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A review of impacts of temperature and relative humidity on various activities of honey bees
Abstract
The importance of pollination services by honey bees (Apis mellifera L.) and their products is well-known.
However, honey bee colonies currently face many challenges. These challenges include both biotic and abiotic
factors. In this article, the impacts of abiotic factors (mainly temperature and relative humidity) on honey bee activities are reviewed. The suitable ranges of these two factors and the potential impacts of atypical minimal or maximal limits are presented. Social homeostasis of honey bees, and activities inside and outside the colony that are influenced by these two factors are included, followed by a suggestion of additional studies.
... Previous studies have highlighted the negative effects of heat stress on honey bee workers (Bordier et al. 2017;Abou-Shaara et al. 2017). In particular, prolonged exposure to high temperatures during heat waves can have harmful effects on honey bees, such as decreased life span, compromised immune systems, reduced body size, and changes in the shape of the forewing (Medina et al. 2018;Poot-Baez et al. 2019;Medina et al. 2020). ...
... While a colony can have thousands of drones when environmental conditions are optimal (Boomsma et al. 2005), queen pupae are present only at specific times during the hive life cycle, such as when the colony swarms or its queen is superseded (Oliver 2021). As a result, there is limited information on the direct effects of heat stress on honey bee reproductive individuals in warm environments (Abou-Shaara et al. 2017). Nevertheless, beekeeping in tropical areas is a crucial contributor to the world production of honey and represents a significant source of income in marginalized regions. ...
... Subsequently, other worker bees initiate . 2 Regression of the symmetric component (regression score 1) with the centroid size asymmetry scores with 90% confidence ellipses for the means of non-heat-stressed (blue) and heat-stressed (red) drones (circles) and queens (squares), showing clear differences in centroid size asymmetry among treated drones but only subtle differences among treatment queens fanning, actively creating cool and humid air that circulates throughout the beehive, thereby reducing the temperature (Jones and Oldroyd 2006). In dry weather, this is a very efficient way to keep the brood area cool, and it is necessary to maintain the relative humidity at an appropriate level, at least around 50%, for the correct development of the immature bees (Abou-Shaara et al. 2017). But those mechanisms are not infallible, at least in Africanized honey bees in humid tropics. ...
Global warming may have a significant negative impact on insects in the tropics due to an increase in the frequency and intensity of heat waves. Heat waves may have a particularly harsh impact on the relatively sessile juvenile stages of holometabolous insects, such as larvae and pupae. The honey bee (Apis mellifera L.) is an important tropical holometabolous insect whose queens and drones may also be negatively impacted by heat waves during their development, leading to reduced reproductive capacity. However, we have little information on the thermal tolerance of honey bee subspecies in tropical regions. To address this knowledge gap, we evaluated the effect of simulated heat waves during development on drones and queens of Africanized A. mellifera in terms of the size, shape, and symmetry of their forewings, as well as their reproductive traits such as sperm concentration and viability in drones, and ovariole number and spermatheca volume in queens. Drones raised at high temperatures were more asymmetric in forewing size but not in shape, and had a smaller body size and reduced sperm concentration and viability compared to those raised at normal hive temperatures. In contrast, no effect of an elevated temperature regime during development was seen in queens in terms of the size and symmetry of the forewing, the number of ovarioles, and the volume of the spermatheca. Our results support the notion that males of insects are more susceptible to high temperatures compared to females. We discuss the implications of our findings for the reproductive fitness of honey bee colonies in tropical regions.
... For egg hatching, the optimal RH range goes from 90 to 95%, while values lower than 50% hinder this phase [27]. RH can also influence the development of parasites and pathogens; specifically, values between 55% and 70% favor the reproduction of varroa (Varroa destructor), while higher values reduce its reproduction [28]. ...
... Subspecies of A. mellifera are found in a wide range of climates, from hot and dry to tropical and temperate [27]. Hives are evidently affected by the external weather conditions [61]. ...
... Foraging activity takes place in a wide range of temperatures, from 10 to 40 • C [27]. Ambient temperature interferes with the life of the colonies; when temperature is too high or too low compared to the temperature of 35 • C which guarantees regular breeding of the brood, bees have to invest significant energy resources to cool or heat the hive, respectively. ...
... With respect to the honey bee (Apis mellifera), it is well established that temperature control inside their nests is critical. Bees have receptors in their antennae that are capable of monitoring temperature fluctuations of 0.2 degrees Celsius [64]. Unlike many other animals, bees lack a temperature-regulating mechanism in their bodies. ...
... Generally, queens mate at temperatures below 25 degrees Celsius. Extremely high (or extremely low) temperatures have a detrimental effect on mating flights [64]. The brood region requires a temperature of between 30 and 36 degrees Celsius to produce the brood. ...
... Regardless of the temperature, bees will not fly if there is no light [67]. During the night, the bees remain dormant outside the hive, even if there is sufficient moonlight [64]. ...
Bees are commonly thought to be useful for generating honey. In the natural environment, pollination of flowers, on the other hand, has the greatest ecological impact on bees. Both the importance of bees to humans and the urgent need to take action to prevent their unjustifiable and slow elimination are generally understood. Bees are now subjected to a variety of stresses and problems. They had to face with the natural challenges in their environment, such as temperature, humidity and predators etc. The major goals of this project are to employ sustainable energy technologies to eliminate the most serious threat to bees, Varroa mites, to design a practical prototype that is easy enough for beekeepers to use, and to show that heat treatment is a non-harmful technique for bees and their products. The current study looks into the possibility of using phase change materials (PCMs), specifically Sodium Acetate Trihydrate (SAT), as a heat source for thermal treatment. Following a study of phase change materials, it was determined that SAT was the best material for thermal treatment applications due to its thermal, physical, and chemical capabilities. When an active PCM pack is placed to the brood box, a simple mathematical model is used to approximate the thermal interaction that happens. The findings showed that, even under ideal operating conditions, the PCM pack is incapable of overheating the interior of the beehive. The major simulations aided in forecasting PCM pack behaviour, identifying temperature distribution, and estimating the time required to reach the thermotherapy temperature. In addition, an observation beehive was employed to monitor many laboratory and outdoor studies. All of the experiments were planned ahead of time. The goal of these tests was to figure out the most efficient way to process heat treatment. The results of the intended simulations were obtained and analysed. The temperature variation in the brood chamber was found to be quite close to that observed in laboratory testing and comparable to that reported in apiary investigations. Any type of mesh in the brood box's lowest half blocked the free transfer of heat, according to laboratory research. A thermal insulation top cover was also determined to be required to prevent heat from escaping. The outcomes of the on-site tests demonstrated that the external ambient temperature has a considerable impact on the performance of the PCM pack. In conclusion, it was proved that the Varroa mite, the principal pest that threatens bees in the United Kingdom and around the world, can be eradicated using sustainable energy technology such as PCMs. In this study, developing a basic mathematical model that approximates the thermal interaction was achievable. The purpose of these testing was to learn more about the most efficient approach to undertake heat treatment. The findings of the on-site testing revealed that the surrounding environment's temperature has a significant impact on the PCM pack's performance. The prototype developed will help in the reduction of Varroa mite infestations in UK apiaries, which will improve bee living conditions, will not harm other species with harmful chemical substances, will be reusable and thus environmentally friendly, bee losses will be reduced, Varroa mites will cease developing pesticide resistance and pollination of agricultural products that are critical for human sustenance and corners will be reduced. This research could lead to a lot of additional work, such as improving the prototype and developing an in-depth assessment approach to confirm that this technology effectively eliminates the Varroa mite from the brood box.
... As bee breads are stored in the comb, which has different abiotic conditions than the outside [30], it might favor a different bacterial population than the bee pollen. Scientific attention has been focused largely in order to investigate the gut microbiome of honeybees and, on the other hand, there are comparatively less data on bee bread or bee pollen. ...
... Honeybees maintain microclimatic conditions within their beehives. The normal range of temperature within a honeybee colony is reported within the range of 33 to 36 • C [30,44], which is favorable to most of the bacterial population. They also maintain relative humidity (RH) as a RH lower than 50% inhibits the hatching of eggs and a RH of 90-95% is optimum for egg hatching (reviewed by Abou-Shaara et al. [30]). ...
... The normal range of temperature within a honeybee colony is reported within the range of 33 to 36 • C [30,44], which is favorable to most of the bacterial population. They also maintain relative humidity (RH) as a RH lower than 50% inhibits the hatching of eggs and a RH of 90-95% is optimum for egg hatching (reviewed by Abou-Shaara et al. [30]). In addition to these abiotic conditions, the preparation of bee bread involving glandular secretions and mixing of bee pollen and nectar [13] could contribute the microbial load to bee bread. ...
We investigated the bacterial community of bee bread and bee pollen samples using an approach through 16 s rRNA high-throughput sequencing. The results revealed a higher bacterial diversity in bee bread than in bee pollen as depicted in taxonomic profiling, as well as diversity indices such as the Shannon diversity index (3.7 to 4.8 for bee bread and 1.1 to 1.7 for bee pollen samples) and Simpson’s index (>0.9 for bee bread and 0.4–0.5 for bee pollen). Principal component analysis showed a distinct difference in bacterial communities. The higher bacterial diversity in the bee bread than bee pollen could presumably be due to factors such as storage period, processing of food, fermentation, and high sugar environment. However, no effect of the feed (rapeseed or oak pollen patties or even natural inflow) was indicated on the bacterial composition of bee bread, presumably because of the lack of restriction of foraged pollen inflow in the hive. The diverse bacterial profile of the bee bread could contribute to the nutritional provisioning as well as enhance the detoxification process; however, a thorough investigation of the functional role of individual bacteria genera remains a task for future studies.
... The development and functioning of a honey bee colony strongly depends on the ambient temperature that determines the activities of a colony and each individual bee, and also determines the course of metabolic processes (Abou-Shaara et al., 2017;Cook et al., 2021). Inside the nest, the temperature is actively regulated by the workers and adapted to the colony's needs (Stabentheiner, Kovac & Brodschneider, 2010;Stabentheiner et al., 2021). ...
... Inside the nest, the temperature is actively regulated by the workers and adapted to the colony's needs (Stabentheiner, Kovac & Brodschneider, 2010;Stabentheiner et al., 2021). In the centre of the nest, in the place of the brood rearing, the temperature is maintained at a level of 33-36 • C (Kleinhenz et al., 2003;Abou-Shaara et al., 2017). As the distance from the nest centre increases, the temperature decreases. ...
... The temperature of a honey bee nest meets the thermal requirements of all the bees, but this does not mean that particular individuals always stay at their preferred temperature. The research has so far focused mainly on the range of the thermal functioning of individual bees, and their behaviour in different temperatures (Free nest, some drones can stay at the range of their preferred temperatures, whereas others will only stay within the range of tolerated temperatures due to temperatures fluctuations (Abou-Shaara et al., 2017;Cook et al., 2021) or the presence of parasites (Duay, De Jong & Engels, 2002). ...
The thermal preferences of Apis mellifera carnica drones (male individuals) are poorly understood, though their reproductive quality affects the quality of the inseminated queen and the whole honey bee colony. Therefore, the aim of this study was to determine the thermal preferences of individual drones according to their age and sexual maturity. Drones at the ages of 1, 5, 10, 15, 20 and 25 days were tested. The drones were placed on a platform in a temperature gradient in the range 20 °C and 46 °C. The thermal preferences of the drones were measured with the use of a thermal-imaging camera. Drones significantly differed with their choice of a preferred temperature. The one-day-old and the 25-day-old drones preferred the lowest temperatures. A slightly higher temperature was preferred by the 5-day-old drones, and the highest temperature was chosen by the drones at the ages of 10, 15, and 20 days. The changes in the thermal preferences of drones correspond to physiological changes occurring with age and connected with the rate of sexual maturation.
... These creatures now inhabit in most parts of the world and are considered as beneficial social insects. The rearing of honeybees and production of honey had begun 4500 years ago by humans [3][4][5][6]. "The center of origin for all the extant species excluding Apis mellifera is said to be in South and Southeast Asia including Philippines" [7][8][9]. ...
... They can include: unhooked wings, distended abdomens. Controlling nosema disease can be accomplished by feeding the antibiotic fumagillin, marketed under the trade names of Fumidil B and/or Nosem-X [4]. ...
Honeybees are essential pollinators that play a crucial role in maintaining the global ecosystem and food security. However, in recent years, honeybee populations have been declining rapidly due to a combination of factors, including environmental stresses. Environmental stresses such as habitat loss, pesticide use, climate change, and disease are some of the major stresses that affect the survival and health of honeybee colonies. These stresses can affect honeybees in several ways, including reduced foraging efficiency, impaired immune function, decreased reproductive success, and increased susceptibility to pathogens. Habitat loss and fragmentation have a direct impact on honeybees' foraging efficiency by reducing the availability of floral resources. Pesticide use, especially neonicotinoids, has been shown to affect honeybees' immune function, navigation, and Review Article Yashdeep et al.; Int. 2088 communication. Climate change can affect the time of flowering and alter the distribution of floral resources, which can lead to reduced foraging efficiency. Varroa mites, Nosema, and American foulbrood are some of the diseases that can cause significant damage to honeybee colonies. The presence of these diseases can lead to reduced reproductive success, impaired immune function, and increased mortality.
... These creatures now inhabit in most parts of the world and are considered as beneficial social insects. The rearing of honeybees and production of honey had begun 4500 years ago by humans [3][4][5][6]. "The center of origin for all the extant species excluding Apis mellifera is said to be in South and Southeast Asia including Philippines" [7][8][9]. ...
... They can include: unhooked wings, distended abdomens. Controlling nosema disease can be accomplished by feeding the antibiotic fumagillin, marketed under the trade names of Fumidil B and/or Nosem-X [4]. ...
Honeybees are essential pollinators that play a crucial role in maintaining the global ecosystem and food security. However, in recent years, honeybee populations have been declining rapidly due to a combination of factors, including environmental stresses. Environmental stresses such as habitat loss, pesticide use, climate change, and disease are some of the major stresses that affect the survival and health of honeybee colonies. These stresses can affect honeybees in several ways, including reduced foraging efficiency, impaired immune function, decreased reproductive success, and increased susceptibility to pathogens. Habitat loss and fragmentation have a direct impact on honeybees' foraging efficiency by reducing the availability of floral resources. Pesticide use, especially neonicotinoids, has been shown to affect honeybees' immune function, navigation, and communication. Climate change can affect the time of flowering and alter the distribution of floral resources, which can lead to reduced foraging efficiency. Varroa mites, Nosema, and American foulbrood are some of the diseases that can cause significant damage to honeybee colonies. The presence of these diseases can lead to reduced reproductive success, impaired immune function, and increased mortality.
... Chen et al. (2018) reported that the lethal temperatures for most insects are usually between 40°C and 50°C, depending on the species and life stage. Some insects are even at risk of extinction at current projected rates of global warming (García-Robledo et al., 2016;Abou-Shaara et al., 2017;Wang et al., 2017). For example, when the growth temperatures are higher than 36°C, a colony of honey bees is likely to be exposed to superheated temperatures, which would impact the adult brain (Abou-Shaara et al., 2017); short-term high-temperature stress can also decrease oviposition in Bactrocera cucurbitae and Carposina sasakii (Zeng et al., 2019;Zhang et al., 2020), and increase the instantaneous death risk of Ostrinia furnacalis . ...
... High-temperature stress poses a serious risk to Osmia excavata Temperature is one of the most important external conditions affecting the life activities of insects (Dongmo et al., 2021;Gaytán et al., 2022), but an abnormal high-temperature environment has a serious impact on growth and development, and even causes the risk of extinction in some insects (García-Robledo et al., 2016;Abou-Shaara et al., 2017;Wang et al., 2017). Populations of O. excavata are more easily affected by adverse factors because they only have one generation a year . ...
The population of Osmia excavata , an important pollinator in commercial orchards, has been in serious decline over recent years. To evaluate the risk of high-temperature stress on O. excavata , we evaluated the high-temperature tolerance and potential physiological and biochemical responses of O. excavata after a series of high-temperature stresses. The results showed that the mortality rates of O. excavata increased gradually with increases in temperature and duration of stress ( R ² = 0.88–0.99; p < 0.05). The larvae of O. excavata were more sensitive to temperature stress than adults, and the median lethal time (LT 50 ) value of the former was smaller than the latter in the acute response test. By comparing the results of acute and chronic responses of O. excavata to high-temperature stress, we found that the LT 50 values of natural cocoon-break adults at slightly higher temperatures (35°C and 40°C) were smaller than those of artificial cocoon-break adults, but the LT 50 values were similar under extreme high-temperature stress (45°C). Furthermore, the acute and chronic responses on the fat content of adult Osmia obtained by artificial and natural cocoon-break methods were significantly different ( F = 5.03; p < 0.05). Additionally, the mortalities of the young larvae and artificial cocoon-break adults were both significantly and positively correlated with trehalose content ( r = 0.78–0.82, p < 0.05). However, the mortality of the natural cocoon-break adults was negatively related to the acetylcholinesterase activity ( r = −0.93, p < 0.001). Overall, these results suggested that O. excavata has a low tolerance to high-temperature stress and provide evidence of causes that could be contributing to the population decline of O. excavata.
... Experiments have shown that less than 40% relative humidity can dry the eggs and this results in significant reduction in numbers of hatching eggs [38], so nurse bees cover the brood area to decrease the loss of moisture [39]. Literature suggests that honeybees maintain relative humidity levels above 50% in the brood area [40]. Honeybee larvae are fed with a jelly excreted by nurse bees, and total composition of this jelly is around 67% water. ...
... The relative humidity inside the hive is usually above 50% [40], which not only impacts the readings of some sensors but can also cause corrosion in the long-term. Honeybees have a tendency to cover any alien objects in the hive such as exposed sensors with bee glue i.e. propolis [108], which impacts the performance of sensors. ...
Honeybees play a vital role in sustaining our agricultural economy and maintaining the ecosystem. A healthy and well spread bee population is crucial for better pollination of local crops as well as non-agricultural flora. The decline in global bee population and increased instances of Colony Collapse Disorder (CCD) have drawn attention of researchers all over the world. Recent technological advancements have impacted the bee-keeping industry in numerous ways, and electronic beehive monitoring has significantly improved over the past few years. Monitoring systems have been developed to observe temperature, humidity and acoustics inside the hive, overall weight of the hive and outgoing/incoming bee traffic to gauge the health of beehives. These monitoring systems aided by various wireless communication technologies make it possible for the beekeepers to monitor a large number of hives continuously, simultaneously, from a distance, and only intervene when required.
The most important characteristic of a monitoring system is the set of parameters used for monitoring. Each commercially available solution makes use of its own set of parameters to determine the health of bees. Most of the research carried out in this area focuses on a small set of two to three sensors in each study, rather than examining a bigger set for its collective usefulness. For communication, the monitoring systems rely on either 3G/4G or WiFi networks which are not accessible everywhere, or on satellite communication which can be very expensive. Despite having a high price tag, most of the monitoring systems provide beekeepers with just the raw data from sensors without any analysis on bee health. Proposed systems in the literature have also not been able to make the most of deep learning algorithms, mostly because the data used for training is collected over a short period of time, and from hives with little geographic diversity. Use of such small datasets with limited variations often leads to inconclusive and unreliable results. Beekeepers, in particular from Australia, have not been able to take full advantage of these electronic monitoring systems because of the aforementioned limitations. The vast landscape with no cellular coverage, and the high associated costs of using such monitoring systems are the major challenges faced by the local honeybee industry.
This work addresses the design and development of a beehive monitoring system capable of long range communication with low power consumption. Appropriate sensors for the proposed system are selected after an extensive review of literature. This selection is based on the relevance of sensor with bee health/activity, suitability for long distance transmission over low capacity channels, and optimal use of power. Extraction of appropriate features from sensor data is the key requirement for remote deployment. Different experiments were performed to evaluate various sensors and their features for their importance, and viability for hive deployment. A total of eight sensor systems were deployed in multiple hives, at different locations, and in varying environmental conditions over a 12 month period. During these deployments, Narrow Band Internet of Things (NB-IoT) was thoroughly tested for its communication feasibility from remote sites. Based on the findings, use of NB-IoT is proposed for low cost and reliable communication from remote beehives. The design of this system has also been made available for other researches to use and improve upon.
The aim of sensor deployments in this study is not only to test different sensors and communication for beehive monitoring, but also to build a quality sensor dataset from beehives deployed at different sites. Beehive data collection is a slow process based on the natural activity and life cycle of honeybees. The harsh environment of remote sites, sensor failures, and communication issues make it a very challenging task. A dataset of 2,170 days of beehive sensor data, weather data, and seasonal information has been collected during this study. The resolution of 144 data points per day in this dataset provides a good picture of daily bee activity, and facilitates the use of machine learning in beehive health monitoring. Random forests are used to evaluate the contribution of different sensors in this dataset, as well as of the performance of monitoring system.
Daily hive weight variations are a crucial aspect of hive health and bee activity. Hive weight is affected by multiple complex internal and external factors. Traditionally, an expensive and difficult to deploy weighing scale is used to monitor the hive weight. This is the first work to propose the use of machine learning for beehive weight estimation. Latest machine learning algorithms were tested for their suitability with beehive monitoring and weight estimation, and modified to make most of the information available in beehive sensor data. This work presents two deep learning models for beehive weight estimation, WE-Bee and Apis-Prime. The features for training and testing these models were selected after an in-depth study of bee behaviour, and the impact of environment on bee foraging activity. WE-Bee uses Long Short Term Memory (LSTM) encoders and decoders with temporal attention, whereas Apis-Prime uses self-attention encoders for the same task. These models were tested on sensor systems and hives which were not part of the training set. The promising results validate the good performance of both networks for unseen data. The hives used for the data collection were allowed their natural variations in colony strengths and forager activity, and were moved to sites at a significant distance from each other to collect geographically diverse data. The diversity of the training data played a significant role in the quality of estimations. Use of these machine learning models has the potential to eliminate expensive beehive weighing scales, and reduce the cost of beehive monitoring systems by more than half.
Evaluation of sensors and contribution of features towards a specific task is important for improving and fine-tuning the design of monitoring systems. This work proposes the use of attention weights of self-attention encoders to evaluate sensors and sensor features, as well as to identify the times of day when sensor data carries most information. This enables a significant reduction in the number of features used for estimation. The equally good results of weight estimation with reduced features signify the usefulness of self-attention encoders for feature selection. These findings not only help assess the bee health/activity remotely, but also significantly reduce the monitoring costs. The estimates about hive weight variations using machine learning provide the beekeepers with important information about the hive without using an expensive weighing scale. The promising weight estimates indicate that the proposed system collects important data from the hive, which can also be utilized for a variety of beehive health monitoring tasks.
... Shifts in many abiotic factors, such as luminosity, temperature, and humidity, influence the activity and abundance of bee populations (Pollato et al., 2014;Escobedo-Kenefic et al., 2020). The seasonal changes in bee activity patterns are regulated by their physiology, such as water stress and the thermal regulation of their bodies (Sarospataki et al., 2009;Abou-Shaara et al., 2017). Additionally, differences in abiotic conditions might reflect the availability of the plant resources used by the bees. ...
... Seasonality is often considered an important factor in regulating the activity of bee communities (e.g., Abou-Shaara et al., 2017;Medeiros et al., 2017;de Assis et al., 2020), and, therefore, it is crucial to use trapping methods that would adequately show the seasonal shifts of these insects. Among the three trapping methods used here, arboreal pitfalls were the most sensitive to the sampling season, with higher species richness and more individuals in the dry season. ...
Insect pollinators, including bees and wasps, are facing a marked decline in their native populations, caused mainly by human activities, such as forest fragmentation, urbanization, and the use of agrochemicals. To help mitigate the rapid decline of pollinators, new efforts towards understanding basic and applied aspects of these organisms are necessary. Among these efforts, there is a focus on increasing the sampling efficiency, including a broader range of targeted groups and collection methods. Although each method has its advantages and disadvantages, the pollinators' crisis calls for alternative methods to analyze bee and wasp diversity and population dynamics. Here, we assess the potential role of incidental captures of bees and wasps by a method widely used to collect ants but not targeted for bees: arboreal pitfall traps. We compared the sampling efficiency of human urine‐baited arboreal pitfall traps and two traditional methods for bee sampling: pan traps and scent traps. Arboreal pitfalls collected a high diversity of bees and sphecoid wasps, and when compared with pan traps and scent traps, they had the highest species richness and the second‐highest abundance. Although the three trapping methods shared most species, each method collected particular groups of species, and there were indicator species for each trapping method. When used in pairs with pan traps, arboreal pitfalls collected a higher species diversity than pan traps paired with scent traps. In addition, each trapping method responded differently to seasonal variations, and although arboreal pitfalls had lower diversity during the rainy season, scent traps detected differences only in species abundance, and pan traps detected no differences at all. Our study reinforces the importance of complementary methods in sampling bees and wasps and the use of non‐traditional methods to increase the sampling coverage of these insects.
... In honeybees, heat stress can impact growth and development of larval and pupal stages, and their ability to learn and forage as adults. In addition, it can promote senescence and death (Tautz et al., 2003;Abou-Shaara, 2015;Abou-Shaara et al., 2017). It could be expected that ROS are overproduced in the warmer urban conditions, negatively affecting bees; therefore, this is a new analysis that should be performed through both laboratory a s s a y s a n d p h y s i o l o g i c a l i n v e s t i g a t i o n s o n fi e l dcollected individuals. ...
Urbanization leads to cities having higher temperatures than surrounding non-urban areas [this is known as the urban heat island (UHI) effect]. Very little is known about the impacts of the UHI effect on bees, despite the importance of temperature on many aspects of bees' life suggesting that these may be not negligible. In this study, we aimed to highlight how the UHI effect could impact relevant functional traits of bees in cities, proposing several ad hoc hypotheses for traits that have thus far been investigated only in few studies or not at all, based on what we know from non-urban studies. The UHI effect was shown to influence bee body size, and generally tended to reduce the body size of bees in cities. Urban temperature may also affect bees' wing morphology, and thus their overall flight morphology parameters. Individuals may be more brightly colored in cities. Bee ommatidial size and the number of antennal thermoreceptors they have may be smaller and fewer, respectively, in cities than in non-urban areas. As expected, because urban bees face a higher risk of desiccation, higher proportions of alkanes and longer main-carbon chain lengths are expected in their cuticular hydrocarbon (CHC) profiles. Stress biomarkers can also occur at greater concentrations in bees in cities and specific bacteria in the bee gut may occur at lower abundances. Warm urban temperatures may impact the life cycle of pathogens by reducing their proliferation. Aggression levels may be increased, and eusocial species may present more worker phases per year due to the UHI effect. All of these proposed impacts could be likely more visible in solitary and primitively eusocial bee species, which are those suspected to have a more limited dispersal ability. Comparative studies would help in the proper testing of these hypotheses.
... The first study to associate variation in physical pollen collecting behaviors with floral identity. Previous research indicates that foraging can be influenced by numerous aspects including the natural unpredictability of resource availability across the floral marketplace (Dunlap et al. 2017), fluctuations in temperature and seasonality (Abou-Shaara et al. 2017;Aleixo et al. 2017), anther length ) and even foragers' previous experiences (Dunlap et al. 2017;Russell et al. 2016). Floral diversity is an important aspect of providing suitable habitat for pollinators. ...
Urban areas boast high bee species richness and abundance, but little is known of their overall behavior or potential plasticity. The physical movements of bees on flowers are an extremely important aspect of their behavioral repertoire, as foraging for pollen has implications for bee population health and plant reproductive success. In this study we used classic ethological techniques to document and quantify pollen collecting behavior common sweat bee species, Halictus ligatus, residing in both urban and exurban habitats, and assess the role of environmental factors on behavioral differences. Overall, time budgets of bee foraging behavior between urban and exurban H. ligatus were similar, with scraping as the primary method used for pollen extraction. However, we observed a novel foraging behavior for Halictus bees – tapping, which varied significantly between urban and exurban bee foragers. Additionally, environmental characteristics including temperature, floral richness and floral identity were the strongest predictors of pollen collecting behavior. Lastly, we found significant differences in the sequences of behaviors performed by urban and exurban H. ligatus. This study is the first to utilize ethological methods to describe and document pollen gathering in an urban sweat bee species, and explore the potential mechanisms driving behavioral differences. The physical actions involved in pollen removal are crucial for plant pollination, particularly in urban regions with high habitat heterogeneity and resource patchiness. As urbanization continues to expand, more targeted behavioral studies applied to urban animal populations will aid in our understanding of animal behavior, plasticity, and the potential implications for ecosystem services.
... The importance of temperature and relative humidity for the internal and external activities of honeybees is well documented [52,53]. These factors can also affect the quantity and concentration of sugar in the flower nectar, subsequently affecting the foraging behaviour of honeybees [54]. ...
Plant species and abiotic factors including season appear to be the most important variables influencing the frequency of visits by honeybees (Apis mellifera L.). In the present study, we evaluated the activity of honeybee workers visiting runner bean (Phaseolus coccineus L.) local cultivar ‘Piękny Jaś’. The runner beans are widely cultivated in south-eastern Poland, and are an important forage plant for honeybees in agroecosystems. We aimed at a comprehensive monitoring of the health of colonies and symptoms in A. mellifera in response to acute exposure to pesticides. The most numerous visits of A. mellifera were observed at the highest flower opening of the runner bean. A very weak positive correlation was observed between the number of honeybees on P. coccineus, the number of visited flowers, the time spent per flower and air temperature. The visitation rates of honeybees were more frequent at mid-day and decreased after 15:00. Signs of poisoning were detected in two out of seven apiaries monitored for acute pesticide exposure symptoms on runner bean plantations. The analysis of dead honeybee samples revealed the acute exposure of honeybees to the imidacloprid (neonicotinoid) and chlorpyrifos (organophosphorus) insecticides, which are highly toxic and banned in the European Union. Hazard quotient (HQ) screening showed an elevated burden of imidacloprid and chlorpyrifos corresponding to 7.1% and 10% of the LDD50, respectively, most likely indicating bee poisoning due to chronic exposure to these substances with contaminated food. Noteworthy was the presence of three fungicides that could pose a risk of poisoning in honeybees.
... The meteorological factors, mainly sunshine duration and air temperature, had the strongest effect on hive weight changes in our study. These findings are in line with the results of studies concerning the flight activity of honey bees (Burrill and Dietz, 1981;Vicens and Bosch, 2000;Abou-Shaara, 2014;Gebremedhn et al., 2014;Polatto et al., 2014;Abou-Shaara et al., 2017;Clarke and Robert, 2018). Our results indicate that sunshine duration considerably affects hive weight changes when direct solar irradiance exceeds 5 h per day. ...
Bees are strongly dependent on environmental and climatic conditions. Anthropogenic and climate changes are mainly responsible for restricted access of bees to food resources. Therefore, this study aimed to evaluate the effect of the most important meteorological and environmental variables affecting food collection by honey bees. Using electronic beehive scales, remote monitoring of daily hive weight changes of 60 colonies from 60 apiaries was performed during three beekeeping seasons. The hive weight changes mainly depended on the meteorological variables, particularly sunshine duration and air temperature. The topographic (e.g. landscape structure, forest habitat type, the share of the area with plant species attractive to honey bees) and spatial (e.g. proportion of forest, arable land, green area) variables contributed to the hive weight changes to a much lesser extent. Monitoring of the hive weight revealed that the meteorological conditions and the share of the area with most attractive plant species affected food collection by honey bees the most strongly. In conclusion, the long-term remote monitoring of honey bee colony hive weight changes on a large scale can be a source of substantial data about the impact of environmental and climate changes on bees and their food resources in order to restore and conserve the environment that will meet the nutritional needs of different species of bees.
... Some factors lead to higher yields of honey bees. These factors can be listed as genotype, in-hive factors, temperature control, humidity and ventilation (Abou-Shaara et al., 2017). The hive can be made more comfortable for bees by leaving sufficient spaces for ventilation coupled with the use of materials that can isolate heat and humidity during the construction of the hive. ...
... There exist notable distinctions in temperature and humidity levels between honey bee hives and bumble bee nests. Honey bee hives maintain a temperature range of 33-36 � C with an average humidity of approximately 52% (Abou-Shaara et al., 2017). On the other hand, bumble bee nests exhibit a lower temperature range of 25-30 � C and a higher humidity level ranging from 70% to 80% (Weidenm€ uller et al., 2002). ...
... Honeybee colonies exposed to high external temperatures may experience a rise in hive temperature, which can have a negative impact on honeybee growth, metabolism, and physiological responses [2][3][4]. More so, temperature and relative humidity have a significant impact on the honeybee colony's homeostasis in the hive [5]. The level of honeybee activity in the hives and its surroundings is highly influenced by ambient temperature and relative humidity, which, if consistently observed, might be used to determine the harvest season [6,7]. ...
... Honeybee colonies exposed to high external temperatures may experience a rise in hive temperature, which can have a negative impact on honeybee growth, metabolism, and physiological responses [2][3][4]. More so, temperature and relative humidity have a significant impact on the honeybee colony's homeostasis in the hive [5]. The level of honeybee activity in the hives and its surroundings is highly influenced by ambient temperature and relative humidity, which, if consistently observed, might be used to determine the harvest season [6,7]. ...
Hive cover designs majorly affects the microclimate and colony establishment of African honeybee colonies in Nigeria. It became pertinent therefore to assess the effect of modified hive cover designs on the internal microclimate and colony establishment of West African honeybee (Apis mellifera adansonii L.) Colonies in Awka, Nigeria. Four insulating materials were used to construct 2 the covers of twelve modified frame bar hives and designated: Control (plywood); T1 (warped boards); T2 (PVC) and T3 (foam). Each hive treatment was replicated three times. Data on ambient and hive microclimate as well as the colonization of honeybees' colonies were observed and reported. The results indicated that the control had the highest temperature (31.86 ºC) while T1 (30.40ºC) had the least. The hive temperature was higher in March, 2023 (32.72°C) while August (29.87°C) had the least. The highest relative humidity (73.18%) was recorded in T1 while the control had the least (64.38%). The hive temperature and relative humidity was significantly affected by hive cover designs and different months of the study period (P<0.05). The highest colonization by African honeybees was observed in the control (100%) but none occurred in T2 (0.00%). Colonization of the Control hives occurred in July, October, and November, 2022 while that of T1 and T3 occurred in December, 2022. Colony establishment of African honeybees was not significantly affected by hive cover designs (p=0.26) and different months of the study period (p=0.24). It was concluded that beekeepers should adopt the insulation of hiver covers with plywood wood since it had 100% colonization of West African honeybees'.
... The flight activity of honey bee foragers depends on the temperature and increases along with an increase of temperature in the range of 15 to 25 °C (Abou-Shaara et al. 2017). The results of the present study indicate that temperature strongly affected changes in hive weight, but a significant impact on hive weight was seen at an air temperature of 28 °C (at 1:00 p.m.). ...
Bee development is determined by the quantity and quality of food resources available in the environment that can be used by bees only to a certain extent. Therefore, this study aimed to evaluate, by means of changes in hive weight, the amount of food collected by honey bees in various landscapes, in relation to meteorological conditions, landscape, and forest structure. The monitored colonies (n = 104) were placed on electronic beehive scales, which provided data about hive weight, temperature, and humidity over two beekeeping seasons. The landscape valuation within a 2 km radius from each beehive was prepared based on digital maps. The seasonal distribution of food resources collected by honey bees was determined based on hive weight changes analysed in 5-day-periods (i.e. pentads). The hive weight changes mainly depended on the observation period and the air temperature. The hive weight increased from April to the last 10 days of June and when the air temperature was over 24 °C. The proportions of agricultural lands and forests, as well as the air humidity,
had a small effect on hive weight changes. Continuous monitoring of the weight of honey bee colonies on a large scale showed that honey bees collected food stores in their nests mainly in the spring. Then, they collected a small amount of food, probably due to limited access to food resources from the last 10 days of June until the end of the growing season.
... Impacts of temperature and relative humidity on brood development have been reviewed by Abou-Shaara et al. (2017). An optimal relative humidity is especially important for the hatching rate of young larvae from eggs (Doull, 1976). ...
Coumaphos is one of the most frequently detected pesticides in recycled beeswax. The objective was to assess the maximal level of coumaphos in foundation sheets that could exist without lethal effects on the honey bee larvae. Brood development was followed in cells drawn on foundation squares containing coumaphos ranging from 0 to 132 mg/kg. Furthermore, larval exposure was determined by measuring the coumaphos level in the drawn cells. Coumaphos levels in the initial foundation sheets up to 62 mg/kg did not increase brood mortality, since the emergence rates of bees raised on these foundation squares were similar to controls (median of 51%). After a single brood cycle, coumaphos levels in the drawn cells were up to three times lower than the initial levels in foundation sheets. Hence, coumaphos levels of 62 mg/kg in the initial foundation sheets, the one but highest exposures, resulted in levels of 21 mg/kg in drawn cells. A significantly reduced emergence rate (median of 14%) was observed for bees raised on foundation sheets with initial coumaphos levels of 132 mg/kg, indicating increased brood mortality. Such levels resulted in coumaphos concentrations of 51 mg/kg in drawn cells, which is close to the median lethal concentration of 50% (LC50 ) as determined in previous in vitro experiments. In conclusion, brood mortality was increased on wax foundation sheets with initial coumaphos levels of 132 mg/kg, while no elevated mortality was observed for levels up to 62 mg/kg.
... Changes in wind direction, for instance, can disorient and reduce bee activity (Dag and Eisikowitch, 1995). High temperatures may cause a decrease in bee activity due to stress, and the intensity of UV light and humidity within enclosed fields can change bee foraging behaviour and impact their health (Abou-Shaara et al., 2017;Pinzauti, 1994). Yet few studies have actually compared covered and uncovered (control) environments when specifically studying impacts on pollination. ...
Protective covers are commonly employed in agricultural systems to reduce the impacts of extreme weather events, pest species and to control the environmental conditions in which crop plants are grown. As protected cropping systems are expanding rapidly, there is an urgent need to better understand how variations in netting practices might impact pollination service delivery by wild and managed insects to pollinator dependent crops. We used southern highbush blueberry (Vaccinium corymbosum L. interspecific hybrid) crops to investigate (i) how variations in protected cropping structures (fully netted, partially netted and unnetted blocks) influence the amount and composition of pollen deposited on crop stigmas; (ii) to what extent blueberry floral abundance and plant richness in remnant vegetation influence pollen composition on crop stigmas; and (iii) the difference between stigmatic pollen load composition in the middle and at the edge of crop blocks. We collected data from 15 field blocks of 6 different cultivars distributed on 10 farms. We collected blueberry stigmas to analyse the pollen load and measured blueberry floral abundance and richness of flowering plant taxa in remnant vegetation every two weeks. Our results indicate that blueberry pollen abundance on stigmas was reduced by up to 81% under full netting and 36% by partial netting. On blueberry stigmas, we identified a total of 31 morphospecies of non-blueberry pollen from 20 plant families. There was no relationship between blueberry stigmatic pollen loads and blueberry floral abundance. Moreover, the composition of non-blueberry pollen on stigmas differed between blueberry blocks under different netting categories. However, there was no relationship between plant taxa present in the surrounding remnant vegetation of each block and the pollen load on the stigmas of each block. Combining all netting treatments, stigmas located at the edge of the blocks received a greater amount of both conspecific (5% more) and heterospecific (40% more) pollen grains than those within the middle of blocks. Pollen flow in fields is reduced under netting structures as well as in the middle of blocks. Reduced blueberry pollen flow under nets may be detrimental to fruit yield and quality for some varieties of pollinator dependent crops, particularly those that are self-incompatible.
... The main objective of the ventilation hole at the bottom of the hive is to get rid of the accumulated moisture in the hive, which negatively affects the respiration of the brood and the respiration of the colony bees, and the consumption of honey and sugar feeding. In the hive, if it rises to more than 80%, then the colony will be threatened by brood diseases and other bee pests [6,7]. It is worth noting that getting rid of moisture and air saturated with heat and CO 2 is not the result of air currents due to movement The wings of the bees are as in the normal situation without openings, but due to the air pressure and convection currents, as the air resulting from the breathing of bees and the respiration of the brood is relatively hot to the temperature of the space of the hive, and the pressure of this air is high and its weight is lighter, so it rises to the top of the hive with the characteristic of convection currents and this air is Loaded with brood breathing moisture, this air is directed to the top of the cell surface as a result of the hotter air pressure coming from the brood area. ...
This study was conducted in the Al-Hadid-Baquba/Diyala governorate during the months of September, October and November of 2021 to increase ventilation and reduce the humidity inside the bee colonies by the use of ventilation holes and the addition of waterers to increase the thermal balance inside the hive. 24 Beehives were used in the experiment and divided into eight treatments. T1 control treatment (beehives with no ventilation holes and without waterers ), T2: Beehives containing waterers, T3, T4 and T5 Beehives contain one, two, and three ventilation holes without waterers; T6, T7, and T8, contain one, two, and three ventilation holes with waterers, respectively. The statistical data obtained from the computer monitoring system showed that the treatments led to a highly significant decrease (P≤0.01) in the temperature and relative humidity recorded inside the beehives. The average temperature during The autumn was 37.50, 36.20, 34.44, 33.90, 33.45, 33.33, 33.49 and 33.96 ° C, while the humidity was 65.59, 67.96, 56.01, 56.23, 61.39, 52.39, 53.18 and 53.96% in treatments T1, T2, T3, T4, T6, T7 and T8 respectively.
... In addition, packaging has an important role in maintaining sensory quality (aroma, color, and taste), decreased enzyme activity, antibacterial, and other biological functions (Missio da Silva et al., 2020;Samborska et al., 2015). The critical factors in the honey storage process are temperature, light, and relative humidity (Abou-Shaara et al., 2017). Materials that are safe for honey are usually made of bottles or dark plastic to protect the honey from damage caused by light (Pohl et al., 2009). ...
Introduction. Klanceng honey (Tetragonula laeviceps) is in great demand because of its benefits. There is no information on the expiration date of the Klanceng honey. Objective. To predict the shelf life of Klanceng honey by evaluating the effect of heating (40 ºC / 48 h and 70 ºC / 7 h) and storage for two years. Materials and methods. The analysis was carried out three times (2020, 2021, and 2022) at the National Innovation Research Agency Laboratory, Jakarta, Indonesia. Samples of Klanceng honey (Tetragonula laeviceps) were taken from a bee farm in Magetan, East Java, Indonesia. The sample (5 kg) was divided into 3: without heating process (UT), heating at 40 ºC / 48 h (T1), and heating at 70 ºC / 7 h (T2). Then analyzed the activity of HMF, diastase, invertase, acid phosphatase (AP), glucose oxidase (GO), DPPH, honey color, and phenolic at 0, 12 and 24-months. Results. The results showed that short heating at high temperature (70 ºC / 7 h) had a greater impact on decreasing enzyme activity compared to prolonged heating at low temperature (40 ºC / 48 h). Storage had a major impact on the increase of 5-hydroxymethyl (furan)-2-carbaldehyde (HMF) compared to the heating process. During storage (24-months) the HMF value exceeded the maximum limit. Conclusions. The HMF value (55.33 ± 0.57 mg/kg) exceeded the maximum allowable limit (max 40 ppm), this was due to the significant effect of heating on T2 and the storage process. The shelf life of Klanceng honey was two years, as long as it was not heated to high temperatures (70 ºC).
... Humidity is known to play a vital role in the development of brood. Investigations into the effect of humidity were initially made possible by controlled laboratory incubators with more recent data being collected from hives in the field with smaller embedded sensors [1][2][3][4][5][6][7][8][9][10]. Carbon dioxide has long been known as a narcotic for the honeybee and is used to immobilize them during scientific manipulation or transfer. ...
Non-dispersive infra-red (NDIR) detectors have become the dominant method for measuring atmospheric CO2, which is thought to be an important gas for honeybee colony health. In this work we describe a microcontroller-based system used to collect data from Senserion SCD41 NDIR sensors placed in the crown boards and queen excluders of honeybee colonies. The same sensors also provide relative humidity and temperature data. Several months of data have been recorded from four different hives. The mass change measurements, from hive scales, when foragers leave the hive were compared with the data from the gas sensors. Our data suggest that it is possible to estimate the colony size from the change in measured CO2, however no such link with the humidity is observed. Data are presented showing the CO2 decreasing over many weeks as a colony dies.
... According to the Codex Alimentarius, the water content of honey should not exceed 20%. The relative humidity and temperature affect the water content during honey production by honeybees [72]. ...
This study was conducted to assess the bioactive value of Tamarix gallica honey samples collected from three countries. In total, 150 Tamarix gallica honey samples from Saudi Arabia (50), Libya (50), and Egypt (50) were collected and compared, based on the results of the melissopalynological analysis, their physicochemical attributes, antioxidant and antimicrobial activities, and biochemical properties, together with their total phenolic and total flavonoid contents. Depending on the geographical origin, we observed different levels of growth suppression for six resistant bacterial strains. The pathogenic microorganisms tested in this study were Staphylococcus aureus, Streptococcus mutans, Klebsiella pneumoniae, Escherichia coli, Proteus vulgaris, and Pseudomonas aeruginosa. There was a strong correlation between the polyphenol and flavonoid contents, as well as significant (p < 0.05) radical scavenging activities. The melissopalynological analysis and physicochemical properties complied with the recommendation of the Gulf and Egyptian Technical Regulations on honey, as well as the Codex Alimentarius of the World Health Organization and the European Union Normative related to honey quality. It was concluded that Tamarix gallica honey from the three countries has the capacity to suppress pathogenic bacterial growth and has significant radical scavenging activities. Moreover, these findings suggest that Tamarix gallica honey may be considered as an interesting source of antimicrobial compounds and antioxidants for therapeutical and nutraceutical industries or for food manufacturers.
... If not warmed up, the hypo-thermic bees that were removed from the hive would die. This has been a problem in apiculture under sudden extreme cold weather conditions (Abou-Shaara et al. 2017;Döke et al. 2015). In contrast, extremely hot weather may reduce the differences in CHEs, thus delaying corpse removal until pathogen transmission. ...
Removing dead conspecifics reduces pathogen transmission in social insects. Undertakers of the hive-bees can quickly detect and remove dead bees. The signals indicating instant death are unclear. In this study, we identified that undertaking was quickly elicited by the reduction in evaporated cuticular hydrocarbons (CHC emissions, CHEs). CHEs from dead bees were much lower than those from live bees, whereas heated dead bees with reproduced CHEs were not instantly removed. Physiological tests further showed that undertakers perceived and discriminated the major CHCs, and heated synthetic CHCs inhibited the undertaking behaviour. This study thus indicates that the reduced emissions of CHCs, particularly heptacosane and nonacosane, due to lower body temperatures in dead bees, are used by undertakers as a signal for detecting dead bees. Heptacosane and nonacosane emissions at hive temperatures are life signals. By changing the vapour pressure, then the ratio of emitted compounds, insect chemical communication can be fine-tuned by body temperature. The increasing frequency of extreme weather events may cause inaccurate death recognition, harming bee health.
... The Apis mellifera species are widely distributed in diverse climates around the world as a result of being potential for honey production. Climatic conditions have a direct influence on inside/outside colony activities like thermoregulation (Stabentheiner et al., 2010), egg laying rate (Abou-Shaara et al., 2017), food storing (Seeley and Visscher, 1985), flight and foraging activity (Haftom Gebremedhn et al., 2014) and honey production (Neupane and Thapa, 2005). One of the biggest challenge's beekeepers face is estimating the effects of extremely low temperatures and high humidity during the winter season, which can lead to a significant reduction in honey harvest. ...
... It isanticipated that the rise in temperature would have a passive impact on foraging activities. On the other hand, relative humidity had a lesser influence on flight activity (Abou-Shaara et al., 2017). More study is needed to comprehend these phenomena completely. ...
... Temperature and humidity are important abiotic factors that affect honeybees physiology (Abou-Shaara et al. 2017). In natural, changes in temperature and humidity have an important impact on the physiological metabolism of bees (Dalmon et al. 2019, Giannoni-Guzmán et al. 2021. ...
Temperature and humidity are important factors affecting the honeybees physiological metabolism. When honeybees are stressed by high temperature and high humidity, various physiological stress mechanisms evolved by bees are activated in response to injury. The accumulation of some sugars, polyols, and free amino acids can effectively protect cell structure stability and resist temperature stress. In this study, the changes of glucose, trehalose, cholesterol, sorbitol, sorbitol dehydrogenase, mannitol, and free amino acids content of worker honeybees [Apis cerana cerana Fabricius and Apis mellifera Ligustica (Hymenoptera: Apidae)] under different temperature and humidity conditions were measured. Our research results show that high temperature has an important impact on the metabolism of honeybees. Heat stress can cause the accumulation of various antistress substances in worker. The contents of sugars, polyols, and some free amino acids accumulated in high temperature were significantly higher than those in the control, while the influence of high humidity was less. Although high humidity was improved compared with the control, the difference was not obvious. It provides a theoretical basis for exploring the physiological mechanism of individual heat resistance of honeybees.
... The majority of these issues stem from the devastation and disintegration of the natural and semi-natural ecosystem, as well as the increased crop farming landscape alterations and flora and fauna variety. These practices significantly reduced the value of honeybees and their contributions to the environment [30]. Synthetic pesticides (Fipronil) have a negative influence on honeybees and their products due to dispersion, leftovers, toxicity and durability. ...
The honeybee (Hymenoptera apidae) is a valuable insect that can be found all around the globe, except in polar regions. Apis mellifera contributes over US$200 billion to the world's economy annually. In Pakistan, pollination-dependent crops have a productivity worth US$1590 million with 61 main crops relying on the pollination of honeybees. Loss of honeybees to a certain level may lead to starvation. In a developing country like Pakistan, it is an issue with food security. Many biotic and abiotic factors are challenging in brooding and rearing honeybees in the country. Excessive use of pesticides, lack of skilled personnel and deforestation is leading to a decline in the population of honeybees. While the need for honeybee products is tremendously increasing with every passing day. The country's unique vegetative diversity has a significant ecological and economic impact on local wildlife conservation. If properly developed, it offers enormous potential for a long-term beekeeping enterprise. Beekeeping is primarily practiced in Khyber Pakhtunkhwa and the central and northern areas of the Punjab provinces of Pakistan. Pakistani honey is well-known throughout the Middle East for its distinct flavor and high quality. Every year, Pakistan sells roughly 4000 tons of honey to Arab countries, costing about US$23 million. This review study briefly describes different honeybee species' potential constraints and management in Pakistan and will be helpful in developing a sense of awareness that conserving honeybees is a matter of food security.
... Relative humidity (RH) is another important factor for larvae growth, colony development, and bee behavior, where changes in water transportation and larvae feeding have been reported as a function of ambient humidity, hive temperature, and nectar moisture [17]. The authors in [18] used temperature and humidity sensors to monitor ambient conditions, as well as conditions within the breeding comb and the nectar areas. ...
The vital role of honeybees in pollination and their high rate of mortality in the last decade have raised concern among beekeepers and researchers alike. As such, robust and remote sensing of beehives has emerged as a potential tool to help monitor the health of honeybees. Over the last decade, several monitoring systems have been proposed, including those based on in-hive acoustics. Despite its popularity, existing audio-based systems do not take context into account (e.g., environmental noise factors), and thus the performance may be severely hampered when deployed . In this paper, we investigate the effect that three different environmental noise factors (i.e., nearby train rail squealing, beekeeper speech, and rain noise) can have on three acoustic features (i.e., spectrogram, mel frequency cepstral coefficients, and discrete wavelet coefficients) used in existing automated beehive monitoring systems. To this end, audio data were collected continuously over a period of three months (August, September, and October) in 2021 from 11 urban beehives located in downtown Montréal, Québec, Canada. A system based on these features and a convolutional neural network was developed to predict beehive strength, an indicator of the size of the colony. Results show the negative impact that environmental factors can have across all tested features, resulting in an increase of up to 355% in mean absolute prediction error when heavy rain was present.
... The latter could be interpreted as an effect of the inconsistency of precipitation patterns within a given state and quarter, which may affect the effectiveness of foraging behaviors (bees do not fly during heavy precipitation) and thus increase the probability of colony loss. This supports existing studies connecting colony loss with changing weather patterns 24,26,27,37,43,55,56 . ...
Honey bee ( Apis mellifera ) colony loss is a widespread phenomenon with important economic and biological implications, whose drivers are still an open matter of investigation. We contribute to this line of research through a large-scale, multi-variable study combining multiple publicly accessible data sources. Specifically, we analyzed quarterly data covering the contiguous United States for the years 2015-2021, and combined open data on honey bee colony status and stressors, weather data, and land use. The different spatio-temporal resolutions of these data are addressed through an up-scaling approach that generates additional statistical features which capture more complex distributional characteristics and significantly improve modeling performance. Treating this expanded feature set with state-of-the-art feature selection methods, we obtained findings that, nation-wide, are in line with the current knowledge on the aggravating roles of Varroa destructor and pesticides in colony loss. Moreover, we found that extreme temperature and precipitation events, even when controlling for other factors, significantly impact colony loss. Overall, our results reveal the complexity of biotic and abiotic factors affecting managed honey bee colonies across the United States.
... ( (77). Honey moisture content provides information in its degree of maturation (78). ...
Objective: The aim of the study was to characterize varieties of Moringa alfileria honey (unfloral and polyfloral) from Saudi Arabia based on antibacterial, antioxidant activities, physicochemical, melissopalynological analysis, total phenolic and flavonoid contents. Material and Methods: The fresh 376 honey samples (3 kg of each) were kindly provided by Alnahal aljwal Company, 2021 flowering season. The honey samples collected in sterile universal glass containers and kept at 2– 8°C until tested. Antibacterial, antioxidant activities and physiochemical analysis were done. Determination of sediment content, total grains, moisture content, water-soluble solids, acidity, electrical conductivity, total sugars content, inverted sugars, glucose (g/100 g), fructose (g/100 g), total glucose + fructose, fructose/ glucose ratio, sucrose (g/100 g), diastase enzyme activity and HMF were calculated. As well as total phenolic and flavonoid contents Results: Antibacterial activity and physiochemical analysis of honey samples w varied. All parameters studied were significantly different (P < 0.05) among all honey varieties. The results of the physiochemical analysis were compared with Saudi National Standard, Codex standard, as well as published data in the literature. Conclusion: It was obvious that the honey quality was varied based on the botanical origins
... This allows the pinpointing of the time points close to the swarming event, providing differentiation between late detection and real-time occurrence. For example, bees tend to regulate the temperature inside the hive to around 35 degrees, but during swarming, the temperature varies from 17 to 36 degrees (constituting real-time detection) [10]. ...
This paper presents a machine-learning approach for detecting swarming events. Three different classification algorithms are tested: The k-Nearest Neighbors algorithm (k-NN) and Support Vector Machine (SVM), and a newly proposed by the authors, U-Net Convolutional Neural Network (CNN), developed for biomedical image segmentation. Next, the authors present their experimental scenario of collecting audio data of swarming and non-swarming events and evaluating the results from the k-NN and SVM classifiers and their proposed CNN algorithm. Finally, the authors compare these three methods and present the cross-comparison results of the optimal method for early and late/close-to-the-event detection of swarming.
... Nesse sentido, as abelhas em colmeias desse estudo podem ter dado prioridade à coleta de água, uma vez que para minimizar as elevadas temperaturas internas as operárias espalham pequenas gotas de água sobre os alvéolos com o intuito de resfriar o ninho, por meio da evaporação da água (Abou-Shaara et al., 2017). Salienta-se que em condições de altas temperaturas, fato que foi observado no período seco do ano (gráfico 2), a coleta de água pelas abelhas passa a ser um elemento que auxilia no resfriamento evaporativo, contribuindo para a homeostase da colônia (Human et al., 2006). ...
O monitoramento da termorregulação interna das colmeias e do ambiente do apiário tornam-se imprescindíveis para o sucesso do sistema de produção, uma vez que podem afetar o desenvolvimento das crias e atividades diárias desenvolvidas pelas abelhas, e nesse sentido, objetivou-se monitorar a temperatura interna de colmeias de abelhas africanizadas Apis mellífera L. no munícipio de Cocal-PI no período de Janeiro a outubro de 2021. Os resultados coletados no decorrer do ciclo produtivo (período chuvoso e seco) indicaram que a temperatura interna nas colmeias de abelhas africanizadas oscilaram ao longo dos meses, de janeiro a outubro, mantendo-se em conformidade ao recomendado. As temperaturas ambientais declinaram a conforme passaram os meses do ano, sendo observadas as maiores temperaturas para o mês de janeiro, média de 34,1ºC e elevando-se do período seco do ano, alcançando valor médio de 33,8ºC no mês de outubro. As abelhas Apis mellifera africanizadas mantém a homeostase do ninho no período seco e chuvoso do ano. A umidade do ar teve comportamento contrário a temperatura do ambiente no período chuvoso, elevando-se com o passar dos meses ao passo que, no período seco do ano, observou-se a redução da umidade do ar. As abelhas Apis mellifera africanizadas mantém a homeostase do ninho no período seco e chuvoso do ano. Há variações de temperatura interna nas colmeias ao longo do ano sem alterar o equilíbrio homeostático interno. As flutuações na umidade do ar e temperaturas do ambiente decorrem em função das variações nas condições climáticas ao longo dos meses do ano.
... Given that beekeeping practices in most countries are more-or-less uniform, drivers of annual fluctuations of colony losses must be sought beyond structural beekeeping constraints. It is well-known that the physiology and phenology of the honey bees are governed by the abiotic environment [16][17][18]. Seeley and Visscher [16] concluded that "the timings of colony growth and reproduction are essential elements in the honeybee's suite of adaptations for winter survival". The start of brood development in honey bees in late winter is mainly driven by temperature but modulated by photoperiod [19]. ...
Winter loss rates of honey bee colonies may fluctuate highly between years in temperate climates. The present study combined survey data of autumn and winter loss rates in Germany (2012–2021) with estimates of honey flow—assessed with automated hive scales as the start of honey flow in spring and its magnitude in summer—with the aim of understanding annual fluctuations in loss rates. Autumn colony loss rates were positively and significantly correlated with winter loss rates, whereas winter loss rates were inversely related to loss rates in autumn of the following year. An early start of net honey flow in spring predicted high loss rates in both autumn and winter, whereas high cumulative honey flow led to lower loss rates. The start of net honey flow was related to temperature sums in March. Combined, the results implied that the winter loss rate in one year was influenced by the loss rate of the preceding winter and shaped by honey flow dynamics during the following year. Hence, the rate of colony loss in winter can be viewed as a cumulative death process affected by the preceding one and a half years.
... Humidity sensors are also very commonly used in monitoring systems. Literature suggests that honeybees maintain relative humidity levels above 50% in the brood area (Abou-Shaara et al., 2017). Low humidity levels can dry the eggs, so nurse bees cover the brood area to decrease the loss of moisture (Al-Ghamdi et al., 2014). ...
Decision making capability of a system is highly dependent upon the quality and quantity of training data. Majority of beehive monitoring systems developed for research purposes are designed to collect data through a small set of sensors, and from locations with little geographic diversity. This hinders the development of a dataset that can be used to effectively train machine learning models. In this work, we explain the design and development of a multi-sensory, remote data acquisition system for beehives (BeeDAS), with focus on low-power consumption and long-range communication. We address design challenges associated with such systems and highlight the critical issues that need consideration. The proposed system enables collection of data from beehives at remote locations and harsh environment. Results of field deployments elucidate the effectiveness of various sensors which measure temperature, humidity, atmospheric pressure, CO, acoustics, vibrations and the weight of a hive in hostile environment. This work also uses random forest regression to evaluate the feature importance of different sensors, environmental variables such as temperature, humidity, rain, wind speed as well as the information related to seasons, towards estimating the daily hive weight change, on a dataset comprised of 1,250 days of sensor recordings. We also evaluate the protocol designed for communication using Narrow Band Internet of Things (NB-IoT). The issues related to power optimization, sleep intervals and data storage in remote monitoring are also discussed.
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... Joshi and Joshi (2010), however, found a weak impact of RH on flight activity. In an interesting work by Abou-Shaara et al. (2017), the authors reviewed the impacts of both temperature and relative humidity on the honeybees' activities, presenting also specific thresholds and optimum values. ...
Bee productivity is an essential factor affecting, not only the production of honey or other beehive products but also food security due to the very important role of bees as pollinators. The behavior of the bees and thus their productivity is highly affected by the weather fluctuations. In the present study, five years (2015-2019) of beehive weight data were analyzed to assess the impact of the prevailing weather conditions at an east Mediterranean island, on the productivity of bees. The results indicate that temperature and water-related parameters, significantly affect beehive productivity. Specifically, temperature optimum values of 17oC in spring and 26oC in summer, are associated with higher daily relative changes of the beehive weight, while bee productivity enhances at daily temperatures between 14 and 28oC, presenting negative values beyond this range. The effects of temperature, windspeed, diurnal temperature range, vapor pressure deficit, saturation vapor pressure, and the duration of hot and dry periods, on beehive productivity are strong and negative, whereas the effect of relative humidity is also significant but positive. The results of the study enhance the knowledge of the weather impacts on beehive production especially under the climatic conditions of a small east Mediterranean island, with applications in beekeepers scheduling and hive designing, to maximize beehive productivity.
Two of the most relevant gasses correlating to honeybee colony health are likely carbon dioxide and humidity. Non-Dispersive Infra-Red (NDIR) detectors have become the dominant method for measuring atmospheric CO2. In this work, we describe a microcontroller-based system used to collect data from two models of these NDIR sensors that also provide humidity and temperature data. Placement in a frame in the brood box and in the crown board and queen excluder is investigated. With several thousands of hours of data for comparison, we demonstrate both the daily and long-term trends in these important gasses in multiple honeybee colonies.
The western honey bee, Apis mellifera , lives worldwide in approximately 102 million managed hives but also wild throughout much of its native and introduced range. Despite the global importance of A. mellifera as a crop pollinator, wild colonies have received comparatively little attention in the scientific literature and basic information regarding their density and abundance is scattered. Here, we review 40 studies that have quantified wild colony density directly ( n = 33) or indirectly using genetic markers ( n = 7) and analyse data from 41 locations worldwide to identify factors that influence wild colony density. We also compare the density of wild and managed colonies at a regional scale using data on managed colonies from the Food and Agriculture Organization (FAO). Wild colony densities varied from 0.1 to 24.2/km ² and were significantly lower in Europe (average of 0.26/km ² ) than in Northern America (1.4/km ² ), Oceania (4.4/km ² ), Latin America (6.7/km ² ) and Africa (6.8/km ² ). Regional differences were not significant after controlling for both temperature and survey area, suggesting that cooler climates and larger survey areas may be responsible for the low densities reported in Europe. Managed colony densities were 2.2/km ² in Asia, 1.2/km ² in Europe, 0.2/km ² , in Northern America, 0.2/km ² in Oceania, 0.5/km ² in Latin America and 1/km ² in Africa. Wild colony densities exceeded those of managed colonies in all regions except Europe and Asia. Overall, there were estimated to be between two and three times as many wild colonies as managed worldwide. More wild colony surveys, particularly in Asia and South America, are needed to assess the relative density of wild and managed colonies at smaller spatial scales.
The foraging activities of pollinators depend on a variety of factors, such as the availability of pollen and nectar resources or the seasonality. We performed measurements on the activity patterns of Apis mellifera adansonii Latreille by focusing on different factors: (i) we counted the number of bees entering the hives during 10 min per hour starting from 05:00 AM to 06:00 PM, once a month and along the year, (ii) we measured the hive weights at different intervals during the study and (iii) we characterised the diversity of melliferous plants within a 1 km radius around the hives. Our results show that melliferous flora is composed of 83 species. During the dry season, the honey bees foraged on flowering trees and shrubs, whereas in the rainy season herbaceous plants provided forage for honey bees. The results revealed a significant correlation between foraging activity and the mean hive weights (r = 0.9) while relative humidity was negatively correlated but not significantly with, respectively, mean hive weights (r = −0.5) and foraging activity (r = −0.6). Thus, the combination of biotic and abiotic factors resulted in two distinct periods, namely a phase of honey flow followed by a phase of honey scarcity.
Day‐to‐day synchrony between flower opening and pollinator activity is important for maximizing plant fitness. A succulent, Bulbine frutescens (L.) Willd., is an ideal model for studying synchrony in response to daily weather as it flowers year‐round. Additionally, it has self‐incompatible flowers that open for just one day, making it essential that flower opening matches pollinator activity.
Observations were made on urban plants in California, USA, with validation measurements in the native range in South Africa. Independent observations indicated that flowers open primarily after favourable conditions the previous day, specifically air temperatures above 15°C. Solar radiation was experimentally shown to have limited, but significant effects. Pollinators, mostly bee species, had similar temperature thresholds to flowers.
Developmental constraints on flowers were hypothesized to delay opening by a day. Flower bud growth was closely related to temperature, with warm days resulting in sufficient growth for buds to become competent to open the following day. Laboratory experiments demonstrated that competent flowers were suppressed from opening until at least 16 h was accumulated in which temperatures were above 12°C; thus, on many cool days, sufficient development to cause flower opening would only occur a day after favourable weather.
Based upon regression models of pollinator and flower response to weather, fitness was estimated as a function of synchrony, over 20 years of weather from California and across the natural range in South Africa. Flowers responding to either the previous day's or current day's weather resulted in similar predicted fitness, with flower response to the current day's weather leading to a slightly higher cost, that is, flowers opened when pollinators would be absent.
Multiple temperature responsive constraints on bud growth and development result in delays in flower opening, such that flower opening occurs the day after favourable weather. Given the high correlation between daily temperatures in USA and South African winter‐rainfall environments, behaviour predicting the following day's weather results in high fitness. Many pollinators share similar temperature thresholds for activity, thus diverse plants may have evolved predictive behaviour maximizing daily synchrony between pollinators and flower opening.
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High temperature affects behavior, physiology, survival, and the expression of related genes in adult honeybees. Apis mellifera is the common pollinator in greenhouse and is susceptible to high temperature stress. To further explore the molecular basis related to heat stress, we compared the transcriptome profiles of adult worker bees at 25 and 45°C, and detected the expression patterns of some differentially expressed genes (DEGs) in different tissues by q RT-PCR. Differential expression analysis showed that 277 DEGs were identified, including 167 genes upregulated and 110 genes downregulated after heat stress exposure in adult worker bees. In GO enrichment analysis, DEGs were mostly enriched for protein folding, unfold protein binding, and heme binding terms. Protein processing in endoplasmic reticulum and longevity regulating pathway-multiple species were significantly enriched in KEGG. The expression levels of 16 DEGs were consistent with the transcriptome results. The expression patterns of 9 DEGs in different tissues revealed high levels in the thorax, which was supposed that the thorax may be the most important part in the response to heat stress. This study provided valuable data for exploring the function of heat resistance-related genes.
The risk of poisoning bees by sprayed pesticides depends on the attractiveness of plants and environmental and climatic factors. Thus, to protect bees from pesticide intoxication, an usual exemption to pesticide regulations allows for spraying on blooming flowers with insecticides or acaricides when no bees are foraging on crops. Nevertheless, decision-making criteria for farmers to assess the absence of bees on their crops remain under debate. To fill this gap, we present here a review of the literature and an analysis of weather conditions and environmental factors that affect the presence of bees on flowering crops that may be treated with pesticides, with the objective of proposing to farmers a series of decision-making criteria on how and when to treat. We conclude that the criteria commonly considered, such as ambient temperature, crop attractiveness, or distance from field edges, cannot guarantee the absence of forager exposure during pesticide sprays. Nocturnal sprays of pesticides on crops would be the most effective action to help farmers avoid unintentional acute poisoning of bees.
The urban environment is a particular ecosystem because of its abiotic conditions but also because of its spatial configuration of habitats. Indeed, this fragmented environment, inhabited by humans, could be an interesting ecosystem to host a diversity of pollinators. The study of pollinators in the urban environment raises many questions. The main objective of the study is to investigate and determine the most important factors for predicting pollinator species richness in the city of Louvain-la-Neuve. In order to achieve this objective, the study is divided into several experiments and observations. The first part, observatory, is based on the realization of inventories of plants and pollinators in numerous open spaces (called "meadows") categorized according to the specific richness of flowering plants in order to evaluate the population composition of flowering plants and pollinators in meadows. These inventories are useful for investigating the relationship between flowering plant richness and floral units density with pollinator abundance and species richness, thus providing insight into habitat quality. A more detailed investigation of plant-pollinator interactions is conducted by the co-memorator of this study, Jeanne David. A second, applied part focuses on the study and description of the urban landscape around the study sites to determine their influences on pollinators. The description of the landscape is also used to study the movement of bumblebees (Bombus sp. and Psithyrus sp.) via a CMR experiment and to calculate least-cost corridors via the elaboration of a friction matrix between different types of city meadows. The combination of the two studies thus attempts to link the plant-pollinator diversity found in patches to landscape elements, patch treatment and potential connectivity between these patches. The results of this study show that the distribution, species richness and abundance of pollinators mainly follow the distribution, species richness and density of flowering plants. Spatial analysis showed very few significant results, with only the amount of impervious surfaces having a significant negative effect on pollinator abundance. No significant effect was found on plants.
The study of connectivity shows that the movement of pollinators is mainly between nearby sites, but also between sites rich in floral resources. The number of bumblebees found within each site is consistent with the floral resources. Because of their mobility and foraging strategies, bumblebees do not seem to be strongly affected by the barriers of the urban environment.
In order to improve diversity within LLN, the results encourage increasing the availability of resources within the city by adapting the management regime of the sites, adding sites rich in flowering plants but also improving connectivity between sites for less mobile insects.
A system of remote monitoring and automation apiary has been developed. This is a low-cost and scalable solution designed for deployment in distant rural areas. An unconventional solution is applying the industrial standard Modbus protocol to transfer data from the hives to a central server. This made it possible to reduce the cost of the system and standardize it. Monitoring the temperature and humidity inside the hives is important for analyzing the condition of bee colonies. The automation of the temperature and humidity control process is implemented based on a fuzzy model of the servo drive of the hive door.
The effect of capped queen cell incubation temperature on the quality of honey bee queens was examined. It was shown that the period of pre-imaginal development in the queen bees from queen cells incubated at 32°C was longer by 1 day and 3 hours when compared to those being incubated at 34.5°C, for which this period amounted to 16 days and 1 hour. On the other hand, the quality of queens from cells incubated at 32°C and 34.5°C was similar, they did not differ in body weight, spermathecal volume, ovariole number in both ovaries, or onset of oviposition.
Apis mellifera drones have only one role, mating when they are sexually mature. They first make a reconnaissance flight after a few days, and begin the chase for virgin queens. The aim of this study was to evaluate the influence of climate factors on the flight activity of drones. Temperature and light conditions significantly influenced flight activity: with increases of temperature and luminosity, the number of drones leaving the colony increased. However, changes in relative humidity and wind speed did not affect the number of individuals leaving the colony. The peak of flight activity was between 11:00 and 15:00 h. The drones also remained longer outside the colony during this time, which demonstrates that these bees prefer the warmest time of day to mate.
Few studies have been performed on honey bee eggs to date, particularly on egg hatchability and other egg characteristics. In the harsh environmental conditions of Saudi Arabia, it has been found that honey bee eggs from different subspecies are impacted by low relative humidity (RH). Therefore, the hatching rates of eggs of two subspecies, Yemeni (Apis mellifera jemenitica) and hybrids of Carniolan honey bees (Apis mellifera carnica), were studied under different RH gradients, and various egg characteristics (morphology, egg surface chemicals and egg water content) were described for these two subspecies. The results of these analyses demonstrated that Yemeni honey bee eggs displayed higher hatching rates than Carniolan honey bee eggs across the humidity gradient, although no eggs were able to hatch at a relative humidity of 30%. Differences in egg morphology were detected between the two subspecies. The egg surface chemicals were approximately the same for Carniolan and Yemeni honey bee eggs, while the Yemeni honey bee eggs exhibited a higher water content. The differences between the two subspecies in egg hatching rates could be attributed to differences in egg water content as well as to some internal factors within the eggs.
In honeybees fast and efficient exploitation of nectar and pollen sources is achieved by persistent endothermy throughout the foraging cycle, which means extremely high energy costs. The need for food promotes maximisation of the intake rate, and the high costs call for energetic optimisation. Experiments on how honeybees resolve this conflict have to consider that foraging takes place in a variable environment concerning microclimate and food quality and availability. Here we report, in simultaneous measurements of energy costs, gains, and intake rate and efficiency, how honeybee foragers manage this challenge in their highly variable environment. If possible, during unlimited sucrose flow, they follow an ‘investment-guided’ (‘time is honey’) economic strategy promising increased returns. They maximise net intake rate by investing both own heat production and solar heat to increase body temperature to a level which guarantees a high suction velocity. They switch to an ‘economizing’ (‘save the honey’) optimisation of energetic efficiency if the intake rate is restricted by the food source when an increased body temperature would not guarantee a high intake rate. With this flexible and graded change between economic strategies honeybees can do both maximise colony intake rate and optimise foraging efficiency in reaction to environmental variation.
Beekeeping is a dynamic activity and is impacted by many factors. A comprehensive survey was done from September, 2013 to April, 2015 to understand the current status of beekeeping in the Arabian countries and to identify the urgent needs for beekeeping development. Modern social communication means were utilized to perform the survey. Total of 138 respondents had participated in the study from 14 Arabian countries. Most of the respondents were with age from 31-45 years old (42.8% of the total). The most of them were also with high educational level with B.Sc. or higher degree (81.2% of the total) and 58.7% of them were with experience less than 10 years in beekeeping. The majority of the respondents preferred the indigenous bee races over the imported ones and 51.4% of them were only honey producers. The incorrect management of bee colonies was considered by the majority of the respondents as the most important factor behind death of the bee colonies. It could be concluded that planned training programs on beekeeping are highly required. The roles of the extension agencies are very essential to prepare suitable training programs for beekeepers. The use of the indigenous bee races in beekeeping should be supported. Effective laws and legislations to prevent honey adulteration and organize honey marketing issues are recommended to be done. Information about beekeeping in many Arabian countries are not available. Therefore, the results of this study can be considered as a baseline for any future investigations.
Background
Honey bee (Apis mellifera) drones and workers show differences in morphology, physiology, and behavior. Because the functions of drones are more related to colony reproduction, and those of workers relate to both survival and reproduction, we hypothesize that the microclimate for worker brood is more precisely regulated than that of drone brood.
Methodology/Principal Findings
We assessed temperature and relative humidity (RH) inside honey bee colonies for both drone and worker brood throughout the three-stage development period, using digital HOBO® Data Loggers. The major findings of this study are that 1) both drone and worker castes show the highest temperature for eggs, followed by larvae and then pupae; 2) temperature in drones are maintained at higher precision (smaller variance) in drone eggs and larvae, but at a lower precision in pupae than the corresponding stages of workers; 3) RH regulation showed higher variance in drone than workers across all brood stages; and 4) RH regulation seems largely due to regulation by workers, as the contribution from empty honey combs are much smaller compared to that from adult workers.
Conclusions/Significance
We conclude that honey bee colonies maintain both temperature and humidity actively; that the microclimate for sealed drone brood is less precisely regulated than worker brood; and that combs with honey contribute very little to the increase of RH in honey bee colonies. These findings increase our understanding of microclimate regulation in honey bees and may have implications for beekeeping practices.
Abstract
Survival rates were monitored among three honey bee subspecies under two ecological regions within Saudi Arabia; Riyadh characterized
by desert climate and Albaha resembling semiarid climate. Frequency of colony losses were counted and categorized
within three temperature ranges of maximum monthly temperatures (20-28, 29-37 and 38-46 °C) for 24 months. Out of 420 colonies
included in this study, 101 colonies were able to survive during the whole period of assessment. Survival rates among subspecies
were highly associated with temperature ranges (χ
2
= 40.6, df = 4, P < 0.001) and were significantly different between
both ecological regions (χ
2
= 10.6, df = 2, P < 0.005). Most of these losses (76%) occurred in summer months, August and September,
when average maximum monthly temperature ranges between 38-46 °C. The highest losses were recorded in exotic honey
bee subspecies; Apis mellifera carnica (92%) and Apis mellifera ligustica (84%), compared to (46%) in the local honey bee colonies,
Apis mellifera jemenitica. Apparently extreme ambient temperatures during the summer season are highly detrimental to exotic
honey bee colonies. Additionally, Varroa mite and Nosema spp. were the main pests that can contribute to colony losses
throughout the period of the study. Results indicate low tolerance of the exotic honey bee subspecies to temperatures extremes of
Saudi Arabia during the summer, thus selection and conservation of the indigenous honey bee race is highly demanded.
Key words: survival frequency, drought, Yemeni honey bee, Italian honey bee, Carniolan honey bee.
Observations on foraging behaviour, time spent per flower and number of flowers visited per minute by the two species of honey bee viz. Apis cerana and A. mellifera were made and a significant and nonlinear relationship was found. The number of flowers visited by each bee was also examined and it was found that A. cerana visited higher number of flowers than that of A. mellifera. Similarly the exotic A. mellifera carried heavier pollen loads than the native bee A. cerana. The foraging activity of A. cerana was observed at a peak between 1100 to 1300 hrs and then a steady decline was recorded which abruptly decreased between 1700 to 1800 hrs. However, in the case of A. mellifera, the increase was steady and reached its peak between 1300 to 1500 hrs. [New York Science Journal 2010;3(3):71-76]. (ISSN: 1554-0200).
The honey bee, Apis mellifera, is a cosmopolitan pollination insect. Recently, global populations of honey bees have rapidly declined owing to colony collapse disorder (CCD), the mechanism of which is still unknown. Here, we used mRNA levels of heat shock protein (HSP) genes as molecular markers of response to three types of external stress: thermal shock, flower-thinning agents, and pesticides. When worker bees were exposed to temperatures of 4, 27, 40, 45 and 50 °C for 1 h, decreased survival occurred only at 50 °C. Further, increased levels of hsp70, grp78, and hsp90, but not hsp40, were detected, and reached a maximum at 45 °C, particularly in the hypopharyngeal glands and fat bodies. Artificial ingestion of two flower-thinning agents containing either 0.1% boron and zinc, or 1% sulfur increased hsp70 and grp78 levels at different rates without affecting hsp40 and hsp90 levels, and had no effect on workers' mortality. However, ingestion of imidacloprid solution (0.5–50 ppm) increased mortality in workers and decreased the levels of hsp70, grp78, and hsp90 in a dose-dependent manner. Our results showed that the responses of honey bees to each hsp are differential and highly specific to different stresses. This study suggests that the unique expression profiles of hsps can be used as valuable tools for monitoring the susceptibility of honey bees to various environmental impacts.
Foraging behaviour is one of the distinctive behaviours of honey bees, Apis mellifera. This behaviour is the link between the honey bee colony and the ambient environment. Therefore, various in-colony and out-colony factors have an impact on this behaviour, and many studies have been employed to investigate these factors. Foraging behaviour is not advantageous only for the colony and for plant pollination but also has other benefits. In contrast, some disadvantages have also been discovered to be linked with foraging activity. Practically speaking, the control over this behaviour is very important to maximize colony products as well as to increase other agricultural benefits. This paper presents a review on foraging activity including; the regulation of foraging tasks, factors impacting this behaviour, foraging preference, variations between subspecies, monitoring methods as well as the possible methods for controlling this behaviour. As concluded from this review, more work needs to be performed in order to elucidate certain aspects of foraging behaviour.
Reproduction by colony fission, or swarming, is a spectacular example of a behavior that requires the simultaneous coordination of the activities of thousands of honey bee workers and their queen. The successful execution of this collective phenomenon relies on the appropriate response of individuals in swarms to a myriad of signals that are produced by workers and queens to synchronize their nest exodus, subsequent house hunting, and eventual relocation to a new nest site. In this review, we describe our current understanding of the social factors that trigger swarming in colonies and the nonchemical and chemical signals that mediate a coordinated transition between its stages. We also highlight emerging work on the physiological and genomic mechanisms underpinning swarming behavior. Finally, we discuss the possible evolutionary origins of swarming behavior, through comparisons with related behaviors of migration, overwintering, estivation, and diapause in honey bees and other insects.
The Western honeybees Apis mellifera carnica and A. m. ligustica are closely related subspecies living in neighbouring regions. Metabolism and the upper lethal thermal limits are crucial physiological traits, adapted in the evolutionary process to environment and climate conditions. We investigated whether samples from these two ecotypes differ in these traits. The standard metabolic rate was higher in the A. m. ligustica population only at a high temperature (T
a ~ 40 °C; dVCO2 = 12 nl s−1; P < 0.05), probably due to a higher body temperature (dTthorax = 1.5 °C; P < 0.01). The critical thermal maximum of activity and respiration was similar (difference activity CTmax = 0.8 °C, respiratory CTmax = 1.1 °C). The lethal temperature (LT50, 8h) revealed higher tolerance and survival rates of the Ligustica bees (Carnica 50.3 °C; Ligustica 51.7 °C; P < 0.02). Results reveal the adaptation of the two subspecies to their historic climate conditions, possibly favouring Ligustica in a warming environment.
A study was carried out to investigate pollen foraging, storage and its impact on Apis mellifera L brood production throughout the year under Terai condition of Nepal in 2003-2005. Number of pollen foragers, amount of pollen stored as beebread and brood in the colony differed significantly during different seasons. Number of pollen foragers (117.5 bees/ hive/ 5 min) and amount of pollen as beebread (2439.0 gm/hive) and number of brood (14787.2 brood cells/hive) were the highest during spring season, while the lowest number of pollen foragers (38.1 bees/ hive/5 min.) stored the lowest amount of beebread or pollen store (152.5 gm /hive) and produced the lowest number of brood (3811.7 brood cells/ hive) and bees in rainy season. Autumn, winter and summer seasons were normal for pollen collection and brood production, while starvation and nutritional deficiencies due to the acute shortage of pollen in rainy season was the major reason to decline or collapse the bee population before the honey flow season. Therefore, feeding bees with adequate amount of nutritionally rich pollen during rainy season is essential to maintain a healthy and strong bee colony for the production of higher honey and other hive products.
Honey bee foraging activity on the flowers of two spring rapeseed varieties 'SW Savann' and 'Ural' was evaluated. High air temperature throughout the study period allowed us to investigate the interaction between plants and their pollinators under weather conditions unusual for Lithuania. Analysis of flowering intensity and honey bee density in the two rape varieties showed that 'Ural' produced on average 4.6% more flowers than 'SW Savann', however, honey bee density in 'Ural' plots was about 4% lower than that in 'SW Savann' plots. A decrease in flowering intensity was followed by a decrease in honey bee density in both rape varieties. A strong increase in ambient temperature had a negative impact on the foraging of honey bees on flowering plants. The lowest honey bee density in the investigated rape plots was recorded in the afternoon, when air temperature reached +43°C. High ambient temperature affected oilseed rape flowering and pollinator density on flowers and this could have had a negative effect on seed yield of oilseed rape. times 9% of all insect pollinators (Koltowski, 2001). Bumble bees being important pollinators of many agricultural crops, however, make up only 2% of all insect pollinators in rape crops (Cresswell, 1999; Koltowski, 2001). The attractiveness of plants to pollinators depends on a variety of factors. Climate changes due to global warming are assumed to have impact on the already established mutualistic rela-tionships between flowering plants and insect pol-linators (Blažytė-Čereškienė, 2007, review). It should be noted that in Lithuania more and more often we witness climate changes that are related to global warming, i.e. warmer winter temperatures and longer periods of hot weather in summer. More frequent losses of winter rape crops both in Lithuania and neighbouring countries (Kol-towski, 2001) encouraged farmers to focus more on spring varieties.
Heterothermic insects like honeybees, foraging in a variable environment, face the challenge of keeping their body temperature high to enable immediate flight and to promote fast exploitation of resources. Because of their small size they have to cope with an enormous heat loss and, therefore, high costs of thermoregulation. This calls for energetic optimisation which may be achieved by different strategies. An 'economizing' strategy would be to reduce energetic investment whenever possible, for example by using external heat from the sun for thermoregulation. An 'investment-guided' strategy, by contrast, would be to invest additional heat production or external heat gain to optimize physiological parameters like body temperature which promise increased energetic returns. Here we show how honeybees balance these strategies in response to changes of their local microclimate. In a novel approach of simultaneous measurement of respiration and body temperature foragers displayed a flexible strategy of thermoregulatory and energetic management. While foraging in shade on an artificial flower they did not save energy with increasing ambient temperature as expected but acted according to an 'investment-guided' strategy, keeping the energy turnover at a high level (∼56-69 mW). This increased thorax temperature and speeded up foraging as ambient temperature increased. Solar heat was invested to increase thorax temperature at low ambient temperature ('investment-guided' strategy) but to save energy at high temperature ('economizing' strategy), leading to energy savings per stay of ∼18-76% in sunshine. This flexible economic strategy minimized costs of foraging, and optimized energetic efficiency in response to broad variation of environmental conditions.
We used radio-frequency identification (RFID) to record the duration and frequency of nuptial flights of honey bee queens (Apis mellifera carnica) at two mainland mating apiaries. We investigated the effect of a number of factors on flight duration and frequency: mating apiary, number of drone colonies, queen’s age and temperature. We found significant differences between the two locations concerning the number of flights on the first three days. We also observed an effect of the ambient temperature, with queens flying less often but longer at high temperatures compared to lower temperatures. Increasing the number of drone colonies from 33 to 80 colonies had no effect on the duration or on the frequency of nuptial flights. Since our results agree well with the results of previous studies, we suggest RFID as an appropriate tool to investigate the mating behavior of honey bee queens.
Honey bees have good thermoregulation and rapidly respond to any changes in the
microclimatic conditions of their colonies. However, colony losses can occur during very
cold or hot months. Honey bee colonies are often kept in modified beehives during such
times to save the honey bees lives. In the present study, the abilities of four beehive
types to enhance the performance of two honey bee races (Carniolan and Yemeni honey
bees) were compared under hot and arid environmental conditions. The results indicated
performance differences between the two races and between the selected beehive
types. For the Carniolan honey bees, better results were obtained in colonies provided
with insulated cover boxes (ICB) than in thermoregulatory beehives (TBH), insulated
beehives with a back drawer (IBD), and normal beehives (NB) in that order. In contrast,
better Yemeni honey bee results were obtained in the TBH, followed by ICB, NB, and
finally IBD. Maintaining honey bees in a suitable beehive type is a promising method for
saving honey bees lives and enhancing their performance under harsh environmental
conditions.
Endothermic heat production is a crucial evolutionary adaptation that is, amongst others, responsible for the great success of honeybees. Endothermy ensures the survival of the colonies in harsh environments and is involved in the maintenance of the brood nest temperature, which is fundamental for the breeding and further development of healthy individuals and thus the foraging and reproduction success of this species. Freshly emerged honeybees are not yet able to produce heat endothermically and thus developed behavioural patterns that result in the location of these young bees within the warm brood nest where they further develop and perform tasks for the colony. Previous studies showed that groups of young ectothermic honeybees exposed to a temperature gradient collectively aggregate at the optimal place with their preferred temperature of 36°C but most single bees do not locate themselves at the optimum. In this work we further investigate the behavioural patterns that lead to this collective thermotaxis. We tested single and groups of young bees concerning their ability to discriminate a local from a global temperature optimum and, for groups of bees, analysed the speed of the decision making process as well as density dependent effects by varying group sizes. We found that the majority of tested single bees do not locate themselves at the optimum whereas sufficiently large groups of bees are able to collectively discriminate a suboptimal temperature spot and aggregate at 36°C. Larger groups decide faster than smaller ones, but in larger groups a higher percentage of bees may switch to the sub-optimum due to crowding effects. We show that the collective thermotaxis is a simple but well evolved, scalable and robust social behaviour that enables the collective of bees to perform complex tasks despite the limited abilities of each individual.
This study aims to explore the effect of ambient temperature on foraging the activity of Apis cerana and Apis mellifera colonies. We recorded ambient temperature, the time at which foraging commenced, worker thoracic temperature, and brood nest temperature at the same apiary in Kunming, China. We found that A. cerana start foraging earlier and at lower temperatures than do A. mellifera. A. cerana foraging (departures per minute) also peaked earlier and at lower temperature than did A. mellifera foraging. At the same ambient temperature, departing A. mellifera foragers and workers sampled from the brood nest had a higher thoracic temperature than departing A. cerana foragers and brood nest workers. A. mellifera colonies also maintained their brood nest temperature significantly higher than did A. cerana. Our results suggest that the larger A. mellifera foragers require a higher thoracic temperature to be able to forage.
Honey bee queens are highly polyandrous and mate in flight. Instrumental insemination is an essential tool that provides complete control of honey bee mating for research and breeding purposes. The technique requires specialized equipment to anesthetize and immobilize the queen and to collect and deliver semen from the drones. Semen is harvested from mature drones by hand eversion of the endophallus and collected into a syringe. The queen is placed in a chamber and anesthetized during the procedure of insertion of semen into the oviducts. Queens are introduced into colonies and their performance can equal to that of naturally mated queens, given proper technique and care.
Pollination services are known to provide substantial benefits to human populations and agriculture in particular. Although many species are known to provide pollination services, honeybees (Apis mellifera) are often assumed to provide the majority of these services to agriculture. Using data from a range of secondary sources, this study assesses the importance of insect pollinated crops at regional and national scales and investigates the capacity of honeybees to provide optimal pollination services to UK agriculture. The findings indicate that insect pollinated crops have become increasingly important in UK crop agriculture and, as of 2007, accounted for 20% of UK cropland and 19% of total farmgate crop value. Analysis of honeybee hive numbers indicates that current UK populations are only capable of supplying 34% of pollination service demands even under favourable assumptions, falling from 70% in 1984. In spite of this decline, insect pollinated crop yields have risen by an average of 54% since 1984, casting doubt on long held beliefs that honeybees provide the majority of pollination services. Future land use and crop production patterns may further increase the role of pollination services to UK agriculture, highlighting the importance of measures aimed at maintaining both wild and managed species.
Temperatures were monitored around emergency queen cells in queenless honeybee hives to determine the effect of temperature on queen color. Concurrently, sister queens of those reared in the queenless colony were placed in incubators set at 31.1, 32.8, or 34.4-degrees-C for the post-capping interval. Queens from the 34.4-degrees-C incubator were significantly lighter in color than those in the 31.1-degrees-C in all but one trial. Queens that developed in the colony were not significantly different in color rank from those that emerged in the 34.4-degrees-C incubators in any trial, and from the 32.8 or 31.1-degrees-C incubators in most trials. The median color ranks of queens emerging in the colony did not differ throughout the year.
Summary A. laboriosa lives in the Himalayas under harsh conditions. We compared the start of flight activity of A. laboriosa with that of the closely related A. dorsata living in territories with a higher temperature. We compared also the reaction of flight activity to temperature changes in A. laboriosa with that of A. mellifera living in similar temperature conditions. The results show that closely related A. dorsata workers started foraging at a temperature of 18°C, and A. laboriosa at a lower temperature of 10°C. However, the unrelated A. laboriosa and A. mellifera living in territories under similar ambient conditions started foraging at the same temperature of 10°C. The increase in temperature to 12°C resulted in a 10-fold increase in the number of foragers leaving the nests of both species, and their flight activity reaction to temperature changes was similar. High correlation between the temperature and the number of foragers was found in both species, at temperatures below 16°C. The environmental conditions in which the bees were living for longer period influence their behavior more than the phylogenic relationship.
Alarmed by reports of high losses of honey bee colonies in other countries, and with no field data available for Austria, a mixed media survey on winter mortality of honey bee colonies was carried out in Austria for the overwintering periods of 2007-8 and 2008-9. In addition, the survey was extended to South Tyrol (Italy) in 2007-8. Data presented for 2007-8 were gathered at eight beekeeping conventions in Austria (374 beekeepers; 16,217 colonies, representing 1.7% of beekeepers and 5.8% of colonies, respectively) and one convention in South Tyrol (115 beekeepers; 3,999 colonies, representing 3.7% of beekeepers and 10.6% of colonies, respectively). During the overwintering period of 2007-8 we calculated a total loss of 13.3% of colonies in Austria, ranging from 9.2 to 17.1% in different regions. Overwintering mortality in South Tyrol was 12.3%. In 2009, data were collected at nine beekeeping conventions in Austria and from some respondents who returned the questionnaire which was also published in the Austrian beekeeping journal and on our website (575 beekeepers; 18,141 colonies, representing 2.6% of beekeepers and 6.5% of colonies, respectively). Total colony losses were calculated as 9.3%, ranging from 6.0% to 17.8% in different provinces of Austria. Respondents attributed Varroa destructor as a key factor in the occurrence of high colony losses during overwintering in our area of investigation, followed by queen loss and starvation. We analyzed the impact of hive management (operation size, date of carbohydrate feeding, type of carbohydrates fed before winter, V destructor treatment and migratory beekeeping) on colony loss. We also reported observed biases due to different survey methods in the second year.
Altogether 70 queens, 7-8 days old were instrumentally inseminated with 8 mm3 of semen. They were introduced in groups per 10 to 150, 350 and 750 workers in 1- and 4-comb mating boxes, and to 10 larger nuclei with 9500 workers on 5 normal combs. The nuclei were checked daily, and the initiation of egg laying, as well as the temperatures inside the bee cluster and outdoors were recorded. Queens attended by 150, 350 and 750 workers started to lay eggs in 1-comb mating boxes 15.1, 13.5 and 11.5 days after insemination, respectively; in 4-comb mating boxes 12.6, 12.1 and 9.9 days after insemination; and in the large nuclei, 6.9 days after insemination. Increase of the number of attendants by 100 workers accelerated initiation of egg laying by 0.59 or 0.46 day in 1-comb or in 4-comb mating boxes, respectively. Logarithmic regression curve y = 26.37 - 2.2 1n x fits well for initiation of egg laying by queens in 1-comb boxes and y = 18.30 - 2.2 1n x for queens in 4-comb boxes. Doubling the number of attendants accelerated initiation of egg laying by 0.8 - 0.9 day. Increase of the number of workers from 150 to 750 raised the temperature in the bee cluster in mating boxes from 2.3-degrees-C to 4.6-degrees-C above the 19.5-degrees-C of the average outdoor temperature. Increase of workers by 100 raised the temperature by 0.26-degrees-C or 0.33-degrees-C in 1- or 4-comb boxes, respectively. Logarithmic regression curve y = 3.3 + 1.2 1n x fits well for the rise of temperature generated by increasing number of workers in 4-comb boxes. Doubling the number of workers raised the temperature by 0.8-degrees-C. Increase of temperature by 1-degrees-C was associated with acceleration of the initiation of egg laying by about 1-2 days.
There are various factors that can have an effect on honey bee colonies. Temperature and relative humidity, in particularly, have special importance for honey bee colonies. Relatively few studies have been conducted on the effects of temperature and relative humidity on honey bee races. Here, the effects of different levels of temperature and relative humidity on survival, tolerance and body water loss were investigated on two races, one adapted to harsh conditions (Yemeni honey bees) and the other adapted to normal conditions (Carniolan honey bees). Results showed that temperature had higher effect than relative humidity on workers survival and Yemeni honey bees were
more tolerant to elevated temperature than Carniolan honey bees. Moreover, rates of body water loss for the two races were high under elevated temperature and low humidity conditions. In general, the response of the two races in the studied treatments was somewhat similar. However, under extreme conditions at elevated temperature or low humidity, Yemeni honey bees showed higher tolerance than
Carniolan honey bees.
This study records the fifth consecutive year that winter losses of managed honey bee (Apis mellifera) colonies in the USA have been around 30%. In April 2011, a total of 5,441 US beekeepers (an estimated 11% of total US beekeepers) responded to a survey conducted by the Bee Informed Partnership. Survey respondents reported that they had lost an average of 38.4% of their colonies, for a total US colony loss of 29.9% over the winter of 2010-11. One-third of respondents (all classified as backyard beekeepers, i.e. keeping fewer than 50 colonies) reported no winter loss. There was considerable variation in both the average and total loss by state. On average, beekeepers consider acceptable losses to be 13.2%, but 68% of all responding beekeepers suffered actual losses in excess of what they considered acceptable. Of beekeepers who reported losing at least one colony, manageable conditions, such as starvation and a weak condition in the fall, were the leading self-identified causes of mortality. Respondents who indicated that varroa mites (Varroa destructor), small hive beetles (Aethina tumida), poor wintering conditions, and / or Colony Collapse Disorder (CCD) conditions were a leading cause of mortality in their operations suffered a higher average loss than beekeepers who did not list any of these as potential causes. In a separate question, beekeepers who reported the symptom “no dead bees in hive or apiary” had significantly higher losses than those who did not report this symptom. In addition, commercial beekeepers were significantly more likely to indicate that colonies died with this symptom than either backyard or sideliner beekeepers.
Este estudio registra por quinto año consecutivo que las pérdidas invernales de abejas manejadas (Apis mellifera) en Estados Unidos están en torno al 30%. En abril del 2011, un total de 5,441 apicultores de los EE.UU. (se estima que el 11% del total de apicultores de EE.UU.) respondieron a una encuesta realizada por la Bee Informed Partnership. Los encuestados indicaron que habían perdido un promedio de 38.4% de sus colonias, con una pérdida total de colonias en EE.UU. del 29.9% durante el invierno de 2010-11. Un tercio de los encuestados (todos ellos clasificados como apicultores aficionados, es decir, con menos de 50 colonias) indicaron que no tuvieron pérdidas de invierno. Hubo una variación considerable tanto en la media como en el total de pérdidas por Estado. Por término medio, los apicultores consideran aceptables pérdidas del 13.2%, sin embargo, el 68% de todos los apicultores encuestados sufrieron pérdidas reales superiores a lo que consideran aceptable. Entre los apicultores que informaron de la pérdida de al menos una colonia, las principales causas de mortalidad identificadas por ellos fueron condiciones de manejo, tales como el hambre o una condición débil de las abejas en el otoño. Los encuestados que indicaron como principales causas de mortalidad de sus colmenas a los ácaros de Varroa (Varroa destructor), los escarabajos de las colmenas (Aethina tumida), las malas condiciones de invernada y / o condiciones del Síndrome de Colapso de las Colmenas (SCC), sufrieron una pérdida media mayor que aquellos apicultores que no incluyeron ninguna de estas causas potenciales. En una cuestión aparte, los apicultores que indicaron el síntoma “sin abejas muertas en la colmena o apiario” tenían pérdidas muy superiores a aquellos que no registraron ese síntoma. Además, los apicultores comerciales fueron significativamente más propensos a indicar que las colonias morían con este síntoma que los apicultores aficionados o los apicultores semi-profesionales.
Honey bee, Apis mellifera L., drones and workers were used to examine how differences in morphology, physiology, and behavior affect heat exchange and thorax temperature (Tth) during flight. Drones had twice the body mass (Mb) of workers (199.4 ± 2.5 versus 101.8 ± 3:3 mg) and exhibited Tth > 2°C higher. Drones were unable to lower Tth through regurgitation or through shunting heat to the abdomen. Heat production during hovering increased with Mb whereas total heat loss increased with Mb and with flight speed (V). Despite their larger size and higher Tth, drones flew slower than workers. A heat budget model predicted that Tth would decrease sharply with V, increase with body mass, and increase with the ratio of thorax mass to body mass. The model closely predicted the Tth difference between drones and workers and demonstrated that the higher Tth of drones is primarily (75%) an effect of large Mh, somewhat (15%) a result of the high ratio of thorax to body mass and, to a lesser degree (10%), a result of slower V. These morphological and behavioral traits are sufficient to account for the difference in Tth between drones and workers.
For many animals, maintaining a specific range of temperatures during offspring development is critical for the survival of the young. While this is most studied in birds and mammals, some insects regulate nest temperatures to create an ideal environment for larval development. Here, we explore the thermoregulatory fanning behavior in honeybees performed to maintain colony temperatures in the presence of larvae. We found that honeybees are more likely to fan when larvae are present, but need direct contact with larvae to fan. We found no evidence that exposure to brood pheromone plays a role in stimulating fanning behavior. Finally, we saw a shift in the fanning response seasonally. These results show that the presence of developing offspring influences the fanning response in honeybees and help us to understand how honeybee colonies achieve the fine thermoregulation necessary for healthy larval development.