Conventional and novel body temperature measurement during rest and exercise induced hyperthermia

Despite technological advances in thermal sensory equipment, few core temperature (T_CORE) measurement techniques have met the established validity criteria in exercise science. Additionally, there is debate as to what method serves as the most practically viable, yet upholds the proposed measurement accuracy. This study assessed the accuracy of current and novel T_CORE measurement techniques in comparison to rectal temperature (T_REC) as a reference standard. Fifteen well-trained subjects (11 male, 4 female) completed 60 min of exercise at an intensity equating to the lactate threshold; measured via a discontinuous exercise test. T_REC was significantly elevated from resting values (37.2±0.3 °C) at the end of moderate intensity exercise (39.6±0.04 °C; P=0.001). Intestinal telemetric pill (T_PILL) temperature and temporal artery temperature (T_TEM) did not differ significantly from T_REC at rest or during exercise (P>0.05). However, aural canal temperature (T_AUR) and thermal imaging temperature (T_IMA) were both significantly lower than T_REC (P<0.05). Bland Altman analysis revealed only T_PILL was within acceptable limits of agreement (mean bias; 0.04 °C), while T_TEM, T_AUR and T_IMA demonstrated mean bias values outside of the acceptable range (>0.27 °C). Against T_REC, these results support the use of T_PILL over all other techniques as a valid measure of T_CORE at rest and during exercise induced hyperthermia. Novel findings illustrate that T_IMA (when measured at the inner eye canthus) shows poor agreement to T_REC during rest and exercise, which is similar to other ‘surface’ measures.     

Thermoregulatory responses of lower limb amputees during exercise in a hot environment

Lower limb amputees (LLAs) have less skin surface required for sweating; thus, the ability to dissipate heat from the body may decrease and the risk of heat illness may increase during exercise in a hot environment. However, no study has compared the thermoregulatory responses during exercise between LLAs and able-body (AB) individuals with different body surface areas. This study aimed to compare the thermoregulatory responses of LLAs with those of AB individuals during exercise in a hot environment. Seven LLAs (LLA group) and 7 able-body individuals (AB group) participated in the study. A 60% peak power output of arm crank upper-body exercise was performed for 60 min in a hot environment (32 °C, 50% relative humidity). There was no difference in the increase in rectal temperature (LLA: 0.8 ± 0.2 °C, AB: 0.8  ± 0.2 °C) and mean skin temperature between the groups during the 60-min exercise. In the LLA group, the accumulated local sweat rate of the thigh during exercise was significantly higher on the non-cut side than on the cut side (64.6 ± 43.0 mg/h vs. 37.0 ± 27.2 mg/h, p < 0.05). The total sweat rate was significantly higher in the LLA group than in the AB group (1.18 ± 0.37 kg/h vs. 0.84 ± 0.10 kg/h, p < 0.05). Thermal sensation and comfort were lower in the LLA group than in the AB group. Different heat loss responses were observed in the AB and LLA groups during exercise in the heat. The LLA group compensates for sweating on the cut side due to an increase in sweat loss on the intact limb, thereby preserving appropriate thermoregulation during exercise.     

Heat acclimation does not modify autonomic responses to core cooling and the skin thermal comfort zone

Exercise heat acclimation (HA) is known to magnify the sweating response by virtue of a lower threshold as well as increased gain and maximal capacity of sweating. However, HA has been shown to potentiate the shivering response in a cold-air environment. We investigated whether HA would alter heat loss and heat production responses during water immersion. Twelve healthy male participants underwent a 10-day HA protocol comprising daily 90-min controlled-hyperthermia (target rectal temperature, T_re 38.5 °C) exercise sessions. Preceding and following HA, the participants performed a maximal exercise test in thermoneutral conditions (ambient temperature 23 °C, relative humidity 50%) and were, following exercise, immersed in 28 °C water for 60 min. Thermal comfort zone (TCZ) was also assessed with participants regulating the temperature of a water-perfused suit during heating and cooling. Baseline pre-immersion T_re was similar pre- and post-HA (pre: 38.33 ± 0.33 °C vs post: 38.12 ± 0.36 °C, p = 0.092). The T_re cooling rate was identical pre-to post-HA (−0.03 ± 0.01 °C·min⁻¹, p = 0.31), as was the vasomotor response reflected in the forearm-fingertip temperature difference. Shivering thresholds (p = 0.43) and gains (p = 0.61) were not affected by HA. TCZ was established at similar temperatures, with the magnitude in regulated water temperature being 7.6 (16.3) °C pre-HA and 5.1 (24.7) °C post-HA (p = 0.65). The present findings suggest that heat production and heat loss responses during whole body cooling as well as the skin thermal comfort zone remained unaltered by a controlled-hyperthermia HA protocol.     

Combined effects of spray‐drying conditions and postdrying storage time and temperature on Salmonella choleraesuis and Salmonella typhimurium survival when inoculated in liquid porcine plasma

The objective of this study was to determine the effectiveness of the spray‐drying process on the inactivation of Salmonella choleraesuis and Salmonella typhimurium spiked in liquid porcine plasma and to test the additive effect of immediate postdrying storage. Commercial spray‐dried porcine plasma was sterilized by irradiation and then reconstituted (1:9) with sterile water. Aliquots of reconstituted plasma were inoculated with either S. choleraesuis or S. typhimurium, subjected to spray‐drying at an inlet temperature of 200°C and an outlet temperature of either 71 or 80°C, and each spray‐drying temperature combinations were subjected to either 0, 30 or 60 s of residence time (RT) as a simulation of residence time typical of commercial dryers. Spray‐dried samples were stored at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days. Bacterial counts of each Salmonella spp., were completed for all samples. For both Salmonella spp., spray‐drying at both outlet temperatures reduced bacterial counts about 3 logs at RT 0 s, while there was about a 5·5 log reduction at RT 60 s. Storage of all dried samples at either 4·0 ± 3·0°C or 23·0 ± 0·3°C for 15 days eliminate all detectable bacterial counts of both Salmonella spp.

Significance and Impact of the Study

Safety of raw materials from animal origin like spray‐dried porcine plasma (SDPP) may be a concern for the swine industry. Spray‐drying process and postdrying storage are good inactivation steps to reduce the bacterial load of Salmonella choleraesuis and Salmonella typhimurium. For both Salmonella spp., spray‐drying at 71°C or 80°C outlet temperatures reduced bacterial counts about 3 log at residence time (RT) 0 s, while there was about a 5.5 log reduction at RT 60 s. Storage of all dried samples at either 4.0 ± 3.0°C or 23.0 ± 0.3°C for 15 days was effective for eliminating detectable bacterial counts of both Salmonella spp.     

Validation of a freehand 3D ultrasound system for morphological measures of the medial gastrocnemius muscle

Muscle volume and length are important parameters for examining the force-generating capabilities of muscle and their evaluation is necessary in studies that investigate muscle morphology and mechanical changes due to age, function, pathology, surgery and training. In this study, we assessed the validity and reliability of in vivo muscle volume and muscle belly length measurement using a multiple sweeps freehand 3D ultrasound (3DUS). The medial gastrocnemius of 10 subjects was scanned at three ankle joint angles (15°, 0° and ?15° dorsiflexion) three times using the freehand 3DUS and once on the following day using magnetic resonance imaging (MRI). All freehand 3DUS and MRI images were segmented, volumes rendered and volumes and muscle belly lengths measured. The freehand 3DUS overestimated muscle volume by 1.9±9.1 mL, 1.1±3.8% difference and underestimated muscle belly length by 3.0±5.4 mm, 1.3±2.2% difference. The intra-class correlation coefficients (ICC) for repeated freehand 3DUS system measures of muscle volume and muscle belly length were greater than 0.99 and 0.98, respectively. The ICCs for the segmentation process reliability for the freehand 3DUS system and MRI for muscle volume were both greater than 0.99 and muscle belly length were 0.97 and 0.99, respectively. Freehand 3DUS is a valid and reliable method for the measurement of human muscle volume and muscle belly length in vivo. It could be used as an alternative to MRI for measuring in vivo muscle morphology and thus allowing the determination of PCSA and estimation of the force-generating capacity of individual muscles within the setting of a biomechanics laboratory.     

Reproductive responses to photoperiod and temperature by artificially hibernated bumblebee (Bombus terrestris) queens

Post‐hibernated bumblebee (Bombus terrestris) queens were kept for 1 week under photoperiodic conditions of 8 h light : 16 h dark, and at four different temperatures (24, 28, 32 and 36°C). The reproductive performance of the queens was then observed. It was found that exposure temperature and hibernation duration did not affect the oviposition rate. The pre‐oviposition period was found to be shortest (3.8 ± 0.7 days) for queens that had hibernated for 4.0 months and had been activated at 28°C. Timing of the initiation of the switch‐point was not affected by exposure temperature and hibernation duration. Significantly higher numbers of workers (268.0 ± 31.4) and sexual queens (119.3 ± 16.8) were produced by the queens that had hibernated for 3.0 months and had been activated at 28 and 36°C, respectively. The queens that had hibernated for 4.0 months and had been activated at 36°C produced the highest number of males (296.2 ± 32.3).     

Effect of body temperature on acute ethanol toxicity

We studied the effect of elevated rectal temperature on ethanol toxicity and the effect of ethanol on the mean lethal temperature (LT50). The rectal temperature was maintained at a preselected level for 4 h. Ethanol (23% w/v) was injected i.p. In control mice anesthetized with pentobarbital, the 4 h LT50 was 41.8 ± 0.1°C (mean ± standard error). In mice which had received a non-lethal ethanol dose (6 g/kg), the LT50 was decreased to 39.0 ± 0.2°C (p< 0.001). In control mice, whose temperature dropped, the 4 h ethanol LD50 was 8.5 ± 0.8 g/kg. If the rectal temperature of the mice was maintained instead at a maximum of 38.5 – 40°C, the LD50 was decreased to 5.7 ± 0.8 g/kg (p < 0.02). The results show that ethanol increases the susceptibility of mice to hyperthermic damage, and conversely, that hyperthermia increases the toxicity of ethanol.     

Viability of Rhodococcus equi and Parascaris equorum Eggs Exposed to High Temperatures

There is great concern about the potential pathogen contamination of horse manure compost spread in the same fields horses graze in. To ensure that pathogen destruction occurs, temperatures need to be sufficiently high during composting. Here, we investigated the survival rate of two marker organisms, Rhodococcus equi and Parascaris equorum eggs, exposed to temperatures potentially encountered during horse manure composting. Our results show that the time required to achieve a 1 log10 reduction in R. equi population (D-value) are 17.1 h (±1.47) at 45°C, 8.6 h (±0.28) at 50°C, 2.9 h (±0.04) at 55°C and 0.7 h (±0.04) at 60°C. For P. equorum eggs we show that at 45 and 50°C, 2 log10 reduction of viability is reached between 8 and 24 h of incubation and that it takes less than 2 h at 55 and 60°C to achieve a viability reduction of 2 log10. These results are useful for identifying composting conditions that will reduce the risk of environmental contamination by R. equi and P. equorum eggs.     

Behavioral thermoregulation and critical thermal limits of giant keyhole limpet Megathura crenulata (Sowerby 1825) (Mollusca; Vetigastropoda)

The thermoregulatory behavior of the giant keyhole limpet Megathura crenulata was determined in a horizontal thermal gradient during the day at 18.9 °C and 18.3 °C for the night. The final preferendum determined for giant keyhole limpets was of 18.6±1.2 °C.Limpets' displacement velocity was 10.0±3.9 cm h⁻¹ during the light phase and 8.4±1.6 cm h⁻¹ during the dark phase. The thermotolerance (measured as CTMax at 50%) was determined in a keyhole limpet in three acclimation temperatures 17, 20, and 23 °C. Limpets were subjected to water increasing temperatures at a rate of 1 °C every 30 min, until they detached from the substrate. The critical thermal maximum at 50% was 27.2, 27.9 and 28.3 °C respectively.     

Repeatability of a running heat tolerance test

At present there is no standardised heat tolerance test (HTT) procedure adopting a running mode of exercise. Current HTTs may misdiagnose a runner's susceptibility to a hyperthermic state due to differences in exercise intensity. The current study aimed to establish the repeatability of a practical running test to evaluate individual's ability to tolerate exercise heat stress. Sixteen (8M, 8F) participants performed the running HTT (RHTT) (30 min, 9 km h⁻¹, 2% elevation) on two separate occasions in a hot environment (40 °C and 40% relative humidity). There were no differences in peak rectal temperature (RHTT1: 38.82±0.47 °C, RHTT2: 38.86±0.49 °C, Intra-class correlation coefficient (ICC)=0.93, typical error of measure (TEM)=0.13 °C), peak skin temperature (RHTT1: 38.12±0.45, RHTT2: 38.11±0.45 °C, ICC=0.79, TEM=0.30 °C), peak heart rate (RHTT1: 182±15 beats min⁻¹, RHTT2: 183±15 beats min⁻¹, ICC=0.99, TEM=2 beats min⁻¹), nor sweat rate (1721±675 g h⁻¹, 1716±745 g h⁻¹, ICC=0.95, TEM=162 g h⁻¹) between RHTT1 and RHTT2 (p>0.05). Results demonstrate good agreement, strong correlations and small differences between repeated trials, and the TEM values suggest low within-participant variability. The RHTT was effective in differentiating between individuals physiological responses; supporting a heat tolerance continuum. The findings suggest the RHTT is a repeatable measure of physiological strain in the heat and may be used to assess the effectiveness of acute and chronic heat alleviating procedures.     

Differential changes of regional cerebral blood flow in two bat species during induced hypothermia measured by perfusion-weighted magnetic resonance imaging

Cerebral blood flow (CBF) of a vespertilionid bat, Miniopterus fuliginosus (M. f.), and a pteropodid bat, Rousettus leschenaultii (R. l.) was measured non-invasively during induced hypothermia (37–10°C for M. f. and 37–24°C for R. l.) with perfusion-weighted magnetic resonance imaging. In both species, the average CBF was found to decrease with rectal temperature. The patterns of hypothermia-induced regional CBF changes, however, were different between the two species. In the pteropodid bat, the extent of CBF decrease at lower rectal temperature was similar in the cortex and thalamus, resulting in an unchanged thalamus/cortex CBF ratio. In contrast, the thalamus/cortex CBF ratio in the vespertilionid species increased progressively with decreasing rectal temperature (1.52 ± 0.14 at 37 ± 1°C vs. 2.28 ± 0.29 at 10 ± 1°C). These results suggest that the manner in which the two bat species cope with low body temperature may be reflected by a differential CBF regulation between thalamus and cortex.     

Reliability and validity of skin temperature measurement by telemetry thermistors and a thermal camera during exercise in the heat

New technologies afford convenient modalities for skin temperature (T_SKIN) measurement, notably involving wireless telemetry and non-contact infrared thermometry. The purpose of this study was to investigate the validity and reliability of skin temperature measurements using a telemetry thermistor system (TT) and thermal camera (TC) during exercise in a hot environment. Each system was compared against a certified thermocouple, measuring the surface temperature of a metal block in a thermostatically controlled waterbath. Fourteen recreational athletes completed two incremental running tests, separated by one week. Skin temperatures were measured simultaneously with TT and TC compared against a hard-wired thermistor system (HW) throughout rest and exercise. Post hoc calibration based on waterbath results displayed good validity for TT (mean bias [MB]=−0.18 °C, typical error [TE]=0.18 °C) and reliability (MB=−0.05 °C, TE=0.31 °C) throughout rest and exercise. Poor validity (MB=−1.4 °C, TE=0.35 °C) and reliability (MB=−0.65 °C, TE=0.52 °C) was observed for TC, suggesting it may be best suited to controlled, static situations. These findings indicate TT systems provide a convenient, valid and reliable alternative to HW, useful for measurements in the field where traditional methods may be impractical.     

Seasonal variation of Sargassum ilicifolium (Phaeophyceae) growth on equatorial coral reefs

Temporal and spatial variations in Sargassum ilicifolium thallus density and length were investigated on equatorial coral reefs in Singapore from November 2011 to October 2012. Thalli density varied little throughout the year, however, we found strong seasonal patterns in thallus length and identified temperature as the significant driver. Sargassum ilicifolium reached maximum length in December (110.39 ± 2.37 cm) during periods of cooler water temperatures, and minimum length in May (9.88 ± 0.48 cm) during periods of warmer water temperatures. Significant spatial variation was also observed for both thallus density and length of S. ilicifolium among reefs. Within reefs, densities of S. ilicifolium were higher on reef flats (20.40 ± 0.40 individuals · 0.25 m^?2) compared to upper reef slopes (5.66 ± 0.23 individuals · 0.25 m^?2). Our findings highlight that marked seasonality in the growth of canopy‐forming macroalgae can occur within equatorial reef systems where temperature ranges are restricted (<3°C).     

Constant and fluctuating temperature acclimations have similar effects on phenotypic plasticity in springtails

Much interest exists in the extent to which constant versus fluctuating temperatures affect thermal performance traits and their phenotypic plasticity. Theory suggests that effects should vary with temperature, being especially pronounced at more extreme low (because of thermal respite) and high (because of Jensen's inequality) temperatures. Here we tested this idea by examining the effects of constant temperatures (10 to 30 °C in 5 °C increments) and fluctuating temperatures (means equal to the constant temperatures, but with fluctuations of ±5 °C) temperatures on the adult (F2) phenotypic plasticity of three thermal performance traits – critical thermal minimum (CT_min), critical thermal maximum (CT_max), and upper lethal temperature (ULT₅₀) in ten species of springtails (Collembola) from three families (Isotomidae 7 spp.; Entomobryidae 2 spp.; Onychiuridae 1 sp.). The lowest mean CT_min value recorded here was -3.56 ± 1.0 °C for Paristoma notabilis and the highest mean CT_max was 43.1 ± 0.8 °C for Hemisotoma thermophila. The Acclimation Response Ratio for CT_min was on average 0.12 °C/°C (range: 0.04 to 0.21 °C/°C), but was much lower for CT_max (mean: 0.017 °C/°C, range: -0.015 to 0.047 °C/°C) and lower also for ULT₅₀ (mean: 0.05 °C/°C, range: -0.007 to 0.14 °C/°C). Fluctuating versus constant temperatures typically had little effect on adult phenotypic plasticity, with effect sizes either no different from zero, or inconsistent in the direction of difference. Previous work assessing adult phenotypic plasticity of these thermal performance traits across a range of constant temperatures can thus be applied to a broader range of circumstances in springtails.     

The neotropical shrub Lupinus elegans,from temperate forests,may not adapt to climate change

Considering that their distribution is limited to altitudinal gradients along mountains that are likely to become warmer and drier, climate change poses an increased threat to temperate forest species from tropical regions. We studied whether the understorey shrub Lupinus elegans, endemic to temperate forests of west‐central Mexico, will be able to withstand the projected temperature increase under seven climate change scenarios. Seeds were collected along an altitudinal gradient and grown in a shade‐house over 7 months before determining their temperature tolerance as electrolyte leakage. The plants from colder sites tolerated lower temperatures, i.e. the temperature at which half of the maximum electrolyte leakage occurred (LT₅₀), ranged from −6.4 ± 0.7 to −2.4 ± 0.3 °C. In contrast, no pattern was found for tolerance to high temperature (LT₅₀ average 42.8 ± 0.3 °C). The climate change scenarios considered here consistently estimated an increase in air temperature during the present century that was higher for the maximum air temperature than for the mean or minimum. In particular, the anomaly from the normal maximum air temperature at the study region ranged from 2.8 °C by 2030 to 5.8 °C by 2090. In this respect, the inability of L. elegans to adapt to increasingly higher temperatures found here, in addition to a possible inhibition of reproduction caused by warmer winters, may limit its future distribution.     

Sows’ responses to increased heat load – A review

There is a comprehensive body of literature on how increased air temperature affects the physiology, production and behaviour of sows, while very few studies consider the thermal effects of air humidity and air velocity.This review summarises studies that have investigated effects of air temperature by reviewing published literature in which sows were exposed to at least two different levels of air temperature ranging from 15 °C to 39 °C. Increased rectal temperature was investigated in the majority of the studies (26) and on average, the rectal temperature increased by 0.099 °C per °C increased air temperature above 25 °C. The increase was smaller at lower air temperatures, and it was suggested that rectal temperature is practically unaffected by air temperatures in the range of 15 °C–21 °C. This review elucidates how air temperature also affects performance indicators such as respiration rate, vaginal temperature, skin temperature, feed intake, milk yield, body weight loss during lactation, mortality, litter daily weight gain during lactation and sow behaviour.One study reported how respiration rate, rectal temperature, vaginal temperature and skin temperature were affected by both air temperature and air humidity, and the results suggest that the relative significance of air temperature and humidity may be similar for sows and finishing pigs (e.g. an increase of 40% relative humidity at an air temperature of 30 °C has a similar effect as a 1.9 °C increase in temperature).Studies on mitigation methods against the effects of high temperature and humidity such as snout cooling, drip cooling and floor cooling were reviewed to extract knowledge related to the effects of air velocity, temperatures of surrounding surfaces and the opportunity for sows to moisten their skin.     

Effect of temperature on development time and life table parameters of Nephus hiekei Fürsch,the important predator of Phenacoccus solenopsis Tinsley

The cotton mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) has become a serious threat to agricultural and ornamental plants in Southwest Iran. Pest-control studies have found Nephus hiekei Fürsch (Coleoptera: Coccinellidae), in large numbers on Phenacoccus solenopsis Tinsley, as a potential predator. However, there has been no investigation on this predator. In this research, the biology and age-stage, two-sex life table parameters of N. hiekei feeding on Ph. solenopsis were investigated at three constant temperatures (27, 32 and 37 ± 1 °C, 65 ± 5% RH and a photoperiod of 16: 8 (L: D) h. The duration of total pre-adult stage was found to decrease raising temperature from 26.98 ± 0.36 days at 27 °C to 14.24 ± 0.27 days at 37 °C. The oviposition period lasted 63.95 ± 3.14, 66.42 ± 3.34 and 25.20 ± 1.59 days at 27, 32, and 37 °C, respectively. Females laid an average of 365.68 ± 22.36, 543.79 ± 27.27 and 106.25 ± 6.38 eggs, at these three temperatures, respectively. The intrinsic rate of increase (r_m = 0.1333 ± 0.0050 d^–1), finite rate of increase (λ = 1.1423 ± 0.0057 d^–1) and net reproductive rate (R₀ = 188.89 ± 28.34 offspring) as well as gross reproductive rate (GRR = 308.31 ± 39.54 offspring) were greatest at 32 °C. The shortest mean generation time (T = 26.74 ± 0.65 days) was recorded at 37 °C and the longest at 27 °C (T = 56.48 ± 1.0 days). These results indicate that N. hiekei can successfully survive and reproduce at temperatures of around 32 °C, and has good potential to be an effective biological control agent of Ph. solenopsis.     

Development of Sarcophaga dux (diptera: Sarcophagidae) at constant temperatures and differential gene expression for age estimation of the pupae

Sarcophaga dux (Diptera: Sarcophagidae) is a necrophagous flesh fly species with potential forensic value for estimating minimum postmortem interval (PMI_min). The basic developmental data and precise age estimates of the pupae are significant for PMI_min estimation in forensic investigations. In the present study, we investigated the development data of that species at seven constant temperatures varying from 16 °C to 34 °C, including body length changes of the larve, developmental duration and accumulated degree hours of the preadults. Several reference genes for relative quantification of the differentially expressed genes (DEGs) were firstly selected and evaluated in the pupae of different ages under different temperatures. The DEGs of the insects during the pupal period at different constant temperatures (34, 25 and 16 °C) were further analyzed for more precise age estimation. The results showed that the developmental durations of the preadults at 16, 19, 22, 25, 28, 31 and 34 °C were 1478.6 ± 18.3 h, 726.1 ± 15.8 h, 538.5 ± 0.9 h, 394.1 ± 9.5 h, 375.6 ± 10.8 h, 284.1 ± 7.3 h, and 252.5 ± 6.1 h, respectively. The developmental threshold temperature the flies was 12.27 ± 0.35 °C, and the thermal summation constant was 5341.71 ± 249.29° hours. The most reliable reference genes during the pupal period at different temperatures were found: GST1 and 18S rRNA for the 34 °C group, GST1 and RPL49 for 25 °C, and 18S rRNA and 28S rRNA for 16 °C. The four differential expression genes (Hsp60, A-alpha, ARP, and RPL8) have the potential to be used for more precise age estimation of pupal S. dux. This work provides important basic developmental data and a more precise age estimation method for pupal S. dux, and improves the value of this species for PMI_min estimation in forensic investigations.     

Predicting military working dog core temperature during exertional heat strain: Validation of a Canine Thermal Model

Military working dogs (MWDs) operate under a wide range of conditions, including hot environments. Predicting how long a MWD can safely work without overheating is important for both health and performance. A Canine Thermal Model (CTM) was developed to predict core temperature (Tc) of MWDs. The CTM calculates heat storage from the balance of heat production from metabolism and heat exchange with the environment. Inputs to the CTM are: meteorological conditions (ambient temperature, relative humidity, solar radiation and wind speed), physical characteristics of the dog (mass, length), and metabolic activity (MET level, estimated from accelerometer data). The CTM was validated against Tc measured in 23 MWDs during training sessions (11.6 ± 5.0 min (mean ± standard deviation), range 4–26 min) in October (24 °C, 52% RH), March (14 °C, 74% RH), or August (28 °C, 64% RH), and 24 kennel MWDs during a standard exercise walk (11.4 ± 3.3 min, range 5.6–18 min) in July (26 °C, 77% RH). The CTM was considered acceptable if predicted Tc was within ±0.5 °C of measured Tc at the end of exercise. Compared to Tc at the end of training sessions (39.8 ± 0.6 °C, range 38.4–41.1 °C) and exercise walks (40.0 ± 0.7 °C, range 38.9–41.4 °C), the CTM-predicted Tc was within ±0.5 °C for 71 of 84 cases (85%) and 19 of 24 cases (79%), respectively. The mean difference between CTM-predicted and measured final Tc during training was -0.04 ± 0.43 °C, with 80 of 84 cases (95%) within the range of ±2 SD (Bland Altman comparison). During exercise walks the mean difference was -0.15 °C ± 0.57, with 23 of 24 cases (96%) within ±2 SD. These results support the use of the CTM to predict Tc of MWDs for the types of physical activities described above.     

Life table parameters of an indigenous strain of Neoseiulus californicus McGregor (Acari: Phytoseiidae) when fed Tetranychus urticae Koch (Acari: Tetranychidae)

The life table of the indigenous Neoseiulus californicus was studied at different temperatures and 65 ± 5% relative humidity under conditions of 16 h light : 8 h dark (LD 16:8). The total developmental period from egg to adult varied from 3.0 to 14.0 days at 15 to 35°C. Survival to adulthood ranges from 86.21 to 93.94%, with the highest rate at 25°C. The lower threshold temperature from egg to adult stages of females and males was 10.84 and 10.72°C, respectively, and the thermal constant was 57.14 degree‐days (DD) for females and 56.18 DD for males. Total number of eggs laid by each female was the highest (70.38 eggs) at 25°C, whereas average daily fecundity was the highest (3.69 eggs/female/day) at 30°C. The net reproductive rate was the highest (48.49) at 25°C and lowest (26.18) at 30°C. Mean generation time decreased from 19.04 to 11.47 days with increasing temperature from 20 to 30°C. Both intrinsic rate of natural increase (0.284) and finite rate of increase (1.32) were maximum at 30°C. Adult longevity was the highest (42.75 days for females and 32.60 days for males) at 20°C and lowest (22.70 days for females and 15.30 days for males) at 30°C. Sex ratio was female biased and was the highest (78.08) at 25°C and lowest (70.24) at 30°C. Developmental data of five constant temperatures, temperature thresholds and thermal requirements may be used to predict the occurrence, number of generations and population dynamics of N. californicus as an important biocontrol agent of Tetranychus urticae.