Understanding how flying insects manage heat exchange is critical for predicting their survival in dynamic thermal environments. To fly, insects propel air downwards to offset body weight, inducing airflow over their bodies. Remarkably, the potential cooling effect of this self-generated airflow is largely unstudied. We measured induced airflow and wingbeat kinematics for hovering bumble bees (Bombus impatiens) across a range of body sizes and then measured the cooling effect of airflows of the same magnitude in a vertical wind tunnel. We combined these data in heat balance models to predict transient and equilibrium body temperatures of hovering bumble bees with and without self-generated wind. Measured self-induced airflow was substantial (up to 1 m s-1) and varied with body size and wingbeat kinematics, contributing significantly to thermal stability. Without this self-induced airflow, simulated bees of all sizes rapidly overheated across a range of environmental conditions, highlighting the importance of this overlooked heat-loss mechanism in the heat budget of flying insects. Our findings suggest that shifts in wingbeat kinematics required for altered force production not only affect energetics and, therefore, heat production, but also alter the induced airflow and associated convective heat loss.

Anthropogenic noise can have diverse effects on natural ecosystems, but less is known about the degree to which noise can alter organisms in comparison to other disturbances. A variety of frequencies are produced by man-made objects, ranging from high to low frequencies, and we studied infrasound (<20 Hz) produced by wind turbines and trains. We estimated the number, mass and viability of seeds produced by flowers of Plains pricklypear (Opuntia polyacantha Haw.) that were left open to pollinators, hand-pollinated or bagged to exclude pollinators. Each pollination treatment was applied to plants at varying distances from wind turbines and railways (≤25 km). Self-pollinated Opuntia polyacantha and plants within the wind facility produced ≥1.6 times more seeds in the bagged treatments compared to more distant sites. Seed mass and the percent of viable seeds decreased with distance from infrasound. Viability of seeds was >70% for most treatments and sites. If wind facilities, railways and other man-made structures produce infrasound that increases self-pollination, crops and native plants near sources may produce heavier seeds with higher viability in the absence of pollinators, but genetic diversity of plants may decline due to decreased cross-pollination.

Many organisms cope with highly variable environmental temperatures by differentiating body temperature from that of the environment through thermoregulation. Heterotherms can both endogenously maintain body temperature with metabolic heat and behaviourally thermoregulate by selecting suitable microclimates. Expending excess energy to maintain stable high body temperatures may be prioritized during certain times of the year, or for certain activities (e.g. reproduction, escape from predation). Alternatively, behavioural thermoregulation may take precedence when energy savings are critical. The degree to which heterotherms rely on these different strategies has rarely been studied. To address this gap, we measured body temperature and selected temperatures on a thermal gradient for heterothermic bumble bee queens (Bombus huntii) at two life stages: during spring, when ovary development prior to colony establishment is critical, and in autumn, when they build energy stores for overwintering. Not only did spring queens have a narrower range of body temperatures than autumn queens, but they maintained higher body temperatures at cooler gradient temperatures. These results suggest that thermoregulatory strategy varies seasonally to sustain key activities but is context dependent: when ambient temperatures are cool, metabolic heat production is relied upon if reproductive pressure is high and reduced if accumulating energy reserves is critical.

Bees are vital pollinators that maintain plant populations by transporting pollen among individuals; however, bees are declining, and information on how habitat characteristics alter the catch of bees in traps is needed to better assess monitoring. Few studies have measured how catch in passive traps may be altered by floral resources despite the well-known dependence of pollinators on forbs. We investigated the degree to which pollinating insects were attracted to vane traps and bee bowls placed at sites that varied in flower densities (0–800 flowers/m2). We also assessed if the catch of bees was better explained by flower characteristics directly around traps (subsite) or average flower characteristics at a site. Floral density, richness and surface area were measured in 1 m2 quadrats at each subsite. The surface area of flowers explained more variance in bees captured compared to the density or richness of flowers. Traps placed in areas with lower flower surface area captured the more bees and a more diverse sample. Floral resources at the subsite and site explained a similar amount of variance in the number of bees captured, suggesting that pollinators respond to flowers at both scales. We provide a method of correcting pollinator abundance by flower surface area to make catch in passive traps more comparable among areas. We can select sites that minimize or maximize the catch of bees by understanding how floral resources change the effectiveness of passive traps.

Changing climates are driving population declines in diverse animals worldwide. Winter conditions may play an important role in these declines but are often overlooked. Animals must not only survive winter but also preserve body condition, a key determinant of growing season success. We hypothesized that ectotherms overwintering in soil face a trade-off between risks of cold damage (including freezing) near the surface and elevated energy use at deeper depths. To test this hypothesis, we developed landscapes of mortality risk across depth for overwintering bumble bee queens. These critical pollinators are in decline in part because of climate change, but little is known about how climate affects overwintering mortality. We developed a mechanistic modeling approach combining measurements of freezing points and the temperature dependence of metabolic rates with soil temperatures from across the United States to estimate mortality risk across depth under historic conditions and under several climate change scenarios. Under current conditions, overwintering queens face a Goldilocks effect: temperatures can be too cold at shallow depths because of substantial freezing risk but too hot at deep depths where they risk prematurely exhausting lipid stores. Models suggest that increases in mean temperatures and in seasonal and daily temperature variation will increase risk of overwinter mortality. Better predictions of effects of changing climate on dormant ectotherms require more measurements of physiological responses to temperature during dormancy across diverse taxa.

Addressing global bee declines requires multidisciplinary, coordinated, and collaborative action. This contribution highlights ongoing efforts to build multidisciplinary and international partnerships among researchers from the University of Wyoming, the University of Kansas, and the Universidade de São Paulo, Brazil, spanning nearly 65 degrees of latitude, to explore how bees respond to changing temperatures. This document summarizes key insights from a mini-symposium held on May 12, 2025, and preliminary collaborative studies conducted between May 8 and 15, 2025, at the Universidade de São Paulo. The mini-symposium brought together faculty and researchers from different Brazilian universities, along with both undergraduate and graduate students, creating a dynamic exchange of ideas across institutions and career stages. Emerging themes from the discussions included the inconsistent use of terminology and methods for assessing thermal biology, critical gaps in taxonomic and life-history coverage, restricted access to expensive equipment and the need for more accessible approaches, and the opportunity to incorporate alternative metrics of thermal tolerance in future studies. Resumo. Ações coordenadas, colaborativas e multidisciplinares são essenciais para enfrentar o declínio global das abelhas. Esta contribuição destaca um esforço atual para estabelecer parcerias internacionais e interdisciplinares entre pesquisadores da Universidade de Wyoming, da Universidade do Kansas e da Universidade de São Paulo (Brasil), abrangendo quase 65 graus de latitude, com o objetivo de investigar como as abelhas respondem às mudanças de temperatura. O documento apresenta os principais insights de um mini-simpósio realizado em 12 de maio de 2025, bem como de estudos colaborativos preliminares conduzidos entre 8 e 15 de maio de 2025, na Universidade de São Paulo. O evento reuniu docentes e pesquisadores de diversas universidades brasileiras, além de alunos de graduação e pós-graduação, promovendo uma troca rica e dinâmica de ideias entre diferentes instituições e níveis de experiência acadêmica. Entre os temas emergentes das discussões destacaram-se: o uso inconsistente de terminologias e métodos na avaliação da biologia térmica, lacunas significativas na cobertura taxonômica e de história de vida, o acesso limitado a equipamentos caros e a consequente necessidade de metodologias mais acessíveis e a oportunidade de incorporar métricas alternativas de tolerância térmica em pesquisas futuras.

Monitoring declining species is crucial to inform conservation but is challenging for rare species with limited information. The Western Bumble Bee (Bombus occidentalis) was previously common in the western United States but has drastically declined. Despite documented populations in the Intermountain West, many areas remain under-sampled. Species distribution models (SDM) can guide sampling efforts in large areas by predicting where the highest probability of suitable habitat may occur. We developed a sampling SDM using historical observations (1910–2010) in Wyoming to predict suitable habitat in the past. Using the model, we selected sampling sites that ranged from low to high predicted habitat suitability and we revisited historical locations where B. occidentalis were observed. Using all data (historical and current), we selected the predictors that explained the most variance, and created separate historical and current (2017–2018) SDM using the same variables to assess how predicted habitat suitability changed. We detected B. occidentalis at 30% of the revisited historical sites and 25% of all sites sampled. Areas predicted to be highly suitable for B. occidentalis in Wyoming declined by 5%; a small decrease compared to declines in the western portion of their range. Predicted habitat suitability increased the most in foothill areas. Creating SDM with landscape and climatic variables can bolster models and identify highly contributing variables. Regional SDM complement range-wide SDM by focusing on a portion of their range and assessing how predicted habitat changed.

Bumble bees are common in cooler climates and many species likely experience periodic exposure to very cold temperatures, but little is known about the temporal dynamics of cold response mechanisms following chill exposure, especially how persistent effects of cold exposure may facilitate tolerance of future events. To investigate molecular processes involved in the temporal response by bumble bees to acute cold exposure, we compared mRNA transcript abundance in Bombus impatiens workers exposed to 0 degrees C for 75 min (inducing chill coma) and control bees maintained at a constant ambient temperature (28 degrees C). We sequenced the 3 ' end of mRNA transcripts (TagSeq) to quantify gene expression in thoracic tissue of bees at several time points (0, 10, 30, 120 and 720 min) following cold exposure. Significant differences from control bees were only detectable within 30 min after the treatment, with most occurring at the 10 min recovery time point. Genes associated with gluconeogenesis and glycolysis were most notably upregulated, while genes related to lipid and purine metabolism were downregulated. The observed patterns of expression indicate a rapid recovery after chill coma, suggesting an acute differential transcriptional response during recovery from chill coma and return to baseline expression levels within an hour, with no long-term gene expression markers of this cold exposure. Our work highlights the functions and pathways important for acute cold recovery, provides an estimated time frame for recovery from cold exposure in bumble bees, and suggests that cold hardening may be less important for these heterothermic insects.

IntroductionWarming summer temperatures have the potential to harm managed pollinators, impacting both summer performance and overwintering success. The alfalfa leafcutting bee, Megachile rotundata, is a solitary bee used for commercial pollination of alfalfa. M. rotundata undergoes facultative diapause in the prepupal stage. Prepupae that diapause early in the season are exposed to warm temperatures for a longer period of time than the individuals that start diapause closer to fall, which may reduce lipid reserves required for overwintering survival. Warm temperatures may also contribute to pollen ball incidence, which is when a provision is present but there is no sign of a larva in the brood cell. Our goal was to identify factors that regulate diapause and pollen ball incidence and examine effects of pre-wintering field conditions on post-overwintering energy reserves in M. rotundata.MethodsNest boxes were installed near Fargo, ND, Laramie, WY, and Las Cruces, NM, which exposed bees to different photoperiods and thermal regimes. Three nest boxes were placed at each site. We monitored nesting conditions and diapause and pollen ball incidence throughout the season. Lipids, sugars, and glycogen reserves were measured in adults after overwintering.Results and DiscussionOur models indicate that most of the variation in diapause incidence was explained by nest, with individuals within a nest tending to have the same diapause outcome. This suggests that the environmental conditions experienced by the mother, or genetic predisposition, influences offspring diapause. We also found evidence that high cavity temperatures can cause diapause aversion. In addition, our study is the first to link high nesting cavity temperatures to increased pollen ball incidence. Exposure to stressful temperatures during development and early diapause resulted in an increase in adult lipid reserves after overwintering. Adult sugar and glycogen reserves were not affected by exposure to warm temperatures during development and early diapause. In conclusion, maternal effects and temperature were important factors for diapause and pollen ball incidence in M. rotundata with macronutrient reserves similar for early and late season bees.

Climate warming is considered to be among the most serious of anthropogenic stresses to the environment, because it not only has direct effects on biodiversity, but it also exacerbates the harmful effects of other human-mediated threats. The associated consequences are potentially severe, particularly in terms of threats to species preservation, as well as in the preservation of an array of ecosystem services provided by biodiversity. Among the most affected groups of animals are insects-central components of many ecosystems-for which climate change has pervasive effects from individuals to communities. In this contribution to the scientists' warning series, we summarize the effect of the gradual global surface temperature increase on insects, in terms of physiology, behavior, phenology, distribution, and species interactions, as well as the effect of increased frequency and duration of extreme events such as hot and cold spells, fires, droughts, and floods on these parameters. We warn that, if no action is taken to better understand and reduce the action of climate change on insects, we will drastically reduce our ability to build a sustainable future based on healthy, functional ecosystems. We discuss perspectives on relevant ways to conserve insects in the face of climate change, and we offer several key recommendations on management approaches that can be adopted, on policies that should be pursued, and on the involvement of the general public in the protection effort.

Predicting the effects of climate warming on insect pollinators is challenging. Insects are small, mobile, and can be excellent thermoregulators. We describe behavioral and physiological methods to measure pollinator body temperatures in the field and biophysical modeling approaches to predict the effects of a changing climate on pollinator body temperatures. The mechanisms that pollinators use to thermoregulate, especially in response to high temperatures, are complex, vary with life stage and phylogeny, and have been examined in very few species. Eusocial insect pollinators have coordinated social mechanisms of avoiding overheating that are generally superior to individual insects, but the brood of social insects are often sensitive to thermal variation, so the fitness effects of a failure to thermoregulate are severe. Effects of warming on performance and fitness can be evaluated in the context of thermal performance curves. Warming that raises body temperatures closer to the optimal for performance will generally be beneficial, and this effect will be common for many insects during cooler parts of the day and year. Warming that raises body temperatures above the optimal temperature will generally degrade performance and fitness. Extreme heat poses many physiological challenges, including oxidative damage, protein unfolding, and nervous system shutdown. Considerable evidence suggests that insects may be able to mitigate the effects of climate warming through developmental plasticity, migration, and evolution, but many uncertainties remain. Warming effects on flowering plant fitness and the interactions between warming and other anthropogenic effects complicate predictions but are likely to add to the negative impacts.

Projecting ecological and evolutionary responses to variable and changing environments is central to anticipating and managing impacts to biodiversity and ecosystems. Current modeling approaches are largely phenomenological and often fail to accurately project responses due to numerous biological processes at multiple levels of biological organization responding to environmental variation at varied spatial and temporal scales. Limited mechanistic understanding of organismal responses to environmental variability and extremes also restricts predictive capacity. We outline a strategy for identifying and modeling the key organismal mechanisms across levels of biological organization that mediate ecological and evolutionary responses to environmental variation. A central component of this strategy is quantifying timescales and magnitudes of climatic variability and how organisms experience them. We highlight recent empirical research that builds this information and suggest how to design future experiments that can produce more generalizable principles. We discuss how to create biologically informed projections in a feasible way by combining statistical and mechanistic approaches. Predictions will inform both fundamental and practical questions at the interface of ecology, evolution, and Earth science such as how organisms experience, adapt to, and respond to environmental variation at multiple hierarchical spatial and temporal scales.

Bombus vosnesenskii Radowszkowski, 1862 is one of three bumble bee species commercially available for pollination services in North America; however, little is documented about B. vosnesenskii colony life cycle or the establishment of ex situ rearing, mating, and overwintering practices. In this study, we documented nest success, colony size, and gyne production; recorded the duration of mating events; assessed overwintering survival of mated gynes; and evaluated second-generation nest success for colonies established from low- and high-elevation wild-caught B. vosnesenskii gynes. Of the 125 gynes installed, 62.4% produced brood cells (nest initiation) and 43.2% had at least 1 worker eclose (nest establishment). High-elevation B. vosnesenskii gynes had significantly higher nest initiation and establishment success than low-elevation gynes. However, low-elevation colonies were significantly larger with queens producing more gynes on average. Mating was recorded for 200 low-elevation and 37 high-elevation gynes, resulting in a mean duration of 62 and 51 min, respectively. Mated gynes were then placed into cold storage for 54 days to simulate overwintering, which resulted in 59.1% of low-elevation gynes surviving and 91.9% of high-elevation gynes surviving. For second-generation low-elevation gynes, 26.4% initiated nesting and 14.3% established nesting. Second-generation high-elevation gynes did not initiate nesting despite CO2 narcosis treatments. Overall, these results increase our understanding of B. vosnesenskii nesting, mating, and overwintering biology from 2 elevations. Furthermore, this study provides information on successful husbandry practices that can be used by researchers and conservationists to address knowledge gaps and enhance the captive rearing of bumble bees.

Bumble bee (genus Bombus) populations are increasingly under threat from habitat fragmentation, pesticides, pathogens, and climate change. Climate change is likely a prime driver of bumble bee declines but the mech-anisms by which changing climates alter local abundance, leading to shifts in geographic range are unclear. Heat tolerance is quite high in worker bumble bees (CTmax similar to 48-55 degrees C), making it unlikely for them to experience these high temperatures, even with climate warming. However, the thermal tolerance of whole organisms often exceeds that of their gametes; many insects can be sterilized by exposure to temperatures well below their upper thermal tolerance. Male bumble bees are independent from the colony and may encounter more frequent tem-perature extremes, but whether these exposures compromise spermatozoa is still unclear. Using commercially -reared Bombus impatiens colonies, males were reared in the lab and spermatozoa were exposed (in vivo and isolated in vitro) to sublethal temperatures near lower and upper thermal tolerance (CTmin and CTmax, respec-tively). Heat exposure (45 degrees C for up to 85 min) reduced spermatozoa viability both for whole males (in vivo; control = 79.5 %, heat exposed = 58 %, heat stupor = 57.7 %) and isolated seminal vesicles (in vitro; control = 85.5 %, heat exposed = 62.9 %). Whole males exposed to 4 degrees C for 85 min (in vivo; control = 79.2 %, cold = 72.4 %), isolated seminal vesicles exposed to 4 degrees C for 85 min (in vitro; control = 85.5 %, cold = 85.1 %), and whole males exposed to for 4 degrees C for 48 h (in vivo; control = 88.7 %, cold = 84.3 %) did not differ significantly in spermatozoa viability. After<85 min at 45 degrees C, males had significantly reduced spermatozoa viability, suggesting that short-term heat waves below CTmaxcould strongly reduce the fertility of male bumble bees with potential population-level impacts.

Global declines in abundance and diversity of insects are now well-documented and increasingly concerning given the critical and diverse roles insects play in all ecosystems. Habitat loss, invasive species, and anthropogenic chemicals are all clearly detrimental to insect populations, but mounting evidence implicates climate change as a key driver of insect declines globally. Warming temperatures combined with increased variability may expose organisms to extreme heat that exceeds tolerance, potentially driving local extirpations. In this context, heat tolerance limits (e.g., critical thermal maximum, CTmax) have been measured for many invertebrates and are often closely linked to climate regions where animals are found. However, temperatures well below CTmax may also have pronounced effects on insects, but have been relatively less studied. Additionally, many insects with out-sized ecological and economic footprints are colonial (e.g., ants, social bees, termites) such that effects of heat on individuals may propagate through or be compensated by the colony. For colonial organisms, measuring direct effects on individuals may therefore reveal little about population-level impacts of changing climates. Here, we use bumble bees (genus Bombus) as a case study to highlight how a limited understanding of heat effects below CTmax and of colonial impacts and responses both likely hinder our ability to explain past and predict future climate change impacts. Insights from bumble bees suggest that, for diverse invertebrates, predicting climate change impacts will require a more nuanced understanding of the effects of heat exposure and additional studies of carry-over effects and compensatory responses by colonies.