Effects Of Heat Stress Research Articles

Effects of short-term thermal stress on functional response and interspecific interaction of whitefly parasitoids.

The functional response of a biocontrol agent, as well as its interactions with co-occurring species under thermal stress, are 2 crucial factors in evaluating its ability to control arthropod pests in the context of climate warming. Encarsia formosa (Gahan) (Hymenoptera: Aphelinidae) is one of the most extensively utilized biological control agents for the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). In the present study, we evaluated the effects of short-term heat stress on the functional response and host control efficacy of En. formosa, as well as the interspecific interactions between this parasitoid and the co-occurring parasitoid Eretmocerus hayati (Zolnerowich and Rose) (Hymenoptera: Aphelinidae). At all experimental temperatures, type II functional responses of En. formosa were observed in both parasitism and host feeding. The type of functional response remained unaffected by experimental temperature. Roger's model was utilized to fit the data. Based on the 95% confidence interval, pairwise comparisons of searching rate (a) and handling time (Th) across temperature regimes yielded no significant differences. In most instances, the increased temperatures did not affect the host control efficacy of En. formosa. The coexistence of En. formosa and Er. hayati exhibited a negative impact on En. formosa's parasitism but a positive effect on that of Er. hayati across all temperature regimes. These findings provide valuable knowledge regarding the functional dynamics of En. formosa under climate warming and underscore the importance of understanding interspecific relationships among biocontrol agents to effectively optimize pest management strategies.

Sex-specific variation in thermal sensitivity has multiple negative effects on reproductive trait performance.

Understanding how increasing temperatures influence ectotherm population growth rate is necessary for predicting population persistence. Population growth rate depends on the thermal performance of multiple life-history traits that have different thermal sensitivities. Reproductive traits are considered more thermally sensitive than other life-history traits, such as survival and development rate. Moreover, the thermal sensitivity of reproductive traits can be sex-specific, which may differentially affect population growth. However, research concurrently assessing the sex-specific influence of heat stress on multiple reproductive traits is limited. We investigated the effect of heat stress on pupal survival and reproductive traits in both sexes to determine sex-specific thermal sensitivity and reproductive performance. Individuals of the butterfly Pieris napi were reared at either 22°C or 29°C throughout the larval and pupal stages. The latter temperature reflects the fastest development rate in this population, influencing generation time, a common population growth rate metric. We recorded pupal survival and adult body weight in both sexes. After eclosion, males and females from both treatments were allowed to interact, and mating success, copulation duration, egg production, fertility and male sterility recovery were measured. A subset of mated females was dissected to assess the number and length of fertilising eupyrene and non-fertilising apyrene sperm transferred by males of each treatment. While elevated temperatures reduced pupal survival and resulted in smaller body weights in both sexes, more substantial sex-specific effects on reproductive traits were observed. Mating success was reduced in heat-stressed females but not in males. In contrast, egg production and fertility were unaffected by heat stress in females, while heat-stressed males, despite having longer copulation durations, exhibited near-complete sterility. Male heat-induced sterility was mediated by a disruption to both eupyrene and apyrene sperm production or transfer. Male remating did not recover fertility, suggesting continued negative effects on sperm production. Our results highlight how increasing temperatures affect reproduction, illustrating that temperatures generating optimal performance for non-reproductive traits, like development rate, can negatively and differentially impact sex-specific reproductive fitness. These negative reproductive consequences may impact population persistence, highlighting the necessity to incorporate these findings into future advanced models predicting species' responses to climate warming.

Meta-analysis of heat-induced changes in cardiac function from over 400 laboratory-based heat exposure studies

Heat waves are associated with increased fatalities from adverse cardiovascular events attributed to the negative effects of heat on cardiac function. However, scientific understanding of acute cardiac adjustments to heat has come primarily from laboratory experiments employing insulated and encapsulated heating modalities, most commonly water-perfused suits. We evaluated whether findings from those studies reflect cardiac responses during more natural exposures to hot ambient conditions simulated in climate-controlled chambers by synthesizing the findings from over 400 laboratory-based heat exposure studies (6858 participant-exposures) published between 1961–2024. Among all included studies, median (interquartile range) elevations in core temperature and heart rate from baseline to end-exposure were 0.9 (0.5–1.3)°C and 27 (15–40) beats/min. Multilevel mixed-effects meta-analyses revealed exacerbated elevations in heart rate, cardiac output, and rate pressure product (estimate of cardiac workload) and blunted falls in systolic pressure in participants heated via encapsulated modalities. Leveraging the large dataset, we also provide empirical estimates of body temperature and cardiovascular responses to a wide range of conditions experienced during heat waves. With rising global temperatures, ecologically-minded physiological research is needed to improve understanding of the effects of heat stress on cardiac responses and further the development of robust climate health models and evidence-based heat-health guidance.

Sexual reproduction in plants under high temperature and drought stress.

Sexual reproduction in plants under high temperature and drought stress.

Heat stress effects on offspring compound across parental care.

Heatwaves associated with climate change threaten biodiversity by disrupting behaviours like parental care. While parental care may buffer populations from adverse environments, studies show mixed results, possibly due to heat stress affecting different care components. We investigated how heat stress impacts parental care and offspring performance in the burying beetle Nicrophorus nepalensis under control (17.8°C) and heat stress (21.8°C) conditions. We focused on two critical periods: pre-hatching care (carcass preparation) and post-hatching care (offspring provisioning). To disentangle the vulnerability of these parental care components to heat stress, we reciprocally transferred carcasses prepared under control or heat stress to females breeding under both conditions. Heatwaves affecting only one care period did not alter reproduction, but when both pre- and post-hatching periods experienced heatwaves, reproductive success declined. Females exhibited higher energy expenditure during provisioning, evidenced by greater body mass loss. Notably, heat stress had long-lasting effects on offspring via carcass preparation, resulting in smaller adult size and higher mortality. These results highlight the complexity of environmental stressors on parental care, suggesting that different care components may respond differently to heat stress, and thus need to be examined separately to better understand how parental care responds to, and buffers against, temperature stress.

Impact of heat stress on the development, physiological and biochemical characteristics of Tartary buckwheat flowers, and its transcriptomic analysis.

Impact of heat stress on the development, physiological and biochemical characteristics of Tartary buckwheat flowers, and its transcriptomic analysis.

Modelling heat stress effects on milk production traits in Tunisian Holsteins using a random regression approach.

This study investigated the impact of temperature and humidity on milk production traits in Tunisian dairy cows, analysing population-level trends and individual cow responses using various modelling techniques and heat stress (HS) indices. Two distinct datasets were used for this purpose: the first included 551,139; 331,654 and 302,396 test-day records for milk, fat and protein yields, respectively. The second supplemented the production information with daily average (THIavg) and maximum (THImax) temperature-humidity index (THI) data. Three main parts of analyses were conducted simultaneously: classical least squares, identification of HS thresholds and associated production losses and assessment of individual cow responses using random regression models (RRM) fitting various continuous functions that include/exclude individual effects. The best model, determined by goodness-of-fit measurements, was a cubic polynomial function that accounted for individual variation and THIavg as a heat load measure. HS thresholds were established at THIavg/THImax of 70/74 for milk yield, 50/55 for fat percentage, 59/66 for protein percentage, 54/63 for fat yield and 56/66 for protein yield. According to the fitted polynomial models, daily milk production traits showed a curvilinear decline with accelerated loss rates beyond the established thermal thresholds. However, for all models and thermal indices, maximum daily production losses remained below 164 g/day, 4.4 g/day and 6.1 g/day for milk, fat and protein yields, respectively. Despite these losses, the relatively high thermal thresholds and lower associated production losses suggest that Tunisian dairy cows can tolerate high heat loads. Moreover, observed variations in response patterns indicate potential for selecting heat-tolerant individuals within this population.

Challenges and constraints in the sustainability of poultry farming in Japan.

Poultry products such as chicken meat and eggs are among the most common and popular animal products in Japan. Recently, many chickens, such as broilers and layers, have been raised and their related product consumption has increased. However, the number of farms decreased, which is one of the major challenges faced by the Japanese poultry industry. Similar to that in other countries, high-pathogenicity avian influenza (HPAI) outbreaks negatively affected the distribution of poultry products. Low feed self-sufficiency in Japan is also a serious problem because the prices of diets and products are affected by the situation in foreign countries. Rice is a domestic ingredient of the poultry diet in Japan, and recently, its utilization has increased; however, concerns remain. Global warming likely affects the poultry industry in Japan negatively. The objective of this review is to illustrate the recent situation of the Japanese poultry industry, including 1) an overview; 2) the situation of influence of HPAI ; 3) situation of ingredients for poultry diet; 4) utilization of rice in poultry diet; 5) heat stress in poultry. Overall, investigation of the effects of heat stress on physiology, such as the biological defense system, and its prevention, should be continued to prevent future decreases in productivity in the Japanese poultry industry.

Gene expression of calcium transporters Calbindin-D28K and TRPV6 in Japanese quails (Coturnix japonica) subjected to phytase super-dosing and under different temperatures.

Gene expression of calcium transporters Calbindin-D28K and TRPV6 in Japanese quails (Coturnix japonica) subjected to phytase super-dosing and under different temperatures.

Effect of heat stress on milk production traits and milk coagulation properties in dairy sheep.

Heat stress in farmed animals is becoming a problem of great importance even in temperate climates, especially due to the increase in average global temperatures. Previous studies conducted on sheep have reported negative effects of heat stress on milk yield and composition and on the cheesemaking properties. The study of the effect of heat stress in sheep is complicated by the seasonality of calving and the overlap of the effects of the lactation stage with those of the climate. The aim of this work was to study the effects of heat stress in dairy sheep through a repeated measures model, separating the lactation stage and climate effects. The dataset included 2,695 repeated measurements of 555 Sardinian sheep, raised in 34 farms in Sardinia. The analyzed phenotypes were milk yield, fat, protein, lactose and somatic cell contents, milk coagulation properties (rennet clotting time, curd firming time, curd firmness), and individual laboratory cheese yield (ILCY). Temperature and humidity values of the day of the survey and of the 3 previous days were provided by the regional agency for the protection of the environment (Agenzia Regionale per la Protezione dell'Ambiente of the Sardinia Region). Climate data were then used to calculate the respective temperature and humidity indices. The effect of the temperature-humidity index (THI) was evaluated using a linear mixed model that considered stage of lactation (DIM), parity, maximum value of hourly THI calculated over 24 h (THImax) class (divided into quartiles), DIM × THI interaction, and sampling date; the farm and the animal were considered random effects. The DIM × THI interaction was significant for all parameters except somatic cells and curd firmness. Milk yield showed an increase from the first to the third THImax class and a reduction in the fourth class (THI > 73); this trend was the same in the 3 lactation stages (early, mid, and late). Fat content showed an opposite trend, independent of the lactation stage. Proteins decreased linearly at the beginning and mid lactation whereas they showed no significant changes at the end of lactation. Lactose was reduced in the fourth class of THImax, both in mid and late lactation. Rennet clotting time showed different patterns depending on DIM, whereas ILCY showed worse values as THImax increased, especially in the early and mid lactation. The study of THI in the different phases of lactation made it possible to separate the 2 effects on the parameters studied and highlighted how in dairy sheep, heat stress leads to a reduction in production and a general worsening of the quality of the milk.

Seed Priming with 2,4-Epibrassionolide Enhances Seed Germination and Heat Tolerance in Rice by Regulating the Antioxidant System and Plant Hormone Signaling Pathways.

With global climate warming, enhancing the heat stress tolerance of rice seeds is critical for ensuring crop yields and maintaining global food security. 2,4-Epibrassionolide (EBR) has been shown to effectively alleviate the adverse effects of heat stress on rice seed germination, but its mitigation mechanism has not been fully clarified. In this experiment, exogenous EBR was used as a seed priming agent. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), malondialdehyde (MDA), soluble protein contents, and plant hormone levels were measured during rice seed germination under heat stress (38 °C). We constructed a cDNA library for transcriptome sequencing analysis. The results showed that exogenous EBR could effectively alleviate the effect of heat stress on rice seeds by enhancing SOD, POD, and CAT enzyme activity; reducing the MDA content; and increasing the soluble protein content. Additionally, exogenous EBR increases the levels of GA and IAA while decreasing the ABA content. According to a transcriptomic analysis, exogenous EBR can induce the expression of key genes involved in GA, IAA, and ABA hormone biosynthesis and metabolism, regulating GA-, IAA-, ABA-, and H2O2-mediated signaling pathways to promote the germination of rice seeds under heat stress. This study provides new insights into the application of rice seed priming techniques.

Rumen-protected guanidinoacetic acid improves growth performance in beef cattle under chronic heat stress by reshaping gut microbiota and modulating serum metabolism.

This study aimed to investigate the effects of rumen-protected guanidinoacetic acid (RP-GAA) on growth performance, gut microbiota, and serum metabolism in beef cattle under chronic heat stress. A randomized block design was employed to allocate 14 F1 Simmental crossbred cattle (Simmental ♂ × Bos indicus ♀) with an average body weight of 312.5 ± 55.0 kg into two groups (n = 7): a control group was fed a basal diet without RP-GAA and a treatment group was fed the same basal diet supplemented with 10.0 g/day of RP-GAA. During feeding experiments, at 2 p.m., the average temperature increased to 31.5°C, with a relative humidity of 69.5% and a THI of 83.2. All animals are under chronic heat stress. The results indicated that RP-GAA supplementation significantly increased dry matter intake and feed conversion ratio in beef cattle under chronic heat stress (p < 0.05). RP-GAA supplementation tended to reduce respiratory rate or rectal temperature (p < 0.1). Compared to the control group, the treatment group exhibited significantly higher glucose, blood urea nitrogen, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels (p < 0.05). 16S rRNA gene sequencing revealed that RP-GAA supplementation significantly altered the ruminal microbiota composition, increasing the abundance of Firmicutes and Bacteroidota (p < 0.05), while reducing Proteobacteria (p < 0.01). Principal coordinate analysis (PCoA) and Adonis test (R 2 = 0.190, p = 0.003) jointly revealed a distinct difference in fecal microbiota structures between the two groups. Metabolomic analysis identified significant changes in pathways related to creatine synthesis, energy metabolism, and nitrogen utilization, supported by the orthogonal partial least squares discriminant analysis model (R 2 Y = 0.983, Q 2 = 0.836, p < 0.05). These findings suggest that RP-GAAenhances energy homeostasis, supports gut health, and mitigates the adverse effects of heat stress, providing a promising strategy to improve production efficiency and animal welfare in heat-stressed cattle.

Effects of heat stress on Mediterranean endemic and endangered reef-building coral Cladocora caespitosa: study on physiological and histological markers

Effects of heat stress on Mediterranean endemic and endangered reef-building coral Cladocora caespitosa: study on physiological and histological markers

The Effect of Heat Stress on Wheat Flag Leaves Revealed by Metabolome and Transcriptome Analyses During the Reproductive Stage.

In this study, we were dedicated to investigating the effect caused by heat stress on wheat flag leaves. Metabolome and transcriptome analysis were introduced to identify some key biological processes. As a result, 182 and 214 metabolites were significantly changed at the anthesis and post-anthesis stages, respectively; most of them were lipids, amino acids and derivatives, phenolic acids, and alkaloids. Aminoacyl-tRNA biosynthesis was the most significantly enriched pathway by metabolites at both two stages, each of which included 13 types of amino acid, and 12 of them were shared and up-regulated. Therefore, we further measured 22 kinds of amino acid content in ten different wheat genotypes at the post-anthesis stage. Based on the average content of each amino acid, 17 kinds of them were significantly increased after heat stress, and 4 types were significantly decreased. Both the metabolism analysis and the transcriptome analysis had a higher number of significantly changed metabolites or differential expressed genes at the post-anthesis stage, which indicated that the post-anthesis stage is more sensitive to heat stress, with 21,361 and 17,130 differential expressed genes, respectively. Two pathways, protein processing in endoplasmic reticulum and ABC transporters, were significantly enriched at two stages. The differential expressed genes in processing in endoplasmic reticulum pathway mainly encoded various types of molecular chaperones; among them, the HSP20 family was the most predominant and intensively up-regulated. The ABC transporter gene family is another pathway that is deeply involved in heat-stress response, which could be classified into five subfamilies; among them, subfamilies B and G were the most active. In summary, this study revealed the heat response pattern of amino acids, HSPs, and ABC transporter which may play a vital role during the wheat reproductive stage.

Integrative Trait Analysis for Enhancing Heat Stress Resilience in Tomato (Solanum lycopersicum L.): A Focus on Root, Physiological, and Yield Adaptations.

Tomato (Solanum lycopersicum L.) is an economically important crop worldwide, particularly in tropical and subtropical regions. However, production is significantly and increasingly affected by the impacts of climate change, including heat and drought stress and emerging pests and diseases. This study specifically evaluated the effects of heat stress on root and shoot morphology, photosynthesis, and yield traits in five tomato genotypes, to identify the characteristics that differentiate heat tolerance from susceptibility. Heat stress experiments were conducted in a polyhouse, one during the summer under high temperatures, with a non-stress trial during the winter under conducive natural conditions. Significant reductions in yield, root traits and photosynthesis were observed across all genotypes under heat stress. However, the genotype MG785-1 maintained a relatively higher yield (298.01 ± 25.1 g), a 37.7% reduction compared to non-stress conditions, while CLN4786F1 showed resilience with a 32.3% decrease compared to its non-stress harvest index. Root dry weight (5.91 ± 0.53 g in MG785-1) and root shoot ratio (0.19 ± 0.01 in MG785-1) were identified as key traits for heat tolerance. Physiological traits, such as photosynthetic rate (11.71 ± 1.61 µmol CO2 m-2 s-1 in MG785-1), were critical for maintaining growth under heat stress. In contrast, the heat-sensitive genotype CLN3961D exhibited a significant decline in yield and physiological performance. Root dry weight and root to shoot ratio were key indicators for heat tolerance, while the photosynthetic rate was critical for maintaining plant growth under stress. These findings underscore the importance of integrated root and physiological traits, providing valuable insights for breeding climate-resilient tomato varieties.

Arbuscular mycorrhiza inoculation mitigates the adverse effects of heat stress on yield and physiological responses in strawberry plants.

Arbuscular mycorrhiza inoculation mitigates the adverse effects of heat stress on yield and physiological responses in strawberry plants.

Potential Development of Anti-Heat Stress Broiler Feed Using Dried Rice Waste: A Review

Objective: The objective of this review is to explore the potential development of anti-heat stress broiler feed using dried rice, with the aim of mitigating the adverse effects of heat stress on broiler performance and welfare while improving feed efficiency. Theoretical Framework: This study is grounded in the concepts of poultry nutrition, focusing on Metabolizable Energy (ME) reduction and the inclusion of resistant starch from dried rice. These approaches align with strategies for heat stress management in livestock during extreme weather conditions. Method: This review synthesizes findings from various studies on the use of dried rice as a functional feed ingredient. The approach involves formulating broiler feed with reduced ME by lowering caloric content and incorporating high resistant starch to optimize nutrient absorption and minimize body heat production during heat stress Results and Discussion: The findings indicate that feed formulations with low-calorie and high-resistant starch content effectively reduce heat stress in broilers. These formulations improve productivity, support optimal nutrient absorption, and enhance overall welfare. The discussion highlights the practical application of these formulations and their cost-effectiveness, addressing heat stress challenges in broiler farming. Research Implications: This review provides insights for feed formulation strategies to combat heat stress in poultry, with implications for improving animal welfare, reducing production losses, and promoting sustainable livestock practices. Originality/Value: This study contributes to the literature by emphasizing the innovative use of dried rice, an organic waste product, as a sustainable and functional feed ingredient for broilers under heat stress conditions.

Environmental Heat Stress Detrimentally Affects Match Running Performance of Elite Soccer Teams Competing in the UEFA Champions League.

Modric, T, Clemente, FM, Versic, S, Chmura, P, Andrzejewski, M, Kryściak, J, and Sekulic, D. Environmental heat stress detrimentally affects match running performance of elite soccer teams competing in the UEFA Champions League. J Strength Cond Res 39(2): e142-e148, 2025-This study aimed to examine the effect of environmental heat stress (EHS), defined by wet-bulb globe temperature (WBGT), on match running performance (MRP) while controlling for match-related contextual factors. For this purpose, 2 approaches were implemented: (a) the MRP in heat stress nonrisking environment (NoEHS) (WBGT <22° C) and heat stress risking environment (EHSrisk) (WBGT ≥22° C) were compared and (b) changes in MRP according to the 1° C increase in WBGT were evaluated. Data on MRP were collected using an optical tracking system from all teams ( n = 32) in all UEFA Champions League matches ( n = 125) during the 2022-23 season. Metrics included total distance (TD), low-intensity (LIR), moderate-intensity (MIR), and high-intensity running (HIR) distances. Results indicated that less TD (108.84 vs. 110.71 km; Cohen's d [ d ] = 0.53), MIR (15.91 vs. 17.09 km; d = 0.85), and HIR (8.75 vs. 9.23 km; d = 0.46) were covered in matches played in EHSrisk compared with the NoEHS. Further investigation indicated that for every 1° C increase in WBGT, TD averagely decreased by 0.16 km ( d = -0.48), MIR by 0.13 km ( d = -1.09), and HIR by 0.06 km ( d = -0.69). These findings demonstrated decreased overall and intensive workload during the matches in EHSrisk, suggesting the detrimental effect of EHS on match volume and intensity in elite soccer. When EHS risk is anticipated, consideration of playing and recovery strategies should be implemented by coaches to achieve tactical goals while minimizing physical strain during a match.

The effects of acute operational stress and passive heat stress on physiological and subjective stress responses in military personnel.

The effects of acute operational stress and passive heat stress on physiological and subjective stress responses in military personnel.

Heat health in general practice: An evidence-based approach to the prevention of heat-related illness

The year 2023 was the hottest on record, with heatwaves becoming more frequent and severe due to climate change. Extreme heat is the deadliest climate related event, causing significant morbidity and mortality globally. Vulnerable groups include older people, young children and pregnant women. This paper aims to equip general practitioners (GPs) with evidence-based strategies to prevent and mitigate heat related illnesses. It identifies at-risk populations through life stage analysis and advocates for effective adaptation and mitigation strategies. This paper highlights essential practice points for GPs and discusses the expanding evidence on heat-related health impacts, including direct effects like heat stress and indirect effects such as exacerbation of chronic diseases. The importance of cooling strategies and heat action plans are emphasised while advocating for systemic changes to address the root causes of heat-related health risks.