Effects Of Heat Waves Research Articles

Are hotspots and frequencies of heat waves changing over time? Exploring causes of heat waves in a tropical country.

Heat waves significantly impact people's lives and livelihoods and are becoming very alarming and recognized as hot topics worldwide, including in Bangladesh. However, much less is understood regarding recent hotspots, the frequency of heat waves over time, and their underlying causes in Bangladesh. The objective of the study is to explore the current scenario and frequency of heat waves and their possible causes across Bangladesh. The Mann-Kendall and Sen's slope techniques were used to determine seasonal and annual temperature trend patterns of heat wave frequencies. Daily maximum temperature datasets collected from the Bangladesh Meteorological Department (BMD) during 1991-2021 are applied. The frequency of days with Tmax≥ 36°C as the threshold was used to compute different types of heat waves based on the BMD's operational definition. The results show that the mild heat wave (MHW) days followed the subsequent hotspot order: Rajshahi (103) > Chuadanga (79), Ishurdi (60), and Jessore (58), respectively. The frequency of days with Tmax≥36°C was persistence for many days in 2014, especially in the western part of Bangladesh compared to other parts. Similarly, the heat waves condition shown its deadliest event by increasing more days in 2021. The highest increasing trend was identified at the Patuakhali site, with a rate of 0.516 days/year, while the highest decreasing trend was noticed at the Chuadanga site, with a rate of -0.588 days/year. The frequency of days (Tmax≥36°C) is an increasing trend in the south-western part of Bangladesh. The synoptic condition in and around Bangladesh demonstrates that the entrance of heat waves in Bangladesh is due to the advection of higher temperatures from the south/southwest of the Bay of Bengal. The outcomes will guide the national appraisal of heatwave effects, shedding light on the primary causes of definite heatwave phenomena, which are crucial for developing practical adaptation tools.

Hiding from heat: The transcriptomic response of two clam species is modulated by behaviour and habitat

Rising occurrence of extreme warming events are profoundly impacting ecosystems, altering their functioning and services with significant socio-economic consequences. Particularly susceptible to heatwaves are intertidal shellfish beds, located in estuarine areas already stressed by factors such as rainfall events, red tides, eutrophication, and pollution. In Galicia, Northwestern Spain, these beds support vital shellfisheries, featuring the native clam Ruditapes decussatus and the non-indigenous R. philippinarum. Over recent decades, these populations have experienced notable abundance shifts due to various anthropogenic impacts, including climate change. In this habitat, patches of the seagrass Zostera noltei that coexist with bare sand can act as thermal refuges for benthic organisms such as clams. To assess the impact of heatwaves on these ecosystems, a mesocosm experiment was conducted. Juveniles of both clam species in two habitat types—bare sand and sand with Z. noltei—were exposed to simulated atmospheric heatwaves during diurnal low tide for four consecutive days. Subsequent transcriptomic analysis revealed that high temperatures had a more pronounced impact on the transcriptome of R. philippinarum compared to R. decussatus. The habitat type played a crucial role in mitigating heat stress in R. philippinarum, with the presence of Z. noltei notably ameliorating the transcriptomic response. These findings have direct applications in shellfishery management, emphasizing the importance of preserving undisturbed patches of Z. noltei as thermal refuges, contributing to the mitigation of heatwave effects on shellfish populations.

Examining the Heat Health Burden in Australia: A Rapid Review

Extreme heat has been linked to increased mortality and morbidity across the globe. Increasing temperatures due to climatic change will place immense stress on healthcare systems. This review synthesises Australian literature that has examined the effect of hot weather and heatwaves on various health outcomes. Databases including Web of Science, PubMed and CINAHL were systematically searched for articles that quantitatively examined heat health effects for the Australian population. Relevant, peer-reviewed articles published between 2010 and 2023 were included. Two authors screened the abstracts. One researcher conducted the full article review and data extraction, while another researcher randomly reviewed 10% of the articles to validate decisions. Our rapid review found abundant literature indicating increased mortality and morbidity risks due to extreme temperature exposures. The effect of heat on mortality was found to be mostly immediate, with peaks in the risk of death observed on the day of exposure or the next day. Most studies in this review were concentrated on cities and mainly included health outcome data from temperate and subtropical climate zones. There was a dearth of studies that focused on tropical or arid climates and at-risk populations, including children, pregnant women, Indigenous people and rural and remote residents. The review highlights the need for more context-specific studies targeting vulnerable population groups, particularly residents of rural and remote Australia, as these regions substantially vary climatically and socio-demographically from urban Australia, and the heat health impacts are likely to be even more substantial.

Elevated temperature and nutrients lead to increased N2O emissions from salt marsh soils from cold and warm climates

Salt marshes can attenuate nutrient pollution and store large amounts of ‘blue carbon’ in their soils, however, the value of sequestered carbon may be partially offset by nitrous oxide (N2O) emissions. Global climate and land use changes result in higher temperatures and inputs of reactive nitrogen (Nr) into coastal zones. Here, we investigated the combined effects of elevated temperature (ambient + 5℃) and Nr (double ambient concentrations) on nitrogen processing in marsh soils from two climatic regions (Quebec, Canada and Louisiana, U.S.) with two vegetation types, Sporobolus alterniflorus (= Spartina alterniflora) and Sporobolus pumilus (= Spartina patens), using 24-h laboratory incubation experiments. Potential N2O fluxes increased from minor sinks to major sources following elevated treatments across all four marsh sites. One day of potential N2O emissions under elevated treatments (representing either long-term sea surface warming or short-term ocean heatwaves effects on coastal marsh soil temperatures alongside pulses of N loading) offset 15–60% of the potential annual ambient N2O sink, depending on marsh site and vegetation type. Rates of potential denitrification were generally higher in high latitude than in low latitude marsh soils under ambient treatments, with low ratios of N2O:N2 indicating complete denitrification in high latitude marsh soils. Under elevated temperature and Nr treatments, potential denitrification was lower in high latitude soil but higher in low latitude soil as compared to ambient conditions, with incomplete denitrification observed except in Louisiana S. pumilus. Overall, our findings suggest that a combined increase in temperature and Nr has the potential to reduce salt marsh greenhouse gas (GHG) sinks under future global change scenarios.

Characterization of durum wheat resistance against leaf rust under climate change conditions of increasing temperature and [CO2

Durum wheat cultivation in Mediterranean regions is threatened by abiotic factors, mainly related to the effects of climate change, and biotic factors such as the leaf rust disease. This situation requires an in-depth knowledge of how predicted elevated temperatures and [CO2] will affect durum wheat-leaf rust interactions. Therefore, we have characterised the response of one susceptible and two resistant durum wheat accessions against leaf rust under different environments in greenhouse assays, simulating the predicted conditions of elevated temperature and [CO2] in the far future period of 2070–2099 for the wheat growing region of Cordoba, Spain. Interestingly, high temperature alone or in combination with high [CO2] did not alter the external appearance of the rust lesions. However, through macro and microscopic evaluation, we found some host physiological and molecular responses to infection that would quantitatively reduce not only pustule formation and subsequent infection cycles of this pathogen, but also the host photosynthetic area under these predicted weather conditions, mainly expressed in the susceptible accession. Moreover, our results suggest that durum wheat responses to infection are mainly driven by temperature, being considered the most hampering abiotic stress. In contrast, leaf rust infection was greatly reduced when these weather conditions were also conducted during the inoculation process, resembling the effects of possible heat waves not only in disease development, but also in fungal germination and penetration success. Considering this lack of knowledge in plant-pathogen interactions combined with abiotic stresses, the present study is, to the best of our knowledge, the first to include the effects of the expected diurnal variation of maximum temperature and continuous elevated [CO2] in the durum wheat-leaf rust pathosystem.

Impacts of droughts and heatwaves on river water quality worldwide

Droughts and heatwaves have a major impact on river water quality worldwide. However, previous studies of river water quality under these climate extremes are limited to a small number of river basins and regions, mainly located in North America, Europe or Australia. In this study, we estimate the large-scale effects of droughts, heatwaves and compound drought-heatwave events on river water quality for a total of 314,046 water quality monitoring stations worldwide over the period 1980–2021. We focus on 16 water quality constituents grouped into physical (e.g., temperature, salinity), chemical (e.g., pharmaceuticals, pesticides) and biological constituents (e.g., biochemical oxygen demand, faecal coliform). Further, we analyse the response of each constituent to droughts and heatwaves in relation to climate type, land use and level of wastewater treatment. We find a general deterioration in river water quality under droughts and heatwaves globally for most rivers and water quality constituents considered. For example, there is on average a 27 % increase in river water temperature, 17 % decrease in dissolved oxygen and 24 % increase in salinity under droughts and heatwaves. In addition, we find that climate type, land use and level of wastewater treatment have a significant effect on the magnitude of response in each water quality constituent during these extreme events. The median increase in river water temperature under compound drought-heatwaves is strongly driven by climate zone with higher warming rates at the polar climate zone (+4.5 °C) compared to the tropical zone (+2.1 °C). Increases in salinity under droughts are on average two times larger in irrigated regions compared to non-irrigated regions. The concentrations of nutrients (P and N) in rivers can either increase or decrease under droughts, depending on the nutrient form (dissolved vs. particulate) and land use (urban vs. rural). Higher levels of wastewater treatment contributed to a greater decrease in pathogenic concentrations under droughts and heatwaves (as indicated by faecal coliform). Pharmaceuticals show mixed responses mainly depending on the persistence of the constituent in surface waters, with for instance declines in diclofenac concentrations under droughts and heatwaves due to increased decay under higher water temperatures. The results of this study provide a broader understanding of how droughts and heatwaves affect river water quality compared to previous local and regional-scale analyses. In addition, this study could form the basis for large-scale modelling of river water quality under droughts and heatwaves.

Evaluation of the vulnerability of wild bird populations during heatwave events: implications for biodiversity conservation

Heatwaves, defined as prolonged periods of excessive heat, are becoming more frequent and severe due to global climate change. These extreme heat events can have significant impacts on ecosystems and wildlife, particularly on avian fauna. Birds, as vital components of ecosystems, are highly susceptible to the adverse effects of heatwaves. Impacts directly attributable to adverse weather and changing climate regimes include a higher risk of mortality, reduced breeding success, compromised body condition and immunocompetence, declining populations, range changes, and potentially maladaptive behavioral adjustments in foraging, parental care, and migration. This vulnerability is exacerbated by the loss and degradation of their natural habitats, which hinders their ability to adapt to constantly changing climatic conditions. Understanding the vulnerability of bird populations during heatwaves is essential for devising effective conservation strategies. Conservation efforts should focus on preserving and restoring critical bird habitats, providing access to freshwater sources, and creating artificial shelters. Additionally, public education plays a significant role in raising awareness about the importance of bird conservation during heatwave events and in the broader context of climate change. In analyzing the subject, the study aims to provide more precise information to support the public decisions to be made, as well as to guide awareness for the implementation of conservation actions.

Short-term effects of heatwaves on clinical and subclinical cardiovascular indicators in Chinese adults: A distributed lag analysis

AimsPrevious studies have related heat waves to morbidity and mortality of cardiovascular diseases; however, potential mechanisms remained limited. Our aims were to investigate the short-term effects of heat waves on a series of clinical/subclinical indicators associated with cardiovascular health. MethodsOur study used 80,574 health examination records from the Health Management Center of Nanjing Zhongda Hospital during the warm seasons of 2019–2021, including 62,128 participants. A total of 11 recognized indicators of cardiovascular risk or injury were assessed. Air pollution and meteorological data were obtained from the Nanjing Ecological Environment Bureau and the China Meteorological Data Network, respectively. Heat waves were defined as a daily average temperature over the 95th percentile for three or more consecutive days from May to September. We used a combination of linear mixed effects models and distributed lag nonlinear models to assess the lagged effects of heat waves on clinical and subclinical cardiovascular indicators. Stratified analyses based on individuals' characteristics, including gender, age, body mass index (BMI), diabetes, and hypertension, were also performed. ResultsHeat waves were related to significant changes in most indicators, with the magnitude of effects generally peaking at a lag of 0 to 3 days. Moreover, the cumulative percentage changes over lag 0–7 days were –0.82 % to –2.55 % in blood pressure, 1.32 % in heart rate, 0.20 % to 2.66 % in systemic inflammation markers, 0.36 % in a blood viscosity parameter, 9.36 % in homocysteine, and 1.35 % to 3.25 % in injuring myocardial enzymes. Interestingly, females and males showed distinct susceptibilities in different indicators. Stronger effects were also found in participants aged 50 years or over, individuals with abnormal BMI status, and patients with diabetes. ConclusionShort-term exposure to heat waves could significantly alter clinical/subclinical cardiovascular indicator profiles, including blood pressure changes, increased heart rate, acute systemic inflammation, elevated blood viscosity, and myocardial injury.

Heat wave-induced microbial thermal trait adaptation and its reversal in the Subarctic.

Climate change predictions suggest that arctic and subarctic ecosystems will be particularly affected by rising temperatures and extreme weather events, including severe heat waves. Temperature is one of the most important environmental factors controlling and regulating microbial decomposition in soils; therefore, it is critical to understand its impact on soil microorganisms and their feedback to climate warming. We conducted a warming experiment in a subarctic birch forest in North Sweden to test the effects of summer heat waves on the thermal trait distributions that define the temperature dependences for microbial growth and respiration. We also determined the microbial temperature dependences 10 and 12 months after the heat wave simulation had ended to investigate the persistence of the thermal trait shifts. As a result of warming, the bacterial growth temperature dependence shifted to become warm-adapted, with a similar trend for fungal growth. For respiration, there was no shift in the temperature dependence. The shifts in thermal traits were not accompanied by changes in α- or β-diversity of the microbial community. Warming increased the fungal-to-bacterial growth ratio by 33% and decreased the microbial carbon use efficiency by 35%, and both these effects were caused by the reduction in moisture the warming treatments caused, while there was no evidence that substrate depletion had altered microbial processes. The warm-shifted bacterial thermal traits were partially restored within one winter but only fully recovered to match ambient conditions after 1 year. To conclude, a summer heat wave in the Subarctic resulted in (i) shifts in microbial thermal trait distributions; (ii) lower microbial process rates caused by decreased moisture, not substrate depletion; and (iii) no detectable link between the microbial thermal trait shifts and community composition changes.

Heatwave exposure in relation to decreased sleep duration in older adults

Few studies have delved into the effects of heatwaves on sleep duration loss among older adults. Our study examined correlations between heatwave exposure and sleep duration reductions in this demographic. Utilizing data of 7,240 older adults drawn from the China Health and Retirement Longitudinal Study (CHARLS) from 2015 to 2018, we assessed sleep duration differences between the baseline year (2015) and follow-up year (2018). Absolute reductions in sleep duration were defined as differences of ≥ 1, 1.5, or 2 h. Changes in sleep duration were categorized based on cut-offs of 5 and 8 h, including excessive decrease, moderate to short and persistent short sleep duration types. 12 heatwave definitions combining four thresholds (90th, 92.5th, 95th, and 97.5th percentiles of daily minimum temperature) and three durations (≥2, ≥3 and ≥ 4 days) were used. Heatwave exposure was determined by the difference in the number of 12 preceding months' heatwave days or events in 2015 and the number of 12 preceding months' heatwave days or events in 2018. The results showed that increased heatwave events (defined as ≥ P90th percentile & lasting three days) were associated with a higher likelihood of ≥ 1-hour sleep reduction and persistent short sleep duration. An increase in heatwave event (defined as ≥ P95th percentile & lasting three days) was linked to shifts from moderate to short sleep duration. For the association between an absolute reduction in sleep duration and heatwave exposure, while higher thresholds signified greater sleep reduction risks, the effect estimates of longer durations were not uniformly consistent. We observed that air pollution and green space modified the relationship between heatwaves and sleep duration. Females, urban residents, and individuals with chronic diseases were identified as vulnerable populations. This study found that increased heatwave exposure was associated with a higher risk of sleep duration loss in older adults.

Drought-heatwave compound events are stronger in drylands

Climate change is exacerbating the occurrence of compound droughts and heatwaves (CDHWs), which pose a serious threat to human health and socio-economic development. Using daily maximum temperature (Tmax) and monthly self-calibrating Palmer drought severity index (sc-PDSI) dataset, the evolution patterns of CDHWs and compound wet-heatwave events, the dominant drivers and the relative contributions of droughts and heatwaves in the drylands and humid areas from 1961 to 2020 were compared and analyzed. The results show that the CDHWs are stronger in drylands than in humid areas, the growth rate of CDHWs in drylands was almost twice that of the humid areas, the CDHWs are greater than the multi-year average intensity of compound wet-heatwave events by up to 2.4 times. Moreover, CDHWs has increased significantly from the past period (1961–1990) to the recent warm period (1991–2020), and the heatwave threshold has increased by about 5 °C. In most drylands, the contribution of heatwaves to CDHWs dominates, whereas in humid areas, the droughts contribution to CDHWs does. The compounding effects of droughts and heatwaves may exacerbate the severity of CDHWs regionally and are most pronounced in drylands, taking into account optimal lags. The study findings could provide scientific and technological support to actively address global climate change risks.

Changing nutritional seascapes of kelp forests

Ocean warming and short-term extreme events (e.g. marine heatwaves) are becoming more intense and frequent and have had major impacts on ecosystems. Seaweeds are foundational components of temperate reefs, providing nutrition for a diversity of species and underpinning temperate food webs. While the impacts of climate-driven environmental change on seaweed distribution, abundance and interactions are well studied, potential impacts on the provision of nutrients from seaweeds and their availability to consumers remain poorly understood. Here, we use metabolomic and lipidomic approaches to understand how the provision of nutrients from key seaweeds may be altered under climate change. We optimize a small-scale microextraction technique to test the effects of warming and marine heatwaves on the nutritional quality of two Australian habitat-forming seaweeds; Ecklonia and Sargassum. We then model changes in lipid availability in response to climate-driven ocean warming throughout Ecklonia’s eastern Australian distribution. Contrary to expectations, ocean warming and marine heatwaves had limited effects on seaweed nutritional quality, indicating resilience in the nutritional value of these species to climate-driven warming. However, nutritional quality varied significantly between species, which presents new implications for predicted species redistributions from the base of the food chain. Modelling revealed a projected net loss of 3.5% of lipids across the east coast of Australia by 2100 under RCP 8.5 in response to shifts in the redistribution of Ecklonia biomass. The climate-driven redistribution of seaweeds is likely to alter the availability of seaweed-derived nutrients to consumers, which may have broad implications for the transfer of energy within temperate marine food webs.

HOTFLOOR: A benthic chamber system to simulate warming on the seafloor

AbstractThe frequency of abnormally warm water events is increasing not only in surface waters, but also in subsurface layers, with major impacts on benthic ecosystems. Previous insights on heatwave effects have been obtained through field observations or manipulative laboratory experiments. Here, we introduce a system capable of inducing elevated water temperatures in benthic habitats in situ over several days. The system consists of a commercially available electric boiler, usually applied in domestic underfloor heating, and custom‐designed benthic acrylic glass chambers connected to individual thermostats. Furthermore, the chambers are semi‐open, allowing constant water exchange, maintaining otherwise near‐natural conditions, including oxygen concentrations, while the temperature is elevated. The water exchange can be stopped to facilitate incubations measuring changes in benthic fluxes. We conducted a 15‐d trial study in July 2021 on a bare‐sediment habitat at 2.5 m depth, exposing five chambers to water temperatures 5°C above ambient temperatures for 6 d and comparing with five control chambers. In this assessment, we demonstrate that the temperature control and stability were reliable while maintaining natural oxygen conditions. The modular character of the system permits adaptations for various benthic habitats, facilitating the investigation of elevated temperatures in situ for future climate change scenarios.

Effect of heatwaves on urban sea breeze, heat island intensity, and outdoor thermo-hygrometric comfort in Rome (Italy)

The purpose of this study is to investigate the impact of heatwaves on sea breeze, urban heat island intensity, and outdoor thermo-hygrometric comfort analysing ground-based remote sensing and in-situ meteorological measurements collected in a Mediterranean coastal metropolitan area (Rome, Italy) during the summer of 2022. The dataset (01 May - 31 August 2022) has been divided into heatwaves and not-heatwaves days to highlight the distinctive features of extreme heat episodes. Furthermore, the year 2022 was compared to 2020, the latter having been characterised by temperatures in line with the last two-decades.The heatwaves do not significantly affect the onset time and the duration of sea breeze, while its cooling effect intensifies during the heatwaves. The urban heat island intensity (UHII) is evaluated by computing the hourly-averaged air temperature difference between two stations, one in the urban centre and the other in rural surroundings. Although the daily-averaged UHII does not show significant differences among the years under investigation and the subsets, marked differences can be identified in the urban heat island daily cycle. In fact, during daytime the highest temperatures are detected in rural inland areas while, at night, the city experiences higher temperatures, especially during the heatwaves. Finally, the Mediterranean outdoor comfort index suggests that a heatwave seems to be a not sufficient condition for human thermo-hygrometric stress, even if stronger discomfort is experienced during heatwaves.

Hot Mess: Heatwave Effects on Controlled-release Fertilizer

Controlled-release fertilizers (CRFs) are water-soluble pellets of homo- or heterogenous mineral nutrients covered with polymer or resin that become increasingly porous as temperature increases, releasing water-soluble fertilizer through diffusion. An experiment was carried out at the North Willamette Research and Extension Center located in Aurora, OR, USA (lat. 45°16′51″N, long. 122°45′04″W) with six fertilizer concentrations of a CRF fertilizer that was designed to last 6 to 7 months at 70 °F. During the experiment, the Pacific Northwest experienced a series of early-summer (June) heatwaves that caused an unanticipated and excessive release of mineral salts. Extreme weather adaptation strategies are necessary to sustain horticultural production in a period with increased temperature volatility.

Parental exposure to heat waves improves offspring reproductive investment in Tetranychus urticae (Acari: Tetranychidae), but not in its predator, Phytoseiulus persimilis (Acari: Phytoseiidae).

The more frequent and intense occurrence of heat waves is a challenge for arthropods because their unpredictable incidence requires fast adaptations by the exposed individuals. Phenotypic plasticity within and across generations might be a solution to cope with the detrimental effects of heat waves, especially for fast-developing, small arthropods with limited dispersal abilities. Therefore, we studied whether severe heat may affect the reproduction of a pest species, the spider mite Tetranychus urticae, and its counterpart, the predatory mite Phytoseiulus persimilis. Single offspring females with different parental thermal origins (reared under mild or extreme heat waves) of both species were exposed to mild or extreme heat waves on bean leaves over 10 days, and the oviposition, egg sizes, survival, and escape behavior of the females were evaluated daily. The total losses of predators mainly via escapers were very high compared to prey, which makes a separation between selective and plastic effects on shifted reproductive traits impossible. Predator females laid smaller eggs, while their consumption and oviposition rates were unaffected during extreme heat waves. In comparison, larger prey females fed more and produced more, but smaller, eggs due to within- and trans-generational effects. These advantages for the prey in comparison to its predator when exposed to extreme heat waves during the reproductive phase support the trophic sensitivity hypothesis: higher trophic levels (i.e., the predator) are more sensitive to thermal stress than lower trophic levels (i.e., the prey). Furthermore, the species-specific responses may reflect their lifestyles. The proactive and mobile predator should be selected for behavioral thermoregulation under heat waves via spatiotemporal avoidance of heat-exposed locations rather than relying on physiological adaptations in contrast to the more sessile prey. Whether these findings also influence predator-prey interactions and their population dynamics under heat waves remains an open question.

Economic burden of premature deaths attributable to different heatwaves in China: A multi-site study, 2014–2019

It has been well documented that heatwaves are linked to elevated mortality and morbidity. However, the selection of optimal heatwave definitions for subsequent risk assessment has been inconsistent and there is no full picture of the effects of heatwaves with different intensities on economic losses due to mortality, which can provide important insights for public health considerations. Hence, we used a two-stage time series analysis, combined with values of statistical life (VSL) based on the value of a statistical life year to assess the economic burden of deaths associated with heatwaves of different intensities and durations and to identify the vulnerable populations and regions. We further conducted stratified analyses by age, sex, and region. We found 2.9% (95%CI: 0.0%, 6.5%)‒20.0% (95%CI: 2.9%, 34.2%) of VSL were attributable to heatwaves, corresponding to attributable economic losses (AELs) of 2.20 (95%CI: 0.32, 3.77)‒4.77 (95%CI: 1.53, 7.63) billion CNY. The economic burden of death was most sensitive to heatwave H99P_2D (99th percentile, at last 2 consecutive days), while H97·5P_2D (97.5th percentile, at last 2 consecutive days) caused the highest attributable economic losses. Females and elderly people aged ≥ 65 years were more sensitive. The AELs in the temperate zone and northern regions were larger than those in subtropical zone and southern regions during relatively low-intensity heatwaves, respectively. By contrast, the AELs in subtropical zone and southern regions were relatively higher than those in temperate zone and northern regions during relatively high-intensity heatwaves, respectively. The AELs were larger in urban areas than in rural areas. Tailored intervention strategies, primarily focusing on vulnerable populations and regions, should be formulated to reduce the economic loss due to heatwaves in the context of climate change.

Suitability of the shrub-steppe habitat of Eastern Washington for Halyomorpha halys (Hemiptera: Pentatomidae).

The invasive brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), has spread throughout most of Washington (WA) State since its detection in 2012. While it has emerged as a major agricultural and nuisance pest in the Pacific Northwest (PNW) west of the Cascade Mountains, pest pressure in the major tree fruit-growing areas in semi-arid northern and central WA State remains low. The reasons for this are unclear, although both biotic and abiotic conditions may be contributing factors. We evaluated the suitability of a common shrub-steppe/riparian corridor plant assemblage for supporting H. halys development from egg to adult in summer and fall through controlled feeding studies. Nymphs successfully completed development on this diet of PNW native plants, though it generally resulted in lower survivorship and adult weight and longer developmental times than a modified colony diet or a diet of known hosts from the eastern United States. These developmental data were used to parameterize stage-structured matrix models to predict the impact of diet and extreme heat events on H. halys population growth. The predicted net reproductive rate (R0) of H. halys was consistently and substantially reduced by a diet of PNW native plants, and heat shock imposed further severe reductions in R0. Our results suggest that the combined population effects of suboptimal plant host quality and regional heat waves may explain the lack of landscape-level H. halys pest pressure in semi-arid regions of the PNW.

Analysis of heatwaves based on the universal thermal climate index and apparent temperature over mainland Southeast Asia.

Heatwaves have caused significant damage to human health, infrastructure, and economies in recent decades, and the occurrences of heatwaves are becoming more frequent and severe across the globe under climate change. The previous studies on heatwaves have primarily focused on air temperature, neglecting other variables like wind speed, relative humidity, and radiation, which could lead to a serious underestimation of the adverse effects of heatwaves. To address this issue, this study proposed to the use of more sophisticated thermal indices, such as universal thermal climate index (UTCI) and apparent temperature (AT), to define heatwaves and carry out a comprehensive heatwave assessment over mainland southeast Asia (MSEA) from 1961 to 2020. The traditional temperature-based method was also compared. The results of the study demonstrate that the annual maximum temperature in heatwave days (HWA) and the annual average temperature in heatwave days (HWM) are significantly underestimated if only air temperature is considered. However, UTCI and AT tend to predict a lower frequency of yearly heatwave occurrences and shorter durations. Trend analysis indicates a general increase in heatwave occurrences across MSEA under all thermal indices in the past six decades, particularly in the last 30years. This study's approach and findings provide a holistic view of heatwave characteristics based on thermal indices and highlight the risk of intensified heat stress during heatwaves in MSEA.

Detrimental impact of a heatwave on male reproductive behaviour and fertility

Understanding how heatwaves impact on different aspects of mating behaviour and fertility is getting increasingly important. In this context, laboratory fertility and mating experiments involving manipulation and exposure of insects to different thermal conditions are common procedures. To conduct such experiments practical methods such as dyes are needed for an easy, non-invasive discrimination of individuals. We report here a study measuring the effect of an extended heat stress applied to males on several parameters of mating behaviour and fertility of laboratory populations of Drosophila subobscura derived from two distinct European locations. We found highly detrimental effects of heatwave on mating behaviour—with longer (courtship and copulation) latencies and lower mating occurrence but no changes in mating duration—and fertility, with reduced fecundity and reproductive success. Furthermore, we also tested the efficacy of food dye as a marker for individual discrimination and mating occurrence. While food dye did not allow to infer the occurrence of a mating based on a transfer of coloration from male to female, it did not affect mating and fertility, attesting its utility has a method for discriminating individuals within mating experiments in the context of thermal studies. Importantly, despite the fact that the heatwave was only applied in males, we observed an impact on behaviour of females that mated with stressed males, by often refusing their nuptial feeding. This opens possibilities for further integrated research on the changes of female and male mating behaviour and fertility under different thermal scenarios.