Article

Gone with the wind: effects of wind on honey bee visit rate and foraging behaviour

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Abstract

Wind is an important yet understudied environmental influence on foraging behaviour. We investigated the direct and indirect effects of wind on foraging worker honey bees, Apis mellifera. Bees were trained to an array of artificial flowers providing nectar rewards in a location sheltered from natural wind. To examine the direct effect, fans produced four different wind speeds between 0 and 3 m/s at three different flower spacings: 5 cm (flowers touching) and 10 cm and 20 cm (flowers not touching). To examine the indirect effect of wind moving flowers, flowers were moved 10 cm at three frequencies between 50 and 110 cycles/min at zero wind speed. We recorded the number of successful flower visits, time spent flying, search time on a flower and hesitancy to take off. Bees visited significantly fewer flowers with increasing wind speed which was caused by a significant increase in hesitancy to take off. This difference in flower visits between wind speeds was highest at the 20 cm spacing. Flower movement had no effect on foraging rate; however, there was a significant positive relationship between flower movement and the total time spent flying. This was counterbalanced by a significant reduction in time spent searching for the nectary after landing on a flower at the higher flower frequencies. Our results suggest that it is the direct effect of wind on hesitancy to take off that has the greatest effect on honey bee foraging rate.

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... Suitable abiotic conditions (local climatic conditions and topography) are also important for the survival of bees. Previous researches have shown that weather elements such as temperature, light intensity, wind speed, and rainfall may alter bee species behavior (Hennessy et al., 2020;Rajkhowa & Deka, 2013) and hence ultimately influencing bee abundance, diversity, and distribution. Different bee species have different weather preferences and also take less than a minute to react to weather changes (Riessberger & Crailsheim, 1997). ...
... Different bee species have different weather preferences and also take less than a minute to react to weather changes (Riessberger & Crailsheim, 1997). However, most studies on weather effects on bees are biased toward laboratory investigations (Cooper et al., 1985;Hennessy et al., 2020), which cannot assess the synergistic impacts of habitat type and weather parameters, yet habitats due to their unique structure and composition may buffer or increase adverse effects of weather conditions. This information is important in guiding management decisions in the development of area-specific conservation efforts of greater impact. ...
... The probability of finding bees marginally decreased with increases in wind speeds, which is understandable as many findings have shown the negative impact of wind speed on flight performance (Combes & Dudley, 2009) and landing of bees (Chang et al., 2016) with implications on energy costs. Due to predicted increases in wind speeds associated with deforestation and climate change (Walker & Crane, 2000), new technologies for minimizing the impacts of strong winds on bees are imperative such as placing hives in sheltered locations (Hennessy et al., 2020) for domesticated species and windbreaks as suggested by Moisan-DeSerres et al. (2015) to safeguard native bee species that cannot tolerate high wind speeds such as the Lipotriches, which were more associated with low wind speeds. Different tolerance levels of bee species to wind speeds are mainly due to diverse body sizes and morphologies (Combes & Dudley, 2009). ...
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• Worldwide bees provide an important ecosystem service of plant pollination. Climate change and land-use changes are among drivers threatening bee survival with mounting evidence of species decline and extinction. In developing countries, rural areas constitute a significant proportion of the country's land, but information is lacking on how different habitat types and weather patterns in these areas influence bee populations. • This study investigated how weather variables and habitat-related factors influence the abundance, diversity, and distribution of bees across seasons in a farming rural area of Zimbabwe. Bees were systematically sampled in five habitat types (natural woodlots, pastures, homesteads, fields, and gardens) recording ground cover, grass height, flower abundance and types, tree abundance and recorded elevation, temperature, light intensity, wind speed, wind direction, and humidity. Zero-inflated models, censored regression models, and PCAs were used to understand the influence of explanatory variables on bee community composition, abundance, and diversity. • Bee abundance was positively influenced by the number of plant species in flower (p < .0001). Bee abundance increased with increasing temperatures up to 28.5°C, but beyond this, temperature was negatively associated with bee abundance. Increasing wind speeds marginally decreased probability of finding bees. • Bee diversity was highest in fields, homesteads, and natural woodlots compared with other habitats, and the contributions of the genus Apis were disproportionately high across all habitats. The genus Megachile was mostly associated with homesteads, while Nomia was associated with grasslands. • Synthesis and applications. Our study suggests that some bee species could become more proliferous in certain habitats, thus compromising diversity and consequently ecosystem services. These results highlight the importance of setting aside bee-friendly habitats that can be refuge sites for species susceptible to land-use changes.
... Suitable abiotic conditions (local climatic conditions and topography) are also important for the survival of bees. Previous researches have shown that weather elements such as temperature, light intensity, wind speed, and rainfall may alter bee species behavior (Hennessy et al., 2020;Rajkhowa & Deka, 2013) and hence ultimately influencing bee abundance, diversity, and distribution. Different bee species have different weather preferences and also take less than a minute to react to weather changes (Riessberger & Crailsheim, 1997). ...
... Different bee species have different weather preferences and also take less than a minute to react to weather changes (Riessberger & Crailsheim, 1997). However, most studies on weather effects on bees are biased toward laboratory investigations (Cooper et al., 1985;Hennessy et al., 2020), which cannot assess the synergistic impacts of habitat type and weather parameters, yet habitats due to their unique structure and composition may buffer or increase adverse effects of weather conditions. This information is important in guiding management decisions in the development of area-specific conservation efforts of greater impact. ...
... The probability of finding bees marginally decreased with increases in wind speeds, which is understandable as many findings have shown the negative impact of wind speed on flight performance (Combes & Dudley, 2009) and landing of bees (Chang et al., 2016) with implications on energy costs. Due to predicted increases in wind speeds associated with deforestation and climate change (Walker & Crane, 2000), new technologies for minimizing the impacts of strong winds on bees are imperative such as placing hives in sheltered locations (Hennessy et al., 2020) for domesticated species and windbreaks as suggested by Moisan-DeSerres et al. (2015) to safeguard native bee species that cannot tolerate high wind speeds such as the Lipotriches, which were more associated with low wind speeds. Different tolerance levels of bee species to wind speeds are mainly due to diverse body sizes and morphologies (Combes & Dudley, 2009). ...
... (C) We investigate and quantify how the prediction of a single variable, e.g., CO 2 concentration, is affected by the inclusion of additional regressors (e.g., temperature, humidity). The multivariable time series is used to run forecasting models and risk assessments [28][29][30][31], issue warnings and alert signals and make historical analysis with applied confidence intervals. ...
... There are dozens of machine learning techniques that can be applied to a time series problem, to interpret the series and extract information about underlying relationships between the target series and the regressors (e.g., bee counts or CO 2 concentration), and this work is not about finding the optimal one. Deep, learning techniques, transformers, recurrent neural networks (RNNs), multivariate linear regression (MLR) and a long shortterm memory neural networks (LSTM), gradient boosted trees, ARIMA, support vector machines, autoregressive models are typically used in time series' forecasting [28][29][30][31]. In this work we are mainly interested in high interpretability, and therefore we chose an additive regression model, with three principal components (trend, seasonality and cyclicity). ...
Article
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We present a custom platform that integrates data from several sensors measuring synchronously different variables of the beehive and wirelessly transmits all measurements to a cloud server. There is a rich literature on beehive monitoring. The choice of our work is not to use ready platforms such as Arduino and Raspberry Pi and to present a low cost and power solution for long term monitoring. We integrate sensors that are not limited to the typical toolbox of beehive monitoring such as gas, vibrations and bee counters. The synchronous sampling of all sensors every 5 minutes allows us to form a multivariable time series that serves in two ways: (a) it provides immediate alerting in case a measurement exceeds predefined boundaries that are known to characterize a healthy beehive, and (b) based on historical data predict future levels that are correlated with hive’s health. Finally, we demonstrate the benefit of using additional regressors in the prediction of the variables of interest. The database, the code and a video of the vibrational activity of two months are made open to the interested readers.
... C) We investigate and quantify how the prediction of a single variable e.g., CO2 concentration is affected by the inclusion of additional regressors (e.g., temperature, humidity). The multivariable timeseries is used to run forecasting models and risk assessments [28][29][30][31], issue warnings and alert signals and make historical analysis with applied confidence intervals. Our aim is to offer technological services that will allow beekeepers and researchers to actively participate in colony surveillance programs accurately and responsively, having less cost than the labor costs for inspecting the hive. ...
... There are dozens of machine learning techniques that can be applied to a timeseries problem, to interpret the series and extract information about underlying relationships between the target series and the regressors (e.g., bee counts or CO2 concentration), and this work is not about finding the optimal one. Deep, learning techniques, transformers, recurrent neural networks (RNNs), multivariate linear regression (MLR) and a long short-term memory neural networks (LSTM), gradient boosted trees, ARIMA, support vector machines, autoregressive models are typically used in timeseries' forecasting [28][29][30][31]. In this work we are mainly interested in high interpretability, and therefore we choose an additive regression model, with three principal components (trend, seasonality and cyclicity). ...
Preprint
We present a custom platform that integrates data from several sensors measuring synchronously different variables of the beehive and wirelessly transmits all measurements to a cloud server. There is a rich literature on beehive monitoring. The choice of our work is not to use ready platforms such as Arduino and Raspberry Pi and to present a low cost and power solution for long term monitoring. We integrate sensors that are not limited to the typical toolbox of beehive monitoring such as gas, vibrations and bee counters. The synchronous sampling of all sensors every 5 minutes allows us to form a multivariable timeseries that serves two-ways: a) it provides immediate alerting in case a measurement exceeds predefined boundaries that are known to characterize a healthy beehive, and b) based on historical data predict future levels that are correlated with hive’s health. Finally, we demonstrate the benefit of using additional regressors in the prediction of the variables of interest. The database, the code and a video of the vibrational activity of two months are made open to the interested readers.
... Deviations of beelines could be associated with wind speeds and direction. Strong winds may force honeybees to drift from their flight paths (Hennessy et al., 2020). Honeybees face challenges in finding suitable flight paths through congested environments. ...
... Most studies on the impact of bioclimatic factors on honeybees were biased toward laboratory investigations (Hennessy et al., 2020) and this study helps to bridge the gap. An understating of honeybee distribution and possible factors influencing their distribution is important in understanding the level of protection needed and their vulnerability (Tarakini et al., 2021). ...
Article
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Species Distribution Models (SDM) play an essential role in establishing factors affecting honeybee species spatial population distribution and ensuring effective niche habitat protection. This study aimed to assess the precision of the triangulation bee lining technique in locating Apis mellifera scutellata colonies within wild habitats, locate A. m. scutellata colony site population distribution and develop a predictive model of A. m. scutellata habitat suitability using SDM algorithms within Hurugwe Safari Area (HSA)-Rifa section, northern Zimbabwe. A survey of A. m. scutellata was carried out between February and October 2019. The triangulation bee lining technique was used to track wild bees to their colony sites. The bee lining technique was evaluated to assess its precision in locating honeybee colonies. Ensemble models were used to develop a predictive suitability niche ecosystem for A. m. scutellata nesting sites. The study located wild honeybee colonies using the triangulation bee lining technique with an 18% accuracy. Bee colonies were found at a mean distance of 27.7 m ± 2.06 from triangulated points. The predicted suitable areas were primarily areas close to the water sources and low-lying areas. The study recommended the use of the triangulation honeybee hunting method in locating wild honeybee colonies for research purposes, wild bee colony inspection for pests and diseases and sustainable organic honey collection.
... Abiotic factors such as weather have also been identified amongst major factors influencing bee behavior and ultimately affecting their survival (Alqarni 2020;Schua 1952). Several studies have reported species tolerance to different microclimatic ranges of temperature (Souza-Junior et al. 2020), humidity, light intensity (Jones et al. 2020), wind speed ranges (Hennessy et al. 2020) beyond which these ranges have proven to be lethal. However, impacts of weather on bee activities have mainly been assessed in laboratories (Cooper et al. 1985;Hennessy et al. 2020) or at a landscape scale (St Clair et al. 2020). ...
... Several studies have reported species tolerance to different microclimatic ranges of temperature (Souza-Junior et al. 2020), humidity, light intensity (Jones et al. 2020), wind speed ranges (Hennessy et al. 2020) beyond which these ranges have proven to be lethal. However, impacts of weather on bee activities have mainly been assessed in laboratories (Cooper et al. 1985;Hennessy et al. 2020) or at a landscape scale (St Clair et al. 2020). Relatively less information exists on how weather influences foraging decisions made at a patch scale yet the information will give us an insight on how foraging strategies will change in the face of climate change. ...
Article
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This study aimed to evaluate the influence of crop type, cropping systems and weather elements on foraging behaviour of pollinators, which is imperative for designing pollinator friendly agricultural systems. Generalised linear models were used to assess foraging time and visitation frequency of the honey bee Apis mellifera scutellata and the stingless bee Hypotrigona gribodoi across monocultures and polyculture systems of butternut, dry bean and mustard at two garden sites in Zvimba district, Zimbabwe. A total of 120 bee visitations across the crops and 103.4 min of foraging bouts were recorded. The honey bee had longer foraging bouts periods in monoculture system, but there were no differences in the stingless bee. Across the two bee species, mustard had the longest foraging bouts, and least in dry beans. Foraging time generally decreased with increasing temperatures, but the decreases in polyculture systems were less severe for the honey bee. Only the honey bee foraging time was shorter in the presence of competitors. We therefore conclude that there are possible negative impacts of projected increases in temperature due to global warming and agricultural intensification on foraging behaviour of important pollinators such as bees.
... Temperature is a very important driver for plants and animals (Bishop et al., 2014;Peters et al., 2016), and can limit diversity by modulating their physiology (Brown et al., 2004) and the usability of resources and accelerate evolutionary and ecological rates (Classen et al., 2015). Other climatic variables can also underpin diversity, such as precipitation, which indirectly controls habitat productivity (Hawkins et al., 2003), and wind speed, which affects flight performance (Pasek, 1988) and disturbs pollination behavior (Hennessy et al., 2020). ...
... In fact, some bee (Nemésio & Vasconcelos, 2013) and ant (Dunn et al., 2009) species may prefer areas with a less seasonal precipitation regime. We found γ-diversity for bees and wasps to decrease in areas with lower temperatures and intense winds, which are variables that can negatively influence flight performance (Pasek, 1988) and disturbs pollination behavior (Hennessy et al., 2020). For wasps, γ-diversity also decreased with higher wind speeds, with a weak interaction with increasing precipitation, both variables that represent adverse weather conditions (Weisser et al., 1997) with increasing elevation (Perillo et al., 2017). ...
Article
Ancient tropical mountains are megadiverse, yet little is known about the distribution of their species. We aimed to disentangle the effects of latitudinal and elevational gradients on the distribution of species of Aculeata and to understand the effects of climatic variables across different spatial scales of diversity (α‐, γ‐, and β‐diversity). Campo rupestre in the Espinhaço Mountain Range, Southeast Brazil. Bees, wasps, and ants (Aculeata: Hymenoptera). We used a unique dataset built from sampling species of Aculeata at 24 study sites across 12 mountains, covering 1200 km from south to north and an elevational range of 1000 to 2000 m. We explored the elevational and latitudinal patterns of α‐ (site), γ‐ (mountain), and β‐diversity among samples at each location (βLocal). We also tested the effect of elevational range on β‐diversity in each mountain (βMountain) and, on a larger scale (βRegional), if β‐diversity is influenced by geographical and environmental distances. Finally, we tested whether climatic variables underpin the observed patterns. Latitude had no effect on diversity. We found a decrease in both site and mountain diversity and, only for bees, βLocal increased with elevation. Climatic variables (temperature, wind, and precipitation) and their interactions were important drivers of diversity, with temperature being the most important. Finally, βMountain increased with mountain elevation range, and βRegional increased with the geographical and environmental distances. Our results showed that variation in species richness and composition across mountains is strongly associated with elevational gradient, which showed stronger climatic variation than latitudinal gradient. Therefore, despite having narrow elevational ranges, the biogeographical effects of tropical mountains drive high diversity. Facing global climate changes, this limited elevational gradient may limit species range shifts, leading to severe biodiversity losses.
... Electronic beehive monitoring researchers have used sensors to measure internal and external temperature, humidity, atmospheric pressure, wind direction and speed, rainfall, shortwave radiation, weight, and traffic. While many researchers have investigated the relationship between traffic and weather (e.g., [10][11][12]) or weight and weather (e.g., [9,[13][14][15][16]), the literature on continuous beehive monitoring, with few notable exceptions (e.g., [6]), has a dearth of studies on the relationship of hive weight and traffic. This problem is fundamental, because hive weight and traffic affect many aspects of colony dynamics. ...
Article
Full-text available
The relationship between beehive weight and traffic is a fundamental open research problem for electronic beehive monitoring and digital apiculture, because weight and traffic affect many aspects of honeybee (Apis mellifera) colony dynamics. An investigation of this relationship was conducted with a nondisruptive two-sensor (scale and camera) system on the weight and video data collected on six Apis mellifera colonies in Langstroth hives at the USDA-ARS Carl Hayden Bee Research Center in Tucson, Arizona, USA, from 15 May to 15 August 2021. Three hives had positive and two hives had negative correlations between weight and traffic. In one hive, weight and traffic were uncorrelated. The strength of the correlation between weight and traffic was stronger for longer time intervals. The traffic spread and mean, when taken separately, did not affect the correlation between weight and traffic more significantly than the exact traffic counts from videos. Lateral traffic did not have a significant impact on weight.
... For example, greater air speeds will disperse the odors of plants and animals farther, but the resulting turbulence is likely to disrupt the spatial distribution of odor plumes, challenging the ability of organisms to navigate toward the odor source (i.e., anemotaxis; Murlis, 1997;Conover, 2007;Bingman and Moore, 2017). This tradeoff in signal propagation and efficacy is well-studied in insects, which optimize their flight paths in response to air speed while tracking odor plumes (Aluja et al., 1993;Cardé and Willis, 2008;Hennessy et al., 2020). At the same time, many mammals possess relatively complex olfactory systems, and they, too, are sensitive to variations in the aeroscape (Moulton, 1967;Svensson et al., 2014). ...
Article
Full-text available
Aeroscapes—dynamic patterns of air speed and direction—form a critical component of landscape ecology by shaping numerous animal behaviors, including movement, foraging, and social and/or reproductive interactions. Aeroecology is particularly critical for sensory ecology: air is the medium through which many sensory signals and cues propagate, inherently linking sensory perception to variables such as air speed and turbulence. Yet, aeroscapes are seldom explicitly considered in studies of sensory ecology and evolution. A key first step towards this goal is to describe the aeroscapes of habitats. Here, we quantify the variation in air movement in two successional stages (early and late) of a tropical dry forest in Costa Rica. We recorded air speeds every 10 seconds at five different heights simultaneously. Average air speeds and turbulence increased with height above the ground, generally peaked midday, and were higher overall at the early successional forest site. These patterns of lower air speed and turbulence at ground level and overnight have important implications for olfactory foraging niches, as chemotaxis is most reliable when air movement is low and steady. We discuss our results in the context of possible selective pressures and observed variation in the foraging ecology, behaviors, and associated morphologies of resident vertebrates, with a focus on mammals. However, these data also have relevance to researchers studying socioecology, invertebrate biology, plant evolution, community ecology and more. Further investigation into how animals use different forest types, canopy heights and partition activities across different times of day will further inform our understanding of how landscape and sensory ecology are interrelated. Finally, we emphasize the timeliness of monitoring aeroecology as global wind patterns shift with climate change and human disturbance alters forest structure, which may have important downstream consequences for biological conservation.
... In line with the conclusions of previous studies investigating the links between climate and the diversity of wild bee communities (Hennessy et al., 2020;Marshall et al., 2018), the following climate variables were collected at each study location: precipitation (in mm), average temperature (in Celsius), surface net solar radiation (in J/m 2 ), surface air pressure (in hPa), and average wind speed (in m/s) per month (Table A.6). This data was collected using ERA5-Land database ranging from March to September (following Bui et al., 2021), from 2006 to 2019, and averaged for the total period (Muñoz-Sabater, 2019). ...
Article
Climate, landscape composition, management practice, and wild bee pollination are all variables thought to play significant roles in commercial apple production. However, how these variables affect production efficiency under field-realistic conditions has not been investigated at large geographical scales. We combined intensive standardized field surveys (using netting and pan traps) with structural equation models to explore the relative impact of biotic and abiotic variables on bee diversity, apple yield and fruit quality, and their ability to represent reliable proxies of apple production. Here we show that apple yields are mainly driven by management practice, without evidence for a significantly superior contribution by managed honey bees. Total wild bee diversity, while negatively correlated with honey bee dominance, promoted apple quality by enhancing seed set number. Our study demonstrates that even across a broad geographical range there is potential to harness wild bee diversity as nature-based solution and as a substitute to an exclusive reliance on honey bees in the context of commercial apple production.
... PLoS ONE 17(3): e0265911. https:// environments containing unpredictable winds and cluttered vegetation, each of which can pose distinct challenges to flight [5][6][7][8]. Furthermore, the heterogeneity of natural landscapes results in multiple route options for bees, so the unique behavioral choices made by individual bees can dictate the microhabitat (e.g., wind, clutter) that bees encounter, and thus the specific flight challenges that they must overcome [9]. ...
Article
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Bees flying through natural landscapes frequently encounter physical challenges, such as wind and cluttered vegetation, but the influence of these factors on flight performance remains unknown. We analyzed 548 videos of wild-caught honeybees (Apis mellifera) flying through an enclosure containing a field of vertical obstacles that bees could choose to fly within (through open corridors, without maneuvering) or above. We varied obstacle field height and wind condition (still, headwinds or tailwinds), and examined how these factors affected bees’ flight altitude, ground speed, and side-to-side casting motions (lateral excursions). When obstacle fields were short, bees flew at altitudes near the midpoint between the tunnel floor and ceiling. When obstacle fields approached or exceeded this midpoint, bees tended to increase their altitude, but they did not always avoid flying through obstacles, despite having the freedom to do so. Bees that flew above the obstacles exhibited 40% faster ground speeds and 36% larger lateral excursions than bees that flew within the obstacle fields. Wind did not affect flight altitude, but bees flew 12–19% faster in tailwinds, and their lateral excursions were 19% larger when flying in headwinds or tailwinds, as compared to still air. Our results show that bees flying through complex environments display flexibility in their route choices (i.e., flying above obstacles in some trials and through them in others), which affects their overall flight performance. Similar choices in natural landscapes could have broad implications for foraging efficiency, pollination, and mortality in wild bees.
... The mentioned works include important factors indicating their individual value, such as temperature and humidity, and their influence on swarming or feeding [15,16], ref. [17][18][19] vibration and sound [20][21][22][23][24][25][26], the presence of gases [27,28], rain and wind [29], the amount and intensity of daylight, and UV and IR radiation indices; this paper covers all these factors together. There are also time series of recording and data collection, which were performed in hourly or daily time series in the mentioned works. ...
Article
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A significant number of recent scientific papers have raised awareness of changes in the biological world of bees, problems with their extinction, and, as a consequence, their impact on humans and the environment. This work relies on precision beekeeping in apiculture and raises the scale of measurement and prediction results using the system we developed, which was designed to cover beehive ecosystem. It is equipped with an IoT modular base station that collects a wide range of parameters from sensors on the hive and a bee counter at the hive entrance. Data are sent to the cloud for storage, analysis, and alarm generation. A time-series forecasting model capable of estimating the volume of bee exits and entrances per hour, which simulates dependence between environmental conditions and bee activity, was devised. The applied mathematical models based on recurrent neural networks exhibited high accuracy. A web application for monitoring and prediction displays parameters, measured values, and predictive and analytical alarms in real time. The predictive component utilizes artificial intelligence by applying advanced analytical methods to find correlation between sensor data and the behavioral patterns of bees, and to raise alarms should it detect deviations. The analytical component raises an alarm when it detects measured values that lie outside of the predetermined safety limits. Comparisons of the experimental data with the model showed that our model represents the observed processes well.
... Wind speed can have a negative effect on honeybee foraging (Howlett et al., 2013), while honeybee visitation to watermelon and apple trees has also been shown to decrease with increasing wind speeds (Pinzauti, 1986;Vicens and Bosch, 2000). This negative effect of elevated wind speeds has been linked to hesitancy in workers to take off during high winds (Hennessy et al., 2020) and increased resource handling times at flowers (Hennessy et al., 2021). However, some studies have found that honeybee numbers do not respond to changes in wind speed (Nielsen et al., 2017;Clarke & Robert, 2018). ...
Thesis
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Insect pollinators in Ireland have experienced substantial declines in recent decades, largely as the result of agricultural intensification and climate change. The foraging activity of flower-visiting insects can be heavily influenced by floral resource density and weather conditions, though often in contrasting ways. This study elucidated the effects of floral density and richness, and weather factors, including temperature, wind speed, relative humidity, and light intensity, on the foraging activity of bumblebees, honeybees, and hoverflies in a wildflower meadow setting at Rosemount Environmental Research Station, University College Dublin. This study further examined the effects of floral density at artificial stands of potted Sinapsis alba on pollinator foraging patterns. The effects of observation length and floral density on the proportion of pollinator surveys that returned zero counts were also investigated. Pollinator numbers were greatest at high floral density, both within observation plots and at artificial stands. Light intensity had a small but positive effect on the number of foraging pollinators in the wildflower meadow. Increasing observation length decreased the proportion of surveys that had zero counts for pollinators, with a faster rate of decrease at high floral density plots for social bees, but not for hoverflies. The observation length required to mitigate excess zero counts also varied depending on the floral density within the plot. By drawing attention to the benefits that dense floral resources can provide for pollinator populations, conservationists and stakeholders in agriculture may reap the rewards of establishing densely flowering areas on farmland, either as sown wildflower strips or stands of potted plants. Finally, by scaling observation times with floral densities, future pollinator foraging studies could mitigate excess zero counts and improve data collection efficiency.
... This flight of the visiting bee, in the space of vegetative architecture, represents more than a visible environmental service of harvesting and pollination, it establishes a link between the plants that the bees visit to stimulate their development and ensure their reciprocal survival through a tacit communication between both organisms [7,12,27]. This meaning explains a cognitive -neuroanatomical association where predictability as well as information storage coexist, one more operation within the bee functions [16,19,22,24,[28][29][30]. ...
... Wind variability represents one of the most important, and potentially most challenging, components of environmental complexity for flying animals. It is not well described how the find affects the flight activity and there appear to be no data directly measuring the effect of wind speed on the foraging rates of individual bees (Hennessy et al., 2020), but it is clear that strong wind prevents bees from active flying, or bees have to spend more energy for the foraging and flying processes. Despite being subjected to a wide range of speeds and turbulence intensities, some authors found that bees do not avoid foraging in windy conditions (Crall et al., 2017). ...
... Furthermore, the bumblebees in our experiment were tested in optimal environmental conditions. Environmental factors such as wind speed (Hennessy et al. 2020), extreme temperatures and humidity (Sanderson et al. 2015), and biotic stressors such as parasites (Gegear et al. 2006) could all interact with pesticide exposure to exacerbate the effects on foraging decisions. ...
Article
Bumblebees are important pollinators of agricultural crops and wildflowers, but many species are in decline. Neonicotinoid insecticides are the most commonly used insecticide globally and can have negative sublethal effects on bumblebee colony growth and reproduction. Individual bumblebees can visit hundreds to thousands of flowers a day to forage for their colony. As such, they are a model species for studying optimal foraging, and small impairments to an individual’s foraging decisions may have compounding effects on the colony’s nutritional intake. We exposed bumblebees (Bombus impatiens) to an acute, field-realistic dose of the neonicotinoid insecticide imidacloprid, before allowing them to forage on an artificial floral array. We found that neonicotinoid-exposed bumblebees made suboptimal foraging decisions, as they were more likely to visit flowers located further apart than control bees. This indicates that for a given flower patch, individual bees exposed to a neonicotinoid will likely use more energy and forage less efficiency than unexposed bees, although further studies that directly measure energetic cost are required to confirm this. Given the robust and growing body of evidence demonstrating negative sublethal effects of neonicotinoids on bees, sublethal assessments on non-Apis bees should be made mandatory within the regulatory process.
... Each mill was placed on non-glare green card, and providing a gap of 60 mm from the end of the mill arm (mill radius = 135 mm), we encircled each mill with a vertical border (border radius = 195 mm) of alternating black and white vertical stripes (Tosi et al., 2017; diameter of each stripe = 35 mm). The border (a) prevented potential interfering air currents, as wind speed has been shown to affect the hesitancy for worker flight take-off (Hennessy et al., 2020); (b) allowed relative isolation from neighbouring mills and (c) presented an identical visual stimulus to each tested worker, which can be a contributing factor in determining flight velocity (Baird et al., 2005). ...
Article
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The effects of environmental temperature on components of insect flight determine life‐history traits, fitness, adaptability and, ultimately, organism ecosystem functional roles. Despite the crucial role of flying insects across landscapes, our understanding of how temperature affects insect flight performance remains limited. Many insect pollinators are considered under threat from climatic warming. Quantifying the relationship between temperature and behavioural performance traits allows us to understand where species are operating in respect to their thermal limits, helping predict responses to projected temperature increases and/or erratic weather events. Using a tethered flight mill, we quantify how flight performance of a widespread bumblebee, Bombus terrestris, varies over a temperature range (12–30℃). Given that body mass constrains insect mobility and behaviour, bumblebees represent a useful system to study temperature‐mediated size dependence of flight performance owing to the large intra‐colony variation in worker body size they exhibit. Workers struggled to fly over a few hundred metres at the lowest tested temperature of 12℃; however, flight endurance increased as temperatures rose, peaking around 25℃ after which it declined. Our findings further revealed variation in flight capacity across the workforce, with larger workers flying further, longer, and faster than their smaller nestmates. Body mass was also positively related with the likelihood of flight, although importantly this relationship became stronger as temperatures cooled, such that at 12℃ only the largest workers were successful fliers. Our study thus highlights that colony foraging success under variable thermal environments can be dependent on the body mass distribution of constituent workers, and more broadly suggests smaller‐bodied insects may benefit disproportionately more from warming than larger‐bodied ones in terms of flight performance. By incorporating both flight endurance and likelihood of flight, we calculated a simple metric termed ‘temperature‐mediated foraging potential’ to gain a clearer understanding of how temperature may constrain colony foraging. Of our tested temperatures, 27℃ supported the highest potential, indicating that for much of the range of this species, higher mean daily temperatures as forecasted under climate warming will push colonies closer to their thermal optimum for flight. Subsequently, warming may have positive implications for bumblebee foraging returns and pollination provision. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.
... Generally, pollinator species may respond differently to weather changes (Fr€ und, Zieger, & Tscharntke, 2013). For example, pollinator activity of honey bees decreases during strong winds and at low temperatures, whereas bumblebees can continue foraging under colder temperatures (Fr€ und, Dormann, Holzschuh, & Tscharntke, 2013;Hennessy et al., 2020;Tuell & Isaacs, 2010). Furthermore, flowering can be reduced as well as dehiscence accelerated, and pollen germination, ovule fertilization, or pollen transfer impaired (Dorsey, 1920). ...
Article
Global pollinator declines and land-use change can lead to pollination limitation with implications for agricultural productivity. Hand pollination is used in agricultural production as a technique to manually pollinate crops. But the prevalence of hand pollination, as well as benefits and costs, remain unknown. We systematically reviewed the literature for examples, methods, drivers, and economic motivations of hand pollination. Furthermore, we discuss the risks, constraints, and opportunities of hand pollination. We found evidence for 20 hand-pollinated crops, including minor but also economically important crops (e.g. apple, oil palm, cacao). The lack of pollinators was the most important reason for the application of hand pollination (50% of crops), while insufficient proportion or proximity of pollinizers (8% of crops) and skewed sex ratio or dichogamy (8% of crops) were second most important. The main economic motivations for practicing or recommending hand pollination were to increase fruit set, and/or fruit quality (78% of crops). Hand pollination is practiced in large- and small-scale farming, home gardens, and greenhouses. Opportunities of hand pollination are the control of pollen origin and quantity, pollination timing and frequency as well as independence from environmental fluctuations. Farmers can increase yields, improve fruit quality, avoid fruit abortion, increase employment, and secure subsistence food. The main constraints of hand pollination are high labor inputs, high material costs, and required skills. Major risks of hand pollination include management ignoring pollinator conservation, high food prices, over-pollination, labor accidents, and unfair labor. We conclude that in the face of global change, hand pollination allows improved control of pollination and is likely to increase in importance. The benefits of hand pollination need to outweigh the costs and fair labor is essential. Altogether, hand pollination can be a valuable tool for crop systems where pollinators are absent or are not reliable for sustaining high-quality crop production.
... Because pollination is so important to plants, they adapt to be more appealing to pollinators [124,125]. Plants possess several means to attract bees, including flower color [126,127], flower motion as in the case of bumble bees [128], the type of plant cells (e.g., conical epidermal cells) as in bumble bees [129], visual and olfactory cues as in honey bees and apple pollination [130] and the production of nectar and pollen grains [131,132], as shown in Figure 1. Thus, plants play an important role in influencing the visitation rate of their pollinators [133]. ...
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Simple Summary: There is a rising demand for food security in the face of threats posed by a growing human population. Bees as an insect play a crucial role in crop pollination alongside other animal pollinators such as bats, birds, beetles, moths, hoverflies, wasps, thrips, and butterflies and other vectors such as wind and water. Bees contribute to the global food supply via pollinating a wide range of crops, including fruits, vegetables, oilseeds, legumes, etc. The economic benefit of bees to food production per year was reported including the cash crops, i.e., coffee, cocoa, almond and soybean, compared to self-pollination. Bee pollination improves the quality and quantity of fruits, nuts, and oils. Bee colonies are faced with many challenges that influence their growth, reproduction , and sustainability, particularly climate change, pesticides, land use, and management strength, so it is important to highlight these factors for the sake of gainful pollination. Citation: Khalifa, S.A.M.; Elshafiey, E.H.; Shetaia, A.A.; El-Wahed, A.A.A.; Algethami, A.F.; Musharraf, S.G.; AlAjmi, M.F.; Zhao, C.; Masry, S.H.D.; Abdel-Daim, M.M.; et al.
... Visual detection of a predator depends on the spectral sensitivity of the prey's eye (the ability of the eye to respond to specific wavelengths of the light spectrum 5 ), spatial acuity (the capacity to discriminate shape and pattern details 6 and temporal resolution (time taken to process visual information 5 ). Furthermore, abiotic factors such as wind or obstacles can add to the visual clutter in a habitat 7,8 and consequently hinder predator detection. ...
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Ambush predators depend on cryptic body colouration, stillness and a suitable hunting location to optimise the probability of prey capture. Detection of cryptic predators, such as crab spiders, by flower seeking wasps may also be hindered by wind induced movement of the flowers themselves. In a beach dune habitat, Microbembex nigrifrons wasps approaching flowerheads of the Palafoxia lindenii plant need to evaluate the flowers to avoid spider attack. Wasps may detect spiders through colour and movement cues. We tracked the flight trajectories of dune wasps as they approached occupied and unoccupied flowers under two movement conditions; when the flowers were still or moving. We simulated the appearance of the spider and the flower using psychophysical visual modelling techniques and related it to the decisions made by the wasp to land or avoid the flower. Wasps could discriminate spiders only at a very close range, and this was reflected in the shape of their trajectories. Wasps were more prone to making errors in threat assessment when the flowers are moving. Our results suggest that dune wasp predation risk is augmented by abiotic conditions such as wind and compromises their early detection capabilities.
... Data required to optimize bee foraging includes information and knowledge about a region -location, terrain, climate, local nectar and pollen plants, coverage of internet or mobile network; apiary size, bee species and their activities; weather conditions, especially precipitation and wind. There are also environmental conditions that affect a plant in terms of nectar production -air temperature, relative air humidity, rain, wind, sun lightning and it is intensity [26], [27]. There are typically regional beekeeping organizations, like Latvian Beekeeping Association and The British Beekeepers Association, responsible for delivering an overview about local plants, their flowering periods and productivity. ...
Conference Paper
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The monitoring and predictions of various multi-level states of honeybee colonies are performed using emerging Internet of Things technologies and data processing methods. It is become common to use multiple sensors and devices providing multi-modal data to monitor a single activity. Modern data analysis and data processing procedures include a step of data fusion in order to provide more accurate input data. This, however, requires implementation of machine learning and large data sets, whereas gathering large data sets of real time and observation data is a common problem for small to medium size apiaries. This why there are no real implementation of data fusion method in precision beekeeping field. The aim of this paper was to introduce the concept of data layering, which aims to solve the global precision beekeeping problems without implementation of machine learning. The concept was demonstrated within the scope of foraging optimization problem using three data sets: flowering calendar data, rainfall precipitation data and bee activity data.
... Traffic-generated turbulence at the road edge (gusts of wind equivalent to an average wind speed of approximately 16 km h -1 ; Bani-Hani et al., 2018) might disturb pollinators and is likely to make foraging more difficult (Hennessy et al., 2020). One study has considered this. ...
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1. To tackle pollinator declines, there is a major need to increase the quantity of flower‐rich habitats. Road verges offer one such opportunity but are exposed to diverse forms of pollution from roads and road traffic. 2. To inform management decisions, we carried out a broad initial assessment to establish if and how pollution affects the quality of road verges as pollinator foraging environments. We assessed the spatial distribution of pollution, flowers and pollinators in road verges, then used field experiments to simulate and measure the impacts of four ubiquitous and little studied forms of road pollution (noise, turbulence, dust and metals) on pollinator densities and foraging behaviour. 3. We found that pollinators in road verges were exposed to noise, turbulence, dust and metal pollution, which decreased with distance from the road edge but, with the exception of turbulence, extended more than 8 m into road verges. 4. Pollinator densities were lower closer to the road edge – particularly within first 2 m (55% lower than at 7‐9 m) – where pollution is greatest, despite a similar density and species richness of flowers. 5. Simulated turbulence deterred pollinators by causing intermittent disturbance (reducing visit duration by up to 54%), and some pollinator taxa preferentially avoided concentrations of metals that were more frequently found in flowers within 2 m of roads (resulting in up to 75% fewer visits), whilst noise and dust had no apparent effect. 6. Synthesis and applications. Pollinators in road verges are exposed to many forms of pollution, and we found impacts of roadside‐realistic levels of turbulence and metals on pollinator densities and foraging behaviour, which could be addressed by practical intervention. Although the findings suggest that road verges are largely suitable for pollinator conservation, management enhancements should prioritise areas more than 2 m from the road edge, and verges along roads with relatively lower traffic densities.
... The benefits of windbreaks are numerous and dependent on the windbreak's intended function. When designed for wind reduction purposes, these systems can create more favorable conditions that enhance field and orchard crop production (Osorio et al., 2018;Kort, 1988) (Table 1), improve crop quality and marketability by reducing damage caused from wind-blown particle abrasion (Norton, 1988) or fruit rubbing against other parts of the plant during high wind (Peri and Bloomberg, 2002;Norton, 1988), decrease premature fruit drop (Hodges and Brandle, 2006;Norton, 1988), reduce the spread of crop diseases like citrus canker (Tamang et al., 2010), reduce honey bee mortality during the winter (Hendrickson, 2015;Conrad, 2013), increase foraging of honey bees during times of high wind (Hennessy et al., 2020), increase livestock production during inclement weather (Anderson and Bird, 1993), reduce risk of livestock mortality during winter storm events (Brandle et al., 2004;Gregory, 1995), reduce soil erosion, increase water-use efficiency, reduce energy and heating costs (Dewalle and Heisler, 1988), and offer control of blowing snow, dust, odor, and chemical sprays (pesticides, herbicides, etc.) (Hand et al., 2019;Brandle et al., 2004;Laughlin, 1989). When used for non-wind purposes, windbreaks can provide shade for livestock, visual screening, aesthetics, recreational opportunities and wood and nontimber forest products (NTFPs) (Hand et al., 2019;Tyndall, 2009;Grala et al., 2008;Brandle et al., 2004). ...
Article
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Windbreaks are an agroforestry practice used to provide simultaneous economic, environmental and social benefits that occur when trees are deliberately integrated into an agroecosystem. To date, no systematic review has been conducted on windbreak adoption in the U.S., which is needed to assess whether broader trends exist that may affect future research, extension delivery and policy development. This synthesis covers windbreak adoption studies in the U.S. from the earliest identified study in 1949 through 2020. A key finding from this synthesis is that producers use windbreaks on agricultural lands mostly for indirect economic benefits (soil erosion control, livestock protection, wind protection and snow control). This is followed by direct agricultural benefits (increased crop and livestock production) and intrinsic values (aesthetics and wildlife habitat). Direct economic benefits from forestry (timber and non-timber forest products) were often ranked last, despite most producers utilizing their windbreak trees for some economic gain. Windbreak satisfaction was also found to be high among U.S. producers (72–99%), with the beneficial functions varying by windbreak type (field, livestock, and farmstead). The main drivers causing producers to remove windbreaks were poor condition, age, and conflict with farming practices, while the primary reasons for non-adoption of windbreaks were lack of land and windbreak upkeep. Key information gaps needing further investigation include a greater understanding of producer-reported challenges and management activities associated with windbreak planting and maintenance, identifying and monetizing windbreak systems capable of producing marketable products, and valuation of ecosystem services provided by windbreaks over space and time and the potential for developing those markets. Link to open access article: https://doi.org/10.1016/j.agsy.2020.103032
... Wind has also been shown to affect insect-dispersed pollination, but the direction is unclear. Young et al. (2018) found that wind positively affected bee-pollination, while Hennessy et al. (2020) found that the rate of bee foraging decreased with wind speed. Surrounding vegetation can also affect insect-dispersed pollen dispersal, both positively (Van Geert et al., 2014) and negatively (Vamosi et al., 2006). ...
Article
Premise: Pollen dispersal, the main component of overall plant gene flow, generally decreases with increasing distance from the pollen source, but the pattern of this relationship may differ among sites. Although site-based differences in pollen dispersal may lead to over- or underestimation of gene flow, no studies have investigated pollen dispersal patterns among differing urban site types, despite the incongruent range of habitats in urban areas. Methods: We used paternity assignment to assess pollen dispersal patterns in a wind-pollinated species (waterhemp; Amaranthus tuberculatus) and in an insect-pollinated species (tomato; Solanum lycopersicum) in experimental arrays at four disparate sites (two roof-level sites, two ground-level sites) in the New York (New York, USA) metropolitan area. Results: The number of seeds or fruits, a proxy for the number of flowers pollinated, decreased with increasing distance from the pollen donors at all sites for both species. However, the mean number of Amaranthus tuberculatus seeds produced at a given distance differed two-fold among sites, while the slope of the relationship between Solanum lycopersicum fruit production and distance differed by a factor of four among sites. Conclusions: Pollen dispersal patterns may differ substantially among sites, both in the amount of pollen dispersed at a given distance and in the proportional decrease in pollen dispersal with increasing distance, and these effects may act independently. Accordingly, the capacity of plant species to adapt to climate change and other selection pressures may be different from predictions based on pollen dispersal patterns at a single location.
... One previous experiment examined the separate effects of controlled flower motion and wind on foraging behavior (e.g. flower visitation rate) in honeybees, and found that the most notable effects were due to wind, although the combination of wind and flower motion was not examined (Hennessy et al., 2020). ...
Article
Bees often forage in habitats with cluttered vegetation and unpredictable winds. Navigating obstacles in wind presents a challenge that may be exacerbated by wind-induced motions of vegetation. Although wind-blown vegetation is common in natural habitats, we know little about how bees’ strategies for flying through clutter are affected by obstacle motion and wind. We filmed honeybees, Apis mellifera, flying through obstacles in a flight tunnel with still air, headwinds or tailwinds. We tested how their ground speeds and centering behavior (trajectory relative to the midline between obstacles) changed when obstacles were moving vs. stationary, and how bees’ approach strategies affected flight outcome (successful transit vs. collision). We found that obstacle motion affects ground speed: bees flew slower when approaching moving vs. stationary obstacles in still air but tended to fly faster when approaching moving obstacles in head- or tailwinds. Bees in still air reduced their chances of colliding with obstacles (whether moving or stationary) by reducing ground speed - whereas flight outcomes in wind were not associated with ground speed, but rather with improvement in centering behavior during the approach. We hypothesize that in challenging flight situations (e.g., navigating moving obstacles in wind), bees may speed up to reduce the number of wing collisions that occur if they pass too close to an obstacle. Our results show that wind and obstacle motion can interact to affect flight strategies in unexpected ways, suggesting that wind-blown vegetation may have important effects on foraging behaviors and flight performance of bees in natural habitats.
... On the one hand, climate affects vegetation development, thus determines the availability and quality of floral resources for bees (OGILVIE et al., 2017). On the other hand, daily weather conditions can affect bee foraging behaviors directly, i.e., by temperature (AUBLET et al., 2009;COMBA, 1999), rain (HE et al., 2016), but also potentially by wind (COMBA, 1999;HENNESSY et al., 2020). ...
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Bees are essential pollinators and their protection is relevant to secure biodiversity and agricultural production. MonViA-project members and partners collaborate in monitoring projects to develop effective policies to support biodiversity in Germany. In the current case-study, the impact of climate on honey bee population performance was assessed. We modeled year-to-year Central-European honey yield changes and found + 1°C temperature change to stimulate annual honey yield by + 0.9 kg per colony, and + 100 mm precipitation to reduce honey yields – 0.4 kg. In regard to different climate change scenarios for Germany, our modelling suggests a potential + 0.4 to + 0.8 kg honey yield gain per colony in 2050, as compared to 2020. We conclude that the German honey bee population may benefit by rising temperatures. We discuss how bee performance is linked to weather and how our analysis would be strengthened by including more data, with a higher temporal and spatial resolution, i.e., intra-annually and -nationally. Pollinator trend monitoring should be extended with analyses that include e.g., extreme weather conditions, disease loads, availability of floral resource, beekeeping practice, land use and landscape structure.
Preprint
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Insect pollination by both managed and unmanaged bees is a highly valued ecosystem service that ensures plant reproduction and the production of high-quality crops. Bee activity is known to be influenced by the weather, and as the global climate continues to change, the flying frequency and foraging behaviour of bees may also change. To maximize the benefits of pollination in a changing world we must first understand how current weather conditions influence the activity of both unmanaged and managed bees. This is of particular interest in a country such as Ireland where inclement weather conditions are nominally sub-optimal for foraging. We observed honeybee (Apis mellifera; largely managed) and buff-tailed bumblebee (Bombus terrestris; largely unmanaged) colonies across a variety of weather conditions within seven apple orchards to determine how four weather variables (temperature, relative humidity, solar radiation, wind) influence the flight activity of each species. Our results indicate bumblebees could compensate for low honeybee activity in inclement conditions, which supports the theory that pollinator diversity provides resilience. This may be particularly important in management of pollinators in crops that flower in the spring when weather is more variable. We found pollen-foraging individuals in both species increase with temperature, but this rate decreases with humidity. On the whole honeybees are more sensitive to changes in weather than bumblebees and could be more predisposed to changes in future within-day weather conditions.
Article
The response of bees to changing environmental temperatures has implications for pollination in natural and agricultural systems, with rising average temperatures and increased environmental stochasticity predicted to cause pollinator population declines. A growing body of evidence for the role of native bees in crop pollination suggests that understanding the temperatures at which bees are active is important for maintaining agricultural productivity under climate change. This study used two methods to sample bees at strawberry farms in south‐eastern Australia, matching activity observations with microclimate temperature to understand how temperature impacts bee activity. Apart from Apis mellifera (introduced), two native bees were identified, Lasioglossum spp. and Exoneura robusta. Apis mellifera was the most abundant species across all environmental temperatures, and E. robusta the least. Visual and sweep‐netting survey results found activity temperature range was broader for A. mellifera (16.21–41.05°C) than Lasioglossum (16.49–38.91°C) and E. robusta (26–38.82°C). The results suggest that activity temperature varies among bee species, with potential implications for community composition and plant pollination under climate change.
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Bees flying through natural landscapes encounter physical challenges, such as wind and cluttered vegetation. The influence of these factors on the flight performance of bees remains unknown. We analyzed 548 videos of wild-caught honeybees ( Apis mellifera ) flying through an enclosure containing a field of vertical obstacles that bees could fly within (through open corridors, without maneuvering) or above. We examined how obstacle field height, wind presence and direction (headwinds or tailwinds) affected altitude, ground speed, and side-to-side casting (lateral excursions) of bees. When obstacle fields were short, bees flew at altitudes near the midpoint between the tunnel floor and ceiling. When obstacle fields approached or exceeded this midpoint, bees typically, but not always, increased their altitudes to fly over the obstacles. Bees that flew above the obstacle fields exhibited 40% faster ground speeds and 36% larger lateral excursions than bees that flew within the obstacle fields, likely due to the visual feedback from obstacles and narrow space available within the obstacle field. Wind had a strong effect on ground speed and lateral excursions, but not altitude. Bees flew 12-19% faster in tailwinds than in the other wind conditions, but their lateral excursions were 19% larger in any wind, regardless of its direction, than in still air. Our results show that bees flying through complex environments display flexible flight behaviors (e.g., flying above versus within obstacles), which affect flight performance. Similar choices in natural landscapes could have broad implications for foraging efficiency, pollination, and mortality in wild bees.
Article
Wind is an understudied environmental variable capable of having profound impacts upon the foraging behaviour of flying organisms. We investigated the effects of wind and temperature on honey bees, Apis mellifera, foraging on two plant varieties, Lavandula x intermedia ‘Grosso’ and Origanum vulgare to determine how wind influences foraging behaviour and whether responses differ between the plant varieties. Fans and an artificial wind break were used to generate wind speeds from 0 to 3.5 m/s with the following behaviours examined in a minute of foraging: number of flower visits, handling time per flower, interflower flight duration and proportion of flowers walked to. Flower movement was quantified using video footage and imageJ tracking software. Bees visited significantly fewer flowers with increasing wind speed on both plant varieties, with an average decrease of 38% between the lowest and highest wind speeds. However, the reduction was significantly steeper when foraging on O. vulgare. The reduction was due to an increase in handling time on both varieties, with interflower flight duration unaffected. Temperature had no effect on flower visit rate for either plant variety. The only behaviour influenced by flower movement was handling time, which was found to increase with flower movement. However, this increase did not result in fewer flower visits. Our results support previous work on artificial flowers which determined that the direct effect of wind on the bee influences foraging efficiency and behaviour more than the indirect effect of flower movement.
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Global climate model simulations from the 'Half a degree Additional warming, Prognosis and Projected Impacts' (HAPPI) project were used to assess how wind power generation over Europe would change in a future world where global temperatures reach 1.5 °C above pre-industrial levels. Comparing recent historical (2006–2015) and future 1.5 °C forcing experiments highlights that the climate models demonstrate a northward shift in the Atlantic jet, leading to a significant (p < 0.01) increase in surface winds over the UK and Northern Europe and a significant (p < 0.05) reduction over Southern Europe. We use a wind turbine power model to transform daily near-surface (10 m) wind speeds into daily wind power output, accounting for sub-daily variability, the height of the turbine, and power losses due to transmission and distribution of electricity. To reduce regional model biases we use bias-corrected 10 m wind speeds. We see an increase in power generation potential over much of Europe, with the greatest increase in load factor over the UK of around four percentage points. Increases in variability are seen over much of central and northern Europe with the largest seasonal change in summer. Focusing on the UK, we find that wind energy production during spring and autumn under 1.5 °C forcing would become as productive as it is currently during the peak winter season. Similarly, summer winds would increase driving up wind generation to resemble levels currently seen in spring and autumn. We conclude that the potential for wind energy in Northern Europe may be greater than has been previously assumed, with likely increases even in a 1.5 °C warmer world. While there is the potential for Southern Europe to see a reduction in their wind resource, these decreases are likely to be negligible.
Article
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The fitness and survival of organisms ultimately depend on their feeding. Therefore, foraging behaviors should be selected to maximize cost-benefit ratio. Wind may restrict and modify animal movements increasing the cost of foraging, especially when the animal carries resources that intercept wind. We quantified the effect of wind on the foraging of leaf-cutting ants and evaluated whether this effect varies with 1) leaf fragment traits, such as area, mass, and shape, and 2) the characteristics of the foraging trail system. We also tested whether these ants show a short-term response to wind by selecting loads with characteristics that reduce wind interception, and a long-term response, by arranging the spatial design of the trail system in a way that reduces that effect. We found that in windy conditions, the speed of loaded ants was reduced by 55%, and ants were blown off the trail 28 times more than in windless conditions. However, wind only affected ants walking along trails that were perpendicular to wind direction or parallel upwind. Wind effect increased with area, mass, and shape of loads. At the short term, ants reduced the negative effect of wind by selecting smaller, lighter, or more elongated loads. However, trails showed no particular spatial distribution in relation to wind direction. This is the first study that quantifies the negative consequences of wind on leaf-cutting ants’ foraging and reports behaviors that can reduce this effect. Our work illustrates how short-term behavioral responses can mitigate the negative effect of an understudied environmental factor on ant foraging.
Article
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We quantified insect visitation rates by counting how many flowers/inflorescences were probed per unit time for five plant species (four native and one garden: California lilac, bramble, ragwort, wild marjoram, and ivy) growing in Sussex, United Kingdom, by following individual insects (n=2987) from nine functional groups (honey bees (Apis mellifera), bumble bees (Bombus spp.), hoverflies, flies, butterflies, beetles, wasps, non-Apidae bees, and moths). Additionally, we made a census of the insect diversity on the studied plant species. Overall we found that insect groups differed greatly in their rate of flower visits (P<2.2e-16), with bumble bees and honey bees visiting significantly more flowers per time (11.5 and 9.2 flowers/minute, resp.) than the other insect groups. Additionally, we report on a within-group difference in the non-Apidae bees, where the genus Osmia, which is often suggested as an alternative to honey bees as a managed pollinator, was very speedy (13.4 flowers/minute) compared to the other non-Apidae bees (4.3 flowers/minute). Our census showed that the plants attracted a range of insects, with the honey bee as the most abundant visitor (34%). Therefore, rate differences cannot be explained by particular specializations. Lastly, we discuss potential implications of our conclusions for pollination.
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There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost-effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost-effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.
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Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple, interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future. Copyright © 2015, American Association for the Advancement of Science.
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Our understanding of how variable wind in natural environments affects flying insects is limited, because most studies of insect flight are conducted in either smooth flow or still air conditions. Here, we investigate the effects of structured, unsteady flow (the von Karman vortex street behind a cylinder) on the flight performance of bumblebees (Bombus impatiens). Bumblebees are "all-weather" foragers and thus frequently experience variable aerial conditions, ranging from fully mixed, turbulent flow to unsteady, structured vortices near objects such as branches and stems. We examined how bumblebee flight performance differs in unsteady versus smooth flow, as well as how the orientation of unsteady flow structures affects their flight performance, by filming bumblebees flying in a wind tunnel under various flow conditions. The three-dimensional flight trajectories and orientations of bumblebees were quantified in each of three flow conditions: (1) smooth flow, (2) the unsteady wake of a vertical cylinder (inducing strong lateral disturbances) and (3) the unsteady wake of a horizontal cylinder (inducing strong vertical disturbances). In both unsteady conditions, bumblebees attenuated the disturbances induced by the wind quite effectively, but still experienced significant translational and rotational fluctuations as compared to flight in smooth flow. Bees appeared to be most sensitive to disturbance along the lateral axis, displaying large lateral accelerations, translations, and rolling motions in response to both unsteady flow conditions, regardless of orientation. Bees also displayed the greatest agility around the roll axis, initiating voluntary casting maneuvers and correcting for lateral disturbances mainly through roll in all flow conditions. Both unsteady flow conditions reduced the upstream flight speed of bees, suggesting an increased cost of flight in unsteady flow, with potential implications for foraging patterns and colony energetics in natural, variable wind environments.
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White clover (Trifolium repens L.) is grown throughout New Zealand in pasture and as a seed crop in the South Island. This investigation was conducted to determine the number of honey bee visits necessary to fully pollinate white clover flowers; the number of foraging honey bees per hectare required to reach the maximum seed number per floret; and to assess the level of white clover pollination in Canterbury. The theoretical maximum number of seeds that can be produced per white clover floret is six, based on the number of ovules present. Based on the number of seeds resulting from a single bee visit (mean = 1.24), it is calculated that in an 8 h foraging day, 19,420 bees would be required per hectare to reach maximum seed number per floret, assuming that no floret received more visits than required. Bee activity was assessed at two clover sites with an estimated 20,124 foraging bees per hectare. This number should have been enough to reach maximum seed number per floret. However, seed set in these fields was approximately half of its theoretical potential.
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By extracting energy from the highly dynamic wind and wave fields that typify pelagic habitats, albatrosses are able to proceed almost exclusively by gliding flight. Although energetic costs of gliding are low, enabling breeding albatrosses to forage hundreds to thousands of kilometers from their colonies, these and time costs vary with relative wind direction. This causes albatrosses in some areas to route provisioning trips to avoid headwind flight, potentially limiting habitat accessibility during the breeding season. In addition, because female albatrosses have lower wing loadings than males, it has been argued that they are better adapted to flight in light winds, leading to sexual segregation of foraging areas. We used satellite telemetry and immersion logger data to quantify the effects of relative wind speed, sex, breeding stage, and trip stage on the ground speeds ( Vg) of four species of Southern Ocean albatrosses breeding at South Georgia. Vg was linearly related to the wind speed component in the direction of flight ( Vwf), its effect being greatest on Wandering Albatrosses Diomedea exulans, followed by Black-browed Albatrosses Thalassarche melanophrys, Lightmantled Sooty Albatrosses Phoebatria palpebrata, and Gray-headed Albatrosses T. chrysostoma. Ground speeds at Vwf = 0 were similar to airspeeds predicted by aerodynamic theory and were higher in males than in females. However, we found no evidence that this led to sexual segregation, as males and females experienced comparable wind speeds during foraging trips. Black-browed, Gray-headed, and Light-mantled Sooty Albatrosses did not engage in direct, uninterrupted, bouts of flight on moonless nights, but Wandering Albatrosses attained comparable Vg night and day, regardless of lunar phase. Relative flight direction was more important in determining Vg than absolute wind speed. When birds were less constrained in the middle stage of foraging trips, all species flew predominantly across the wind. However, in some instances, commuting birds encountered headwinds during outward trips and tail winds on their return, with the result that Vg was 1.0-3.4 m/s faster during return trips. This, we hypothesize, could result from constraints imposed by the location of prey resources relative to the colony at South Georgia or could represent an energy optimization strategy.
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The diel and seasonal activity patterns of salmonids are predominantly governed by the annual changes in photoperiod and temperature. In winter salmonids become increasingly nocturnal, hiding in refuges by day but emerging to feed at night. This behaviour may be linked to either one of the controlling influences mentioned above or to an inherent annual rhythm. Here we show that the previously described switch by Altantic salmon (Salmo salar L.) from predominantly diurnal to nocturnal activity in winter also occurs at other times of the year in response to low, "winter" temperatures; this is demonstrated both in laboratory experiments and by field observations in glacial rivers. This indicates that there is no underlying inherent annual rhythm to this behaviour nor any photoperiodic influence. Furthermore, in the laboratory experiment this temperature-dependent shift to nocturnalism was explained by a suppression of daytime activity rather than an increase in activity at night.
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The influence of rainfall on the foraging patterns of Great Tit Parus major parents while feeding chicks at the nest was investigated using automated nest monitoring with electronic balances and photography. Great Tit females significantly reduced their visit rate to the nest during all rain intensities, while male feeding frequency did not significantly change. The female response was probably due to increased brooding requirements of young since the reduction in visit rate was most apparent at early nestling stages. At this time the chicks are incapable of thermoregulation and females significantly increased their nestbox occupancy time during rain. There was no indication that parents were compensating for periods of female inactivity during rainfall: there was no significant increase in visit rate following rainfall and no significant increase in prey size delivered to the nest during periods of rain. An analysis of data from six consecutive years revealed that the proportion of wet hours within the first week of the nestling period significantly influenced fledging weight in this species.
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The foraging activity of pollinator insects in relation to weather factors (ambient temperature, solar radiation, relative humidity, and wind speed) was studied in an apple orchard with special reference to two managed bee species, Osmia cornuta (Latreille) and Apis mellifera L. Over the range of observed weather values, A. mellifera activity was significantly dependent on temperature, solar radiation, and wind speed; O. cornuta activity was dependent on solar radiation and wind speed. These results were confirmed through video recordings at one O. cornuta nesting shelter and one A. mellifera hive. For both species, daily activity started at lower temperatures than it ceased, whereas solar radiation did not differ between these two events. In general, O. cornuta was active from 10 to 12°C and 200 w/m2, and A. mellifera from 12 to 14°C and 300 w/m2. O. cornuta was the only bee species seen visiting apple flowers under strong wind or light rain. Because of its greater tolerance to inclement weather, O. cornuta pollinated apple flowers for longer periods (both daily and seasonally) than other flower visitors.
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Seasonally breeding predators, which are limited in the time available for provisioning young at a central location, and by the fasting abilities of the young, are likely to maximize energy delivery to the young by maximizing the rate of energy delivery averaged over the whole period of investment. Reduction in food availability or increased foraging costs will alter the optimal behavior of individuals. This study examined the behavioral adaptations of a diving predator, the Antarctic fur seal, to increased foraging costs during lactation. One group of mothers (n=5, treatment) was fitted with additional drag to increase the cost of transport in comparison with a control group (n=8). At the scales of the individual dives, the treatment group made more shorter, shallower (< 30 m) dives. Compensation for slower swimming speeds was achieved by diving at a steeper angle. Overall, diving behavior conformed to several specific theoretical predictions but there were also departures from theory, particularly concerning swimming speed during diving. Diving behavior appears to be adjusted to maximize the proportion of time spent at the bottom of dives. At the scale of diving bouts, no difference was observed between the treatment and control groups in terms of the frequency and duration of bouts and there was also no difference between the two groups in terms of the proportion of time spent diving. At the scale of complete foraging cycles, time taken to return to the pup was significantly longer in the treatment group but there was no difference in the rate of delivery of energy (measured from pup growth rate) to the pups in each group. Since mothers in the treatment group did not use significantly more body reserves, we conclude that behavioral adjustments at the scale of individual dives allowed mothers in the treatment group to compensate for the additional foraging costs. Pup growth rate appears to be less sensitive to the foraging conditions experienced by mothers than foraging trip duration.
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As first described by Aristotle, honey bee (Apis mellifera) workers show a strong tendency to visit flowers of only one type during a foraging trip. It is known that workers rapidly learn a flower colour when rewarded with artificial nectar (sucrose solution). However, some previous studies report that the degree of constancy after training is unaffected by reward quantity and quality when bees are tested in an array of artificial flowers of two easily distinguished colours, such as blue and yellow. One possible reason for this surprising result is that large reward volumes were compared. This is likely to mask the abilities of foragers to make adaptive decisions under more realistic conditions. To test this possibility, we offered untrained honey bee workers ecologically relevant rewards (0.5, 1 or 2 μl of 0.5 or 1 mol l(-1) sucrose solution) on one or two consecutive yellow or blue artificial flowers and then recorded which flowers the bees subsequently landed on in an array of 40 empty flowers. The results showed that an increase in all three factors (volume, concentration and number of rewards) significantly increased constancy (proportion of visits to flowers of the trained colour) and persistence (number of flowers visited) during the foraging bout. Constancy for the least rewarding situation was 75.9% compared with 98.6% for the most rewarding situation. These results clearly show that honey bee workers do become more constant to blue or yellow with increasing nectar rewards, provided that the rewards used are ecologically realistic. As the most rewarding conditions led to nearly 100% constancy, further reward increases during training would not have been able to further increase constancy. This explains why previous studies comparing large rewards found no effect of reward on constancy.
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Few experimental studies have tested theoretical predictions regarding the movement strategies of large herbivores and their consequences for foraging efficiency. We therefore analyze how the movement and foraging behavior of goats are related to patch density, with patches being trees and bushes. We show that their movements become slower and more tortuous when patch density increases, resulting in shorter steps, more acute turns, and a lower net displacement. Furthermore, the movements of the goats can be well described by Lévy walks (LWs). In agreement with hypotheses generated by LW models, the goats move with μ &ap; 2 at low patch density but with μ &ap; 3 when patches are abundant. However, simplified statistical descriptors of movement patterns like the shape of the step/flight length and turn angle distributions become insufficient in predicting foraging efficiency when patch density is high because then the sequence of steps and turns becomes an important determinant of foraging efficiency. By changing their movements and behavior with increasing patch density, the goats intensify their utilization of resources and consequently are able to raise the efficiency of the foraging process more than proportional to the increase in patch density. This resembles the concept of area-restricted search, stating that animals concentrate their foraging effort in areas with high reward, thereby increasing the efficiency of foraging. The findings as presented in this paper provide support for theoretical expectations on the movement and foraging behavior of large herbivores in relation to resource density. Copyright 2007, Oxford University Press.
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Nurses and foragers were observed around noon and around midnight during good and bad weather conditions. Foragers were very busy on sunny days with almost no periods of inactivity. More than 60% of the observation period around noon they spent outside the hive. When foragers were prevented from flight by the lack of light or by bad weather, they showed long periods that were defined as unproductive and trophallactic contacts were reduced. Nurses aged 7-9 days showed a less pronounced behavioural difference between day and night but were highly sensitive to weather alterations. They spent less than half of the time nursing the brood during bad weather conditions compared to good weather conditions, although there was no lack of pollen and honey in the colony. The same tendency was observed in other nurse-related activities. They were less often fed by other bees during days with bad weather conditions than during days with good weather conditions. These dramatic changes in behaviour could be observed even on the first day of rain. We presume that the decline of activity is at least partly caused by the diminishing flow of food within a colony.
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Weather plays an important role in spring-blooming fruit crops due to the combined effects on bee activity, flower opening, pollen germination, and fertilization. To determine the effects of weather on highbush blueberry, Vaccinium corymbosum L., productivity, we monitored bee activity and compared fruit set, weight, and seed number in a field stocked with honey bees, Apis mellifera L., and common eastern bumble bees, Bombus impatiens (Cresson). Flowers were subjected to one of five treatments during bloom: enclosed, open, open during poor weather only, open during good weather only, or open during poor and good weather. Fewer bees of all types were observed foraging and fewer pollen foragers returned to colonies during poor weather than during good weather. There were also changes in foraging community composition: honey bees dominated during good weather, whereas bumble bees dominated during poor weather. Berries from flowers exposed only during poor weather had higher fruit set in 1 yr and higher berry weight in the other year compared with enclosed clusters. In both years, clusters exposed only during good weather had > 5 times as many mature seeds, weighed twice as much, and had double the fruit set of those not exposed. No significant increase over flowers exposed during good weather was observed when clusters were exposed during good and poor weather. Our results are discussed in terms of the role of weather during bloom on the contribution of bees adapted to foraging during cool conditions.
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Bumblebee detection of a flat circular disc (two-dimensional (2D) presentation) and a disc which was presented 10 cm in front of a structured background (and thus provided three-dimensional (3D) cues) was compared. A dual choice test using a Y-maze apparatus was conducted to estimate the minimum visual angle at which the bees were able to detect the disc. At large visual angles of 15, 10 and 5 degrees bees' performance between the 2D and the 3D presentation did not differ. However, when the disc subtended 3 degrees at the bee's eye, the bees performed significantly better when 3D information was available. Overall, bees were able to detect a target subtending a 40% smaller visual angle when it was presented in front of the structured background compared to a 2D presentation. This suggests that previous reports on the limits of target detection in bees using flat stimuli might have underestimated the bees' ability to locate small flowers under natural conditions. Bees use motion parallax, i.e. the apparent relative motion of a stationary object against a background, for perceiving the third dimension. Our data suggest that bumblebees can integrate information from at least two types of feature detectors, motion and area, to improve single target detection.
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In arctic and alpine environments, warm summer temperatures may force a reduction in foraging time of large herbivores, whose tolerance for heat is lower than for species adapted to warmer weather. We constructed time budgets for marked ibex (Capra ibex) males over two summers to test whether warm temperatures constrained foraging behaviour and forced altitudinal migrations. As daily temperature and solar radiation increased, feeding activity was reduced at midday and evening, but increased in the early morning, probably to anticipate for an expected reduction in foraging later in the day. With increasing temperature and solar radiation, ibex moved to higher elevations where they spent very little time feeding. Changes in forage quality and availability could not explain altitudinal migration. Temperatures above 15-20 degrees C apparently result in heat discomfort in male Alpine ibex. As temperature and solar radiation increased, older and larger ibex spent less time feeding during daylight and showed a steeper decrease in feeding time than younger and smaller ibex. Larger males may be more sensitive to temperature and solar radiation, or may have more flexibility in allocating time to different activities, given their lower relative energetic requirements.
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The influence of wind patterns on behaviour and effort of free-ranging male wandering albatrosses (Diomedea exulans) was studied with miniaturized external heart-rate recorders in conjunction with satellite transmitters and activity recorders. Heart rate was used as an instantaneous index of energy expenditure. When cruising with favourable tail or side winds, wandering albatrosses can achieve high flight speeds while expending little more energy than birds resting on land. In contrast, heart rate increases concomitantly with increasing head winds, and flight speeds decrease. Our results show that effort is greatest when albatrosses take off from or land on the water. On a larger scale, we show that in order for birds to have the highest probability of experiencing favourable winds, wandering albatrosses use predictable weather systems to engage in a stereotypical flight pattern of large looping tracks. When heading north, albatrosses fly in anticlockwise loops, and to the south, movements are in a clockwise direction. Thus, the capacity to integrate instantaneous eco-physiological measures with records of large-scale flight and wind patterns allows us to understand better the complex interplay between the evolution of morphological, physiological and behavioural adaptations of albatrosses in the windiest place on earth.
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Developments in satellite telemetry have recently allowed considerable progress in the study of long-range movements of large animals in the wild ([1][1]), but the study of the detailed patterns of their foraging behavior on a small to medium scale is not possible because of the imprecision of
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Bees have an impressive cognitive capacity, but the strategies used by individuals in solving foraging tasks have been largely unexplored. Here we test bumblebees (Bombus terrestris) in a colour-discrimination task on a virtual flower meadow and find that some bees consistently make rapid choices but with low precision, whereas other bees are slower but highly accurate. Moreover, each bee will sacrifice speed in favour of accuracy when errors are penalized instead of just being unrewarded. To our knowledge, bees are the first example of an insect to show between-individual and within-individual speed- accuracy trade-offs.
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Biodiversity of insects is threatened worldwide. Here, we present a comprehensive review of 73 historical reports of insect declines from across the globe, and systematically assess the underlying drivers. Our work reveals dramatic rates of decline that may lead to the extinction of 40% of the world's insect species over the next few decades. In terrestrial ecosystems, Lepidoptera, Hymenoptera and dung beetles (Coleoptera) appear to be the taxa most affected, whereas four major aquatic taxa (Odonata, Plecoptera, Trichoptera and Ephemeroptera) have already lost a considerable proportion of species. Affected insect groups not only include specialists that occupy particular ecological niches, but also many common and generalist species. Concurrently, the abundance of a small number of species is increasing; these are all adaptable, generalist species that are occupying the vacant niches left by the ones declining. Among aquatic insects, habitat and dietary generalists, and pollutant-tolerant species are replacing the large biodiversity losses experienced in waters within agricultural and urban settings. The main drivers of species declines appear to be in order of importance: i) habitat loss and conversion to intensive agriculture and urbanisation; ii) pollution, mainly that by synthetic pesticides and fertilisers; iii) biological factors, including pathogens and introduced species; and iv) climate change. The latter factor is particularly important in tropical regions, but only affects a minority of species in colder climes and mountain settings of temperate zones. A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide. In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments.
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Natural environments are characterized by variable wind that can pose significant challenges for flying animals and robots. However, our understanding of the flow conditions that animals experience outdoors and how these impact flight performance remains limited. Here, we combine laboratory and field experiments to characterize wind conditions encountered by foraging bumblebees in outdoor environments and test the effects of these conditions on flight. We used radio-frequency tags to track foraging activity of uniquely identified bumblebee (Bombus impatiens) workers, while simultaneously recording local wind flows. Despite being subjected to a wide range of speeds and turbulence intensities, we find that bees do not avoid foraging in windy conditions. We then examined the impacts of turbulence on bumblebee flight in a wind tunnel. Rolling instabilities increased in turbulence, but only at higher wind speeds. Bees displayed higher mean wingbeat frequency and stroke amplitude in these conditions, aswell as increased asymmetry in stroke amplitude— suggesting that bees employ an array of active responses to enable flight in turbulence, which may increase the energetic cost of flight. Our results provide the first direct evidence that moderate, environmentally relevant turbulence affects insect flight performance, and suggest that flying insects use diverse mechanisms to cope with these instabilities. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
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Landing is an important but understudied behavior that flying animals must perform constantly. In still air, insects decelerate smoothly prior to landing by employing the relatively simple strategy of maintaining a constant rate of image expansion during their approach. However, it is unclear whether insects employ this strategy when faced with challenging flight environments. Here, we test the effects of wind on bumblebees (Bombus impatiens) landing on flowers. We find that bees' approach paths to flowers shift from multidirectional in still air to unidirectional in wind, regardless of flower orientation. In addition, bees landing in a 3.5 m/s headwind do not decelerate smoothly, but rather maintain a high flight speed until contact, resulting in higher peak decelerations upon impact. These findings suggest that wind has a strong influence on insect landing behavior and performance, with important implications for the design of micro aerial vehicles and the ecomechanics of insect flight.
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The temperature excess developed by insects under known radiation strength equivalent to sunshine has been studied in relation to modifying factors in a wind tunnel in the laboratory. Temperature excess was measured by a thermocouple unit in the larger insects, and by the increase in rate of wing beat in Drosophila. Temperature excess varied directly with radiation strength. For insects of breadth greater than 0·3 cm. spectral composition of radiation over the normal sunshine range was of negligible importance to the temperature excess. The effect of colour on the temperature excess was slight. Absorptivity was estimated by comparing temperatures of normal and black-painted insects. Some insects were hotter in the normal state because of change in the site of absorption of heat. White-painted insects were 64−85 % as hot as when black painted, because the white paint still absorbs infra-red radiation. Temperature excess varied with a power of the size between 0·7 and 0·4 in the plasticine spheres, according to size. Temperature excess of the locust type varied as about the 0·4 power of the size ; of the Diptera-Hymenoptera type, as about the 1·0 power. Size for size, compared with the spheres, the locust became between half as hot again and twice as hot, and the Diptera-Hymenoptera type between half as hot again and three times as hot, as the plasticine spheres. Temperature excess varied inversely as the square root of the wind speed above speeds of 20−30 cm./sec. and tended to become independent at lower speeds, with the transition between forced and natural convection. The latter condition will be more important close to the ground. Temperature rise by flight activity is not additive to temperature rise from radiation because it is associated with extra cooling. Evolution of insects from the type of the Orthoptera to the Diptera and Hymenoptera has been associated with the attainment of greater temperature excess for given body size. This is probably of selective significance.
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1. Lavender (Lavandula spp.) flowers attract more bumble bees (Bombus spp.) than honey bees (Apis mellifera). Counts of bees foraging on Lavandula × intermedia ‘Grosso’ at the University of Sussex campus, showed that bumble bees (92%) greatly outnumbered honey bees (8%). This was not due to a scarcity of honey bees, as the reverse ratio (94% honey bees vs. 6% bumble bees) occurred on borage (Borago officinalis) at the same location. 2. Video analysis of free-flying bees revealed that all bumble bee species present (Bombus terrestris/lucorum, Bombus pascuorum, and Bombus lapidarius) handled lavender flowers three times faster than honey bees (mean extraction times: 0.38, 0.37, 0.34 s respectively, vs. 1.30 s; all P <0.001). Honey bee tongue length (6.6 mm) was approximately 2mm shorter than those of bumble bees (7.8–8.9 mm) and 1mm shorter than the lavender corolla tube (c. 7 mm). In addition, bumble bees probed twice as many lavender flowers encountered than honey bees (86% vs. 46%). 3. Experimentally reducing effective corolla tube length with scalpel incisions significantly decreased extraction time for honey bees (from 1.11 to 0.76 s; P <0.001) but not for bumble bees (0.33 to 0.28 s; P =0.266). 4. Results suggest that honey bees are deterred from foraging on lavender because they are being outcompeted by bumble bees, which forage more efficiently.
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Citation: Møller, A. P. 2013. Long-term trends in wind speed, insect abundance and ecology of an insectivorous bird. Ecosphere 4(1): Abstract. Recent climate change has affected spatial and temporal patterns of temperature and precipitation, but also wind speed. Wind affects the abundance and the distribution of flying insects and can therefore influence the abundance of food for insectivores including insectivorous birds. I tested for temporal trends in wind speed, assessed the effect of wind speed on the abundance of flying insects, and tested for effects of wind speed on reproduction and adult survival rate, using long-term data on the barn swallow Hirundo rustica from 1971–2011. Wind speed varied largely independently among the months April–August, with a decreasing trend during 1971–2011 for July only. The abundance of flying insects decreased strongly with increasing wind speed during summer. Decreasing wind speed during July coincided with the pre-laying period of the second brood of the barn swallow, and years with stronger wind in July had lower abundance of food before laying during 1997–2011 and lower breeding success. Adult barn swallows had lower body mass in years with windy summers, and adult annual survival rate to the next year decreased both when wind speed increased and when body mass was reduced. These findings suggest that wind plays an important role in the ecology of insectivorous birds as shown by relationships with reproductive success and survival.
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SUMMARY Amplitudes of extracellular action potentials in indirect flight muscles of honey- bees and cuculiinid winter moths decline with decreasing muscle temperatures and fall suddenly to zero. Action potential durations increase with amplitude decline. Amplitudes at 11°C are only 20% of values near 30°C in workers of Apis mellifera mellifera. They fall to zero at approx. 10°C. In the cuculiinid winter moth Eupsilia devia, amplitudes at 1°C are approx. 12% of values at 27°C. They fall to zero between 0 and 1°C. The duration of action potentials in bees and cuculiinid winter moths is about 7 ms at 27 °C and increases to 52 ms at 11°C in bees and to 66 ms at 1°C in moths. The ratios of action potential rise time to fall time are about 1 at 27°C for bees and moths. They decrease to 0-45 at 11°C in bees and to 0-56 at 1°C in moths. Results suggest that bees can heat flight muscles only if muscle temperatures are above 10°C, whereas cuculiinid winter moths can shiver with muscle tempera- tures near 0°C.
Article
It is hypothesized that nectar-collecting bumblebees will be found to forage in ways that maximize their net rate of energy intake. Attention is focused, in this paper, on the manner in which these bumblebees move from one flower to another within inflorescences. Observations were made on workers of Bombus appositus, which were collecting nectar from Aconitum columbianum (monkshood). The rule of movement of the bumblebees was determined and compared, in terms of net rate of energy intake, with several possible alternative rules. Two of these alternatives gave equally high net rates of energy intake. The observed rule was very similar in nature to one of these and indistinguishable from both in terms of net rate of energy intake.
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Insect dispersal is affected by the wind and as a result, influenced by the presence of windbreaks. Wind reductions, microclimate modifications and vegetative diversity, influence insect distribution in sheltered areas.Wingless insects and very small insects generally depend on air currents to carry them to new sites, but they tend to settle in areas with low windspeeds. It is often more advantageous for a flying insect to remain within its boundary layer where windspeeds are lower than the insect's flight speed. Flying insects tend to accumulate in areas of reduced windspeed where they have greater control of flight; however, distribution patterns can be modified by directed movements in response to olfactory and visual stimuli. Many insect species are attracted to food and shelter within windbreaks.Windbreaks can concentrate insects in particular areas. Insects accumulate leeward of windbreaks as compared with unsheltered sites. The pattern of distribution may be affected by windspeed, angle of incidence of the wind, permeability of the windbreak, turbulence, source of insects (windbreak, local fields, upwind sites), insect behavior, insect species and vegetative composition. Windbreak vegetation may serve as a source of insect pests and their natural enemies and infestation levels in adjacent fields will be affected by their relative abundance. Knowledge of these distribution patterns should be considered when designing pest-management control strategies.
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Predators often face a trade-off between energy gain and risk of injury, and their foraging decisions should thus vary with conditions that influence this trade-off. We studied how wind speed affected the foraging decisions of Glaucous Gulls preying on Thick-billed Murres breeding on Coats Island, Northwest Territories, Canada in 1990-1992. At this colony, murres bred at varying densities on broad and narrow cliff ledges. Under calm wind conditions (<10 km/h), aerial search and attack activity by gulls' was low. At wind speeds >15 km/h, gulls searched more actively and focused their aerial attacks on nest sites on narrow ledges. Aerial attacks on narrow ledges were less successful (in number of eggs or chicks taken per attack) than attacks made on foot on broad ledges. However, aerial attacks also had a lower incidence of contact with defending murres because: (1) gulls could approach ledges readily by gliding; (2) murres on narrow ledges could not turn to fend off attacking gulls without dislodging their eggs or chicks; and (3) dense groups of murres on broad ledges defended their eggs and chicks communally. Gulls foraged successfully on foot on broad ledges despite communal defense by murres, although they suffered a greater risk of being struck on the head by defending murres. Because gulls favored aerial attacks under windy conditions, we concluded that a trade-off between maximizing energy gain and minimizing risk of injury determines foraging decisions by gulls in this system, and that this trade-off was mediated by wind.
Article
Honey-bees foraging in a specially planted flower garden were chloroformed and given individual marks. Their movements were then recorded from day to day, and a few selected bees were watched continuously for periods of a day or more. It was concluded that: 1. The basic principle underlying the foraging behaviour pattern is the continuous exercise of choice by the bee, which chooses the best portions of the best of any alternative crops with which she becomes acquainted, and compares present crops with her memory of past crops. 2. Bees usually attach themselves to a particular area of the most suitable crop found. The size of this foraging area varies considerably. 3. Examples are given of the use of choice and memory in order to select the most suitable blossoms of the crop which is being worked, when showing a preference for different portions of a foraging area at different times, in order gradually to change the position of a foraging area, when a bee is working one crop and inspecting another, when she is working two crops at once, when she is working two crops at different times of the day, when crops are failing, and when changing crops. The centripetal tendency shown by some foragers is considered to be a consequence of the interplay of choice and memory. 4. Attachment may be of any duration, from a few trips to a lifetime. The proportion of changes of attachment may be expected to vary greatly with local circumstances, because behaviour is labile and readily adaptable to changing conditions. 5. Bees which became attached to sources yielding pollen without nectar remained for only a part of their foraging life. Bees were frequently seen to change their attachment from a pollen crop to a nectar crop, but never vice versa. 6. Nectar gatherers were observed to make from 250 to 1446 flower visits per load, and from about 300 to 1000 flower visits per foraging hour. Pollen gatherers averaged from 7 to 120 flower visits per load, and from about 50 to 150 fruitful flower visits per foraging hour. These limits may possibly be widely exceeded in other circumstances. Such statistics are not an index of the pollinating capacity of the bee, as foraging is often mainly composed of oft-repeated visits to favourite blossoms. The size of foraging area is a more correct index of pollinating capacity.
Article
DAVIES has demonstrated1 in a wind tunnel that Myzus persicae Sulz. did not take to flight in wind speeds greater than 3.75 m.p.h. His experiments, and field observations by other research workers, have given rise to a generalization that aphids do not take off in wind velocities greater than 5 m.p.h.2.
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Provides contrasting examples illustrating different concepts, and points out what these suggest in regard to new and productive research. -from Author
Article
The role of vision in the prey-catching behaviour of Little Penguins Eudyptula minor was tested using four captive penguins in a swimming pool. A live fish was placed in the pool with a penguin at various light intensities before and after dawn and dusk. The penguins' behaviour in the morning was the same as in the evening. As the light decreased, the percentage of fish chased by the penguins decreased, and no fish were caught at a light level less than 0.01 μeinstein/m2/s (which occurs approximately 25 min before sunrise and after sunset at latitude 37d̀S). The time the penguins spent searching for the fish also decreased with decreasing light. The probability of a penguin pursuing a fish was found to be dependent on the amount of light, such that log,(p/1 - p) = 6.323 + 2.08 × log,(light level), where p= the probability of pursuing a fish.
Article
The effect of different wind speeds on take-off and flight orientation of the sweetpotato whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), was studied in the presence of a green visual stimulus which reflected 550 ± 10 nm light, or a white stimulus of the same intensity. When the white light was present, take-off was negatively correlated with wind speed. Analysis of the flight tracks of whiteflies in 0, 15 and 30 cm/s wind with the white light present showed that flight was not directed toward the stimulus in zero wind, and that insects were carried downwind as the wind increased. Net displacement downwind was significantly slower than the wind speed, indicating that B. tabaci can control its rate of displacement relative to its surroundings, and is not always passively transported by the wind. In the presence of the green visual stimulus, take-off and flight behaviour of B. tabaci was markedly different to that observed in the presence of the white light. Taking off was more likely and whiteflies made upwind orientated flights, landing on the illuminated section of the screen when it reflected green light. At all wind speeds tested, the mean ground speeds of B. tabaci were approximately 20 cm/s whether the insects were flying upwind or downwind. This uniformity of ground speed regardless of the changing effects of wind-induced drift in different directions strongly suggests that whiteflies actively control their ground speed using visual flow fields in a manner similar to all other flying insects examined thus far.
Article
The foraging behaviour of the bumblebees Bombus hortorum (Linnaeus)/ Bombus ruderatus (Fabricius), Bombus pascuorum (Scopoli) and Bombus meso-melas Gerstaecker in a monospecific patch of Digitalis ferruginea Linnaeus has been investigated in relation to temperature, wind direction, plant density and patch configuration. D. ferruginea proved to be very attractive for bumblebees, aggregating a large number of foragers (up to two bumblebees per inflorescence at the foraging peak). The number of active bees showed a positive correlation (P < 0.01) with temperature. On windy days, flight distances were longer down-wind than upwind (P = 0.0194), while on calm days or in gentle wind the bees made long flights upwind as well as downwind. In two subunits of the patch, differing in plant density, a larger number (P = 0.0026) of bees foraged in the high plant density unit, and a lower infloescence/bee ratio (P = 0.0367) was found there. The estimated total number of bees foraging at any one time in the two patch subunits differed significantly (5 out of 7 times, P < 0.01 or < 0.05) from the values expected if the bees were distributed in proportion to the num-ber of inflorescences in each patch. Bees foraged within individual undefended and interlaced areas, and flight routes within these areas were maintained for up to at least 10 days. When part of their foraging area was screened by bagging some plants, the workers did not leave the patch, but most of them responded by visiting some adjacent plants or plant groups.
Article
Although homeotherms likely experience costs of both predation risk and thermoregulation while foraging, it is unclear how foragers contend with these costs. We used foraging trays placed in sheltered microsites to determine whether temperature, a direct cue of predator presence (predator urine) and an indirect cue of predation risk (cloudy nights) affect foraging of white-footed mice, Peromyscus leucopus, in winter. Mice were presented with urine from bobcats, Lynx rufus, red foxes, Vulpes vulpes, and coyotes, Canis latrans, an herbivore (whitetailed deer, Odocoileus virginianus), and a water control. To measure rodent foraging, we used seeds of millet mixed with sand to quantify giving-up densities (the number of seeds left in each foraging tray). Giving-up density was not affected by predator urine. Rather, rodent foraging was affected by an interaction of temperature and weather. On overcast nights, when predation risk was likely lower, mice foraged more when soil temperature was higher, presumably reducing thermoregulatory costs. On clear nights, foraging was low regardless of soil temperature, presumably because foraging was more risky. These results suggest that mice consider thermoregulatory costs and predation risk when making foraging decisions, and that the indirect cue afforded by weather, rather than the direct cue of predator urine, is among the cues used to make foraging decisions. Moreover, these results suggest that sensitivity to a particular cue is likely to be context-dependent.
Article
1. A general hypothesis is presented to explain interspecific differences in size-independent resting metabolic rate. This hypothesis is based on a presumed trade-off between a low resting metabolism and adaptations of metabolism during activity. 2. With such a trade-off, selection to reduce resting metabolism is less intense in active species than in species where resting metabolism constitutes a large proportion of the daily metabolic costs. Those animals that spend more energy on activity should therefore have a higher resting metabolic rate than animals that spend less energy on activity. 3. A literature review reveals that flying insects have higher resting metabolic rates than species that use energetically less demanding types of locomotion. 4. Insects producing acoustic advertisement signals can be shown to have higher mass-independent resting metabolic rates than closely related species without this energetically demanding behaviour. 5. Literature data on vertebrate resting metabolic rates are also consistent with the presented hypothesis: the more energy animals spend on activity, the higher the mass-independent resting metabolic rate.
Article
A honey bee colony operates as a tightly integrated unit of behavioral action. One manifestation of this in the context of foraging is a colony's ability to adjust its selectivity among nectar sources in relation to its nutritional status. When a colony's food situation is good, it exploits only highly profitable patches of flowers, but when its situation is poor, a colony's foragers will exploit both highly profitable and less profitable flower patches. The nectar foragers in a colony acquire information about their colony's nutritional status by noting the difficulty of finding food storer bees to receive their nectar, rather than by evaluating directly the variables determining their colony's food situation: rate of nectar intake and amount of empty storage comb. (The food storer bees in a colony are the bees that collect nectar from returning foragers and store it in the honey combs. They are the age group (generally 12–18 day old bees) that is older than the nurse bees but younger than the foragers. Food storers make up approximately 20% of a colony members.) The mathematical theory for the behavior of queues indicates that the waiting time experienced by nectar foragers before unloading to food storers (queue length) is a reliable and sensitive indicator of a colony's nutritional status. Queue length is automatically determined by the ratio of two rates which are directly related to a colony's nutritional condition: the rate of arrival of loaded nectar foragers at the hive (arrival rate) and the rate of arrival of empty food storers at the nectar delivery area (service rate). These two rates are a function of the colony's nectar intake rate and its empty comb area, respectively. Although waiting time conveys crucial information about the colony's nutritional status, it has not been molded by natural selection to serve this purpose. Unlike signals, which are evolved specifically to convey information, this cue conveys information as an automatic by-product. Such cues may prove more important than signals in colony integration.
Article
Migration is a task that implies a route, a goal and a period of time. To achieve this task, it requires orientation abilities to find the goal and energy to cover the distance. Completing such a journey by flying through a moving airspace makes this relatively simple task rather complex. On the one hand birds have to avoid wind drift or have to compensate for displacements to reach the expected goal. On the other hand flight costs make up a large proportion of energy expenditure during migration and, consequently, have a decisive impact on the refuelling requirements and the time needed for migration. As wind speeds are of the same order of magnitude as birds’ air speeds, flight costs can easily be doubled or, conversely, halved by wind effects. Many studies have investigated how birds should or actually do react to winds aloft, how they avoid additional costs or how they profit from the winds for their journeys. This review brings together numerous theoretical and empirical studies investigating the flight behaviour of migratory birds in relation to the wind. The results of these studies corroborate that birds select for favourable wind conditions both at departure and aloft to save energy and that for some long-distance migrants a tail-wind is an indispensable support to cover large barriers. Compensation of lateral wind drift seems to vary between age classes, depending on their orientation capacities, and probably between species or populations, due to the variety of winds they face en route. In addition, it is discussed how birds might measure winds aloft, and how flight behaviour with respect to wind shall be tested with field data.
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Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare.
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Environmental turbulence is ubiquitous in natural habitats, but its effect on flying animals remains unknown because most flight studies are performed in still air or artificially smooth flow. Here we show that variability in external airflow limits maximum flight speed in wild orchid bees by causing severe instabilities. Bees flying in front of an outdoor, turbulent air jet become increasingly unstable about their roll axis as airspeed and flow variability increase. Bees extend their hindlegs ventrally at higher speeds, improving roll stability but also increasing body drag and associated power requirements by 30%. Despite the energetic cost, we observed this stability-enhancing behavior in 10 euglossine species from 3 different genera, spanning an order of magnitude in body size. A field experiment in which we altered the level of turbulence demonstrates that flight instability and maximum flight speed are directly related to flow variability. The effect of environmental turbulence on flight stability is thus an important and previously unrecognized determinant of flight performance.
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Nectar-collecting bumblebees are hypothesized to employ rules of movement which result in the maximum net rate of energy gain (i.e., are optimal). The optimal movement rules are derived from a mathematical model and are used to generate predicted patterns of movement. The predicted patterns are compared with field observations. These observations support the hypothesis. An important component of the mathematical model is the memory of the foraging animal. The field data have implications concerning the memory capabilities of the bumblebees.
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To answer the question whether flowers wave to attract pollinators, we determine: (1) the heritability of floral mobility; (2) whether wavy flowers attract more insects; (3) does the duration of pollination affect seed set; and (4) the relationship between seed set and floral mobility. The pollination ecology of Silene maritima was investigated. Flowers on stalks of different waviness were used to investigate the effect of floral movement on pollinator visits. There is heritable variation in both direct and indirect estimates of floral mobility. The highest insect total visitation times were associated with medium length thin stalks that were visited more frequently and by more insect species. Although mean individual visit durations were less than those of less mobile flowers, this was compensated for by increased visits. Observations of controlled pollinations show that when the visit times are low, so is seed set and therefore low and high mobility flowers might suffer from reduced fitness. Combining these observations provides a mechanism that could be driving stabilizing selection for flower stalk traits, with a trade-off applying between waving to attract pollinators and not being too mobile as to prevent effective pollination. Further evidence for stabilizing selection is provided by the relationship observed in the field between seed set and floral mobility where the highest levels of fitness was associated with intermediate levels of floral waving.
Article
Simultaneous inference is a common problem in many areas of application. If multiple null hypotheses are tested simultaneously, the probability of rejecting erroneously at least one of them increases beyond the pre-specified significance level. Simultaneous inference procedures have to be used which adjust for multiplicity and thus control the overall type I error rate. In this paper we describe simultaneous inference procedures in general parametric models, where the experimental questions are specified through a linear combination of elemental model parameters. The framework described here is quite general and extends the canonical theory of multiple comparison procedures in ANOVA models to linear regression problems, generalized linear models, linear mixed effects models, the Cox model, robust linear models, etc. Several examples using a variety of different statistical models illustrate the breadth of the results. For the analyses we use the R add-on package multcomp, which provides a convenient interface to the general approach adopted here.
Effects of wind on movement of Diachasmimorpha longicaudata, a parasitoid of tephritid fruit flies, in a laboratory flight tunnel
  • Messing
Flower movement increases pollinator preference for flowers with better grip
  • Alcorn