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 specializ...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.展开更多
Bumblebees are a genus of pollinators(Bombus)that play important roles in natural ecosystem and agricultural production.Several bumblebee species have been recorded as under population decline,and the proportion of sp...Bumblebees are a genus of pollinators(Bombus)that play important roles in natural ecosystem and agricultural production.Several bumblebee species have been recorded as under population decline,and the proportion of species experiencing popula-tion decline within subgenus Thoracobombus is higher than average.Bombus opulentus is 1 species in Thoracobombus,but little is known about its recent population dynamics.Here,we employed conservation genomics methods to investigate the population dynam-ics of B.opulentus during the recent past and identify the likely environmental factors that may cause population decline.Firstly,we placed the scaffold-level of B.opulentus ref-erence genome sequence onto chromosome-level using Hi-C technique.Then,based on this reference genome and whole-genome resequencing data for 51 B.opulentus samples,we reconstructed the population structure and effective population size(Ne)trajectories of B.opulentus and identified genes that were under positive selection.Our results revealed that the collected B.opulentus samples could be divided into 2 populations,and 1 of them experienced a recent population decline;the declining population also exhibited lower ge-netic diversity and higher inbreeding levels.Genes related to high-temperature tolerance,immune response,and detoxication showed signals of positive selection in the declining population,suggesting that climate warming and pathogen/pesticide exposures may con-tribute to the decline of this B.opulentus population.Taken together,our study provided insights into the demography of B.opulentus populations and highlighted that popula-tions of the same bumblebee species could have contrasting Ne trajectories and population decline could be caused by a combination of various stressors.展开更多
Areca nut is the basic ingredient of betel quid,which is chewed by hundreds of millions of people in South-Eastern Asia.Chewing of areca nut has been associated with oral cancers potentially due to its specific alkalo...Areca nut is the basic ingredient of betel quid,which is chewed by hundreds of millions of people in South-Eastern Asia.Chewing of areca nut has been associated with oral cancers potentially due to its specific alkaloids,among which arecoline constitutes about 90%of total fraction.Being the world’s fourth most commonly used psychoactive substance,arecoline evokes stimulation,addiction,and other direct neurological effects,while its misuse correlates to neurotoxic effects.However,what might underlie its neurotoxic mechanisms has been poorly documented.The brain is encoded by a complex network of neuronal and glial cell types,and neurotoxicity of hazardous compounds present transcriptional heterogeneity.Recently,the eusocial bumblebee has been used as a model for studying brain effects,with sophisticated cognitive capability and precisely measured brain architecture.Here,we decipher cell-type-specific mental risks to arecoline using bumblebees.Arecoline induced locomotor hyperactivity and cognitive impairment.Single nucleus RNA sequencing(snRNA-seq)unearthed arecoline-induced cell-specific responses,primarily targeted on Kenyon cells(KC).Moreover,high-dose arecoline induced distinctive cell responses among KC subtypes,particularly class I large Kenyon cell(lKC),leading to DNA damage,excitatory/inhibitory(E/I)imbalance,and calcium dyshomeostasis,which potentially resulted in cognitive impairment.Given arecoline’s popularity and growing exposure risks to humans,neurological health risks of areca nut warrant serious consideration.展开更多
Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their...Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their worker force. In bumblebees, so- cial parasitism appeared in at least 3 subgenera independently： in the subgenus Psithyrus consisting entirely of parasitic species, in the subgenus Alpinobombus with Bombus hy- perboreus, and in the subgenus Thoracobombus with B. inexspectatus. Cuckoo bumblebee males utilize species-specific cephalic labial gland secretions for mating purposes that can impact their inquiline strategy. We performed cephalic labial gland secretions in B. hyperboreus, B. inexspectatus and their hosts. Males of both parasitic species exhibited high species specific levels of cephalic gland secretions, including different main com- pounds. Our results showed no chemical mimicry in the cephalic gland secretions between inquilines and their host and we did not identify the repellent compounds already known in other cuckoo bumblebees.展开更多
Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the hab...Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the habitat fragmentation and unduly commercial collections. Previous observation showed that this species has very low and even no fruit set, and the pollinators are not observed before this report. The present observation was conducted at the Shennongjia, Hubei Province during the spring of 2002. The results showed that Bombus (Diversobombus) trifasciatus Smith, B. imitator Pittion and one species of Apis visited the flowers of the orchid, but only B. tritasciatus could carry pollinaria on its body and was the legitimate pollinators of C amoena. During 113 h of observation, only nine visitations were recorded. The bumblebees mainly appeared during 12:00-15:00 during the day. Bumblebees stayed in a flower only a few seconds and never more than ten seconds. The flowers would persist in fresh for about three weeks when they were not pollinated, but 3 or 4 d after pollinated, the pollinated flowers underwent a series of color and morphological changes including stalk elongation and ovary swelling. Therefore, stalk elongation can be considered an index of fruits set. Artificial pollination indicated that C amoena is a highly self-compatible and outcrossing species, but dependent on pollinators for fruit set. Based on the field observations, we concluded that pollination system of C amoena is deceptive. The fruit set in nature is not very low (26.98% on average) compared to other deceptive orchids, which may be related to small population sizes. The number of pollinia removal is much higher than that of fruit set, indicating that there are some degrees of pollinia wasting in C amoena.展开更多
Phylogenetic relationships of 11 bumblebee species,including 5 subgenera:Bombus (5 species),Thoracobombus (3 species),Mendacibombus (1 species),Fervidobombus (1 species) and Pyrobombus (1 species),were analyzed based ...Phylogenetic relationships of 11 bumblebee species,including 5 subgenera:Bombus (5 species),Thoracobombus (3 species),Mendacibombus (1 species),Fervidobombus (1 species) and Pyrobombus (1 species),were analyzed based on the 357?bp mitochondrial cytochrome b gene sequences.There are 65 singleton polymorphic sites and 71 parsimony informative polymorphic sites in this DNA segment,and 45 polymorphic sites within the total 119 translated amino acids segment.Both NJ tree and MP tree show that Mendacibombus (B.avinovielllus) is basal to others,followed by Fervidobombus (B.pensylvanicus);Pyrobombus (B.impatiens) and Bombus are sister subgenera;the subgenus of Bombus is monophyletic,in which B.ignitus diverged first.展开更多
Animals have evolved foraging strategies to acquire blends of nutrients that maximize fitness traits. In social insects, nu trie nt regulation is complicated by the fact that few in dividuals, the foragers, must addre...Animals have evolved foraging strategies to acquire blends of nutrients that maximize fitness traits. In social insects, nu trie nt regulation is complicated by the fact that few in dividuals, the foragers, must address the diverge nt nutritional n eeds of all colony members simulta neously, includi ng other workers, the reproductives, and the brood. Here we used 3D nutritional geometry design to examine how bumblebee workers regulate their collection of 3 major macronutrients in the presence and absenee of brood. We provided small colonies artificial nectars (liquid diets) and pollens (solid diets) varying in their compositions of proteins, lipids, and carbohydrates during 2 weeks. Colo nies give n a choice betwee n nutrition ally complementary diets self-selected foods to reach a target ratio of 71% proteins, 6% carbohydrates, and 23% lipids, irrespective of the presenee of brood. Whe n con fined to a single nutrition ally imbalanced solid diet, colonies without brood regulated lipid collection and over-collected protein relative to this target ratio, whereas colonies with brood regulated both lipid and protein collection. This brood effect on the regulation of nutrient collection by workers suggests that protein levels are critical for larval development. Our results highlight the importa nee of con sidering bee nu trition as a multidimensi onal phe no men on to better assess the effects of environmental impoverishment and malnutrition on population declines.展开更多
Pollen collection is necessary for bee survival and important for flowering plant reproduction, yet if and how pollen extraction motor routines are modified with experience is largely unknown. Here, we used an automat...Pollen collection is necessary for bee survival and important for flowering plant reproduction, yet if and how pollen extraction motor routines are modified with experience is largely unknown. Here, we used an automated reward and monitoring system to evaluate modification in a common pollen-extraction routine, floral sonication. Through a series of laboratory experiments with the bumblebee, Bombus impatiens, we examined whether variation in sonication frequency and acceleration is due to instrumental learning based on rewards, a fixed behavioral response to rewards, and/or a mechanical constraint. We first investigated whether bees could learn to adjust their sonication frequency in response to pollen rewards given only for specified frequency ranges and found no evidenee of instrumental learning. However, we found that absenee versus receipt of a pollen reward did lead to a predictable behavioral resp on se, which depe nded on bee size. Fin ally, we found some evide nee of mechanical con straints, in that flower mass affected sonication acceleration (but not frequency) through an interaction with bee size. In generalz larger bees showed more flexibility in sonication frequency and acceleration, potentially reflecting a size-based constraint on the range over which smaller bees can modify frequency and accelerati on. Overall our results show that although bees did not display instrumental learning of sonication frequency, their sonication motor routine is nevertheless flexible.展开更多
Statistical power, number of replicates and experiment complexity of semi-field and field studies on Apis and non-Apis bee species has become a major issue after publication of the draft European Food Safety Authori...Statistical power, number of replicates and experiment complexity of semi-field and field studies on Apis and non-Apis bee species has become a major issue after publication of the draft European Food Safety Authority （EFSA） Guidance on risk assessment of plant protection products （PPP） on bees （Apis mellifera, Bombus spp. and solitary bees）. According to this guidance document, field studies have to be designed to be able to detect significance differences as low as 7% for certain endpoints such as reduction in colony size. This will require an immense number of replicates which is obviously not feasible. In the present study, key endpoints such as mortality, termination rate and number of brood cells in honeybee studies, cocoon production and flight activity in solitary bee studies and number of gynes in bumble bee studies （just to mention some of the endpoints considered） in semi-field studies were analyzed, with Apis mellifera, Bombus terrestris and Osmia bicornis during the past five years （2013-2017）. The results indicate huge differences in the percentage minimal detectable differences （%MDDs） （MDD expressed as median of control value of the endpoint in percent） depending on endpoint and species tested. For honeybee semi-field studies, the lowest %MDDs recorded were between 10% and 15% for the endpoints foraging, number of brood cells and colony strength. The highest %MDDs were observed for the endpoint termination rate, with a %MDD of almost 50%. For the endpoints in bumble bee semi-field studies the %MDDs varied between 17% for bumble bee colony weight and 53% for average mortality during the exposure period in the tunnel. The %MDD for the number of gynes （young queens） was slightly below 25%. For the semi-field solitary bee test system, the %MDDs for the measured endpoints seem to be lower than those for the other two species tested. The %MDDs for the endpoints hatching of offspring, nest occupation and number of cocoons were 8%, 13% and 14%, respectively. Most of the %MDDs were between 10% and 30% indicating clearly that the currently performed experimental design for the semi-field pollinator studies allowed to determine relatively small effects on key study endpoints. The analysis indicated that for all the three bee species tested, the semi-field test design detected low %MDDs for most of the endpoints. It was also observed that detectable differences between the control and PPP treatments were much lower in semi-field test designs than in field studies with these bee species. The “perfect sample size” really does not exist but test design and statistical analysis can be adapted to lower the %MDDs. Measured and simulated （according to Student’s t-test-distribution） data and results showed that statistical evaluations parameter selection （e.g., alpha value）, data transformation （log10） and the number of replicates had a direct effect on the ability of the test design to detect lower or higher %MDD values. It could show that a change of alpha value from 0.05 to 0.1, increases the ability of the studies to detect lower %MDDs. For most of the measured endpoints, increasing the number of replicates e.g., from four to eight, improved the power of the test design by decreasing the %MDD. The reduction magnitude of the %MDD is dependent on the endpoint and selection of statistical parameters such as the alpha value. Parameters that display effects at a biologically relevant scale will be a better indicator for effects than parameters that are able to detect minor differences that are not biologically relevant.展开更多
Bumblebees play an important ecological economic role as pollinators in natureand agriculture.For reasons of biosecurity,many countries promote the cultivation of na-tive bumblebee species for crop pollination instead...Bumblebees play an important ecological economic role as pollinators in natureand agriculture.For reasons of biosecurity,many countries promote the cultivation of na-tive bumblebee species for crop pollination instead of importing“alien”species.In SouthChina,a few bumblebee species are considered useful in this way,particularly,Bombusatripes,Bombus bicoloratus and Bombus breviceps.However,whether they are suitablefor artificial rearing and forming healthy colonies for pollination,remains unknown.Inthis project,queens from the 3 native species of Guizhou Province were collected andcolonies were started under standardized conditions.The colonies were scored based on19 parameters,including the stage of colony development,number and weight of off-spring,and diet consumed.The data revealed that B.breviceps had the best performance,produced more workers and consumed the smallest diet.Next,we performed 16S rDNAsequencing of the bacterial communities found in the guts of offspring workers,and thena correlation analysis between colony performance and gut bacteria was conducted.Here,B.breviceps showed the highest diversity in gut bacterial composition,dominated by thebacteria Gilliamella,Snodgrassella,Enterobacter,and Lactobacillus Firm5.The higherthe abundance of Snodgrassella,the better the performance of the colony in the founda-tion stage,and later Lactobacillus Firm5,Apibacter and Bifidobacterium were beneficialduring the stages of rapid growth and colony decline.Although we do not understand allof the interactions yet,these correlations explain why B.breviceps demonstrated bettercolony performance.Our data provide valuable information for breeding local Bombusspecies and will contribute to developing strong colonies for crop pollination.展开更多
Recent developments allowed establishing virtual-reality (VR) setups to study multiple aspects of visual learning in honey bees under controlled experimental conditions. Here, we adopted a VR environment to investigat...Recent developments allowed establishing virtual-reality (VR) setups to study multiple aspects of visual learning in honey bees under controlled experimental conditions. Here, we adopted a VR environment to investigate the visual learning in the buff-tailed bumble bee Bombus terrestris. Based on responses to appetitive and aversive reinforcements used for conditioning, we show that bumble bees had the proper appetitive motivation to engage in the VR experiments and that they learned efficiently elemental color discriminations. In doing so, they reduced the latency to make a choice, increased the proportion of direct paths toward the virtual stimuli and walked faster toward them. Performance in a short-term retention test showed that bumble bees chose and fixated longer on the correct stimulus in the absence of reinforcement. Body size and weight, although variable across individuals, did not affect cognitive performances and had a mild impact on motor performances. Overall, we show that bumble bees are suitable experimental subjects for experiments on visual learning under VR conditions, which opens important perspectives for invasive studies on the neural and molecular bases of such learning given the robustness of these insects and the accessibility of their brain.展开更多
基金supported by the National Natural Science Foundation of China Project 32200387.
文摘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.
基金This work was supported by the National Natural Science Foundation of China(Grant numbers 32270445 and 31971397)the Support Project of High-level Teachers in Beijing Municipal Universities in the Period of 14th Fiveyear Plan(Grant number BPHR20220114)the Central Public-interest Scientific Institution Basal Research Fund(Grant numbers Y2019XK13 and Y2021XK16).
文摘Bumblebees are a genus of pollinators(Bombus)that play important roles in natural ecosystem and agricultural production.Several bumblebee species have been recorded as under population decline,and the proportion of species experiencing popula-tion decline within subgenus Thoracobombus is higher than average.Bombus opulentus is 1 species in Thoracobombus,but little is known about its recent population dynamics.Here,we employed conservation genomics methods to investigate the population dynam-ics of B.opulentus during the recent past and identify the likely environmental factors that may cause population decline.Firstly,we placed the scaffold-level of B.opulentus ref-erence genome sequence onto chromosome-level using Hi-C technique.Then,based on this reference genome and whole-genome resequencing data for 51 B.opulentus samples,we reconstructed the population structure and effective population size(Ne)trajectories of B.opulentus and identified genes that were under positive selection.Our results revealed that the collected B.opulentus samples could be divided into 2 populations,and 1 of them experienced a recent population decline;the declining population also exhibited lower ge-netic diversity and higher inbreeding levels.Genes related to high-temperature tolerance,immune response,and detoxication showed signals of positive selection in the declining population,suggesting that climate warming and pathogen/pesticide exposures may con-tribute to the decline of this B.opulentus population.Taken together,our study provided insights into the demography of B.opulentus populations and highlighted that popula-tions of the same bumblebee species could have contrasting Ne trajectories and population decline could be caused by a combination of various stressors.
基金supported by the National Natural Science Foundation of China Project(32200387)the Emergency Project for Risk Assessment of Areca Nut(Key Project of the Department of Agriculture and Rural Affairs of Hainan Province&Wanning Municipal People’s Government).
文摘Areca nut is the basic ingredient of betel quid,which is chewed by hundreds of millions of people in South-Eastern Asia.Chewing of areca nut has been associated with oral cancers potentially due to its specific alkaloids,among which arecoline constitutes about 90%of total fraction.Being the world’s fourth most commonly used psychoactive substance,arecoline evokes stimulation,addiction,and other direct neurological effects,while its misuse correlates to neurotoxic effects.However,what might underlie its neurotoxic mechanisms has been poorly documented.The brain is encoded by a complex network of neuronal and glial cell types,and neurotoxicity of hazardous compounds present transcriptional heterogeneity.Recently,the eusocial bumblebee has been used as a model for studying brain effects,with sophisticated cognitive capability and precisely measured brain architecture.Here,we decipher cell-type-specific mental risks to arecoline using bumblebees.Arecoline induced locomotor hyperactivity and cognitive impairment.Single nucleus RNA sequencing(snRNA-seq)unearthed arecoline-induced cell-specific responses,primarily targeted on Kenyon cells(KC).Moreover,high-dose arecoline induced distinctive cell responses among KC subtypes,particularly class I large Kenyon cell(lKC),leading to DNA damage,excitatory/inhibitory(E/I)imbalance,and calcium dyshomeostasis,which potentially resulted in cognitive impairment.Given arecoline’s popularity and growing exposure risks to humans,neurological health risks of areca nut warrant serious consideration.
文摘Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their worker force. In bumblebees, so- cial parasitism appeared in at least 3 subgenera independently： in the subgenus Psithyrus consisting entirely of parasitic species, in the subgenus Alpinobombus with Bombus hy- perboreus, and in the subgenus Thoracobombus with B. inexspectatus. Cuckoo bumblebee males utilize species-specific cephalic labial gland secretions for mating purposes that can impact their inquiline strategy. We performed cephalic labial gland secretions in B. hyperboreus, B. inexspectatus and their hosts. Males of both parasitic species exhibited high species specific levels of cephalic gland secretions, including different main com- pounds. Our results showed no chemical mimicry in the cephalic gland secretions between inquilines and their host and we did not identify the repellent compounds already known in other cuckoo bumblebees.
文摘Changnienia amoena Chien is a monotypic species and endemic to China, and was listed on the Chinese Red Book in 1992. The species was once abundant but has become rare and endangered in recent years because of the habitat fragmentation and unduly commercial collections. Previous observation showed that this species has very low and even no fruit set, and the pollinators are not observed before this report. The present observation was conducted at the Shennongjia, Hubei Province during the spring of 2002. The results showed that Bombus (Diversobombus) trifasciatus Smith, B. imitator Pittion and one species of Apis visited the flowers of the orchid, but only B. tritasciatus could carry pollinaria on its body and was the legitimate pollinators of C amoena. During 113 h of observation, only nine visitations were recorded. The bumblebees mainly appeared during 12:00-15:00 during the day. Bumblebees stayed in a flower only a few seconds and never more than ten seconds. The flowers would persist in fresh for about three weeks when they were not pollinated, but 3 or 4 d after pollinated, the pollinated flowers underwent a series of color and morphological changes including stalk elongation and ovary swelling. Therefore, stalk elongation can be considered an index of fruits set. Artificial pollination indicated that C amoena is a highly self-compatible and outcrossing species, but dependent on pollinators for fruit set. Based on the field observations, we concluded that pollination system of C amoena is deceptive. The fruit set in nature is not very low (26.98% on average) compared to other deceptive orchids, which may be related to small population sizes. The number of pollinia removal is much higher than that of fruit set, indicating that there are some degrees of pollinia wasting in C amoena.
文摘Phylogenetic relationships of 11 bumblebee species,including 5 subgenera:Bombus (5 species),Thoracobombus (3 species),Mendacibombus (1 species),Fervidobombus (1 species) and Pyrobombus (1 species),were analyzed based on the 357?bp mitochondrial cytochrome b gene sequences.There are 65 singleton polymorphic sites and 71 parsimony informative polymorphic sites in this DNA segment,and 45 polymorphic sites within the total 119 translated amino acids segment.Both NJ tree and MP tree show that Mendacibombus (B.avinovielllus) is basal to others,followed by Fervidobombus (B.pensylvanicus);Pyrobombus (B.impatiens) and Bombus are sister subgenera;the subgenus of Bombus is monophyletic,in which B.ignitus diverged first.
文摘Animals have evolved foraging strategies to acquire blends of nutrients that maximize fitness traits. In social insects, nu trie nt regulation is complicated by the fact that few in dividuals, the foragers, must address the diverge nt nutritional n eeds of all colony members simulta neously, includi ng other workers, the reproductives, and the brood. Here we used 3D nutritional geometry design to examine how bumblebee workers regulate their collection of 3 major macronutrients in the presence and absenee of brood. We provided small colonies artificial nectars (liquid diets) and pollens (solid diets) varying in their compositions of proteins, lipids, and carbohydrates during 2 weeks. Colo nies give n a choice betwee n nutrition ally complementary diets self-selected foods to reach a target ratio of 71% proteins, 6% carbohydrates, and 23% lipids, irrespective of the presenee of brood. Whe n con fined to a single nutrition ally imbalanced solid diet, colonies without brood regulated lipid collection and over-collected protein relative to this target ratio, whereas colonies with brood regulated both lipid and protein collection. This brood effect on the regulation of nutrient collection by workers suggests that protein levels are critical for larval development. Our results highlight the importa nee of con sidering bee nu trition as a multidimensi onal phe no men on to better assess the effects of environmental impoverishment and malnutrition on population declines.
文摘Pollen collection is necessary for bee survival and important for flowering plant reproduction, yet if and how pollen extraction motor routines are modified with experience is largely unknown. Here, we used an automated reward and monitoring system to evaluate modification in a common pollen-extraction routine, floral sonication. Through a series of laboratory experiments with the bumblebee, Bombus impatiens, we examined whether variation in sonication frequency and acceleration is due to instrumental learning based on rewards, a fixed behavioral response to rewards, and/or a mechanical constraint. We first investigated whether bees could learn to adjust their sonication frequency in response to pollen rewards given only for specified frequency ranges and found no evidenee of instrumental learning. However, we found that absenee versus receipt of a pollen reward did lead to a predictable behavioral resp on se, which depe nded on bee size. Fin ally, we found some evide nee of mechanical con straints, in that flower mass affected sonication acceleration (but not frequency) through an interaction with bee size. In generalz larger bees showed more flexibility in sonication frequency and acceleration, potentially reflecting a size-based constraint on the range over which smaller bees can modify frequency and accelerati on. Overall our results show that although bees did not display instrumental learning of sonication frequency, their sonication motor routine is nevertheless flexible.
文摘Statistical power, number of replicates and experiment complexity of semi-field and field studies on Apis and non-Apis bee species has become a major issue after publication of the draft European Food Safety Authority （EFSA） Guidance on risk assessment of plant protection products （PPP） on bees （Apis mellifera, Bombus spp. and solitary bees）. According to this guidance document, field studies have to be designed to be able to detect significance differences as low as 7% for certain endpoints such as reduction in colony size. This will require an immense number of replicates which is obviously not feasible. In the present study, key endpoints such as mortality, termination rate and number of brood cells in honeybee studies, cocoon production and flight activity in solitary bee studies and number of gynes in bumble bee studies （just to mention some of the endpoints considered） in semi-field studies were analyzed, with Apis mellifera, Bombus terrestris and Osmia bicornis during the past five years （2013-2017）. The results indicate huge differences in the percentage minimal detectable differences （%MDDs） （MDD expressed as median of control value of the endpoint in percent） depending on endpoint and species tested. For honeybee semi-field studies, the lowest %MDDs recorded were between 10% and 15% for the endpoints foraging, number of brood cells and colony strength. The highest %MDDs were observed for the endpoint termination rate, with a %MDD of almost 50%. For the endpoints in bumble bee semi-field studies the %MDDs varied between 17% for bumble bee colony weight and 53% for average mortality during the exposure period in the tunnel. The %MDD for the number of gynes （young queens） was slightly below 25%. For the semi-field solitary bee test system, the %MDDs for the measured endpoints seem to be lower than those for the other two species tested. The %MDDs for the endpoints hatching of offspring, nest occupation and number of cocoons were 8%, 13% and 14%, respectively. Most of the %MDDs were between 10% and 30% indicating clearly that the currently performed experimental design for the semi-field pollinator studies allowed to determine relatively small effects on key study endpoints. The analysis indicated that for all the three bee species tested, the semi-field test design detected low %MDDs for most of the endpoints. It was also observed that detectable differences between the control and PPP treatments were much lower in semi-field test designs than in field studies with these bee species. The “perfect sample size” really does not exist but test design and statistical analysis can be adapted to lower the %MDDs. Measured and simulated （according to Student’s t-test-distribution） data and results showed that statistical evaluations parameter selection （e.g., alpha value）, data transformation （log10） and the number of replicates had a direct effect on the ability of the test design to detect lower or higher %MDD values. It could show that a change of alpha value from 0.05 to 0.1, increases the ability of the studies to detect lower %MDDs. For most of the measured endpoints, increasing the number of replicates e.g., from four to eight, improved the power of the test design by decreasing the %MDD. The reduction magnitude of the %MDD is dependent on the endpoint and selection of statistical parameters such as the alpha value. Parameters that display effects at a biologically relevant scale will be a better indicator for effects than parameters that are able to detect minor differences that are not biologically relevant.
基金wasfunded by a project of the Planting Management Depart-ment of the Ministry of Agriculture and Rural Affairs(152307023)the Science and Technology Programof Qiandongnan Prefecture(Qiandongnan[2021]07).
文摘Bumblebees play an important ecological economic role as pollinators in natureand agriculture.For reasons of biosecurity,many countries promote the cultivation of na-tive bumblebee species for crop pollination instead of importing“alien”species.In SouthChina,a few bumblebee species are considered useful in this way,particularly,Bombusatripes,Bombus bicoloratus and Bombus breviceps.However,whether they are suitablefor artificial rearing and forming healthy colonies for pollination,remains unknown.Inthis project,queens from the 3 native species of Guizhou Province were collected andcolonies were started under standardized conditions.The colonies were scored based on19 parameters,including the stage of colony development,number and weight of off-spring,and diet consumed.The data revealed that B.breviceps had the best performance,produced more workers and consumed the smallest diet.Next,we performed 16S rDNAsequencing of the bacterial communities found in the guts of offspring workers,and thena correlation analysis between colony performance and gut bacteria was conducted.Here,B.breviceps showed the highest diversity in gut bacterial composition,dominated by thebacteria Gilliamella,Snodgrassella,Enterobacter,and Lactobacillus Firm5.The higherthe abundance of Snodgrassella,the better the performance of the colony in the founda-tion stage,and later Lactobacillus Firm5,Apibacter and Bifidobacterium were beneficialduring the stages of rapid growth and colony decline.Although we do not understand allof the interactions yet,these correlations explain why B.breviceps demonstrated bettercolony performance.Our data provide valuable information for breeding local Bombusspecies and will contribute to developing strong colonies for crop pollination.
基金This work was supported by the Joint Special Project on Construction of"First-Class Universities and Disciplines"of Yunnan University(202201BF070001-017).
基金This research was supported by the Talent Foundation of China West Normal University(17YC142 and 17YC137)National General Cultivation Project of China West Normal University(19B029).
文摘Recent developments allowed establishing virtual-reality (VR) setups to study multiple aspects of visual learning in honey bees under controlled experimental conditions. Here, we adopted a VR environment to investigate the visual learning in the buff-tailed bumble bee Bombus terrestris. Based on responses to appetitive and aversive reinforcements used for conditioning, we show that bumble bees had the proper appetitive motivation to engage in the VR experiments and that they learned efficiently elemental color discriminations. In doing so, they reduced the latency to make a choice, increased the proportion of direct paths toward the virtual stimuli and walked faster toward them. Performance in a short-term retention test showed that bumble bees chose and fixated longer on the correct stimulus in the absence of reinforcement. Body size and weight, although variable across individuals, did not affect cognitive performances and had a mild impact on motor performances. Overall, we show that bumble bees are suitable experimental subjects for experiments on visual learning under VR conditions, which opens important perspectives for invasive studies on the neural and molecular bases of such learning given the robustness of these insects and the accessibility of their brain.
