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• The field cultivation of oil tree peony experienced a "medium" pollination deficit. • Excluding pollinator pollination reduced the yield of oil tree peony by 44.24%, and oil tree peony showed a high dependence on bumblebee pollination. • Supplemental bumblebee pollination increased the seed yield of oil tree peony by 82.87% and the oil yield by 10.21%, which reduced the degree of pollination defects to a lower level. • Pollination by bumblebees ensures the stability of yield and quality of oil tree peony over time. Oil tree peony is a unique woody oil crop found exclusively in China. Its seed oil is a highly nutritious edible vegetable oil. However, its seed production varies greatly and is often low. Oil tree peony is a plant that relies on insects for pollination, but inadequate pollination is a common occurrence. In this study, we focused on the Paeonia ostii 'Fengdan' species and conducted a five-year study (from 2017 to 2022) in Luoyang, China. Our objective was to assess the extent of pollination deficiency and dependence, as well as quantify the contribution of supplemented bumblebees (Bombus terrestris) to the yield of oil tree peony. We also examined the effect of supplemented bumblebees on the temporal variation in yield through various pollinator survey designs, including supplemented bumblebees (BP), open pollination (OP), pollinator exclusion (EP), self-pollination treatments (SP), and artificial cross-pollination (CP). The results revealed a medium pollination deficit (D = 0.50) at the study sites for three consecutive years from 2020 to 2022, indicating limited pollination for oil tree peony under natural conditions. Importantly, BP significantly compensated for this deficiency (D = 0.22). Over the course of five years, BP increased the yield of oil tree peony by 82.87% on average compared to EP. Furthermore, the yield variation coefficient of EP (CVt=0.20) increased by 100% compared to BP (CVt=0.10). And we also observed significant variability in other yield parameters. Additionally, oil tree peony production was reduced by 44.24% in the absence of flower visitors, and the dependence on BP reached a "high" level. The fatty acid content in the seed oil did not show significant differences across treatments, indicating its stability. Overall, our pollination practices demonstrate that supplementing bee pollination can provide sufficient and stable pollination services, resulting in a higher and more stable yield of oil tree peony seeds. [ABSTRACT FROM AUTHOR]

Nectar composition is an important driver of insect attractiveness. Although bumblebees prefer sucrose-rich nectar, they were found to be the main pollinators of Gentiana lutea, whose nectar is low on sucrose. Therefore, we tested the hypothesis that bumblebees are attracted to the amino acids proline and β-alanine, which are both naturally occurring at high concentrations in the nectar of G. lutea. We analysed the solution consumption and survival of Bombus terrestris L. (Hymenoptera: Apidae) workers fed with artificial nectars enriched with proline, β-alanine or both, at natural and twice the natural concentrations. We found that consumption of nectar enriched with proline at twice the natural concentration was strongly positively correlated with bumblebee weight. However, when adjusting for individual weight, we found that this solution was the least consumed, suggesting the presence of a regulatory mechanism of proline intake to reduce negative effects on survival. We did not find any direct effect of β-alanine on consumption, although our findings suggest a potential interplay between proline and β-alanine in the regulation of proline intake. Bumblebee survival was not affected by any nectar composition. These results suggest that the high visitation rate to flowers of G. lutea by bumblebees observed in natural populations can be partially related to its nectar amino acidic composition, and that protein and non-protein amino acids can affect pollinator preference and foraging behaviour. [ABSTRACT FROM AUTHOR]

Bombus terrestris (Hymenoptera: Apidae) is an efficient pollinator that is widely used in agriculture. High-efficiency pollination is closely related to antennae. As sensory organs, antennae are of great significance in sensing and perceiving the external environment and information exchange between individuals. However, there remains a lack of comprehensive and systematic research on the antennae of B. terrestris. Therefore, we analysed the morphology and distribution of antennal sensilla (chemoreceptors) of B. terrestris using scanning electron microscopy (SEM). The total antennal length of B. terrestris was 7.0657 ± 0.0388 mm for queens, 5.9113 ± 0.0712 mm for workers, and 6.9727 ± 0.1211 mm for males. Queens and males were found to have seven different sensilla types, whereas workers had only six. Furthermore, the ultrastructure and putative functions of each sensilla type in B. terrestris , other bumblebees, and honeybees are described and discussed. These results provide a useful reference and guidance for the study of the pollination behaviour of B. terrestris and may explain the preference for some flower visits. [ABSTRACT FROM AUTHOR]

International companies commercially rear bumblebees worldwide, the trade of which is regulated through agreements established by the World Trade Organization (WTO). Scientific studies have shown multiple negative effects of introduced commercial bumblebees on native bees in Japan, Australia, Sweden, Israel, Chile, and Argentina, calling into question the compliance of exporting with some of the established WTO international sanitary regulations. We analyzed international WTO sanitary regulations focusing on the international trade of bumblebees from the European Union (EU) and Israel, especially regarding bumblebee exports to Chile and their side effects in neighboring Argentina. We have gathered evidence showing that exporters of bumblebees do not comply with WTO international trade agreements in at least two ways: (1) the quality of commercialized bumblebees differs from the quality declared in their certifications, and (2) the countries that sell the bumblebees violate sanitary agreements, producing negative effects on other native pollinating insects and causing a cascade of adverse impacts affecting both the environment and agriculture. This situation suggests that companies that raise bumblebees are currently in breach of WTO regulations and continue to contribute to major environmental damage in southern South America and elsewhere. [ABSTRACT FROM AUTHOR]

[Display omitted] • Elevated developmental temperature affects gene expression in bumblebee workers more than in queens and males. • Elevated developmental temperature increases reactive oxygen species and iron concentrations in the hemolymphs of workers. • Elevated developmental temperature increases the gene expression of superoxide dismutase and transferrin in workers. Climate change can negatively impact bumblebee populations, which are crucial pollinators in agricultural systems and natural ecosystems. Bumblebee nest temperatures typically range from 27 to 32 °C, and workers engage in wing fanning to maintain a nest temperature below 32 °C. We investigated the gene expression profile in queen, worker, and male bumblebees (Bombus terrestris) at 27 °C, which is the optimal ambient temperature, and 32 °C, which is the upper-temperature limit requiring wing fanning. We found that a developmental temperature of 32 °C significantly increased the expression of genes related to growth, immune response, antioxidants, and chaperones in workers. Compared to workers reared at 27 °C, those reared at 32 °C exhibited a significant increase in reactive oxygen species (ROS) and iron concentrations in the hemolymph. Additionally, the gene expression of superoxide dismutase (SOD) and transferrin (Tf) was significantly increased in workers at 32 °C. These findings indicate that a developmental temperature of 32 °C in bumblebees, especially workers, leads to an increase in gene expression, including SOD and TF , in response to thermal stress. [ABSTRACT FROM AUTHOR]

Wildflower plantings are an important mitigation tool within agri-environmental schemes to counter insect decline in resource-scarce agricultural landscapes. Effectiveness of wildflower plantings for insect conservation is typically studied at the community or species level. It is the individual, however, that is subject to changing abiotic and biotic conditions, not the species per se. Accordingly, functional traits of individuals, i.e., the intraspecific functional diversity within species, likely mediate responses to wildflower resources and landscape context. Here we focused on the ecologically and economically important wild insect pollinator Bombus terrestris to study its intraspecific functional diversity and plant-pollinator individual interactions in wildflower plantings. We found considerable trait variation among flower-visiting B. terrestris workers. Locally, this variation could be attributed to flowering plant traits, with larger workers visiting larger inflorescences and individuals with longer tongues preferentially feeding on zygomorphic but not radially symmetrical flowers. In addition, wildflower plantings with high floral abundance attracted individuals with larger pollen baskets. At the landscape scale, increasing proportion of arable land resulted in smaller B. terrestris individuals in wildflower plantings, and a decrease in the overall size diversity of workers. These findings highlight the so far little considered role of intraspecific variation in functional traits of wild pollinators, which can mediate the trait-matching between plants and pollinator individuals. Landscape simplification from agriculture threatens intraspecific pollinator diversity, with potential harmful effects for pollinator fitness and plant reproduction. Tailored wildflower plantings can thus serve as an important tool to increase intraspecific variation in simplified landscapes. When designing seed mixtures for these plantings, high complementarity in plant traits is key for promoting high intraspecific trait diversity of bumblebees and potentially of other associated insect species. [ABSTRACT FROM AUTHOR]

To better understand the potential establishment and spread of B. t. dalmatinus, we compared reproductive outputs of 45 commercially produced B. t. dalmatinus colonies, containing one queen and 50 workers in their natural habitat, greenhouse, and laboratory conditions. The total number of adult gynes and gyne pupae produced per colony was significantly higher in the laboratory colonies (100.90 ± 46.20) than in the field colonies (63.70 ± 44.70) and greenhouse colonies (28.47 ± 12.39), respectively. Although laboratory colonies significantly produced more gynes, reproductive abilities of greenhouse and field colonies show that commercial movement of bumblebee colonies for pollination could have serious impacts on natural ecosystems notably for pollination of open field crops. The nest entrance of all colonies was restricted by fitting with a queen excluder. All vents of the greenhouses were suitably covered with nets. Colonies were removed from the greenhouses about 6 weeks after initial placement. Following these measures, we prevented 266 gynes from escaping from 15 hives in 2.3 ha area of tomato greenhouse. To be 100% effective, we strongly recommend that these measures should be implemented together. [ABSTRACT FROM AUTHOR]

Bumblebees are important pollinators for many wild plants and crops. To explore gene expression characteristics in depth, stable reference genes will be essential across different developmental stages. In this context, we evaluated the stability of eight common reference genes at ten developmental stages in the bumblebee Bombus terrestris (B. terrestris) with four algorithms and two rank approaches. The results showed that all the primers for the reference genes exhibited high specificity, linear correlation (R2-value 0.9917~0.9978) and a good PCR amplification efficiency (E-value 95.4~108.6%). The combined use of RPL13 and RP49 was suggested to be the most suitable reference genes. Our candidate reference genes will help to improve the precision of the detection of gene expression at different developmental stages of bumblebee species. [ABSTRACT FROM AUTHOR]

• The relative abundance of B. terrestris increased from 21% to 79% between 1871 and 2015. • The increase was independent of landscape heterogeneity. • The relative abundance of B. terrestris was largely explained by increasing temperature. • B. terrestris was more common in homogeneous landscapes than the B. lucorum complex. • Male activity period advanced with 41 days between 1900 and 2015 in both taxa. While many bumblebee species decline due to climate and land-use changes, others cope well with contemporary conditions. One example is Bombus terrestris , which is common in intensively managed agricultural landscapes. During the 20th century its subgenus, which includes the B. lucorum complex (B. lucorum, B. cryptarum and B. magnus) came to dominate Scandinavian bumblebee communities, but the specific contribution of B. terrestris remains to be understood. Using historical data on males, we assessed how the relative abundances of B. terrestris and the B. lucorum complex changed over the past 150 years in southernmost Sweden. We tested if these changes differed between simplified and mixed landscapes and whether the relative abundance of B. terrestris was related to annual mean temperatures. Because floral availability has advanced as a response to climate change, we also tested if the activity period of males (estimated as catching date) has advanced and whether the advancement differs between taxa. The relative abundance of B. terrestris increased similarly in both landscapes, from 21% to 79% over the period, and this was largely explained by increasing temperature. Male activity period has advanced similarly in the two taxa, with 41 days between 1900 and 2015. Although the dominance of B. terrestris correlates clearly with annual mean temperature, it remains to disentangle why. It also remains to understand whether the success of B. terrestris occurs at the expense of other species or simply reflects that this species copes better with contemporary conditions. [ABSTRACT FROM AUTHOR]

Bombus terrestris is a bumblebee with a wide geographic range, with subspecies showing a variety of local adaptations. Global export of commercially-reared B. terrestris started in the 1980s; the bees are a mixture of subspecies bred for ease of rearing, bivoltinism and large nests. This paper investigated whether the increase in bivoltinism in UK resident B. terrestris audax populations was related to introgression with imported foreign subspecies. Workers were collected from wild populations in London and Bristol, as well as two commercial suppliers. Fourteen microsatellite loci were used to study population structure, hybridisation and introgression. No introgression with commercial B. t. dalmatinus was detected in wild populations. Hence, the increase in winter activity appears unrelated to introgression. [ABSTRACT FROM AUTHOR]

Tomato flowers are self-fertile, but require pollinators' intervention to increase fruit setting. In this review paper, we present and discuss the current state of knowledge on tomato pollinators. Information on tomato pollinators was extracted from 49 scientific publications, 6 doctoral thesis documents, 4 books, 3 technical sheets, a compilation of conference abstracts and 3 internet publications. We identified from the various publications 77 insects that pollinate tomato flowers. These pollinators were all Hymenoptera and belong to the families, Apidae (61%), Halictidae (35%), Megachilidae (1%), Colletidae (1%), and Andrenidae (2%). Bombus bees were the most represented genus with 16 identified species. These pollinators contribute to the improvement of the fruit set percentage and fruit characteristics. Worldwide, colonies of bumblebees, Bombus terrestris, Bombus impatiens, Bombus occidentalis, Bombus ignitus and Bombus lucorum as well as honeybee, Apis mellifera are managed for tomato pollination. However, the exploitation of managed pollinators is poorly developed in Africa. Similarly, very little research has been conducted on tomato pollinators in Africa and Europe. Further investigations are needed, especially in Africa, to identify insects that are effective in tomato pollination, and to develop management strategies for their efficient exploitation in tomato production. [ABSTRACT FROM AUTHOR]

In agricultural landscapes, differences in floral resources provided by crops compared with adjacent habitats promote the spillover of pollinators seeking to fulfil their feeding needs. These foraging patterns play an important role in both crop production and wild plant fitness. However, in classical observational studies, pollinator spillover patterns may be confounded by differences in pollinator phenologies and population sizes. To avoid these confounding effects, we quantified the combined effect of relative floral availability and season on pollinator spillover between strawberry crops and adjacent pinewoods by using commercial bumblebee colonies. We used 60 colonies that were placed in 6 open polytunnel strawberry crops and in 8 pinewoods adjacent to crops in landscapes with either low or high berry (mostly strawberry) crop cover. We repeated the experiment in winter and in spring to account for differences in flower resource availability. While strawberries were in bloom during the entire study period, wild flowering plants were scarce and abundant in winter and in spring, respectively. Spillover in crops was quantified as the percentage of bumblebee individuals that carried pollen from non-berry flowers, while spillover in pinewoods was quantified as the percentage of individuals that carried pollen from berry flowers. Overall, 526 bumblebees were collected. We found them carrying the pollen of 15 plant taxa in winter and 39 in spring, in accordance with seasonal floral availability. In crop colonies, around 30% of bumblebees spilled over into non-berry habitats in winter and 78% in spring, regardless of crop cover in the surrounding landscape. However, in pinewood colonies, we found an interaction effect between season and crop cover: even though on average 34% of bumblebees spilled over into berry crops, in winter it was almost twice in landscapes with high crop cover. Spillover patterns mainly mirrored seasonal changes in floral availability between habitats. [ABSTRACT FROM AUTHOR]

• Robber flies are important predators of many insects species, mainly Hymenoptera. • Obelophorus terebratus concentrated the majority of hunting behavior on invasive bee. • Bombus terrestris was the prey more common among Chilean robber flies. • Three giant robber fly increasing his distribution thank to citizen science records. Robber flies (Asilidae) are the main predatory fly family feeding on beetles, butterflies, other flies for true flies, and even spiders; however, Hymenoptera is the most common prey. Invasive Hymenoptera species are common in central and southern Chile; however, few predators of these are known. The hunting behavior and prey of Chilean robber fly species are also poorly known. The aim of this study is to provide the first hunting behavior records of five Chilean giant robber fly species on invasive Hymenoptera. In addition, an updated distribution of these species is provided. Records of hunting behavior were based on fieldwork collections and citizen science observations. The historical distribution was compared with citizen science observations using chi-square analyzes. Twelve predation events were recorded. Obelophorus terebratus was the most common predator. Bombus terrestris was the invasive Hymenoptera most preyed upon. Both the extension of occurrence of Lycomya germainii as Obelophorus species showed changes in his distribution. Only O. landbecki shown changes in area of occupancy. Citizen science is playing a key role in the knowledge of biological interactions and distribution of endemic and native Chilean robber fly species. [ABSTRACT FROM AUTHOR]

Bumblebees are important pollinating insects, but many species have suffered declines over the last century. Long-tongued bumblebees have been identified as particularly at risk, partly due to their more selective diet. Attempts to study these species in captivity have been impeded by stress-induced behaviours which cause queens to kill or abandon their brood. Here, we attempt to further develop techniques, using queen pairing and Bombus terrestris cocoons, to successfully rear two common long-tongued bumblebee species (B. pascuorum and B. hortorum) in captivity. Approximately half of queens laid eggs and 29% produced workers. Although challenges remain, there is a great deal to be gained from optimising the captive rearing of these species. [ABSTRACT FROM AUTHOR]

Flupyradifurone (FPF), a novel butenolide insecticide binding to nicotinic acetylcholine receptors (nAChRs), has been shown to be less acutely toxic to western honey bees (Apis mellifera) than other insecticides such as neonicotinoids sharing the same target-site. A previous study revealed that this is due to enhanced oxidative metabolism of FPF, mediated by three cytochrome P450 monooxygenases (P450s), including CYP6AQ1. Therefore, we followed a toxicogenomics approach and investigated the potential role of functional CYP6AQ1 orthologs in FPF metabolism from eight different bee species, including stingless bees (Tribe: Meliponini). We conducted a phylogenetic analysis on four stingless bee species, including Frieseomelitta varia, Heterotrigona itama , Melipona quadrifasciata and Tetragonula carbonaria to identify CYP6AQ1-like functional orthologs. Three non-Meliponini, but tropical bee species, i.e., Ammobates syriacus , Euglossa dilemma and Megalopta genalis were analyzed as well. We identified candidate P450s in all (neo)tropical species with greater than 61% and 67% predicted protein sequence identities when compared to A. mellifera CYP6AQ1 and Bombus terrestris CYP6AQ26, respectively. Heterologous expression in High Five insect cells of these functional orthologs revealed a common coumarin substrate profile and a preference for the O -debenzylation of bulkier substrates. Competition assays using the fluorescent probe substrate 7-benzyloxymethoxy-4-trifluoromethylcoumarin (BOMFC) with these enzymes indicated inhibition of BOMFC metabolism by increasing concentrations of FPF. Furthermore, UPLC-MS/MS analysis revealed the capacity of all CYP6AQ1-like orthologs to metabolize FPF by hydroxylation in vitro at various levels, indicating a conserved FPF detoxification potential in different (neo)tropical bee species including Meliponini. This research, employing a toxicogenomics approach, provides important insights into the potential of stingless and other tropical bee species to detoxify FPF, and highlights the significance of investigating the detoxification mechanisms of insecticides in non- Apis bee species by molecular tools to inform risk assessment and conservation efforts. [Display omitted] • Expression of several functional orthologs of CYP6AQ1 from tropical bee species. • Flupyradifurone is degraded by CYP6AQ1 orthologs present in tropical bee species. • CYP6AQ-related enzymes of four stingless bee species hydroxylate flupyradifurone. • We provided molecular data to inform and support bee pesticide risk assessment. [ABSTRACT FROM AUTHOR]

Animal-mediated pollination is essential for the production and quality of fruits and seeds of many crops consumed by humans. However, crop pollination services might be compromised when wild pollinators are scarce. Managed pollinators are commonly used in crops to supplement such services with the assumption that they will enhance crop yield. However, information on the spatiotemporal pollinator-dependence of crops is still limited. We assessed the contribution of commercial bumble bee colonies compared to the available pollinator community on strawberry (‘Fortuna’ variety) flower visitation and strawberry quality across a landscape gradient of agricultural intensification (i.e. polytunnel berry crop cover). We used colonies of bumble bees in winter and in spring, i.e. when few and most wild pollinators are in their flight period, respectively. The placement of colonies increased visits of bumble bees to strawberry flowers, especially in winter. The use of bumble bee colonies did not affect flower visitation by other insects, mainly honey bees, hoverflies and other Diptera. Flower visitation by both honey bees and wild insects did not vary between seasons and was unrelated to the landscape gradient of berry crop cover. Strawberries were of the highest quality (i.e. weight) when insect-mediated pollination was allowed, and their quality was positively related to wild flower visitors in winter but not in spring. However, increased visits to strawberry flowers by managed bumble bees and honey bees had no effect on strawberry weight. Our results suggest that the pollination services producing high quality strawberry fruits are provided by the flower visitor community present in the study region without the need to use managed bumble bees. [ABSTRACT FROM AUTHOR]

Inbreeding is caused by the mating of closely related individuals and may produce a decrease in the fitness of offspring and have deleterious consequences for adults. In haplodiploid social Hymenoptera inbreeding has a further negative effect due to the production of unviable or sterile diploid males. As a consequence, mechanisms of inbreeding avoidance would be expected to evolve. In this study, we investigated the mating choice between related (inbred) or unrelated (outbred) gynes and males of Bombus terrestris reared in laboratory conditions by performing cage and tunnel experiments. Not only did we find no mating preference for related or unrelated partners (mating success 41.55 ± 3.7 and 39.69 ± 4.4%, respectively), but the mating latency was even shorter in inbred (6.97 ± 0.6 min) than in outbred matings (8.74 ± 0.8 min). We hypothesize that in wild populations of B. terrestris, the lack of incest avoidance could be compensated by tolerance of high levels of inbreeding. [ABSTRACT FROM AUTHOR]

Residues detected in pollen collected by honey bees are often used to estimate pesticide exposure in ecotoxicological studies. However, for a more accurate assessment of pesticides effect on foraging pollinators, residues found directly on flowers are a more realistic exposure approximation. We conducted a multi-residue analysis of pesticides on pollen and nectar of melon flowers collected from five fields. The cumulative chronic oral exposure Risk Index (RI) was calculated for Apis mellifera, Bombus terrestris and Osmia bicornis to multiple pesticides. However, this index could underestimate the risk since sublethal or synergistic effects are not considered. Therefore, a mixture containing three of the most frequently detected pesticides in our study was tested for synergistic impact on B. terrestris micro-colonies through a chronic oral toxicity test. According to the result, pollen and nectar samples contained numerous pesticide residues, including nine insecticides, nine fungicides, and one herbicide. Eleven of those were not applied by farmers during the crop season, revealing that melon agroecosystems may be pesticide contaminated environments. The primary contributor to the chronic RI was imidacloprid and O. bircornis is at greatest risk for lethality resulting from chronic oral exposure at these sites. In the bumblebee micro-colony bioassay, dietary exposure to acetamiprid, chlorpyrifos and oxamyl at residue level concentration, showed no effects on worker mortality, drone production or drone size and no synergies were detected when pesticide mixtures were evaluated. In conclusion, our findings have significant implications for improving pesticide risk assessment schemes to guarantee pollinator conservation. In particular, bee pesticide risk assessment should not be limited to acute exposure effects to isolated active ingredients in honey bees. Instead, risk assessments should consider the long-term pesticide exposure effects in both pollen and nectar on a range of bees that reflect the diversity of natural ecosystems and the synergistic potential among pesticide formulations. [Display omitted] • Nineteen pesticides were detected, eleven of them had not been applied in the crops • Imidacloprid was the main contributor in the cumulative chronic risk index • Mason bees have the greatest risk of lethality associated with chronic oral exposure • Residue dose of one frequently mixture did not affect bumblebee micro-colonies [ABSTRACT FROM AUTHOR]

Spectra of five isolates (LMG 28358 T , LMG 29879 T , LMG 29880 T , LMG 28359 T and R-53705) obtained from gut samples of wild bumblebees of Bombus pascuorum , Bombus lapidarius and Bombus terrestris were grouped into four MALDI-TOF MS clusters. RAPD analysis revealed an identical DNA fingerprint for LMG 28359 T and R-53705 which also grouped in the same MALDI-TOF MS cluster, while different DNA fingerprints were obtained for the other isolates. Comparative 16S rRNA gene sequence analysis of the four different strains identified Gilliamella apicola NCIMB 14804 T as nearest neighbour species. Average nucleotide identity values of draft genome sequences of the four isolates and of G. apicola NCIMB 14804 T were below the 96% threshold value for species delineation and all four strains and G. apicola NCIMB 14804 T were phenotypically distinct. Together, the draft genome sequences and phylogenetic and phenotypic data indicate that the four strains represent four novel Gilliamella species for which we propose the names Gilliamella intestini sp. nov., with LMG 28358 T as the type strain, Gilliamella bombicola sp. nov., with LMG 28359 T as the type strain, Gilliamella bombi sp. nov., with LMG 29879 T as the type strain and Gilliamella mensalis sp. nov., with LMG 29880 T as the type strain. [ABSTRACT FROM AUTHOR]

In this study, we investigated if oral administration of lactic acid bacteria could increase the colony performance of reared bumblebees. We found that a continuous administration of Lactobacillus kunkeei LMG 18925 and Lactobacillus crispatus LMG 9479 could partly compensate the effects of low nutritional pollen, but a permanent colonization in the gut was not detected with Illumina MiSeq 16S rRNA sequencing. Contrary to expectations, a single administration of L. kunkeei LMG 18925 to a high nutritional pollen led to a lower total drone mass. A Bombus-specific strain, Bifidobacterium actinocoloniiforme R-53049, showed potential to colonize the gut permanently after three administrations. Our study represents a first screening for the potential use of probiotic strains in bumblebees. We conclude that both diet and host specificity of bacteria might have an effect on colony performance of indoor-reared bumblebees and play a role in the gut colonization success. [ABSTRACT FROM AUTHOR]

In most bumblebee species, queens mate with only one male, but males can mate more than once. However, the effects of male remating on colony foundation success of queens remain poorly understood. To test for effects of male remating, we assigned Bombus terrestris queens randomly to one of two groups: virgin males or non-virgin males that have mated once before. When males were allowed to mate for a second time with virgin queens, 58.57 % successfully remated. There was no significant difference in queen hibernation survival between groups, but queens mated with non-virgin males were more successful in founding a colony, and produced more workers and males than queens mated with virgin males. The mean copulation duration for the second mating of males (48.02 ± 14.36 min) was substantially longer than for the first mating (32.44 ± 8.74 min). Results also showed that male weight influenced both male remating success and copulation duration. [ABSTRACT FROM AUTHOR]

Tropospheric ozone (O 3) mixing ratios have increased substantially since preindustrial times and high O 3 peaks are increasingly common. Plant-pollinator interactions are central to natural ecosystem functioning and food production systems but could be negatively affected by unfavourable environmental conditions such as elevated O 3. Ecosystem functioning is threatened by O 3 , which can degrade floral volatile organic compounds (VOCs) used by pollinators as olfactory cues during foraging. It can also exert oxidative stress on VOC-emitting plants and receiving organisms, potentially disturbing the sending and receiving of VOC signals. The aim of this study was to determine the effects of elevated ozone on the foraging behaviour of Bombus terrestris on three species of the Brassicaceae, with a particular focus on bumblebee choices and the mechanisms underpinning differences observed. Moreover, the study was designed to fill a gap between observations in small-scale laboratory experiments and large-scale modelling through empirical observations in polytunnels that represent a medium-large-scale artificial environment. Using 10 × 3 × 2 m polytunnels the effects of O 3 on pollinator foraging parameters on Sinapis alba , Sinapis arvensis and Raphanus raphanistrum were assessed. Significant effects of elevated O 3 (100 ± 10 ppb) on the time taken for the first bee to alight on a flower and the cumulative amount of time spent on flowers was observed. To further investigate the underlying mechanisms, a laboratory test was conducted to determine the effects of ozone on the VOC blend composition of S. alba flowers. Synthetic VOC blends representing O 3 -altered and unaltered profiles were reconstituted and utilized in polytunnel and olfactometry experiments. The results indicated that a reduction of olfaction-mediated orientation, probably via VOC-degradation or direct effects of O 3 on bees, was responsible for the altered foraging parameters of B. terrestris , suggesting that the presence of elevated O 3 could have negative effects on the foraging efficiency of important pollinator species. [Display omitted] • Pollinators use floral odors as volatile cues to locate flowers. • Foraging behavior of bumblebees was altered under elevated ozone in a polytunnel. • Ozone degraded floral volatiles, likely explaining the observed altered behavior. • Bumblebees learned to associate rewards with ozone-altered cues. • Ozone pollution has the potential to disrupt pollination services but may be offset by associative learning. [ABSTRACT FROM AUTHOR]

In this project, we showed the influence of diet on the microbial composition in the gut of indoor-reared bumblebees ( Bombus terrestris), using Illumina MiSeq 16S ribosomal RNA (rRNA) sequencing. Three sugar syrups and sterilized pollen from three suppliers were tested. Different effects were observed depending on the developmental stage of the gut microbiota at the start of the dietary treatment. Fructose-rich sugar syrup prevented the colonization of Bifidobacteriaceae in the microbiota of newly emerged bumblebees. This effect was correlated with a lower bacterial community richness and diversity. The pollen diet with the best parameters, regarding the protein content and bumblebee offspring, showed the lowest bacterial richness and diversity. The interaction between diet and the microbiota of bumblebees provides new insights for bumblebee breeders. Diet could be used to modulate the bacterial composition in the gut to improve the health of mass-produced bumblebees used for biological pollination. [ABSTRACT FROM AUTHOR]

Harmonic radar tracking system for insects has been introduced to understand insect movement, particularly those which move at low altitudes and over relatively short ranges. Although entomologists have used direct observation and mark-and-recapture techniques as tracking methods, there are drawbacks such as low recapture rates in the case of marking techniques. The objective of this study was to quantitatively examine adhesive bond strength between radar tag and insect body and to evaluate the effect of tag attachment on flight behavior and capacity of five economically important insect species, including three pest species, Riptortus pedestris (Hemiptera: Alydidae), Lycorma delicatula (Hemiptera: Fulgoridae), and Ricania sp. (Hemiptera: Ricaniidae) and two pollinators, Apis mellifera (Hymenoptera: Apidae) and Bombus terrestris (Hymenoptera: Apidae). The adhesive bond strength was substantially different among these five insect species, but the strength was sufficiently strong for operational use in harmonic radar tagging except in Ricania sp. Bond strength on B. terrestris was 817 ± 43.65 g-forces, which was the strongest among the five species tested, while that on Ricania sp. was 1.7 ± 0.20 g-forces, which was the weakest. For all insects, no significant correlation between bond strength and insect body size was observed. The radar tag attachment affected the flight behavior and capacity of five insect species in different ways. The radar tag attachment did not significantly affect the propensity of R. pedestris , L. delicatula , or B. terrestris to takeoff compared to untagged individuals. However, the takeoff propensities of A. mellifera and Ricania sp. were negatively affected by the radar tag attachment. Flight capacities of R. pedestris , A. mellifera , and B. terrestris were not affected by the tag attachment compared to untagged individuals, but the flight capacity of Ricania sp. was negatively affected by the tag attachment. The results of this study indicate that the radar technique has promising potential for R. pedestris , L. delicatula , and B. terrestris . However, this technique may have limited potential for A. mellifera and Ricania sp. because the radar tag can significantly affect their flight behavior. [ABSTRACT FROM AUTHOR]

Bombus nests consisting of one queen, brood, and worker adults, are produced indoors for biological pollination in agriculture. In this study, we investigated the gut microbial community in workers of Bombus terrestris when the environment is stable (indoors) or variable (outdoors). When nests were reared indoors under standardized conditions, we identified a small gut microbial community consisting of Neisseriaceae, Orbaceae, Lactobacillaceae, and Bifidobacteriaceae, and the age of bumblebee nests and workers did not affect the alpha and beta diversity, confirming a stable microbiota. Secondly, when indoor-reared nests were moved to outdoors, we observed a major shift in the microbial community, especially in the newborn workers fully developed in the outdoor conditions, with a significant colonization of Enterobacteriaceae. Our new findings are discussed in relation to host-associated core and non-core bacteria in bumblebees including possible implications for host functioning. [ABSTRACT FROM AUTHOR]

Recent studies have indicated that the plant volatile methyl benzoate (MB) exhibits significant insecticidal bioactivity against several common insects. However, the potential environmental hazards of MB and its safety to non-target organisms is poorly understood. In the present study, these characteristics were investigated through laboratory experiments and field investigations. The results revealed that MB was highly toxic to the agricultural pest, fall armyworm Spodoptera frugiperda. Compared with the commercial pesticide lambda-cyhalothrin, the toxicities of MB against S. frugiperda larvae and adults were comparable and 3.41 times higher, respectively. Behavioral bioassays showed that the percentage repellency of MB to S. frugiperda larvae was 56.72 %, and MB induced 69.40 % oviposition deterrence rate in S. frugiperda female adults. Furthermore, in terms of median lethal concentration (LC 50) and median lethal doses (LD 50), MB exhibited non-toxic effects on non-target animals with 3-d LC 50 of > 1 % to natural predators (Coccinella septempunctata and Harmonia axyridis), 3-d LD 50 of 467.86 µg/bee to the bumblebee Bombus terrestris , 14-d LC 50 of 971.09 mg/kg to the earthworm Eisenia fetida , and 4-d LC 50 of 47.30 mg/L to the zebrafish Brachydanio rerio. The accumulation of MB in the soil and earthworms was found to be extremely limited. Our comparative study clearly demonstrated that MB is effective as a selective botanical pesticide against S. frugiperda and it is safe to use in the tested environment, with no toxic effects on non-target animals and natural predators. [Display omitted] • Plant volatile compound methyl benzoate (MB) has a significant insecticidal bioactivity against S. frugiperda. • MB has high repellent activity and oviposition-deterring to S. frugiperda larvae and adult. • MB is safe to tested insect predators, pollinating bumblebees, environmental indicators earthworms and zebrafish. • MB has a very limited accumulation in soil and earthworms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nosema microsporidia are prevalent endoparasites of managed and wild bees. • Current molecular methods do not enable accurate Nosema quantification. • We developed qPCR methods to quantify N. apis , N. ceranae , and N. bombi. • Accuracy of parasite loads was validated on honey bee, bumble bee, and mason bee. • qPCR methods open perspectives in nosemosis diagnosis and in bee epidemiology. Among stressors affecting bee health, Nosema microsporidia are prevalent intracellular parasites. Nosema apis and Nosema ceranae have been described in honey bees (Apis spp.), while Nosema bombi has been described in bumble bees (Bombus spp.). Although available molecular methods serve as a complement to microscopic diagnosis of nosemosis, they do not enable accurate quantification of these three Nosema species. We developed three quantitative real-time PCRs (qPCRs) starting from in silico design of specific primers, probes, and recombinant plasmids, to target the RNA polymerase II subunit B1 (RPB1) gene in the three species. The complete methods, including bee grinding, DNA purification, and qPCR, were validated in honey bee (Apis mellifera) homogenate. Specificity was assessed in silico and in vitro with several types of bee samples. The limit of detection was estimated at 4 log 10 copies/honey bee. A small, systematic method bias was corrected for accurate quantification up to 10 log 10 copies/honey bee. Method accuracy was also verified in bumble bee (Bombus terrestris) and mason bee (Osmia bicornis) homogenates in the range of 5 to 10 log 10 copies/bee. These validated qPCR methods open perspectives in nosemosis diagnosis and in the study of the parasite's eco-dynamics in managed and wild bees. [ABSTRACT FROM AUTHOR]

Bumblebee queens require a continuous supply of flowering food plants from early spring for the successful development of annual colonies. Early in spring, Corydalis cava provides essential nectar and pollen resources and a choice of flower colour. In this paper, we examine flower colour choice (purple or white) in C. cava and verify the hypothesis that bumblebee queens differ in their choice of flower colour. A total of 10,615 observations of flower visits were made in spring 2011 and spring 2014 near Poznań, western Poland. Our results suggest that Bombus lucorum/cryptarum used purple flowers less, while Bombus terrestris used purple flowers more and Bombus hortorum showed no preference. Therefore, the colour morphs of C. cava are probably co-evolutionary adaptations to the development of another part of the insect community which has different colour preferences. [ABSTRACT FROM AUTHOR]

The bumblebee, Bombus terrestris , plays an important role as one of alternative pollinators since the outbreak of honeybee colony collapse disorder. Recently, pathogens and parasites such as viruses, bacteria and mites affecting the life span and fecundity of their host have been discovered in B. terrestris . In this study, in order to detect viral infection in B. terrestris , we collected B. terrestris adults and isolated total RNA for diagnostic PCR. The PCR primers specific for pathogenic viruses were newly designed and applied to gene amplification for cloning and detection. Capsid protein gene of black queen cell virus (BQCV) among examined viral genes was only successfully amplified from collected bumblebee adults and sequenced. To optimize the detection of capsid protein gene of BQCV, 4 regions in the capsid protein gene were selected and further analyzed in quantitative real-time PCR (qRT-PCR). The qRT-PCR analysis revealed that capsid protein gene was directly detected with below 200 ng total RNA. This result suggests that an optimized detection via qRT-PCR can be applied for the rapid and sensitive diagnosis of BQCV infection in the field population as well as risk assessment of B. terrestris . [ABSTRACT FROM AUTHOR]

Bumble bees are an outstanding model system in which to study the organization and evolution of complex social behaviour. Bumble bees pass through several distinct phases during their annual life cycle, including solitary and eusocial phases, and the final stage of the colony cycle is marked by intense competition among the queen and workers over the production of males. Furthermore, there are approximately 250 species of bumble bees, and of the few species that have been examined, it is clear that multiple life history strategies are possible. Thus, the ultimate and proximate mechanisms underlying co-operation, conflict, and behavioural plasticity can readily be examined in bumble bees. Here, we describe the current state of knowledge about the evolutionary, ecological, behavioural, physiological, chemical, and genomic mechanisms and factors underpinning bumble bee social behaviour throughout the colony cycle. We highlight long-standing questions in the field and discuss how advances in genomics and comparative approaches across bumble bee species can provide profound insights into this fascinating system and the evolution of social behaviour. [ABSTRACT FROM AUTHOR]

Flowers offer habitats for bacterial communities that are often characterized by low diversities but high densities. The composition of these communities and the dissemination of bacteria between flowers receive increasing attention, whereas the ecological functions of flower-associated but non-phytopathogenic bacteria remain understudied. We screened bacteria isolated from nectar, petals and leaves of two plant species for their potential to affect flower-visitor interactions. We took advantage of the proboscis extension reflex (PER) of bumblebees evoked by sugar and investigated whether bacteria associated with the reward may interrupt this reflex. Cultivated bacteria were transferred into a watery glucose solution in increasing densities and their effect on the proportion of bumblebees displaying the PER after antennal contact with glucose solutions and bacteria was scored. In all but one trial, the proportion of bumblebees that accepted the watery glucose solution was negatively correlated with the bacterial density. Nearly half of the bacteria tested evoked avoidance at naturally occurring densities. Our results suggest that bacteria colonizing flowers have the potential to negatively affect the reproduction of plants via reduced visits by pollinators. [ABSTRACT FROM AUTHOR]

Competition between managed honeybees and wild pollinators is thought to be a key factor in structuring foraging communities on flowers. The majority of studies have focused on impacts such as floral visitation rates and resource overlap. However, direct measurement of fitness is required to fully assess the impacts of competition. We compared in 2 years the weight and reproductive success of bumblebee colonies located at two sites that were either close to or far from a large honeybee apiary, and which were located in the same landscape and with access to similar floral resources. We found that bumblebee colonies located at the site near the honeybee apiary gained less weight, and produced fewer and smaller queens, in both years than colonies at the site far from the apiary. The ratio of queen weight/size was lower in the colonies near honeybees in 1 year, while males were smaller and offspring sex ratio more male biased in colonies close to honeybees than in those far from honeybees. Proximity to managed honeybee hives was therefore associated with significantly reduced fitness of bumblebee colonies, but studies from many more sites are needed to confirm the effect. [ABSTRACT FROM AUTHOR]

Abstract: Neonicotinoid pesticides are currently implicated in the decline of wild bee populations. Bumble bees, Bombus spp., are important wild pollinators that are detrimentally affected by ingestion of neonicotinoid residues. To date, imidacloprid has been the major focus of study into the effects of neonicotinoids on bumble bee health, but wild populations are increasingly exposed to alternative neonicotinoids such as thiamethoxam. To investigate whether environmentally realistic levels of thiamethoxam affect bumble bee performance over a realistic exposure period, we exposed queenless microcolonies of Bombus terrestris L. workers to a wide range of dosages up to 98μgkg−1 in dietary syrup for 17 days. Results showed that bumble bee workers survived fewer days when presented with syrup dosed at 98μg thiamethoxamkg−1, while production of brood (eggs and larvae) and consumption of syrup and pollen in microcolonies were significantly reduced by thiamethoxam only at the two highest concentrations (39, 98μgkg−1). In contrast, we found no detectable effect of thiamethoxam at levels typically found in the nectars of treated crops (between 1 and 11μgkg−1). By comparison with published data, we demonstrate that during an exposure to field-realistic concentrations lasting approximately two weeks, brood production in worker bumble bees is more sensitive to imidacloprid than thiamethoxam. We speculate that differential sensitivity arises because imidacloprid produces a stronger repression of feeding in bumble bees than thiamethoxam, which imposes a greater nutrient limitation on production of brood. [Copyright &y& Elsevier]

Learning olfactory stimuli and their implications is essential in bumblebees for orientation and recognition of nest sites and food sources. To evaluate associative learning abilities in bees under controlled environmental conditions, the proboscis extension response (PER) assay is a well-established method used in honeybees and has recently been successfully adapted to bumblebees. In this study, we examined the cognitive abilities of workers of the eusocial bumblebee, Bombus terrestris, by training individuals in different olfactory learning tasks using classical PER conditioning. We compared learning performance for four different floral odors. Individuals were able to solve absolute (A+) and differential (A+ vs. B−) conditioning tasks, and no differences were found between single odors and odor combinations, respectively. Furthermore, bumblebees performed well on a positive pattern discrimination task (A−, B− vs. AB+), but failed to solve the negative pattern discrimination (A+, B+ vs. AB−). Our results indicate that workers of B. terrestris possess elemental olfactory learning abilities, but, in contrast to previous findings in honeybees, fail in more complex tasks, such as negative pattern discrimination. We discuss possible ultimate causes that have led to the difference in learning capabilities between bumblebees and honeybees. [ABSTRACT FROM AUTHOR]

Despite rising global concerns over the potential impacts of non-native bumble bee (Bombus spp) introduc-tions on native species, large-scale and long-term assessments of the consequences of such introductions are lacking. Bombus ruderatus and Bombus terrestris were sequentially introduced into Chile and later entered Argentina's Patagonian region. A large-scale survey in Patagonia reveals that, in 5 years post-arrival, the highly invasive B terrestris has become the most abundant and widespread Bombus species, and its south-ward spread is concurrent with the geographic retraction of the only native species, Bombus dahlbomii. Furthermore, a 20-year survey of pollinators of the endemic herb Alstroemeria aurea in northern Patagonia indicates that B ruderatus and B terrestris have replaced B dahlbomii, formerly the most abundant pollina-tor. Although the decline's underlying mechanisms remain unknown, the potential roles of exploitative competition and pathogen co-introduction cannot be ruled out. Given that invasive bumble bees can rapidly extirpate native congeners, further introductions should be discouraged. [ABSTRACT FROM AUTHOR]

Social pollinators, like honeybees and bumblebees, have specific microbiota. The specific association between the insect and its gut microbiota could lead to a functional dependence. In this project, we investigated whether an alteration in microbiota could influence the fitness of the generalist pollinator Bombus terrestris. We used bumblebee workers in microcolonies to assess effects on colony development and reproduction. Treatment with 200 ppm streptomycin and tetracycline resulted in a disruption of gut microbiota, and typically there was 100 % worker mortality. In contrast, treatment with streptomycin alone showed an improved reproduction and this concurred with a different gut microbiota pattern. The results are discussed in relation to effects of the gut microbiota on bumblebee fitness and potential beneficial effects by Lactobacillus sp. These data may open new avenues in the mass-rearing of bumblebees used for the biological pollination in agriculture. [ABSTRACT FROM AUTHOR]

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Abstract: Three major components of bumblebee venom are bombolitin, phospholipase A2, and a serine protease, with bombolitin being the most abundant. Here, we describe the molecular cloning of bombolitin isolated from the venom of a bumblebee, Bombus terrestris, and demonstrate its antibacterial activity. The B. terrestris bombolitin gene consists of 2 exons encoding 56 amino acid residues. Comparative analysis shows that mature B. terrestris bombolitin consists of 18 amino acid residues, which are identical to those of B. ignitus bombolitin. B. terrestris bombolitin displayed antibacterial activity against both the Gram-negative bacterium Klebsiella pneumoniae and the Gram-positive bacterium Staphylococcus aureus, indicating that B. terrestris bombolitin may be a potential antimicrobial agent. [Copyright &y& Elsevier]

Abstract: Bumblebee, Bombus terrestris queens undergo winter diapause and show a great difference in diapause duration in natural conditions. Queens emerged from diapause initiate colonies by producing a batch of diploid (fertilised) eggs that develop into workers. In this study we investigated the effects of both the duration of queen diapause (2, 3, 4, or 5months) and colony size (artificially limited to 50, 100, 150, and 200 workers) on the number of sexuals (males or new queens — gynes) produced, when gynes are produced and the longevity of both the foundress queen and the colony. Both worker population and diapause duration showed significant effect on sexual gyne production, foundress queen longevity and colony longevity but their interaction effect was insignificant. The worker number and diapause duration, respectively showed significant effect on sexual male production and gyne emergence period, but their interaction effects were insignificant. [Copyright &y& Elsevier]

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