on moisture alone had R2 values ranging from 0.16 to 0.35, and R2 values from 0.07 to 0.35 were seen in temperature-only predictions. Wood density and surface area were negatively related to CO2 release rates (R2=0.10 and 0.04 respectively, over all groups). We also used daily meteorological measurements to predict WD temperature and moisture. Average air temperatures predicted WD temperatures with R2 values above 0.7 over 35days, but total rainfall was a very weak predictor of WD moisture over any interval. We used temperature – decay relationships to estimate annual total CO2 release from WD groups, and found that their average exponential decomposition rate (K) was 0.09year−1. Based on density loss, most WD in the studied forest would be in the late stage of decay, in contrast to some previous studies. Our results support previous studies on the importance of environmental factors in determining WD decomposition, but with only half of the variation explained, we are challenged to explain the rest. Aggressive interactions are common among WD decomposers, and previous work with simplified microbial communities suggests that high diversity leads to slower decomposition. Uncertain predictions for WD decomposition rates, and their global C- cycle implications, will persist until interactions of WD microbial communities are better understood.

Effect of Trap Design, Chemical Lure, Carbon Dioxide Release Rate, and Source of Carbon Dioxide on Efficacy of Bed Bug Monitors

Bed bugs, (Cimex lectularius L.), are difficult to find because of their nocturnal and secretive behavior. In recent years, a number of monitors containing carbon dioxide (CO2), chemical lures, heat, or both, to attract bed bugs have been developed for detecting bed bugs. Ineffective trap design, lack of attraction of chemical lures, high cost of the CO2 delivery system, or insufficient CO release rates are some factors that limited the wide adoption of these monitors. To develop an affordable and effective monitor, we conducted a series of laboratory and field tests. Specifically, we tested a new pitfall trap design, a chemical lure mixture, different CO2 release rates, and a sugar and yeast mixture as CO2 source. Results show the new pitfall trap design was significantly more effective than Climbup insect interceptor, the most effective passive monitor available in the market for bed bugs. The experimental chemical lure mixture increased Climbup insect interceptor catch by 2.2 times. Results exhibit a distinct positive relationship between the CO2 release rates and bed bug trap catches. There were no significant differences between CO2 derived from cylinders and CO2 generated from sugar and yeast mixture in their attractiveness to bed bugs. The findings suggest an effective and affordable monitor can be made incorporating the new pitfall trap design, a sugar and yeast mixture, and a chemical lure.

New methods for estimating components of lake metabolism based on free-water dissolved-oxygen dynamics

Exchange of carbon between the biosphere and atmosphere is dominated by rates of photosynthetic CO2 uptake and respiratory CO2 release by aquatic and terrestrial ecosystems worldwide. Obtaining accurate estimates of these rates is therefore important. In lakes, the most common estimation method is based on a model of dissolved-oxygen (DO) dynamics and a corresponding time series of DO concentrations measured in freely moving lake water. O2 production and consumption are inferred from changes in DO concentration, then converted to estimates of carbon uptake and release using photosynthetic and respiratory quotients. The traditional method of this type uses a simple accounting procedure to estimate daily gross primary production (GPP), total respiration (R), and net production (NP). Assuming that measured DO concentrations contain no error, it attempts to back-calculate GPP, R, and NP from an observed time series without using statistical techniques. This method produces valid estimates of GPP and the nighttime component of R, but it is unable to estimate the daytime component of R and hence cannot estimate R or NP for a complete dark–light cycle. To obtain estimates of these quantities, one must subjectively assume a value for daytime respiration. We present three new methods for estimating GPP, R, and NP that resolve this problem and also facilitate assessment of model adequacy. We illustrate use of the methods and compare their parameter estimates by applying them to monitoring data from Muskegon Lake, Michigan (USA).

Light saturated RuBP oxygenation by Rubisco is a robust predictor of light inhibition of respiration in Triticum aestivum L

Plant respiratory metabolism is complicated by the fact that the rate of non-photorespiratory mitochondrial CO2 release in the light (R light) may be lower than the rate of leaf respiration in the dark (R dark). A body of work on this topic implies a linkage between light inhibition of respiration and photorespiration, although the direction of effect and underlying mechanisms remain uncertain. In this study we used a variety of short- and long-term environmental manipulations to explicitly manipulate the rate of photorespiration (νo) and quantify the effect on the inhibition of mitochondrial respiration in the light (R light:R dark). We address the following three questions: (i) will the R light:R dark ratio increase or decrease with high CO2 or low O2 and at low temperatures; (ii) does νo correlate with R light:R dark, and if so, in what way; (iii) will suppression of respiration by light (the 'Kok effect') be seen to the same extent in Zea mays, a C4 plant, and in Triticum aestivum, a C3 plant? We found that Rlight :Rdark decreased under conditions that suppressed νo in wheat, and this resulted in a positive relationship between R light:R dark and νo. Inhibition of respiration by light in C4 maize did not respond to environmental treatment, and the fixed R light:R dark (0.46-0.72) was consistent with the wheat response, assuming a νo approaching zero. The most likely mechanism to explain this finding is that R light increases (or the inhibition of respiration by light decreases) when there is an increase in photorespiration and thus an increase in the demand for TCA cycle substrates associated with the recovery of photorespiratory cycle intermediates in the peroxisome. This work is significant because it combines a comparison of C3 and C4 metabolism with a range of environmental treatments to independently suppress νo.

Effects of organic matter on carbonate stable isotope ratios (δ13C, δ18O values) – implications for analyses of bulk sediments

Stable isotope ratio (δ(13)C, δ(18)O values) analyses of carbonates can be biased by CO(2) release from organic impurities. This is most critical for carbonate isotope analyses from bulk sediments containing comparably high amounts of organic matter (OM). Several methods have been developed to remove OM prior to analyses, but none of them can be universally applied. Moreover, pretreatment methods cause isotopic bias in themselves and should probably best be avoided. Thus, it is essential to have indicators for reliable isotope values of untreated carbonate-OM mixtures. Artificial mixtures of organic compounds with a standard carbonate were analyzed to investigate the bias on carbonate isotope ratios caused by OM in the sample. The total-inorganic-carbon to total-organic-carbon ratio (TIC/TOC) was used as a measure for the " organic impurity" of the sample. The target was to evaluate TIC/TOC as a measure for sample quality and to define TIC/TOC thresholds for reliable isotope measurements of mixtures between calcium carbonate and organic compounds. The effect of organic impurities on carbonate stable isotope values depended on the specific OM compound and the respective TIC/TOC ratio. Different CO(2) release rates were determined for the pure OM compounds. A sample TIC/TOC ratio ≥0.3 was found to be a threshold for reliable measurements of the isotope composition of calcium carbonate. Bulk carbonate analyses from carbonate-OM mixtures are reliable only if the TIC/TOC values do not fall below certain thresholds. This has implications for carbonate isotope studies from bulk sediments for which the TIC/TOC ratios should be considered as an easy-to-determine measure for sample-quality assessment.

Agricultural waste-based composts exhibiting suppressivity to diseases caused by the phytopathogenic soil-borne fungi Rhizoctonia solani and Sclerotinia minor

On-farm composting is an efficient, environmentally safe and cost-effective process for recycle vegetable residues into productive cycles. Benefits of these composts could include their ability to mediate soil-borne plant pathogen suppression with a significant impact on eco-friendly crop management. In this work, on-farm composts were assayed for ability to control, both in vitro and in vivo, damping-off causing pathogens Rhizoctonia solani and Sclerotinia minor. Tomato and escarole-derived compost was the most suppressive and, furthermore, together with that derived from artichoke wastes, exhibited multi-suppressive activity. Compost communities, characterized at metabolic and global levels by Biolog system, microbial counting, CO2-release and FDA hydrolysis rate, play a major role in compost-based biological control. The complete biotic inactivation by autoclaving composts, has, in fact, reduced or eliminated their ability in pathogen suppression. Solid state 13C CPMAS-NMR spectroscopy revealed that spectral areas typical for phenolic C, as well as methoxyl C, may be associated to suppressivity mechanism(s). These evidences suggested that the ecological relationships between organic carbon molecular distribution and microbial structure may contribute to discriminate suppressive composts from null and conducive ones. Nutritional microniches in compost may then have profound effects on the community functions, including those linked to the suppressiveness.

Determination of Mineralization Rate of Organic Materials Using Carbon Dioxide Evolution as an Index

A study was conducted on a sandy loam soil to determine the rate of CO 2release by Kola Pod Husk (KPH) and Pacesetter Grade B (PGB) (sorted city waste plus cow dung) in southwest Nigeria. Each of KPH and PGB was applied at 0.25 g to 50 g soil; and control without treatment application was incubated for 16 weeks. The treatments were replicated four times on a completely randomized design. Evolution of CO 2by all the treatments increased as the period of incubation increased from the first week to the 5th week of the experiment. After the 6 th week, PGB decreased CO 2at 7 th and 8 th week and increased it between 9 th and 11 th week and thereafter finally decreased it as incubation period progressed. KPH decreased CO 2 between 7

Studies on Respiration Rates in Coccinia grandis (Ivy Gourd) at Different Temperatures

Ivy gourd is one of the indigenous vegetable grown in India. The edible part of the ivy gourd is fruit and are mostly used for culinary purposes and also consider as a nutritious vegetable. Though it is a nutritious vegetable, the shelf life of ivy gourd is only 3-4 days in room temperature and 7-8 days in refrigerated conditions. The research maturity index and respiration rate are important in designing a packaging material for extending the shelf life at different storage conditions. Measurement of Respiration rates were carried out by conducting experiments at different temperatures of 10, 15, 20, 30 and 40°C. The respiration rates were calculated as the rate of release of CO2 relevant to the rate of O2 consumption of ivy gourd. The CO2 production and O2 consumption is maximum at higher temperature of 40°C. The O2 concentration decreased from 19.5 to 10.41 percentages and the rate CO2 release increased from 0.60 to 19.33%. The predictive models were developed for calculating the CO2 release rate and O2 consumption rates.

Metal carbonyls supported on iron oxide nanoparticles to trigger the CO-gasotransmitter release by magnetic heating

Magnetic iron oxide, maghemite (Fe2O3) nanoparticles with covalent surface-bound CO-releasing molecules (CORMs) can be triggered to release CO through heating in an alternating magnetic field. In the proof-of-concept study the rate of CO-release from [RuCl(CO3)(μ-DOPA)]@maghemite nanoparticles was doubled upon exposure to an external alternating magnetic field (31.7 kAm(-1), 247 kHz, 25 °C, 39.9 mTesla, DOPA = dioxyphenyl-alaninato).

Vasorelaxing effects and inhibition of nitric oxide in macrophages by new iron-containing carbon monoxide-releasing molecules (CO-RMs)

Carbon monoxide-releasing molecules (CO-RMs) are a class of organometallo carbonyl complexes capable of delivering controlled quantities of CO gas to cells and tissues thus exerting a broad spectrum of pharmacological effects. Here we report on the chemical synthesis, CO releasing properties, cytotoxicity profile and pharmacological activities of four novel structurally related iron-allyl carbonyls. The major difference among the new CO-RMs tested was that three compounds (CORM-307, CORM-308 and CORM-314) were soluble in dimethylsulfoxide (DMSO), whereas a fourth one (CORM-319) was rendered water-soluble by reacting the iron-carbonyl with hydrogen tetrafluoroborate. We found that despite the fact all compounds liberated CO, CO-RMs soluble in DMSO caused a more pronounced toxic effect both in vascular and inflammatory cells as well as in isolated vessels. More specifically, iron carbonyls soluble in DMSO released CO with a fast kinetic and displayed a marked cytotoxic effect in smooth muscle cells and RAW 247.6 macrophages despite exerting a rapid and pronounced vasorelaxation ex vivo. In contrast, CORM-319 that is soluble in water and liberated CO with a slower rate, preserved smooth muscle cell viability, relaxed aortic tissue and exerted a significant anti-inflammatory effect in macrophages challenged with endotoxin. These data suggest that iron carbonyls can be used as scaffolds for the design and synthesis of pharmacologically active CO-RMs and indicate that increasing water solubility and controlling the rate of CO release are important parameters for limiting their potential toxic effects.

A removal mechanism for organics and nitrogen in treating leachate using a semi-aerobic aged refuse biofilter

A removing mechanism for organics and nitrogen using a semi-aerobic aged refuse biofilter (SAARB) was evaluated based on the space structure, the aged refuse conformation and characteristics, as well as the degradation theories of organic matter and nitrogen-based substances, which could provide a fundamental theory to more effectively treat organic matter and nitrogen-based pollutants in leachate. The experimental results indicated that the average removal rate of chemical oxygen demand and total nitrogen reached 96.61 and 95.46%, respectively. The aerobic–anoxic–anaerobic zones appeared alternately in both the space structure and the granule conformation inside of the SAARB, which promoted various physical, chemical and biological reactions. Most biodegradable organic matter was converted to CO2 and CH4. The average CO2 release rate was 1.567 L/(h m2) in the winter and 1.467 L/(h m2) in the summer during a single-period experiment. The average CH4 release rate was 0.303 L/(h m2) in the summer; however, it could not be detected in the winter. Moreover, the nitrogen-based pollutants were mostly converted to N2 and N2O through denitrification. Some of the refractory organic matter and nitrogen-based pollutants were likely adsorbed by the aged refuse and biodegraded more slowly. The adsorption rate of biologically degradable matter (BDM) was 0.624 g/(kg d) during the first 40 weeks and the largest absorbance of total nitrogen (TN) was about 7.0 g/kg during this experiment. Therefore, the SAARB can maintain stable and highly efficient environment for removing organic matter and nitrogen-based pollutants.

Syntheses, Structures, and Properties of New Manganese Carbonyls as Photoactive CO-Releasing Molecules: Design Strategies That Lead to CO Photolability in the Visible Region

The unusual role of CO as a signaling molecule in several physiological pathways has spurred research in the area of synthesizing new CO-releasing molecules (CORMs) as exogenous CO donors. Auxiliary control on CO delivery can be achieved if CO can be released under the control of light. To synthesize such photoactive CORMs (photoCORMs) with the aid of smart design, a series of manganese carbonyls have been synthesized with ligands that contain extended conjugation and electron-rich donors on their frames. Five such photoCORMs, namely, [Mn(pimq)(CO)(3)(MeCN)]ClO(4) (1, where pimq = (2-phenyliminomethyl)quinoline), [Mn(qmtpm)(CO)(3)(MeCN)]ClO(4) (2, where qmtpm = 2-quinoline-N-(2'-methylthiophenyl) methyleneimine), [Mn(qmtpm)(CO)(3)Br] (3) [Mn(pmtpm)(CO)(3)(MeCN)]ClO(4) (4, where pmtpm = 2-pyridyl-N-(2'-methylthiophenyl)methyleneimine), and [Mn(pmtpm)(CO)(3)Br] (5), have been synthesized and structurally characterized. These designed carbonyls readily release CO upon exposure to light (400-550 nm). The apparent CO release rates and quantum yield values at 509 nm (φ(509)) of the photoCORMs increase steadily with rise in conjugation in the ligand frame and inclusion of a -SMe group. Addition of Br(-) as an ancillary ligand also improves the CO-donating capacity. Results of density functional theory (DFT) and time dependent DFT (TDDFT) studies indicate that low energy metal-to-ligand charge transfer (MLCT) transitions from Mn-CO bonding into ligand-π orbitals lead to reduction of M-CO(π*) back-bonding and loss of CO from these photoCORMs. Inclusion of -SMe and Br(-) in the coordination sphere attenuates the energies of the HOMO and LUMO levels and causes further enhancement of CO photorelease. Collectively, the results of this work demonstrate that new photoCORMs with excellent sensitivity to visible light can be synthesized on the basis of smart design principles.

An innovative technique for extending shelf life of strawberry: Ultrasound

Ultrasound is one of the newest nonthermal methods to extend shelf life of fresh fruits during storage. The effectiveness of ultrasound depends on wave frequency, power and treatment time. The present study was designed to determine the effect of different ultrasound powers (30 W, 60 W, 90 W) and treatment times (5 min, 10 min) on quality of strawberry. Oxygen concentration inside packages of strawberries which treated with 30 W and 60 W ultrasound powers were higher than 90 W and control (CNT) groups. A sharp increase in CO2 release rate was observed for the CNT and 90 W treatments during the storage. Attributes such as pH, total soluble solid content and color for the 30 W and 60 W treatments were better than CNT and 90 W treatments. Decay incidence analysis confirmed that all ultrasound treatments were effective to reduce mold growth. The 30 W and 60 W treatments maintained better textural properties compared with 90 W and CNT groups. FT-NIR analysis was used to quantify water and sugar content of strawberries. As a result, it was concluded that ultrasound power as high as 90 W resulted in detrimental effects on strawberry quality, while power levels between 30 W and 60 W had improved quality and can be used to extend shelf life of strawberry.

Effects of Fastac 50 EC on bumble bee Bombus terrestris L. respiration: DGE disappearance does not lead to increasing water loss

Sublethal effects of pesticides in insects can be observed through physiological changes, which are commonly estimated by metabolic rate and respiratory patterns, more precisely by the patterns of discontinuous gas-exchange (DGE) cycles. The aim of the present research was to study the effect of some low concentrations of Fastac 50 EC on the cycles of CO2 release and respiratory water loss rates (WLR) in bumble bee Bombus terrestris L. foragers. Bumble bees were dipped into 0.004% and 0.002% Fastac 50 EC solution. Flow-through respirometry was used to record the respiration and WLR 3h before and after the treatment. The respirometry was combined with infrared actography to enable simultaneous recording of abdominal movements. Our results show that Fastac 50 EC has an after-effect on bumble bee respiratory rhythms and muscle activity but does not affect WLR. Treatment with 0.004% Fastac 50 EC solution resulted in disappearance of the respiration cycles; also the lifespan of treated bumble bees was significantly shorter. Treatment with 0.002% Fastac 50 EC solution had no significant effect on respiration patterns or longevity. We found no evidence for the DGE cycles functioning as a water saving mechanism.