Search

South America is populated by a wide range of bumble bee species that represent an important source of biodiversity, supporting pollination services in natural and agricultural ecosystems. These pollinators provide unique specific microbial niches, populated by a wide number of microorganisms such as symbionts, environmental opportunistic bacteria, and pathogens. Recently, it was demonstrated how microbial populations are shaped by trophic resources and environmental conditions but also by anthropogenic pressure, which strongly affects microbes' functionality. This study is focused on the impact of different land uses (natural reserve, agroecosystem, and suburban) on the gut microbiome composition of two South American bumble bees, Bombus pauloensis and Bombus bellicosus. Gut microbial DNA extracted from collected bumble bees was sequenced on the Illumina MiSeq platform and correlated with land use. Nosema ceranae load was analyzed with qPCR and correlated with microbiome data. Significant differences in gut microbiome composition between the two wild bumble bee species were highlighted, with notable variations in α- and β-diversity across study sites. Bombus bellicosus showed a high abundance of Pseudomonas, a genus that includes environmental saprobes, and was found to be the second major taxa populating the gut microbiome, probably indicating the vulnerability of this host to environmental pollution. Pathogen analysis unveils a high prevalence of N. ceranae, with B. bellicosus showing higher susceptibility. Finally, Gilliamella exhibited a negative correlation with N. ceranae, suggesting a potential protective role of this commensal taxon. Our findings underscore the importance of considering microbial dynamics in pollinator conservation strategies, highlighting potential interactions between gut bacteria and pathogens in shaping bumble bee health. [ABSTRACT FROM AUTHOR]

While most models of decision-making assume that individuals assign options absolute values, animals often assess options comparatively, violating principles of economic rationality. Such 'irrational' preferences are especially common when two rewards vary along multiple dimensions of quality and a third, 'decoy' option is available. Bumblebees are models of decision-making, yet whether they are subject to decoy effects is unknown. We addressed this question using bumblebees (Bombus impatiens) choosing between flowers that varied in their nectar concentration and reward rate. We first gave bees a choice between two flower types, one higher in concentration and the other higher in reward rate. Bees were then given a choice between these flowers and either a 'concentration' or 'rate' decoy, designed to be asymmetrically dominated on each axis. The rate decoy increased bees' preference in the expected direction, while the concentration decoy did not. In a second experiment, we manipulated choices along two single reward dimensions to test whether this discrepancy was explained by differences in how concentration versus reward rate were evaluated. We found that low-concentration decoys increased bees' preference for the medium option as predicted, whereas low-rate decoys had no effect. Our results suggest that both low- and high-value flowers can influence pollinator preferences in ways previously unconsidered. [ABSTRACT FROM AUTHOR]

Simple Summary: To understand the processes behind the decline of pollinators, it is also essential to gain insight into their behaviour and identify the factors that drive it. This study focuses on the foraging behaviour of wild bumblebees in urban areas of Terceira, Azores, Portugal. We video-recorded buff-tailed bumblebees on flowering patches of Cretan bird's-foot trefoil, pink-headed knotweed, and red clover for five-minute intervals. We used computer vision-based deep learning models to detect bumblebees. Our results showed that flower cover was the only factor influencing the attractiveness of flower patches for flower-visiting bumblebees, while plant species had no effect. The time bumblebees spent on inflorescences was longer compared to their travelling time between inflorescences on the large-headed red clover than on the smaller-headed trefoil and knotweed. However, the overall time bumblebees spent on the inflorescences did not significantly differ among the plant species. Since our computer vision-based model achieved high accuracy in finding bumblebees on the target plant species, we confirmed that AI-based solutions can provide methods for studying pollinator behaviour and offer valuable insights to support conservation efforts. To understand the processes behind pollinator declines and for the conservation of pollination services, we need to understand fundamental drivers influencing pollinator behaviour. Here, we aimed to elucidate how wild bumblebees interact with three plant species and investigated their foraging behaviour with varying flower densities. We video-recorded Bombus terrestris in 60 × 60 cm quadrats of Lotus creticus, Persicaria capitata, and Trifolium pratense in urban areas of Terceira (Azores, Portugal). For the automated bumblebee detection and counting, we created deep learning-based computer vision models with custom datasets. We achieved high model accuracy of 0.88 for Lotus and Persicaria and 0.95 for Trifolium, indicating accurate bumblebee detection. In our study, flower cover was the only factor that influenced the attractiveness of flower patches, and plant species did not have an effect. We detected a significant positive effect of flower cover on the attractiveness of flower patches for flower-visiting bumblebees. The time spent per unit of inflorescence surface area was longer on the Trifolium than those on the Lotus and Persicaria. However, our result did not indicate significant differences in the time bumblebees spent on inflorescences among the three plant species. Here, we also justify computer vision-based analysis as a reliable tool for studying pollinator behavioural ecology. [ABSTRACT FROM AUTHOR]

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees' ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees' abilities to locate food sources and lead to declines in colonies and populations. [ABSTRACT FROM AUTHOR]

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heatwave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We used experimental heatwaves to determine how high temperatures affect the bumblebees' ability to detect floral scents. Heatwaves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 h after heat events. Our results suggest that the projected increased frequency and severity of heatwaves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees' abilities to locate food sources and lead to declines in colonies and populations. [ABSTRACT FROM AUTHOR]

Heteranthery, the presence of different types of anthers on the same flower, is a floral adaptation that aims to balance the need for pollinators to collect pollen as a food resource while ensuring sufficient pollen for pollination. We investigate the role of heteranthery in the pollination of Senna arnottiana flowers and how it is affected by the behaviour of visiting bee species, with a particular focus on the impact of the invasive bumblebee Bombus terrestris.In three populations of S. arnottiana we measured the size of three sets of anthers and style, stigma–anther separation, pollen quantity and fruit set, and contrasted it with the body size, behaviour, and pollination effectiveness of all floral visitors.Different bee species visited S. arnottiana flowers, and their foraging behaviour varied. Large‐bodied native bees, including Centris cineraria, Caupolicana sp. and Cadeguala occidentalis, preferentially visited short anthers, whereas B. terrestris, an exotic bumblebee, foraged from both short and long anthers without distinction. In addition, B. terrestris contacted the stigma at a lower rate than large‐bodied native bees.Instead of concentrating its pollen‐gathering efforts on the feeding anthers, as predicted by the "division of labor" hypothesis, B. terrestris indiscriminately visited both types of anthers similarly. This behaviour of B. terrestris may disrupt the adaptive significance of heteranthery by mixing the roles of pollination and feeding anthers of S. arnottiana. Therefore, our results highlight the potential disruption of this relationship by exotic pollinators and the need to consider it in conservation efforts. [ABSTRACT FROM AUTHOR]

Novel insecticides are continuously being developed for application in response to increased legal restriction of previously developed insecticides and resistance in target insects. These novel insecticides, such as flupyradifurone (FPF), remain relatively untested on non‐target organisms, including bumblebees. Further, existing tests on honeybees tend to focus on adult mortality and thus sub‐lethal effects, such as impacts on reproductive output, are neglected, despite their importance for population‐level impacts.To address if the novel insecticide FPF has sub‐lethal effects on bumblebee reproduction and behaviour, we established microcolonies and chronically exposed them to field‐realistic concentrations over a 14‐day period.We found that exposure to FPF reduced the bumblebees' reproductive output in terms of the number of larvae produced and the mean mass of each larval instar. FPF‐treated bees also stored less sucrose and constructed fewer honeypots. However, adult bumblebee mortality was similar between control and FPF‐exposed microcolonies.Our results show that field‐realistic FPF exposure leads to increased larval mortality and/or delayed larval development, as well as reduced nectar storage, without affecting adult mortality.Policy implications. Insecticides that impair bumblebee reproduction can have long‐term population‐level consequences, even if adult bees do not experience increased mortality. Despite this fact, sub‐lethal effects, such as impacts on reproduction, are not mandatorily assessed within the regulatory process. Our findings highlight the importance of determining sub‐lethal effects of pesticides across developmental stages, as well as using pollinator species other than honeybees within the regulatory process. [ABSTRACT FROM AUTHOR]

Background and Aims There are intrinsic conflicts between signalling to mutualists and concealing (camouflaging) from antagonists. Like animals, plants also use camouflage as a defence against herbivores. However, this can potentially reduce their attractiveness to pollinators. Methods Using Fritillaria delavayi , an alpine camouflaged plant with inter-population floral colour divergence, we tested the influence of floral trait differences on reproduction. We conducted pollination experiments, measured floral morphological characteristics, estimated floral colours perceived by pollinators, analysed floral scent and investigated reproductive success in five populations. Key Results We found that the reproduction of F. delavayi depends on pollinators. Under natural conditions, a flower-camouflaged population had 100 % fruit set and similar seed set to three out of four yellow-flowered populations. Bumblebees are important pollinators in the visually conspicuous yellow-flowered populations, whereas flies are the only pollinator in the flower-camouflaged population, visiting flowers more frequently than bumblebees. The camouflaged flowers cannot be discriminated from the rock background as perceived by pollinators, but may be located by flies through olfactory cues. Conclusions Collectively, our results demonstrate that the flower-camouflaged population has different reproductive traits from the visually conspicuous yellow-flowered populations. A pollinator shift from bumblebees to flies, combined with high visitation frequency, compensates for the attractiveness disadvantage in camouflaged plants. [ABSTRACT FROM AUTHOR]

Many bees visit just one flower species during a foraging trip, i.e. they show flower constancy. Flower constancy is important for plant reproduction but it could lead to an unbalanced diet, especially in biodiversity-depleted landscapes. It is assumed that flower constancy does not reduce dietary diversity in social bees, such as honeybees or bumblebees, but this has not yet been tested. We used computer simulations to investigate the effects of flower constancy on colony diet in plant species-rich and species-poor landscapes. We also explored if communication about food sources, which is used by many social bees, further reduces forage diversity. Our simulations reveal an extensive loss of forage diversity owing to flower constancy in both species-rich and species-poor environments. Small flower-constant colonies often discovered only 30–50% of all available plant species, thereby increasing the risk of nutritional deficiencies. Communication often interacted with flower constancy to reduce forage diversity further. Finally, we found that food source clustering, but not habitat fragmentation impaired dietary diversity. These findings highlight the nutritional challenges flower-constant bees face in different landscapes and they can aid in the design of measures to increase forage diversity and improve bee nutrition in human-modified landscapes. [ABSTRACT FROM AUTHOR]

Many plants have evolved nutrient rewards to attract pollinators to flowers, but most research has focused on the sugar content of floral nectar resources. Concentrations of sodium in floral nectar (a micronutrient in low concentrations in nectar) can vary substantially both among and within co‐occurring species. It is hypothesized that sodium concentrations in floral nectar might play an important and underappreciated role in plant–pollinator interactions, especially because many animals, including pollinators, are sodium limited in nature. Yet, the consequences of variation in sodium concentrations in floral nectar remain largely unexplored. Here, we investigate whether enriching floral nectar with sodium influences the composition, diversity, and frequency of plant–pollinator interactions. We experimentally enriched sodium concentrations in four plant species in a subalpine meadow in Colorado, USA. We found that flowers with sodium‐enriched nectar received more visits from a greater diversity of pollinators throughout the season. Different pollinator species foraged more frequently on flowers enriched with sodium and showed evidence of other changes to foraging behavior, including greater dietary evenness. These findings are consistent with the "salty nectar hypothesis," providing evidence for the importance of sodium limitation in pollinators and suggesting that even small nectar constituents can shape plant–pollinator interactions. [ABSTRACT FROM AUTHOR]

The extent to which weeds in arable land are useful to pollinators depends in part on the temporal pattern of flowering and insect flight activity. We compiled citizen science data on 54 bees and hoverflies typical of agricultural areas in southern Sweden, as well as 24 flowering weed species classified as pollinator‐friendly in the sense that they provide nectar and/or pollen to pollinators. The flight periods of the bees and hoverflies varied greatly, but there were also some consistent differences between the four groups studied. The first group to fly were the early flying solitary bees (7 species), followed by the social bees (18 species). In contrast, other solitary bees (11 species) and hoverflies (22 species) flew later in the summer. Solitary bees had the shortest flight periods, while social bees and hoverflies had longer flight periods. Flowering of weed species also varied greatly between species, with weeds classified as winter annuals (e.g., germinating in autumn) starting early together with germination generalists (species that can germinate in both autumn and spring). Summer annuals (spring germinators) and perennials started flowering about a month later. Germination generalists had a much longer flowering period than the others. Weekly pollinator records were in most cases significantly explained by weed records. Apart from early flying solitary bees, all models showed strong positive relationships. The overall best explanatory variable was the total number of weeds, with a weight assigned to each species based on its potential as a nectar/pollen source. This suggests that agricultural weeds in Sweden provide a continuous potential supply of nectar and pollen throughout the flight season of most pollinators. [ABSTRACT FROM AUTHOR]

A common management intervention to support declining wild pollinators is 'pollinator planting'. However, despite years of inclusion in conservation initiatives, global pollinator declines continue.Using the agent‐based model BEE‐STEWARD with two example species, Bombus terrestris (L. 1758) and B. pascuorum (Scopoli, 1763) (Hymenoptera: Apidae), we explore when during the year bumblebee resource demand is the highest and how that relates to seasonal changes in colony composition (numbers of eggs, larvae, pupae and adults). We then examine the impact of two‐week periods of resource scarcity across the year. Finally, we explore how enhancement with early spring‐blooming herbaceous species or trees changes colony survival and queen production.In the United Kingdom, there is a previously under‐appreciated 'hungry gap' for bumblebees in March–April, before the peak flight period, driven by the demands of larvae for protein and thermoregulation in the colony, rather than the number of adult bees.A 2‐week gap in forage availability during this period drives a 50%–87% drop in the production of daughter queens. Adding early‐blooming species in the model had significant, positive, long‐term effects on colony survival probability and daughter queen production.Pollinator‐planting initiatives in both national and international conservation schemes need to include plants that flower up to 1 month before the adults of target social pollinator species are apparent in the field, during the period that larvae dominate the colony. This approach is likely to increase colony survival and queen production, contributing towards halting and reversing global pollinator decline. [ABSTRACT FROM AUTHOR]

Bumble bees are the primary commercial pollinators for greenhouse‐grown crops and managing them requires insight into the Bombus life cycle. However, some aspects of the life cycle are not fully understood. Once mated, adult Bombus gynes can be stored for a short term at a constant low temperature (CLT). However, survival rates for some species are low during CLT, particularly when storage periods exceed a month. To address this, we tested the hypothesis that Bombus gynes stored in a fluctuating thermal regime (FTR) have increased survival compared to gynes stored in CLT. Specifically, the FTR had a baseline temperature of 2°C, with a daily fluctuation to 20°C relative to the CLT of 2°C with no warming pulse. We tested the effects of FTR on gyne survival and post‐cold storage lipid content in three species used for commercial pollination in North America: B. vosnesenskii, B. huntii and B. impatiens. We further assessed how additional factors influence cold storage survival, including gyne body weight, body size and colony age. Survival responses varied among species. Bombus vosnesenskii and B. huntii had a lower survival rate in FTR compared to CLT, but B. impatiens gynes had a significantly higher survival rate in FTR. We did not observe significant effects of FTR on lipid stores for any species, but survival increased with an increasing initial weight prior to cold storage. Moreover, gynes produced later in the colony life cycle had lower body weight and decreased survival compared to early emerging gynes. Our study provides insight into how cold storage conditions interact with colony and gyne characteristics to influence captive overwintering survival. Our findings have economic applications for improving commercial rearing and efforts for conservation rearing of at‐risk Bombus species. [ABSTRACT FROM AUTHOR]

Bumblebees are important pollinators in agricultural ecosystems, but their abundance is declining globally. There is an urgent need to protect bumblebee health and their pollination services. Bumblebees possess specialized gut microbiota with potential to be used as probiotics to help defend at‐risk bumblebee populations. However, evidence for probiotic benefits on bumblebees is lacking. Here, we evaluated how supplementation with Lactobacillus melliventris isolated from bumblebee gut affected the colony development of Bombus terrestris. This native strain colonized robustly and persisted long‐term in bumblebees, leading to a significantly higher quality of offspring. Subsequently, the tyrosine pathway was upregulated in the brain and fat body, while the Wnt and mTOR pathways of the gut were downregulated. Notably, the field experiment in the greenhouse revealed the supplementation of L. melliventris led to a 2.5‐fold increase in the bumblebee survival rate and a more than 10% increase in the number of flowers visited, indicating a better health condition and pollination ability in field conditions. Our study represents a first screening for the potential use of the native gut member, L. melliventris, as probiotic strains in hive supplement for bumblebee breeding, which may be a practical approach to improve immunity and hive health. [ABSTRACT FROM AUTHOR]

Agricultural intensification has been identified as one of the key causes of global insect biodiversity losses. These losses have been further linked to the widespread use of agrochemicals associated with modern agricultural practices. Many of these chemicals are known to have negative sublethal effects on commercial pollinators, such as managed honeybees and bumblebees, but less is known about the impacts on wild bees. Laboratory‐based studies with commercial pollinators have consistently shown that pesticide exposure can impact bee behavior, with cascading effects on foraging performance, reproductive success, and pollination services. However, these studies typically assess only one chemical, neglecting the complexity of real‐world exposure to multiple agrochemicals and other stressors. In the summer of 2020, we collected wild‐foraging workers of the common eastern bumblebee, Bombus impatiens, from five squash (Cucurbita) agricultural sites (organic and conventional farms), selected to represent a range of agrochemical, including neonicotinoid insecticide, use. For each bee, we measured two behaviors relevant to foraging success and previously shown to be impacted by pesticide exposure: sucrose responsiveness and locomotor activity. Following behavioral testing, we used liquid chromatography–tandem mass spectrometry (LC–MS/MS) chemical analysis to detect and quantify the presence of 92 agrochemicals in each bumblebee. Bees collected from our sites did not vary in pesticide exposure as expected. While we found a limited occurrence of neonicotinoids, two fungicides (azoxystrobin and difenoconazole) were detected at all sites, and the pesticide synergist piperonyl butoxide (PBO) was present in all 123 bees. We found that bumblebees that contained higher levels of PBO were less active, and this effect was stronger for larger bumblebee workers. While PBO is unlikely to be the direct cause of the reduction in bee activity, it could be an indicator of exposure to pyrethroids and/or other insecticides that we were unable to directly quantify, but which PBO is frequently tank‐mixed with during pesticide applications on crops. We did not find a relationship between agrochemical exposure and bumblebee sucrose responsiveness. To our knowledge, this is the first evidence of a sublethal behavioral impact of agrochemical exposure on wild‐foraging bees. [ABSTRACT FROM AUTHOR]

Temporal changes in population densities and species richness of three main pollinator groups—moths and butterflies (Lepidoptera); bees, wasps and sawflies (Hymenoptera); and hoverflies, horseflies, tachinids and bee flies (Diptera)—were investigated in the Carpathian Basin. Maintaining pollinator diversity is a crucial factor for preserving our biodiversity and ecosystems; furthermore, several pollinator species have a strong economic role in maintaining crop and fruit cultures. Our conclusions are based on our three and four decades of faunistic surveys in various regions of the Carpathian Basin. Analyzing and comparing our data with the historical data of the last 50 years, we concluded that densities of some pollinators declined during the past decade and a half (Symphyta, hoverflies), although populations of several species of Mediterranean origin grew (Aculeata) and new species even migrated from the warmer regions. In numerous cases, this decrease was dramatic: more than 90% decline of certain butterfly species were detected. On the other hand, the composition of pollinator fauna significantly changed due to the disappearance of some mountainous or mesophile species. The main reason for the decrease in pollinator communities is due partly to climatic change and partly to anthropogenic factors. Different groups of pollinators react differently: some groups like Syrphidae, Tachinidae, most of the butterfly families and bumblebees suffered a strong decline in the last two decades; other warm-loving groups like most of Aculeata and horseflies and bee flies showed a significant increase in population densities. Our conclusion: in our region, the pollinator crisis is present but moderate; however, there is a clear sign of the gradual transition of our pollinator fauna towards the Mediterranean type. [ABSTRACT FROM AUTHOR]

In a time of increasing threats to bumble bees (Hymenoptera: Apidae: Bombus), it is important to understand their ecology and distribution. As experts are limited in resources to conduct field surveys, there is potential for community scientists to help. The Bumble Bee Watch (BBW) community science program involves volunteers taking photos of bumble bees in Canada and the USA and submitting them, along with geographic and optional plant information, to a website or through an app. Taxon experts then verify the bee species identification. The Bumble Bees of North America database (BBNA) stores data (no photographs) collected and identified by more traditional scientific methods over the same range. Here we compared BBW data to BBNA data over all years and just 2010–2020 to understand the scientific contribution of community scientists to the state of the knowledge about native bumble bees. We found that BBW had similar geographic and species coverage as BBNA. It had records from all 63 provinces, states, and territories where bumble bees occur (including four more than BBNA in 2010–2020), and represented 41 of the 48 species in BBNA (with ten more species than BBNA in 2010–2020). While BBW contributed only 8.50% of records overall, it contributed 25.06% of all records over 2010–2020. BBW confirmed the persistence of species and identified new locations of species, both inside and outside of the previously known extent of occurrences. BBW also contributed a wealth of ecological information, such as unique plant genera and species data for almost all the bee species. Thus, while BBW had fewer bee records than the BBNA database overall, it helped to fill in data gaps and provided novel information, complementing the traditional methods. This community science program is valuable in helping to inform conservation management for bumble bee species. [ABSTRACT FROM AUTHOR]

Mitochondria are intracellular organelles responsible for cellular respiration with one of their major roles in the production of energy in the form of ATP. Activities with increased energetic demand are especially dependent on efficient ATP production, hence sufficient mitochondrial function is fundamental. In bees, flight muscle and the brain have particularly high densities of mitochondria to facilitate the substantial ATP production required for flight activity and neuronal signalling. Neonicotinoids are systemic synthetic insecticides that are widely utilised against crop herbivores but have been reported to cause, by unknown mechanisms, mitochondrial dysfunction, decreasing cognitive function and flight activity among pollinating bees. Here we explore, using high-resolution respirometry, how the neonicotinoid imidacloprid may affect oxidative phosphorylation in the brain and flight muscle of the buff-tailed bumblebee, Bombus terrestris. We find that acute exposure increases routine oxygen consumption in the flight muscle of worker bees. This provides a candidate explanation for prior reports of early declines in flight activity following acute exposure. We further find that imidacloprid increases the maximum electron transport capacity in the brain, with a trend towards increased overall oxygen consumption. However, intra-individual variability is high, limiting the extent to which apparent effects of imidacloprid on brain mitochondria are shown conclusively. Overall, our results highlight the necessity to examine tissue-specific effects of imidacloprid on respiration and energy production. [ABSTRACT FROM AUTHOR]

Patterns of abundance across space and time, and intraspecific variation in body size, are two species attributes known to influence diet breadth and the structure of interaction networks. Yet, the relative influence of these attributes on diet breadth is often assumed to be equal among taxonomic groups, and the relationship between intraspecific variation in body size on interaction patterns is frequently neglected. We observed bee–flower interactions in multiple locations across Montana, USA, for two growing seasons and measured spatial and temporal patterns of abundance, along with interspecific and intraspecific variation in body size for prevalent species. We predicted that the association between spatial and temporal patterns of abundance and intraspecific variation in body size, and diet breadth, would be stronger for bumble bee compared to non-bumble bee species, because species with flexible diets and long activity periods can interact with more food items. Bumble bees had higher local abundance, occurred in many local communities, more intraspecific variation in body size, and longer phenophases compared to non-bumble bee species, but only local abundance and phenophase duration had a stronger positive association with the diet breadth of bumble bee compared to non-bumble bee species. Communities with a higher proportion of bumble bees also had higher intraspecific variation in body size at the network-level, and network-level intraspecific variation in body size was positively correlated with diet generalization. Our findings highlight that the association between species attributes and diet breadth changes depending on the taxonomic group, with implications for the structure of interaction networks. [ABSTRACT FROM AUTHOR]

Floral features, the pollination process, the breeding system, and fruiting success are documented in the Andean terrestrial orchid Gomphichis valida. Studies were performed at the Department of Ancash, Peru, at ca. 4250 m a.s.l., from June to November 2022. The breeding system was studied through controlled pollinations in plants excluded from pollinators (bagged). Natural pollination was studied in the field and through photos and videos. The flowers are nectariferous and non‐protandrous and present the longest lifespan reported so far for a neotropical terrestrial orchid (53–80 days). This species is pollinator dependent (unable to set fruit and seed without the agency of pollinators) and self‐compatible. The observed pollinators belong to three functional groups that appeared successively (in order of appearance): hummingbirds (Chalcostigma stanleyi), bumblebees (Bombus coccineus and Bombus rubicundus), and solitary Halictidae bees (Augochlorella sp.). All recorded pollinators probe the flowers for nectar. The pollinaria adhere to the bee mouthparts and onto the lateral side of the hummingbird bill. Bumblebees were the most frequent and efficient functional group (up to 62.07% of the observed pollination events), followed by Halictidae (31.03%) and hummingbirds (6.90%). Natural fruiting success is high (66.66%–94.49%). Such high natural fruiting success is unexpected at high altitudes, but it is likely explained by a combination of factors, including the long floral lifespan, nectar secretion, and self‐compatibility. This is the first report of hummingbirds as pollinators of Cranichidinae orchids, and G. valida is, to the best of our knowledge, a neotropical orchidoid orchid with the most generalist pollination biology recorded so far. [ABSTRACT FROM AUTHOR]

The transmission of pathogens from reservoir to recipient host species, termed pathogen spillover, can profoundly impact plant, animal, and public health. However, why some pathogens lead to disease emergence in a novel species while others fail to establish or do not elicit disease is often poorly understood. There is strong evidence that deformed wing virus (DWV), an (+)ssRNA virus, spills over from its reservoir host, the honeybee Apis mellifera, into the bumblebee Bombus terrestris. However, the low impact of DWV on B. terrestris in laboratory experiments suggests host barriers to virus spread in this recipient host. To investigate potential host barriers, we followed the spread of DWV genotype B (DWV-B) through a host's body using RT-PCR after experimental transmission to bumblebees in comparison to honeybees. Inoculation was per os, mimicking food-borne transmission, or by injection into the bee's haemocoel, mimicking vector-based transmission. In honeybees, DWV-B was present in both honeybee faeces and haemolymph within 3 days of inoculation per os or by injection. In contrast, DWV-B was not detected in B. terrestris haemolymph after inoculation per os, suggesting a gut barrier that hinders DWV-B's spread through the body of a B. terrestris. DWV-B was, however, detected in B. terrestris faeces after injection and feeding, albeit at a lower abundance than that observed for A. mellifera, suggesting that B. terrestris sheds less DWV-B than A. mellifera in faeces when infected. Barriers to viral spread in B. terrestris following oral infection may limit DWV's impact on this spillover host and reduce its contribution to the community epidemiology of DWV. [ABSTRACT FROM AUTHOR]

Insect pollination is an important process in the natural ecosystem and plays a vital role in crop reproduction. The bumblebee, Bombus terrestris (L.), is a widely used pollinator for crops, especially tomato. The efficiency of bee pollination is related to many factors, including biotic factors such as bee species, nutrition plants, and herbivores. Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is one of the most common and serious pests of tomato plants. However, whether B. tabaci affects the pollination behaviour of B. terrestris on tomato, and how plant–herbivore–pollinator interactions are unclear. In this study, we found that B. terrestris preferred B. tabaci-damaged plants. Furthermore, plant volatiles of tomato plants damaged by B. tabaci were detected and analysed. Electroantennogram (EAG) and the Y-tube bioassay were used for olfactory responses of B. terrestris to plant volatiles. Interestingly, methyl hexanoate and eugenol induced by B. tabaci in tomato plants were found to significantly attract B. terrestris. Therefore, Bemisia tabaci influenced B. terrestris preference through volatiles. The plant volatile-mediated interaction between B. tabaci and B. terrestris could enrich our understanding of the interaction between herbivores and pollinators. In addition, methyl hexanoate and eugenol could be applied for synergist of pollination. [ABSTRACT FROM AUTHOR]

A rising global population will need more food, increasing demand for insect pollination services. However, general insect declines conflict with this demand. One way to mitigate this conflict is to grow crop flowers that are easier for insects to find and more rewarding to those that visit them. This study quantifies variation in the pollinator‐relevant traits of nectar and pollen production, flower size and flower shape in commercial strawberry, finding significant variation between varieties in all traits. Bumblebees could learn to distinguish between the extremes of variation in flower shape, but this learning is very slow, indicating that this variation is at the limit of that which can be detected by bumblebees. Bee preferences for nectar of differing sugar concentrations at field‐realistic volumes were consistent with previous observations at larger volumes, suggesting that it is valid to translate lab findings to the field. This study builds on our knowledge of the range of pollinator reward present in a single cultivated species and of the impact of field‐realistic levels of variation in floral traits on bumblebee preferences. [ABSTRACT FROM AUTHOR]

Bumblebees are important pollinators in both natural and agricultural ecosystems, but their survival and pollination service are threatened by extensive pesticide use. Due to regulation changes, acetamiprid has become the only neonicotinoid substance that can be used without restrictions and in open‐field cultivations in the European Union. Yet, we know little about how this active ingredient affects bumblebees' foraging behaviour and if such effects are similarly detrimental to those of other neonicotinoids. Here we investigated how a 14‐day‐long (chronic) exposure to low (5 ppb) and high (2500 ppb) concentrations of acetamiprid in syrup affected different aspects of foraging behaviour in buff‐tailed bumblebees (Bombus terrestris, Linnaeus). We recorded individual foraging at artificial food patches during one‐hour‐long trials and then compared several foraging‐related measures between differently dosed individuals. We found that 75.12% of the total syrup consumption occurred at the first‐exploited patch, but individuals did not exhibit any bias toward pesticide‐treated food patches. Chronic exposure to acetamiprid had little effect on individual foraging decisions at the first‐exploited food patch but significantly affected the time to the first feeding and the number of feedings at the second‐exploited patch in interaction with body mass. The duration of the first feeding was affected only by foragers' body mass. Our finding indicates that chronic exposure to a high but field‐realistic concentration of acetamiprid may alter some aspects of bumblebees' foraging behaviour. If such behavioural changes accumulate during consecutive foraging bouts, chronic exposure to this pesticide might lead to a reduction of daily resource collection, ultimately jeopardising colony fitness or plant (crop) pollination. [ABSTRACT FROM AUTHOR]

Social bees are frequently exposed to pesticides when foraging on nectar and pollen. Recent research has shown that pesticide exposure not only impacts social bee host health but can also alter the community structure of social bee gut microbiotas. However, most research on pesticide-bee gut microbiota interactions has been conducted in honey bees; bumble bees, native North American pollinators, have received less attention and, due to differences in their ecology, may be exposed to certain pesticides for shorter durations than honey bees. Here, we examine how exposure to the fungicide chlorothalonil for a short, field-realistic duration alters bumble bee fecal microbiotas (used as a proxy for gut microbiotas) and host performance. We expose small groups of Bombus impatiens workers (microcolonies) to field-re alistic chlorothalonil concentrations for 5 days, track changes in fecal microbiotas during the exposure period and a recovery period, and compare microcolony offspring production between treatments at the end of the experiment. We also assess the use of fecal microbiotas as a gut microbiota proxy by comparing community structures of fecal and gut microbiotas. We find that chlorothalonil exposure for a short duration does not alter bumble bee fecal microbiota structure or affect microcolony production at any concentration but that fecal and gut microbiotas differ significantly in community structure. Our results show that, at least when exposure durations are brief and unaccompanied by other stressors, bumble bee microbiotas are resilient to fungicide exposure. Additionally, our work highlights the importance of sampling gut microbiotas directly, when possible. [ABSTRACT FROM AUTHOR]

Invasive species are predicted to adjust their morphological, physiological and life‐history traits to adapt to their non‐native environments. Although a loss of genetic variation during invasion may restrict local adaptation, introduced species often thrive in novel environments. Despite being founded by just a few individuals, Bombus terrestris (Hymenoptera: Apidae) has in less than 30 years successfully spread across the island of Tasmania (Australia), becoming abundant and competitive with native pollinators. We use RADseq to investigate what neutral and adaptive genetic processes associated with environmental and morphological variation allow B. terrestris to thrive as an invasive species in Tasmania. Given the widespread abundance of B. terrestris, we expected little genetic structure across Tasmania and weak signatures of environmental and morphological selection. We found high gene flow with low genetic diversity, although with significant isolation‐by‐distance and spatial variation in effective migration rates. Restricted migration was evident across the mid‐central region of Tasmania, corresponding to higher elevations, pastural land, low wind speeds and low precipitation seasonality. Tajima's D indicated a recent population expansion extending from the south to the north of the island. Selection signatures were found for loci in relation to precipitation, wind speed and wing loading. Candidate loci were annotated to genes with functions related to cuticle water retention and insect flight muscle stability. Understanding how a genetically impoverished invasive bumblebee has rapidly adapted to a novel island environment provides further understanding about the evolutionary processes that determine successful insect invasions, and the potential for invasive hymenopteran pollinators to spread globally. [ABSTRACT FROM AUTHOR]

Flowers cluster at various spatial scales, so pollinators use information from multiple scales when foraging in natural plant populations. Little is known about the effects of interactions between scales or their relative strength. We examined bumblebee foraging behaviour in a natural population of Salvia nipponica in 10 and 7 patches in 2019 and 2020, respectively. We recorded within-patch factors (display size of racemes and local open raceme densities) and patch-level factors (patch size and distance from the nearest patch) and analysed their relationships with pollinator behaviour. The numbers of visits per raceme and flower were mainly affected by the interaction of patch size and raceme density; they were higher in locations with lower raceme density in larger patches. The ratio of flowers visited to all open flowers in a raceme during a raceme visit, which relates to a bumblebee's choice to leave a raceme, was mainly affected by the interaction of display size and local open raceme density; in 2019 it was higher in racemes with smaller display sizes, while in 2020 the strength and direction of the relationship depended on the open raceme density. These results suggest that pollinators relied on the sizes of flower clusters at different spatial scales when visiting and leaving racemes and adjusted their responses to the sizes of flower clusters depending on the distances between clusters. Therefore, it is important to evaluate factors at various spatial scales and their interactions to fully understand pollinator behaviour in natural plant populations. [ABSTRACT FROM AUTHOR]

Conversion of land for agricultural use is a leading driver of global biodiversity loss. Natural and semi‐natural lands within agricultural landscapes are targeted for protection because they provide habitat for many organisms.Pothole (or kettle) wetlands occur across the Northern Hemisphere and are a focus for conservation both because of their location within agriculturally intensive landscapes and their importance to vertebrates, especially migratory birds.Recent evidence suggests that wetlands may also be an important habitat for arthropods, including insects that provide ecosystem services. To understand how insects associate with wetlands and landscape features, we examine the relationship between bumblebees (Bombus), and wetland area, cropland area and wetland perimeter‐area ratio.We found that wetland area is significantly positively associated with the occurrence and abundance of the species studied. We also found that the relationship between bumblebees and wetland perimeter‐area ratio varied across the growing season. This suggests that the importance of wetland edge as a foraging habitat varies across the season.These results show the utility of wetlands to bees, though their resources are likely not being used uniformly by all bumblebee species or across the entire growing season. Our results also suggest that pothole wetlands in agricultural landscapes are likely to support biodiversity, and their conservation contributes to overall ecosystem health and function. [ABSTRACT FROM AUTHOR]

Foraging theory assumes that animals assess value based on objective payoffs; however, animals often evaluate rewards comparatively, forming expectations based on recent experience. This form of evaluation may be particularly relevant for nectar foragers such as bumblebees, where individuals can visit thousands of flowers daily that vary in nectar quality. While many animals, including bees, demonstrate reference-based evaluation in experimental contexts, it is unclear whether this occurs in the wild. Here, we asked how daily experience with wildflower nectar influenced wild bumblebees' reward evaluation. We measured the daily nectar concentration of bee-visited wildflowers (Penstemon spp.), before presenting foragers with conspecific flowers filled with a range of artificial nectar concentrations. We recorded bees' acceptance of artificial nectar, the probability of subsequent visits to flowers on the same plant, and residence time. While bees had a minimum threshold of nectar acceptability that was unaffected by experience, when there was higher-concentration environmental nectar, they were less likely to accept lower-quality rewards on manipulated plants. Bees also visited more flowers and stayed longer on plants with higher-concentration nectar. This study shows evidence for both absolute and reference-based evaluation in wild bees and points towards differences between bees' behavior in lab- and wild-foraging contexts. [ABSTRACT FROM AUTHOR]

Brahma Kamal are rare flowers found in high-altitude regions of the Himalaya, where bumble bees are the primary pollinators. Bumble bees are cold-adapted bees, and in India their distribution is in Himalayan Mountain ranges. We study this plant and bumble bees in the Bumla pass at about 4300 m above mean sea level (amsl) in the Eastern Himalayan Ranges in the Tawang District, Arunachal Pradesh, India. The present study systematically reported the occurrence of Brahma Kamal, which was rarely recorded in Arunachal along with a report of six species of bumble bee (Bombus abnormis, Bombus lemniscatus, Bombus mirus, Bombus pressus, Bombus prshewalskyi and Bombus sikkimi) visitors from high altitude region of state of Arunachal Pradesh, India. The flowering time of the Brahma Kamal is in the month of August, and the optimal period to record bumble bees is from June to August. This new report focuses on the extreme east of India, in the Eastern Himalaya, and adds to the data on Brahma Kamal distribution and bumble bee occurrence for future research on pollination, species distribution, threat and conservation. [ABSTRACT FROM AUTHOR]

This document is a corrigendum published in the journal Frontiers in Insect Science. It corrects an error in Figure 1 of the article titled "Acute imidacloprid exposure alters mitochondrial function in bumblebee flight muscle and brain." The corrected figure and its caption are provided, and the authors apologize for the error. The corrigendum also includes a note from the publisher stating that the views expressed in the article are solely those of the authors and do not necessarily represent the views of their affiliated organizations or the publisher. The article is open access and can be cited under the terms of the Creative Commons Attribution License. [Extracted from the article]

The article discusses various topics in the field of science. It highlights the discrepancies in the estimates of catchment areas of Indian river basins, emphasizing the need for accurate data in water resource management. The article also explores the use of predatory wasps to control fennel aphids in spice crops, providing a solution to improve seed quality and yield. Additionally, it mentions the discovery of soft-bodied fossils in the Sonia Formation in Jodhpur, shedding light on the evolution of multicellularity. Lastly, the article mentions the presence of bumble bees visiting Brahma Kamal flowers in Arunachal Pradesh, raising questions about their role in pollination. [Extracted from the article]

Crithidia bombi is a trypanosomatid parasite that infects several species of bumble bees (Bombus spp.), by adhering to their intestinal tract. Crithidia bombi infection impairs learning and reduces survival of workers and the fitness of overwintering queens. Although there is extensive research on the ecology of this host-pathogen system, we understand far less about the mechanisms that mediate internal infection dynamics. Crithidia bombi infects hosts by attaching to the hindgut via the flagellum, and one previous study found that a nectar secondary compound removed the flagellum, preventing attachment. However, approaches that allow more detailed observation of parasite attachment and growth would allow us to better understand factors mediating this host-pathogen relationship. We established techniques for genetic manipulation and visualization of cultured C. bombi. Using constructs established for Crithidia fasciculata, we successfully generated C. bombi cells expressing ectopic fluorescent transgenes using two different selectable markers. To our knowledge, this is the first genetic modification of this species. We also introduced constructs that label the mitochondrion and nucleus of the parasite, showing that subcellular targeting signals can function across parasite species to highlight specific organelles. Finally, we visualized fluorescently tagged parasites in vitro in both their swimming and attached forms, and in vivo in bumble bee (Bombus impatiens) hosts. Expanding our cell and molecular toolkit for C. bombi will help us better understand how factors such as host diet, immune system, and physiology mediate outcomes of infection by these common parasites. [Display omitted] • First described method for genetic modification of the bee parasite Crithidia bombi. • Ectopic transgenes can be introduced using multiple selectable markers. • Cytoplasmic and organelle markers can be visualized in swimming and attached developmental forms. • Simplified method for culture adaptation of parasites from bees for subsequent modification. • Imaging of fluorescent C. bombi parasites in vivo in the bumble bee Bombus impatiens. [ABSTRACT FROM AUTHOR]

Bees are declining, which is worrisome since they both have intrinsic conservation value and play a major role as pollinators in both natural and managed ecosystems. Land use change and lack of suitable habitats are often suggested as driving forces of bee decline. To propose mitigation measures to halt bee decline, it is important to understand how land use relates to bee abundance and diversity, and to explore consequences for their provision of pollination services. White clover, Trifolium repens , is an outcrossing mass-flowering crop, which could serve as an abundant, although ephemeral, food resource for bees. We investigated how the bee community in 39 fields of white clover grown for seed, related to local field management (organic, conventional without insecticides and conventional with insecticides) and landscape context (proportion semi-natural land), and how this pollinator community related to white clover seed set. The honey bee, Apis mellifera , was the most commonly observed bee species, and two generalist bumble bee species, Bombus terrestris and B. lapidarius , were the subsequently most common. We observed fewer non- Apis bees, and a lower bee species richness in organic white clover seed fields compared to conventional fields independent of insecticide treatment. Bee species richness in both conventional and organic fields were positively related to the proportion of semi-natural land in the landscape, likely because of a larger species pool in such landscapes. Initial seed set in immature inflorescences was positively related to bee abundance, whereas final seed set in mature inflorescences was unrelated to bee abundance, possibly as a consequence of seed-eating weevils consuming a large proportion of the seeds. We conclude that both bee visitation and seed set in white clover benefit from conventional management and that landscapes rich in semi-natural habitats will make future crop production more resilient. The observed positive relationship between bee abundance and initial seed set suggests that if we can mitigate pest impacts and increase bee abundance in clover seed fields, the final seed yield can be increased. Thus, bee decline should be considered and mitigated both to maintain biodiversity in general and for crop seed production specifically. • Lower (non-Apis) bee abundance and species richness in organic white clover fields • Bee species richness positively related to the proportion of semi-natural land • Initial seed set in immature inflorescences positively related to bee abundance • Final seed set was unrelated to bee abundance, possibly due to seed-eating weevils [ABSTRACT FROM AUTHOR]

Cadmium pollution affects the global ecosystem because cadmium can be transferred up the food chain. The bumblebee, Bombus terrestris , is an important insect pollinator. Their foraging activity on flowers exposes them to harmful heavy metals, which damages their health and leads to massive population declines. However, the effects of chronic exposure to heavy metals on the flight performance of bumblebees have not yet been characterized. Here, we studied variation in the flight capacity of bumblebees induced by chronic cadmium exposure at field-realistic concentrations using behavioral, physiological, and molecular approaches. Chronic cadmium exposure caused a significant reduction in the duration, distance, and mean velocity of bumblebee flight. Transcriptome analysis showed that the impairment of carbon metabolism and mitochondrial dysfunction in the flight muscle were the primary causes. Physiological, biochemical, and metabolomic analyses validated disruptions in energy metabolism, and impairments in mitochondrial respiratory chain complexes activities. Histological analysis revealed muscle fiber damage and mitochondrial loss. Exogenous decanoic acid or citric acid partially restored sustained flight ability of bumblebees by mitigating muscle fiber damage and increasing energy generation. These findings provide insights into how long-term cadmium stress affects the flight ability of insects and will aid human muscle or exercise-related disease research. [Display omitted] • Chronic cadmium exposure at field-realistic concentrations reduced flight capacity. • Chronic cadmium exposure impaired sustained flight by inhibiting energy metabolism. • Citrate synthase was a potential biomarker for chronic cadmium exposure. • Exogenous citric acid or decanoic acid restored damaged flight ability. [ABSTRACT FROM AUTHOR]

"What a Bee Knows: Exploring the Thoughts, Memories, and Personalities of Bees" by Stephen Buchmann is a book that sheds light on the remarkable abilities of bees and their brains. The author covers the basics of bee biology, including how they find food, build nests, interact with each other, and find mates. The book also delves into cutting-edge research on bee learning, cognition, self-awareness, and consciousness. While the book does not provide detailed information on pollinator habitat restoration or conservation resources, it emphasizes the importance of taking action to support bees and other pollinators. Overall, readers will gain a newfound appreciation for bees and their complex lives. [Extracted from the article]