T-RFLP analysis of bacterial communities in the midguts of Apis mellifera and Apis cerana honey bees in Thailand

This study investigated bacterial community structures in the midguts of Apis mellifera and Apis cerana in Thailand to understand how bacterial communities develop in Apis species. The bacterial species present in replicate colonies from different locations and life stages were analysed. PCR amplification of bacterial 16S rRNA gene fragments and terminal restriction fragment length polymorphism analyses revealed a total of 16 distinct terminal restriction fragments (T-RFs), 12 of which were shared between A. mellifera and A. cerana populations. The T-RFs were affiliated to Beta- and Gammaproteobacteria, Firmicutes and Actinomycetes. The Gammaproteobacteria were found to be common in all stages of honey bee, but in addition, the Firmicutes group was found to be present in the worker bees. Bacterial community structure showed no difference amongst the replicate colonies, but was affected to some degree by geographical location, life stage and species of honey bees.     

Diversity and phylotype consistency of bacteria in the guts of three bee species (Apoidea) at an oilseed rape field

The gut of insects may harbour one of the largest reservoirs of a yet unexplored microbial diversity. To understand how specific insects select for their own bacterial communities, the structural diversity and variability of bacteria found in the gut of different bee species was analysed. For three successive years, adults and larvae of Apis mellifera ssp. carnica (honey bee), and Bombus terrestris (bumble bee), as well as larvae of Osmia bicornis (red mason bee) were collected at a flowering oilseed rape field. Total DNA was extracted from gut material and the bacterial diversity was analysed, independent of cultivation, by genetic profiling with single-strand conformation polymorphism (SSCP) of polymerase chain reaction (PCR)-amplified partial 16S rRNA genes. The SSCP profiles were specific for all bee species and for larvae and adults. Qualitative and quantitative differences were found in the bacterial community structure of larvae and adults of A. mellifera, but differences in B. terrestris were mainly quantitative. Sequencing of the PCR products revealed a dominance of Alpha-, Beta-, and Gammaproteobacteria, Bacteroidetes, and Firmicutes in all bee species. Single-strand conformation polymorphism profiles suggested a higher abundance and diversity of lactobacilli in adults of A. mellifera than in larvae. Further phylogenetic analyses indicated common bacterial phylotypes for all three bee species, e.g. those related to Simonsiella, Serratia, and Lactobacillus. Clades related to Delftia acidovorans, Pseudomonas aeruginosa or Lactobacillus intestinalis only contained sequences from larvae. Several of the bee-specific clusters also contained identical or highly similar sequences from bacteria detected in other A. mellifera subspecies from South Africa, suggesting the existence of cosmopolitan gut bacteria in bees.     

Antibacterial Immune Competence of Honey Bees (Apis mellifera) Is Adapted to Different Life Stages and Environmental Risks

The development of all honey bee castes proceeds through three different life stages all of which encounter microbial infections to a various extent. We have examined the immune strength of honey bees across all developmental stages with emphasis on the temporal expression of cellular and humoral immune responses upon artificial challenge with viable Escherichia coli bacteria. We employed a broad array of methods to investigate defence strategies of infected individuals: (a) fate of bacteria in the haemocoel; (b) nodule formation and (c) induction of antimicrobial peptides (AMPs). Newly emerged adult worker bees and drones were able to activate efficiently all examined immune reactions. The number of viable bacteria circulating in the haemocoel of infected bees declined rapidly by more than two orders of magnitude within the first 4–6 h post-injection (p.i.), coinciding with the occurrence of melanised nodules. Antimicrobial activity, on the other hand, became detectable only after the initial bacterial clearance. These two temporal patterns of defence reactions very likely represent the constitutive cellular and the induced humoral immune response. A unique feature of honey bees is that a fraction of worker bees survives the winter season in a cluster mostly engaged in thermoregulation. We show here that the overall immune strength of winter bees matches that of young summer bees although nodulation reactions are not initiated at all. As expected, high doses of injected viable E.coli bacteria caused no mortality in larvae or adults of each age. However, drone and worker pupae succumbed to challenge with E.coli even at low doses, accompanied by a premature darkening of the pupal body. In contrast to larvae and adults, we observed no fast clearance of viable bacteria and no induction of AMPs but a rapid proliferation of E.coli bacteria in the haemocoel of bee pupae ultimately leading to their death.     

Diverse Microbiota Identified in Whole Intact Nest Chambers of the Red Mason Bee Osmia bicornis (Linnaeus 1758)

Microbial activity is known to have profound impact on bee ecology and physiology, both by beneficial and pathogenic effects. Most information about such associations is available for colony-building organisms, and especially the honey bee. There, active manipulations through worker bees result in a restricted diversity of microbes present within the colony environment. Microbial diversity in solitary bee nests remains unstudied, although their larvae face a very different situation compared with social bees by growing up in isolated compartments. Here, we assessed the microbiota present in nests and pre-adults of Osmia bicornis, the red mason bee, by culture-independent pyrosequencing. We found high bacterial diversity not comparable with honey bee colonies. We identified a variety of bacteria potentially with positive or negative interactions for bee larvae. However, most of the other diverse bacteria present in the nests seem to originate from environmental sources through incorporated nest building material and stored pollen. This diversity of microorganisms may cause severe larval mortality and require specific physiological or symbiotic adaptations against microbial threats. They may however also profit from such a diverse environment through gain of mutualistic partners. We conclude that further studies of microbiota interaction in solitary bees will improve the understanding of fitness components and populations dynamics.     

Larval juvenile hormone treatment affects pre-adult development,but not adult age at onset of foraging in worker honey bees (Apis mellifera)

Previous research has shown that juvenile hormone (JH) titers increase as adult worker honey bees age and treatments with JH, JH analogs and JH mimics induce precocious foraging. Larvae from genotypes exhibiting faster adult behavioral development had significantly higher levels of juvenile hormone during the 2nd and 3rd larval instar. It is known that highly increased JH during this period causes the totipotent female larvae to differentiate into a queen. We treated third instar larvae with JH to test the hypothesis that this time period may be a developmental critical period for organizational effects of JH on brain and behavior also in the worker caste, such that JH treatment at a lower level than required to produce queens will speed adult behavioral development in workers. Larval JH treatment did not influence adult worker behavioral development. However, it made pre-adult development more queen-like in two ways: treated larvae were capped sooner by adult bees, and emerged from pupation earlier. These results suggest that some aspects of honey bee behavioral development may be relatively insensitive to pre-adult perturbation. These results also suggest JH titer may be connected to cues perceived by the adult bees indicating larval readiness for pupation resulting in adult bee cell capping behavior.     

Microbial Gut Diversity of Africanized and European Honey Bee Larval Instars

The first step in understanding gut microbial ecology is determining the presence and potential niche breadth of associated microbes. While the core gut bacteria of adult honey bees is becoming increasingly apparent, there is very little and inconsistent information concerning symbiotic bacterial communities in honey bee larvae. The larval gut is the target of highly pathogenic bacteria and fungi, highlighting the need to understand interactions between typical larval gut flora, nutrition and disease progression. Here we show that the larval gut is colonized by a handful of bacterial groups previously described from guts of adult honey bees or other pollinators. First and second larval instars contained almost exclusively Alpha 2.2, a core Acetobacteraceae, while later instars were dominated by one of two very different Lactobacillus spp., depending on the sampled site. Royal jelly inhibition assays revealed that of seven bacteria occurring in larvae, only one Neisseriaceae and one Lactobacillus sp. were inhibited. We found both core and environmentally vectored bacteria with putatively beneficial functions. Our results suggest that early inoculation by Acetobacteraceae may be important for microbial succession in larvae. This assay is a starting point for more sophisticated in vitro models of nutrition and disease resistance in honey bee larvae.     

Profiling the Succession of Bacterial Communities throughout the Life Stages of a Higher Termite Nasutitermes arborum (Termitidae,Nasutitermitinae) Using 16S rRNA Gene Pyrosequencing

Previous surveys of the gut microbiota of termites have been limited to the worker caste. Termite gut microbiota has been well documented over the last decades and consists mainly of lineages specific to the gut microbiome which are maintained across generations. Despite this intimate relationship, little is known of how symbionts are transmitted to each generation of the host, especially in higher termites where proctodeal feeding has never been reported. The bacterial succession across life stages of the wood-feeding higher termite Nasutitermes arborum was characterized by 16S rRNA gene deep sequencing. The microbial community in the eggs, mainly affiliated to Proteobacteria and Actinobacteria, was markedly different from the communities in the following developmental stages. In the first instar and last instar larvae and worker caste termites, Proteobacteria and Actinobacteria were less abundant than Firmicutes, Bacteroidetes, Spirochaetes, Fibrobacteres and the candidate phylum TG3 from the last instar larvae. Most of the representatives of these phyla (except Firmicutes) were identified as termite-gut specific lineages, although their relative abundances differed. The most salient difference between last instar larvae and worker caste termites was the very high proportion of Spirochaetes, most of which were affiliated to the Treponema Ic, Ia and If subclusters, in workers. The results suggest that termite symbionts are not transmitted from mother to offspring but become established by a gradual process allowing the offspring to have access to the bulk of the microbiota prior to the emergence of workers, and, therefore, presumably through social exchanges with nursing workers.     

Specificity between Lactobacilli and Hymenopteran Hosts Is the Exception Rather than the Rule

Lactobacilli (Lactobacillales: Lactobacillaceae) are well known for their roles in food fermentation, as probiotics, and in human health, but they can also be dominant members of the microbiota of some species of Hymenoptera (ants, bees, and wasps). Honey bees and bumble bees associate with host-specific lactobacilli, and some evidence suggests that these lactobacilli are important for bee health. Social transmission helps maintain associations between these bees and their respective microbiota. To determine whether lactobacilli associated with social hymenopteran hosts are generally host specific, we gathered publicly available Lactobacillus 16S rRNA gene sequences, along with Lactobacillus sequences from 454 pyrosequencing surveys of six other hymenopteran species (three sweat bees and three ants). We determined the comparative secondary structural models of 16S rRNA, which allowed us to accurately align the entire 16S rRNA gene, including fast-evolving regions. BLAST searches and maximum-likelihood phylogenetic reconstructions confirmed that honey and bumble bees have host-specific Lactobacillus associates. Regardless of colony size or within-colony oral sharing of food (trophallaxis), sweat bees and ants associate with lactobacilli that are closely related to those found in vertebrate hosts or in diverse environments. Why honey and bumble bees associate with host-specific lactobacilli while other social Hymenoptera do not remains an open question. Lactobacilli are known to inhibit the growth of other microbes and can be beneficial whether they are coevolved with their host or are recruited by the host from environmental sources through mechanisms of partner choice.     

Characterization of gut bacterial flora of Apis mellifera from north-west Pakistan

Gut microbiota has been recognized to play a beneficial role in honey bees (Apis mellifera). Present study was designed to characterize the gut bacterial flora of honey bees in north-west Pakistan. Total 150 aerobic and facultative anaerobic bacteria from guts of 45 worker bees were characterized using biochemical assays and 16S rDNA sequencing followed by bioinformatics analysis. The gut isolates were classified into three bacterial phyla of Firmicutes (60%), Proteobacteria (26%) and Actinobacteria (14%). Most of the isolates belonged to genera and families of Staphylococcus, Bacillus, Enterococcus, Ochrobactrum, Sphingomonas, Ralstonia, Enterobacteriaceae, Corynebacterium and Micrococcineae. Many of these bacteria were tolerant to acidic environments and fermented sugars, hence considered beneficial gut inhabitants and involved the maintenance of a healthy microbiota. However, several opportunistic commensals that proliferate in the hive environment including members Staphylococcus haemolyticus group and Sphingomonas paucimobilis were also identified. This is the first report on bee gut microbiota from north-west Pakistan geographically situated at the crossroads of Indian subcontinent and central Asia.     

Nosema ceranae Can Infect Honey Bee Larvae and Reduces Subsequent Adult Longevity

Nosema ceranae causes a widespread disease that reduces honey bee health but is only thought to infect adult honey bees, not larvae, a critical life stage. We reared honey bee (Apis mellifera) larvae in vitro and provide the first demonstration that N. ceranae can infect larvae and decrease subsequent adult longevity. We exposed three-day-old larvae to a single dose of 40,000 (40K), 10,000 (10K), zero (control), or 40K autoclaved (control) N. ceranae spores in larval food. Spores developed intracellularly in midgut cells at the pre-pupal stage (8 days after egg hatching) of 41% of bees exposed as larvae. We counted the number of N. ceranae spores in dissected bee midguts of pre-pupae and, in a separate group, upon adult death. Pre-pupae exposed to the 10K or 40K spore treatments as larvae had significantly elevated spore counts as compared to controls. Adults exposed as larvae had significantly elevated spore counts as compared to controls. Larval spore exposure decreased longevity: a 40K treatment decreased the age by which 75% of adult bees died by 28%. Unexpectedly, the low dose (10K) led to significantly greater infection (1.3 fold more spores and 1.5 fold more infected bees) than the high dose (40K) upon adult death. Differential immune activation may be involved if the higher dose triggered a stronger larval immune response that resulted in fewer adult spores but imposed a cost, reducing lifespan. The impact of N. ceranae on honey bee larval development and the larvae of naturally infected colonies therefore deserve further study.     

Investigation of gut microbial communities associated with indigenous honey bee (Apis mellifera jemenitica) from two different eco-regions of Saudi Arabia

The microbial communities associated with the alimentary tract of honey bees are very important as they help with food digestion, provide essential nutrients, protect the host from pathogens, detoxify harmful molecules, and increase host immunity. In this study, the structural diversity of the gut microbial communities of native honey bees, Apis mellifera jemenitica from two different geographical regions (Riyadh and Al-Baha) of Saudi Arabia was analyzed by culture-dependent methods and 16S ribosomal RNA (rRNA) gene sequencing. In this study, 100 bacterial isolates were cultivated and phylogenetic analyses grouped them into three phyla: Proteobacteria, Firmicutes, and Actinobacteria. Bacteria in the phylum Proteobacteria were the most dominant (17 species), followed by Firmicutes (13 species) and Actinobacteria (4 species). Some of the identified bacteria (Citrobacter sp., Providencia vermicola, Exiguobacterium acetylicum, and Planomicrobium okeanokoites) were reported for the first time in the genus Apis, while others identified bacteria belonged to the genera Proteus, Enterobacter, Bacillus, Morganella, Lactobacillus, and Fructobacillus. To the best of our knowledge, this is the first study on the gut microbiota of the local honey bees in Saudi Arabia.     

Hunting for healthy microbiomes: determining the core microbiomes of <Emphasis Type="Italic">Ceratina,Megalopta</Emphasis>, and <Emphasis Type="Italic">Apis</Emphasis> bees and how they associate with microbes in bee collected pollen

Social corbiculate bees such as honey bees and bumble bees maintain a specific beneficial core microbiome which is absent in wild bees. It has been suggested that maintaining this microbiome can prevent disease and keep bees healthy. The main aim of our study was to identify if there are any core bacterial groups in the non-corbiculate bees Ceratina and Megalopta that have been previously overlooked. We additionally test for associations between the core bee microbes and pollen provisions to look for potential transmission between the two. We identify three enterotypes in Ceratina samples, with thirteen core bacterial phylotypes in Ceratina females: Rosenbergiella, Pseudomonas, Gilliamella, Lactobacillus, Caulobacter, Snodgrassella, Acinetobacter, Corynebacterium, Sphingomonas, Commensalibacter, Methylobacterium, Massilia, and Stenotrophomonas, plus 19 in pollen (6 of which are shared by bees). Unlike Apis bees, whose gut microbial community differs compared to their pollen, Ceratina adults and pollen largely share a similar microbial composition and enterotype difference was largely explained by pollen age. Megalopta displays a highly diverse composition of microbes throughout all adults, yet Lactobacillus and Saccharibacter were prevalent in 90% of adults as core bacteria. Only Lactobacillus was both a core bee and pollen provision microbe in all three species. The consequences of such diversity in core microbiota between bee genera and their associations with pollen are discussed in relation to identifying potentially beneficial microbial taxa in wild bees to aid the conservation of wild, understudied, non-model bee species.     

Distinctive gut microbiota of honey bees assessed using deep sampling from individual worker bees

Surveys of 16S rDNA sequences from the honey bee, Apis mellifera, have revealed the presence of eight distinctive bacterial phylotypes in intestinal tracts of adult worker bees. Because previous studies have been limited to relatively few sequences from samples pooled from multiple hosts, the extent of variation in this microbiota among individuals within and between colonies and locations has been unclear. We surveyed the gut microbiota of 40 individual workers from two sites, Arizona and Maryland USA, sampling four colonies per site. Universal primers were used to amplify regions of 16S ribosomal RNA genes, and amplicons were sequenced using 454 pyrotag methods, enabling analysis of about 330,000 bacterial reads. Over 99% of these sequences belonged to clusters for which the first blastn hits in GenBank were members of the known bee phylotypes. Four phylotypes, one within Gammaproteobacteria (corresponding to "Candidatus Gilliamella apicola") one within Betaproteobacteria ("Candidatus Snodgrassella alvi"), and two within Lactobacillus, were present in every bee, though their frequencies varied. The same typical bacterial phylotypes were present in all colonies and at both sites. Community profiles differed significantly among colonies and between sites, mostly due to the presence in some Arizona colonies of two species of Enterobacteriaceae not retrieved previously from bees. Analysis of Sanger sequences of rRNA of the Snodgrassella and Gilliamella phylotypes revealed that single bees contain numerous distinct strains of each phylotype. Strains showed some differentiation between localities, especially for the Snodgrassella phylotype.     

First Detection of the Larval Chalkbrood Disease Pathogen Ascosphaera apis (Ascomycota: Eurotiomycetes: Ascosphaerales) in Adult Bumble Bees

Fungi in the genus Ascosphaera (Ascomycota: Eurotiomycetes: Ascosphaerales) cause chalkbrood disease in larvae of bees. Here, we report the first-ever detection of the fungus in adult bumble bees that were raised in captivity for studies on colony development. Wild queens of Bombus griseocollis, B. nevadensis and B. vosnesenskii were collected and maintained for establishment of nests. Queens that died during rearing or that did not lay eggs within one month of capture were dissected, and tissues were examined microscopically for the presence of pathogens. Filamentous fungi that were detected were plated on artificial media containing broad spectrum antibiotics for isolation and identification. Based on morphological characters, the fungus was identified as Ascosphaera apis (Maasen ex Claussen) Olive and Spiltoir, a species that has been reported earlier only from larvae of the European honey bee, Apis mellifera, the Asian honey bee, Apis cerana, and the carpenter bee Xylocopa californica arizonensis. The identity of the fungus was confirmed using molecular markers and phylogenetic analysis. Ascosphaera apis was detected in queens of all three bumble bee species examined. Of 150 queens dissected, 12 (8%) contained vegetative and reproductive stages of the fungus. Both fungal stages were also detected in two workers collected from colonies with Ascosphaera-infected B. nevadensis queens. In this study, wild bees could have been infected prior to capture for rearing, or, the A. apis infection could have originated via contaminated European honey bee pollen fed to the bumble bees in captivity. Thus, the discovery of A. apis in adult bumble bees in the current study has important implications for commercial production of bumble bee colonies and highlights potential risks to native bees via pathogen spillover from infected bees and infected pollen.     

Gut microbiota composition is associated with environmental landscape in honey bees

There is growing recognition that the gut microbial community regulates a wide variety of important functions in its animal hosts, including host health. However, the complex interactions between gut microbes and environment are still unclear. Honey bees are ecologically and economically important pollinators that host a core gut microbial community that is thought to be constant across populations. Here, we examined whether the composition of the gut microbial community of honey bees is affected by the environmental landscape the bees are exposed to. We placed honey bee colonies reared under identical conditions in two main landscape types for 6 weeks: either oilseed rape farmland or agricultural farmland distant to fields of flowering oilseed rape. The gut bacterial communities of adult bees from the colonies were then characterized and compared based on amplicon sequencing of the 16S rRNA gene. While previous studies have delineated a characteristic core set of bacteria inhabiting the honey bee gut, our results suggest that the broad environment that bees are exposed to has some influence on the relative abundance of some members of that microbial community. This includes known dominant taxa thought to have functions in nutrition and health. Our results provide evidence for an influence of landscape exposure on honey bee microbial community and highlight the potential effect of exposure to different environmental parameters, such as forage type and neonicotinoid pesticides, on key honey bee gut bacteria. This work emphasizes the complexity of the relationship between the host, its gut bacteria, and the environment and identifies target microbial taxa for functional analyses.     

Pyrosequencing analysis of the bacterial communities in the guts of honey bees Apis cerana and Apis mellifera in Korea

The bacterial communities in the guts of the adults and larvae of the Asian honey bee Apis cerana and the European honey bee Apis mellifera were surveyed by pyrosequencing the 16S rRNA genes. Most of the gut bacterial 16S rRNA gene sequences were highly similar to the known honey bee-specific ones and affiliated with Pasteurellaceae or lactic acid bacteria (LAB). The numbers of operational taxonomic units (OTUs, defined at 97% similarity) were lower in the larval guts (6 or 9) than in the adult guts (18 or 20), and the frequencies of Pasteurellaceae-related OTUs were higher in the larval guts while those of LAB-related OTUs in the adult guts. The frequencies of Lactococcus, Bartonella, Spiroplasma, Enterobacteriaceae, and Flavobacteriaceae-related OTUs were much higher in A. cerana guts while Bifidobacterium and Lachnospiraceae-related OTUs were more abundant in A. mellfera guts. The bacterial community structures in the midguts and hindguts of the adult honey bees were not different for A. cerana, but significantly different for A. mellifera. The above results substantiated the previous observation that honey bee guts are dominated by several specific bacterial groups, and also showed that the relative abundances of OTUs could be markedly changed depending on the developmental stage, the location within the gut, and the honey bee species. The possibility of using the gut bacterial community as an indicator of honey bee health was discussed.     

Characterization of the active microbiotas associated with honey bees reveals healthier and broader communities when colonies are genetically diverse

Recent losses of honey bee colonies have led to increased interest in the microbial communities that are associated with these important pollinators. A critical function that bacteria perform for their honey bee hosts, but one that is poorly understood, is the transformation of worker-collected pollen into bee bread, a nutritious food product that can be stored for long periods in colonies. We used 16S rRNA pyrosequencing to comprehensively characterize in genetically diverse and genetically uniform colonies the active bacterial communities that are found on honey bees, in their digestive tracts, and in bee bread. This method provided insights that have not been revealed by past studies into the content and benefits of honey bee-associated microbial communities. Colony microbiotas differed substantially between sampling environments and were dominated by several anaerobic bacterial genera never before associated with honey bees, but renowned for their use by humans to ferment food. Colonies with genetically diverse populations of workers, a result of the highly promiscuous mating behavior of queens, benefited from greater microbial diversity, reduced pathogen loads, and increased abundance of putatively helpful bacteria, particularly species from the potentially probiotic genus Bifidobacterium. Across all colonies, Bifidobacterium activity was negatively correlated with the activity of genera that include pathogenic microbes; this relationship suggests a possible target for understanding whether microbes provide protective benefits to honey bees. Within-colony diversity shapes microbiotas associated with honey bees in ways that may have important repercussions for colony function and health. Our findings illuminate the importance of honey bee-bacteria symbioses and examine their intersection with nutrition, pathogen load, and genetic diversity, factors that are considered key to understanding honey bee decline.     

常见疾病、抗生素及农药对意大利蜜蜂(Apis mellifera ligustica)肠道微生物多样性的影响研究进展

蜜蜂是对农业生产十分重要的授粉昆虫。蜜蜂肠道微生物与蜜蜂健康有密切关系,但肠道微生物也会受多种外界因素的影响。本文就蜜蜂疾病、抗生素等蜂病治疗药物、农药,以及益生菌的应用等对意大利蜜蜂工蜂肠道微生物影响的研究进行了归纳总结,并对蜜蜂与其肠道菌关系研究进行了展望。     

Microbial Communities of Three Sympatric Australian Stingless Bee Species

Bacterial symbionts of insects have received increasing attention due to their prominent role in nutrient acquisition and defense. In social bees, symbiotic bacteria can maintain colony homeostasis and fitness, and the loss or alteration of the bacterial community may be associated with the ongoing bee decline observed worldwide. However, analyses of microbiota associated with bees have been largely confined to the social honeybees (Apis mellifera) and bumblebees (Bombus spec.), revealing – among other taxa – host-specific lactic acid bacteria (LAB, genus Lactobacillus) that are not found in solitary bees. Here, we characterized the microbiota of three Australian stingless bee species (Apidae: Meliponini) of two phylogenetically distant genera (Tetragonula and Austroplebeia). Besides common plant bacteria, we find LAB in all three species, showing that LAB are shared by honeybees, bumblebees and stingless bees across geographical regions. However, while LAB of the honeybee-associated Firm4–5 clusters were present in Tetragonula, they were lacking in Austroplebeia. Instead, we found a novel clade of likely host-specific LAB in all three Australian stingless bee species which forms a sister clade to a large cluster of Halictidae-associated lactobacilli. Our findings indicate both a phylogenetic and geographical signal of host-specific LAB in stingless bees and highlight stingless bees as an interesting group to investigate the evolutionary history of the bee-LAB association.     

Study of defense-related gene expression in grapevine infested by <Emphasis Type="Italic">Colomerus vitis</Emphasis> (Acari: Eriophyidae)

As the main source of lipids and proteins in honey bees, pollen is a major nutrient provider involved in development and health and has been studied for tolerance stimulation against pathogens and parasites. In the case of Varroa destructor Anderson & Trueman (Acari, Mesostigmata: Varroidae) parasitization, the lack of a complete laboratory system to rear both the bee larva and the acarian parasite limited the studies concerning larval nutrition effects on the bee tolerance and resistance against varroatosis. Due to the development of this complete rearing protocol, we managed to feed young honey bee larvae with pollen supplemented solutions and to study the effect on their later development under parasitism conditions. In our experimental conditions, pollen influences neither the deformity rate, nor the survival of bees both parasitized and unparasitized. However, pollen extract supplementation seems to significantly impact the weight of the spinning bee larvae without having an effect on the physiological weight loss during pupation, so the differences found at the larval stage remain the same as at emergence. Varroa has a deleterious effect on bee pupae and led to a steady increase of the physiological weight loss experienced during metamorphosis. Interestingly, this ponderal loss associated with Varroa parasitization seems to be reduced in the polyfloral pollen supplementation condition. Altogether, this work is to our knowledge the first to study in laboratory conditions the impact of larval nutrition on the tolerance to parasitism. A diverse pollen diet may be beneficial to the bees’ tolerance against V. destructor parasitism.