Bee Preference Research Articles

Neutral processes related to regional bee commonness and dispersal distances are important predictors of plant–pollinator networks along gradients of climate and landscape conditions

Understanding how niche‐based and neutral processes contribute to the spatial variation in plant–pollinator interactions is central to designing effective pollination conservation schemes. Such schemes are needed to reverse declines of wild bees and other pollinating insects, and to promote pollination services to wild and cultivated plants. We used data on wild bee interactions with plants belonging to the four tribes Loteae, Trifolieae, Anthemideae and either spring‐ or summer‐flowering Cichorieae, sampled systematically along a 682 km latitudinal gradient to build models that allowed us to 1) predict occurrences of pairwise bee–flower interactions across 115 sampling locations, and 2) estimate the contribution of variables hypothesized to be related to niche‐based assembly structuring processes (viz. annual mean temperature, landscape diversity, bee sociality, bee phenology and flower preferences of bees) and neutral processes (viz. regional commonness and dispersal distance to conspecifics). While neutral processes were important predictors of plant–pollinator distributions, niche‐based processes were reflected in the contrasting distributions of solitary bee and bumble bees along the temperature gradient, and in the influence of bee flower preferences on the distribution of bee species across plant types. In particular, bee flower preferences separated bees into three main groups, albeit with some overlap: visitors to spring‐flowering Cichorieae; visitors to Anthemideae and summer‐flowering Cichorieae; and visitors to Trifolieae and Loteae. Our findings suggest that both neutral and niche‐based processes are significant contributors to the spatial distribution of plant–pollinator interactions so that conservation actions in our region should be directed towards areas: near high concentrations of known occurrences of regionally rare bees; in mild climatic conditions; and that are surrounded by heterogenous landscapes. Given the observed niche‐based differences, the proportion of functionally distinct plants in flower‐mixes could be chosen to target bee species, or guilds, of conservation concern.

How foraging preference and activity level of bumble bees contribute to colony flexibility under resource demand

Groups of cooperative organisms, including humans, benefit from the contributions of both specialist and generalist individuals. Group responses to resource or task demand emerge from the specific actions of individuals within the group. Bumble bee colonies need to respond to resource demands for both pollen and nectar for colony growth and reproduction. Bumble bee workers have been shown to display differences in foraging preferences for these essential resources and in activity level. This study investigated the responses of Bombus terrestris individuals to resource demand by subjecting colonies to different pollen and sucrose storage scenarios, considering their individual foraging preferences and activity levels. The sucrose sensitivity and olfactory learning ability of individuals were then compared along a spectrum of foraging preference (between pollen and sucrose foraging) using the proboscis extension reflex paradigm. When sucrose was in demand, individuals with a preference for sucrose showed the largest upregulation in foraging bouts. Individual preference for pollen and activity level correlated with the upregulation of foraging bouts when pollen was in demand. This study detected no relationship between body size, sucrose preference and worker sucrose sensitivity or olfactory learning ability, tested with proboscis extension reflex conditioning. This study highlights the potential value of foraging preferences in bumble bee colonies but also the flexibility these colonies have with a small foraging workforce. • Bumble bees with high sucrose preference upregulate to fill sucrose demands. • Pollen preference and individual activity level predict upregulation in pollen demand. • Body size and sucrose preference do not predict worker sucrose sensitivity. • Body size and sucrose preference do not predict odour learning performance. • Workload is not evenly split between individuals.

Pollen preferences of stingless bees in the Amazon region and southern highlands of Ecuador by scanning electron microscopy and morphometry.

Stingless bees are effective pollinators of native tropical flora. Their environmental service maintains flow of pollen through pollination, increase reproductive success and influence genetic structure in plants. The management of stingless bees “meliponiculture”, is an activity limited to the countryside in Ecuador. The lack of knowledge of their managers about pollen resources can affect the correct maintenance/production of nests. The objective is to identify botanical families and genera of pollen grains collected by stingless bees by morphological features and differentiate potential species using geometric morphometry. Thirty-six pot pollen samples were collected from three Ecuadorian provinces located in two climatically different zones. Pollen type identification was based on the Number, Position, Character system. Using morphological features, the families and genera were established. Morphometry landmarks were used to show variation for species differentiation. Abundance, diversity, similarity and dominance indices were established by counting pollen grains, as well as spatial distribution relationships by means of Poisson regression. Forty-six pollen types were determined in two study areas, classified into 27 families and 18 genera. In addition, it was possible to identify more than one species, classified within the same family and genus, thanks to morphometric analysis. 1148 ± 799 (max 4211; min 29) pollen grains were counting in average. The diversity showed a high richness, low dominance and similarity between pollen resources. Families Melastomataceae and Asteraceae, genera Miconia and Bidens, were found as the main pollen resources. The stingless bee of this study are mostly generalist as shown the interaction network. The results of the present survey showed that stingless bees do not collect pollen from a single species, although there is evidence of a predilection for certain plant families. The diversity indexes showed high richness but low uniformity in the abundance of each family identified. The results of the study are also meaningful to the meliponiculture sector as there is a need to improve management practices to preserve the biodiversity and the environment.

The Foraging preference of stingless beekeeping in three types of land use at Lombok Island

The success of stingless beekeeping was supported by site suitability and the availability of floral sources. Bee feed is an important requirement for the sustainability of stingless beekeeping because it determines the qualities and quantities of bee products. The study aimed to examine the level of feed preference for stingless bees. The research location was divided into three types, i.e., agroecosystems, forests, and settlements. Acetolysis of the pollen where came from the hive was used to examine the foraging preferences of stingless bees. The results of the study were four species of stingless bee were identified, i.e., Tetragonula fuscobalteata, Tetragonula laeviceps, Tetragonula clypearis, and Heterotrigona erythrogastra. Based on the results of the data analysis, T. fuscobalteata was mostly cultivated in the settlement areas, T. laeviceps and T. clypearis were mostly found at the sites that were close to the agroecosystems, while H. erythrogastra was cultivated near the forest areas. The pollen that be favorite feed plants of Tetragonula was Bromeliaceae and Cyperaceae, while for H. erythrogastra, Rubiaceae was the preference of forage plants. However, the PCA showed that the preference of forage plants for the beekeeping of stingless bees was influenced by the availability of feed sources around their hives.

Honey DNA metabarcoding revealed foraging resource partitioning between Korean native and introduced honey bees (Hymenoptera: Apidae)

Honey DNA metabarcoding provides information of floral sources of honey and foraging plant preferences of honey bees. We evaluated the floral composition of honey from two different species of honey bees, Apis cerana honey (ACH) and A. mellifera honey (AMH) in a mixed apiary located in a semi-forest environment to understand the floral preference and level of interspecific competition on floral resource. Three honey samples were collected from different hives of each species in mid-August. In total, 56 plant taxa were identified across the honey samples and among them, 38 taxonomic units were found in ACH compared with a total of 33 in AMH. The number of major plants (> 1% of reads) in honey samples was 9 and 11 in ACH and AMH respectively indicating the higher diversity of plant taxa in AMH. 23 taxonomic units were found exclusively in ACH, 18 taxonomic units were found only in AMH and 15 taxonomic units were shared between ACH and AMH indicating that 73% of the taxonomic units were present only in honey originated from one of the honeybee species. Qualitative and quantitative analyses of the shared major plants revealed the division of floral resource between these co-existing honey bee species pointing to a low level of interspecific competition between these two important pollinators.

The Effect of Supplementary Feeding with Different Pollens in Autumn on Colony Development under Natural Environment and In Vitro Lifespan of Honey Bees.

Simple SummaryIn the present study, the effect of feeding with pollen sources with different protein content on colony performance, wintering ability and in-vitro longevity of colonies that weakened after feeding with pine honey in autumn or that needed to enter the winter period were investigated. The experiment was carried out in 48 colonies divided into six groups as follows: control, syrup, mixed pollen, Cistus creticus pollen (Pink rock-rose), Papaver somniferum pollen (Opium poppy), and commercial bee cake group. The effect of nutritional differences on survival was found to be statistically significant in vitro and this supports the colony results in the natural environment. As a result, P. somniferum pollen is a good preference to be used in feeding colonies in beekeeping, due to its rich nutritional content.Honey bees need pollen and nectar sources to survive in nature. Particularly, having young bees in colonies is vital before wintering, and proper feeding is necessary to achieve this. In the present study, the effect of feeding with pollen sources of different protein content on colony performance, wintering ability and in-vitro longevity of colonies that weakened after feeding with pine honey in autumn, or that needed to enter the winter period, was investigated. The experiment was carried out in 48 colonies divided into six groups as follows: control, syrup, mixed pollen, Cistus creticus pollen (Pink rock-rose), Papaver somniferum pollen (Opium poppy), and commercial bee cake groups. In particular, the P. somniferum pollen group was different (p < 0.01) from the other experiment groups with the number of bee frames (3.44), the area with brood (1184.14 cm2) and the wintering ability of 92.19%. The effect of nutritional differences on survival was found to be statistically significant in vitro and this supports the colony results in the natural environment (p < 0.001). The P. somniferum group has the longest longevity with 23 days. Pollen preferences of honey bees were P. somniferum, C. creticus, and mixed pollen, respectively.

Nest preference and ecology of cavity-nesting bees (Hymenoptera: Apoidea) in Punjab, Pakistan

• Artificial nest boxes, an effective tool for nesting and conservation of bees. • Colonization of bees helpful in studying ecology and nesting biology. • The efficacy of nest boxes depends on nesting materials and dimensions of cavities. • Bamboo and drilled wooden log is the most preferred nesting material. • Six bee species along with one parasitic bee did nesting in our nesting materials. Among bees, 85 % are solitary species, most of them are ground-nester and some are cavity-nesting and construct their nests in pre-existing cavities. This work was conducted to evaluate the substrate preference and nest architecture (acceptance, occupation percentage, seasonality and parasitism) of cavity-nesting bees in different substrates. Trap nests offered comprised five different materials (drilled cavities in wood, bamboo, cardboard tubes, plastic soda straws, and mud blocks). These were installed in four districts for two years. The nesting cavities of five different diameters (6, 8, 10, 12 and 14 mm) were provided in each nesting material with an average length of 180 ± 9.92 mm. In all the materials, 5400 nesting cavities were offered, out of which 628 were colonized by bees from two families (Megachilidae and Apidae) and six species ( Megachile cephalotes, M. lanata, M. bicolor, Xylocopa basalis, X. fenestrata and Ceratina smaragdula ), including one parasitic bee ( Euaspis carbonaria ). The bee species differed significantly in occupying five nesting materials. The most preferred diameters were 8 mm and 10 mm, with 52.20% and 29.45% of colonization, respectively. Nesting was done throughout the year except in winter. This study will serve as a baseline for future studies and conservation programs of cavity-nesting bees in Pakistan.

Floral volatiles may influence honey bee visitations in oilseed Brassica species

ABSTRACT Understanding foraging preferences of honey bees (Apis mellifera L.) is essential to maneuver pollinator movement to enhance outcrossing and hence the crop yields. In this communication, we report the role of floral volatile organic compounds (VOCs) in structuring foraging decisions of honey bees. Supercritical fluid extraction of VOCs, coupled with gas chromatography-mass spectrometry, revealed 75 VOCs. Of these, 19 were strong attractants and 8 were strong repellants. Moreover, we detected significant, but variable, species- or genome-level differences in floral scents. Honey bees avoided Brassica juncea cv. PBR357 (0.81 bee visits/sq m/min) and B. carinata cv. PC5 (0.77 bee visits/sq m/min), which possessed peak concentrations of antifeedants or repellents (dibutyl phthalate and 9-octadecenoic acid) in their floral volatiles. B. napus cvs. GSC6 and GSC7 attracted the highest number of bee visitations (1.07 and 0.99 bee visits/sq m/min, respectively), as these possessed VOCs with honey-fruity odor in high amounts and negligible levels of antifeedants. Our results highlight that variability in floral reward chemistry should be considered when breeding crops that are frequently visited upon by bee pollinators to support bee pollinators, in general, and honey industry, in particular.

Impact of Neonicotinoid Insecticides on the Foraging Preference of Indian Honey Bee, Apis cerana indica (Fab.) (Hymenoptera, Apidae) Visiting Sunflower Helianthus annus L. Crop

Aim: Forage preference of Indian honey bee on neonicotinoid insecticides treated sunflower&#x0D; Study Design: Randomized Block Design (RBD)&#x0D; Place and Duration of Study: Insectary, Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore between August 2021 to December 2021 during the Adipattam season&#x0D; Methodology: Bee activity was recorded by in situ counting method. Seven treatments with three replications (5flowers/replication) in Randomized Block Design were followed. Different treatments viz., Imidacloprid 17.8 SL @ 280µl/l, Clothianidin 50 WDG @ 80µg/l, Thiamethoxam 25 WG @ 250µg/l, Thiacloprid 21.7 SC @ 1100/µl, Dimethoate 30 EC @ 1400µl/l (chemical check), Water control (Water spray) and Absolute control (no spray) were given at 50% flowering period using Knapsack sprayer. The number of bees visiting 5 flowers per 5 minutes was observed during morning (09.00-11.00), afternoon (13.00-15.00) and evening (16.00-18.00) hours of the day for seven days after spray (DAS). DAS. Statistical Analysis Software (SAS) academics was used to statistically analyse the data.&#x0D; Results: The mean population of Apis cerana indica Fab. was more in absolute control (5.97) followed by water control (4.77), imidacloprid (4.10), clothianidin (3.40), thiacloprid (3.21), thiamethoxam (3.14) and dimethoate (1.90) during morning hours (09.00-11.00) of the day. The mean bee visitation rate was high in control (3.40), followed by water control (2.65), imidacloprid (1.77), clothianidin (1.52), thiacloprid (1.55), thiamethoxam (1.40) and dimethoate (1.17) during afternoon hours (13.00-15.00) of the day. In the evening hours (16.00-18.00), mean bee activity was high in control (4.95) followed by water control (4.27), imidacloprid (3.40), clothianidin (3.13), thiamethoxam (2.75), thiacloprid (2.53) and dimethoate (1.88). Among these different hours, morning forage activity of the bees are high in morning hours of the day followed by evening and very less in afternoon hours.&#x0D; Conclusion: The present study revealed that Indian honey bees preferred to forage both on neonicotinoid treated, however at a reduced rate, and untreated flowers. Since, neonicotinoids are odourless, tasteless compounds that increase the risk of pesticide exposure for the bee colony owing to less capability for segregation of insecticide treated surfaces.

Cell orientation characteristics of the natural combs of honey bee colonies.

The cell orientation characteristics of the natural combs of honey bees have received much research attention. Although natural combs have been shown to be composed of cells with three orientations—vertical, intermediate (oblique), and horizontal—the proportion of comb cells in these three orientations varies. Knowledge of the comb-building preferences of honey bees is essential for the installation of wax comb foundations, and clarification of the cell orientation characteristics of natural honey bee combs is important for beekeeping. The purpose of this study was to determine the cell orientation characteristics of natural combs of Eastern honey bees (Apis cerana cerana) and Western honey bees (Apis mellifera ligustica). Newly built combs were used to measure the orientation of hexagonal cells and calculate the proportion of cells in different orientations relative to the total number of cells. The number of eggs laid by queens in the cells of different orientations was also determined. The orientation of cells in the natural combs of Eastern and Western honey bees was determined based on the value of the minimum included angle between the pair of parallel cell walls and a vertical line connecting the top and bottom bars of the movable frame in the geometric plane of the comb: 0°≤θ≤10°, 10°<θ≤20°, and 20°<θ≤30° for vertical, intermediate, and horizontal orientations, respectively. Natural combs were composed of cells with at least one orientation (vertical or horizontal), two orientations (vertical + intermediate (oblique) or vertical + horizontal), or three orientations (vertical + intermediate + horizontal), and the proportions of combs with the three aforementioned configurations differed. Both Eastern honey bees and Western honey bees preferred building combs with cells in a vertical orientation. Queens showed no clear preference for laying eggs in cells of specific orientations. The results of this study provide new insight that could aid the production and cutting of wax comb foundations of Eastern and Western honey bees. Our study highlights the importance of installing wax comb foundations compatible with the comb-building preferences of bees.

Variations in Nutritional Requirements Across Bee Species

With 2,000 species currently recorded in Europe, bees are a highly diversified and efficient group of pollinating insects. They obtain their nutrients from nectar and pollen of flowers. However, the chemical composition of these resources, especially of pollen (e.g., protein, lipid, amino acids, fatty acids, or sterol content), is highly variable among plant species. While it is well-known that bees show interspecific variation in their floral choices, there is a lack of information on the nutritional requirements of different bee species. We therefore developed original experiments in laboratory conditions to evaluate the interspecific variations in bee nutritional requirements. We analyzed the chemical content of eight pollen blends, different in terms of protein, lipid, amino acids, and sterols total concentration and profiles. Each pollen blend was provided to four different bee model species: honey bees (Apis mellifera), bumblebees (Bombus terrestris), mason bees (Osmia bicornisandOsmia cornuta). For each species, specific protocols were used to monitor their development (e.g., weight, timing, survival) and resource collection. Overall, we found that the nutritional requirements across those species are different, and that a low-quality diet for one species is not necessarily low-quality for another one. While honey bees are negatively impacted by diets with a high protein content (~40%), bumblebees and mason bees develop normally on these diets but struggle on diets with a low total amino acid and sterol content, specifically with low concentrations of 24-methylenecholesterol and β-sitosterol. Overall, our study supports the need of conserving and/or introducing plant diversity into managed ecosystems to meet the natural nutritional preferences of bees at species and community level.

Floral preferences of mountain bumble bees are constrained by functional traits but flexible through elevation and season

Patterns of resource use by animals can clarify how ecological communities have assembled in the past, how they currently function and how they are likely to respond to future perturbations. Bumble bees (Hymentoptera: Bombus spp.) and their floral hosts provide a diverse yet tractable system in which to explore resource selection in the context of plant–pollinator networks. Under conditions of resource limitation, the ability of bumble bees species to coexist should depend on dietary niche overlap. In this study, we report patterns and dynamics of floral morphotype preferences in a mountain bumble bee community based on ~13 000 observations of bumble bee floral visits recorded along a 1400 m elevation gradient. We found that bumble bees are highly selective generalists, rarely visiting floral morphotypes at the rates predicted by their relative abundances. Preferences also differed markedly across bumble bee species, and these differences were well‐explained by variation in bumble bee tongue length, generating patterns of preference similarity that should be expected to predict competition under conditions of resource limitation. Within species, though, morphotype preferences varied by elevation and season, possibly representing adaptive flexibility in response to the high elevational and seasonal turnover of mountain floral communities. Patterns of resource partitioning among bumble bee communities may determine which species can coexist under the altered distributions of bumble bees and their floral hosts caused by climate and land use change.

Young honeybees show learned preferences after experiencing adulterated pollen

Pollen selection affects honeybee colony development and productivity. Considering that pollen is consumed by young in-hive bees, and not by foragers, we hypothesized that young bees learn pollen cues and adjust their preferences to the most suitable pollens. To assess whether young bees show preferences based on learning for highly or poorly suitable pollens, we measured consumption preferences for two pure monofloral pollens after the bees had experienced one of them adulterated with a deterrent (amygdalin or quinine) or a phagostimulant (linoleic acid). Preferences were obtained from nurse-aged bees confined in cages and from nurse bees in open colonies. Furthermore, we tested the bees’ orientation in a Y-maze using a neutral odour (Linalool or Nonanal) that had been previously associated with an amygdalin-adulterated pollen. Consumption preferences of bees, both in cages and in colonies, were reduced for pollens that had been adulterated with deterrents and increased for pollens that had been supplemented with linoleic acid. In the Y-maze, individuals consistently avoided the odours that they had previously experienced paired with the deterrent-adulterated pollen. Results show that nurse-aged bees associate pollen-based or pollen-related cues with either a distasteful/malaise experience or a tasty/nutritious event, leading to memories that bias their pollen-mediated response.

Elevated Temperature May Affect Nectar Microbes, Nectar Sugars, and Bumble Bee Foraging Preference

Floral nectar, an important resource for pollinators, is inhabited by microbes such as yeasts and bacteria, which have been shown to influence pollinator preference. Dynamic and complex plant-pollinator-microbe interactions are likely to be affected by a rapidly changing climate, as each player has their own optimal growth temperatures and phenological responses to environmental triggers, such as temperature. To understand how warming due to climate change is influencing nectar microbial communities, we incubated a natural nectar microbial community at different temperatures and assessed the subsequent nectar chemistry and preference of the common eastern bumble bee, Bombus impatiens. The microbial community in floral nectar is often species-poor, and the cultured Brassica rapa nectar community was dominated by the bacterium Fructobacillus. Temperature increased the abundance of bacteria in the warmer treatment. Bumble bees preferred nectar inoculated with microbes, but only at the lower, ambient temperature. Warming therefore induced an increase in bacterial abundance which altered nectar sugars and led to significant differences in pollinator preference.

Ratios rather than concentrations of nutritionally important elements may shape honey bee preferences for ‘dirty water’

1. Honey bees require minerals for a complete diet. However, minerals from flowers can be inadequate in concentration and composition. Therefore, honey bees may drink ‘dirty water’ from natural sources such as puddles. Some research has attempted to simulate this through honey bee bioassays, but to date, these have tested minerals individually, not as mixtures as would occur in nature. Here, for the first time, we use honey bees in bioassays in which a range of mineral mixtures are presented together in choice experiments.2. Six minerals (NaCl, KCl, CaCl2, MgCl2, NH4Cl, and KH2PO4) were used in mixtures to simulate different mineral stoichiometries, which may occur in ‘dirty water’, such as puddles, from which honey bees often drink. Based on the honey bee mineral tolerance ranges from the literature, these mixtures were offered in aqueous solutions at low, medium, high, and mixed molar concentrations. Deionised water and sucrose were neutral and positive controls, respectively. Petri dishes were set up in containers in a laboratory. Twenty worker honey bees (Apis mellifera L.) were placed into each container and observed for drinking behaviour for 1 h.3. Honey bees preferred the mixed molar treatment comprising a high Na:K ratio, a medium molarity of NaCl and a low molarity of the other minerals. This novel finding suggests that mixed mineral ‘dirty water’ should be investigated on a larger scale with multiple hives in the field and highlights the importance of stoichiometrically balanced honey bee diets.

Melissopalynological Determination of Pollen Density and Botanical Origin of Autumn Honeys of Kullu Hills, Himachal Pradesh, India

Background: Geographical and botanical origins of honeys are determined by melissopalynological analysis. Pollen contents of 12 autumn honeys collected from Indian honey bee, Apis cerana F. hives located in different localities of Kullu hills of Himachal Pradesh were analysed. Kullu hills having varied geography, climatic condition with diversified and rich flora is ideal for apiculture. So, it is of utmost importance to study the floral richness of the area and preferences of honey bees for nectar and pollen in order to obtain maximum production of a good quality of honey. Thus, the present work was carried out to determine the critical analysis of honey samples and to identify the different pollen types which are major plant sources that contribute to the increase of yield of honey.Methods: Melissopalynological studies were conducted between 2009 to 2012. Reference pollen slides of honey samples were prepared and identified. Quantative analysis is done with the help of a haemocytometer and pollen spectra, absolute pollen count as well as percentage of pollen types were calculated. Reference slides were also prepared.Result: Microscopic analysis yielded that in honey samples, 5 pollen types were present as predominant; 17 were secondary, while, 38 were important minor and minor pollen sources. Out of 12 honey samples analysed, 5 were unifloral, whereas, 7 were multifloral. In the unifloral honeys, the predominant sporomorphs were: Prunus cerasoides, Eriobotrya japonica, Prinsepia utilis, Plectranthus sp. and Solidago sp. Forty four pollen types were necteriferous, while, 6 were nectarless represented by Cannabis sativa, Juglans regia, Rumex nepalensis, Polygonum sp. and Zea mays. Among different plant families, Lamiaceae (8), Asteraceae (7), Rosaceae (7), Fabaceae (4), Polygonaceae (3) and Apiaceae (2) highly contributed for nectar and pollen sources of honey bee. Twenty five botanical families with 50 different pollen taxa were identified indicating the various plants visited by honeybees and the sources of nectar used in the production of honey. The high concentration and diversity of pollen types showed that the samples were of botanical origin.

Pollen Sources in Honey Bee (Apis mellifera) Diet in Ellis County, Kansas

Pollinators are integral to plant ecology as well as to worldwide food availability and security. Understanding the diet of honey bees (Apis mellifera) and knowing how human-driven land use change impacts the nutrition of managed honey bees is important in pollinator conservation efforts and can contribute towards combating recent pollinator declines. The objective of this study was to determine sources of forage for honey bees across different land use types in Ellis County, Kansas, through pollen analysis and taxonomic identification. Replicate study colonies were placed in three separate land use types: urban, cropland, or native/semi-native prairie. Pollen was sampled every 7 to 14 days throughout a growing season (April 1 to September 30) to identify key resources and their availability throughout time and space. Images of pollen from 110 species are presented. Pollen abundance (mass) varied greatly throughout time and across treatments, although urban colonies trended toward higher pollen abundance and cropland colonies trended toward reduced pollen abundance. Pollen from 41 different plant taxa was collected from experimental hives, with willows (Salix) and clovers (Melilotus/Trifolium) observed in abundance among all land use treatments. Unique distinctions among floral resources utilized in the three land use treatments included the abundance of trees in urban habitat, the prevalence of weedy species in cropland habitat, and the lack of grass pollen collected in cropland habitat. These results provide insight on available resources as well as honey bee preferences and foraging behaviors. Understanding the availability of floral resources in prairies can help to inform conservation decisions and improve understanding of community ecology and health of native pollinators in prairies.

Red mason bee (Osmia bicornis) thermal preferences for nest sites and their effects on offspring survival

Ectotherms usually require a narrow range of thermal conditions for development; thus, parental selection of oviposition sites is crucial. In a field experiment, we investigated female solitary red mason bee (Osmia bicornis) preferences for potential nest site temperatures and their effects on offspring development. The results showed that bees detected and avoided nest sites with high temperatures (28°C) and often chose cooler (24°C) or ambient temperatures (average 18–20°C). This is a protective behaviour because offspring survival decreases with increasing nest temperature, mostly due to mortality at the egg stage. Elevated temperatures also led to weight loss in adult bees. However, hot nest temperatures appeared to deter adults or kill parasite larvae, as the highest numbers of parasites were observed in unheated nests. We concluded that choosing the proper temperature for nests is an important element in bee life strategies, especially in warming environments.

Sublethal agrochemical exposures can alter honey bees' and Neotropical stingless bees' color preferences, respiration rates, and locomotory responses.

Stingless bees such as Partamona helleri Friese play important roles in pollination of native plants and agricultural crops in the Neotropics. Global concerns about declining bee populations due to agrochemical pollutants have, however, been biased towards the honey bee, Apis mellifera Linnaeus. Here, we analysed the unintended effects of commercial formulations of a neonicotinoid insecticide, imidacloprid, and a fungicide mixture of thiophanate-methyl and chlorothalonil on color preference, respiration rates and group locomotory activities of both P. helleri and A. mellifera. Our results revealed that P. helleri foragers that were not exposed to pesticides changed their color preference during the course of a year. By contrast, we found that pesticide exposure altered the color preference of stingless bees in a concentration-dependent manner. In addition, imidacloprid decreased the overall locomotion of both bee species, whereas the fungicide mixture increased locomotion of only stingless bees. The fungicide mixture also reduced respiration rates of forager bees of both species. Forager bees of both species altered their color preference, but not their locomotory and respiration rates, when exposed to commercial formulations of each fungicidal mixture component (i.e., chlorothalonil and thiophanate-methyl). Our findings emphasize the importance of P. helleri as a model for Neotropical wild pollinator species in pesticide risk assessments, and also the critical importance of including groups of agrochemicals that are often considered to have minimal impact on pollinators, such as fungicides.

Honey bee (Apis mellifera) preference towards micronutrients and their impact on bee colonies.

Honey bees are important pollinators and take micronutrients from different natural floral resources and turbid water to adequately meet their nutritional requirements. But the role of micronutrients for honey bee health is not well understood. Here, the present study was conducted to determine honey bees' micronutrients preference in summer and winter seasons. Also, the impact of micronutrients on foraging behaviour and brood increase was studied in different honey bee colonies. The results elucidated that honey bees exhibited a strong preference for a salt solution compared to deionized water during the summer and winter seasons. However, there was a notable switch in salt preference between seasons. Overall, honey bees showed significantly more foraging activity, more pollen collection, and increased brood area after sodium consumption compared to other minerals in the summer season. Further, pollen collection and brood area were significantly higher after the use of potassium in the winter season. Thus, the food preference of honey bees is strongly linked with the seasons and the availability of the floral resources. Our data suggested that honey bees may seek specific nutrients during variation of the seasonal conditions.