Nosema apis and
Nosema ceranae are intracellular microsporidian parasites infecting the midgut epithelial cells of adult honey bees.
N. ceranae was considered to be restricted to the Asian honey bee,
...Apis cerana, but is nowadays a parasite found also in the European honey bee (
Apis mellifera) across most of the world. Recent surveys and experimental work suggest that
N. ceranae is a serious threat to the global beekeeping industry. It has been suggested that
N. ceranae induces significantly higher mortality in honey bees than
N. apis, but little is known about their comparative virulence. In this study, we used
in vivo infection experiments to study the two parasites’ different virulence (i.e. multiplication rate and infectivity). A qPCR was developed to elucidate within host competition between the two parasites using mixed infections. The outcome of the experiments indicates minor differences in infectious dose and multiplication rate between the two species. Moreover, the mortality caused by
N. ceranae was not significantly higher than for
N. apis and
N. ceranae appeared to have no competitive advantage within host.
It has been suggested that the widespread use of neonicotinoid insecticides threatens bees, but research on this topic has been surrounded by controversy. In order to synthesize which research ...approaches have been used to examine the effect of neonicotinoids on bees and to identify knowledge gaps, we systematically reviewed research on this subject that was available on the Web of Science and PubMed in June 2015. Most of the 216 primary research studies were conducted in Europe or North America (82%), involved the neonicotinoid imidacloprid (78%), and concerned the western honey bee Apis mellifera (75%). Thus, little seems to be known about neonicotinoids and bees in areas outside Europe and North America. Furthermore, because there is considerable variation in ecological traits among bee taxa, studies on honey bees are not likely to fully predict impacts of neonicotinoids on other species. Studies on crops were dominated by seed-treated maize, oilseed rape (canola) and sunflower, whereas less is known about potential side effects on bees from the use of other application methods on insect pollinated fruit and vegetable crops, or on lawns and ornamental plants. Laboratory approaches were most common, and we suggest that their capability to infer real-world consequences are improved when combined with information from field studies about realistic exposures to neonicotinoids. Studies using field approaches often examined only bee exposure to neonicotinoids and more field studies are needed that measure impacts of exposure. Most studies measured effects on individual bees. We suggest that effects on the individual bee should be linked to both mechanisms at the sub-individual level and also to the consequences for the colony and wider bee populations. As bees are increasingly facing multiple interacting pressures future research needs to clarify the role of neonicotinoids in relative to other drivers of bee declines.
Lactic acid bacteria (LAB) are well recognized beneficial host-associated members of the microbiota of humans and animals. Yet LAB-associations of invertebrates have been poorly characterized and ...their functions remain obscure. Here we show that honeybees possess an abundant, diverse and ancient LAB microbiota in their honey crop with beneficial effects for bee health, defending them against microbial threats. Our studies of LAB in all extant honeybee species plus related apid bees reveal one of the largest collections of novel species from the genera Lactobacillus and Bifidobacterium ever discovered within a single insect and suggest a long (>80 mya) history of association. Bee associated microbiotas highlight Lactobacillus kunkeei as the dominant LAB member. Those showing potent antimicrobial properties are acquired by callow honey bee workers from nestmates and maintained within the crop in biofilms, though beekeeping management practices can negatively impact this microbiota. Prophylactic practices that enhance LAB, or supplementary feeding of LAB, may serve in integrated approaches to sustainable pollinator service provision. We anticipate this microbiota will become central to studies on honeybee health, including colony collapse disorder, and act as an exemplar case of insect-microbe symbiosis.
Nosema ceranae is a microsporidian parasite described from the Asian honey bee,
Apis cerana. The parasite is cross-infective with the European honey bee,
Apis mellifera. It is not known when or where
...N. ceranae first infected European bees, but
N. ceranae has probably been infecting European bees for at least two decades.
N. ceranae appears to be replacing
Nosema apis, at least in some populations of European honey bees. This replacement is an enigma because the spores of the new parasite are less durable than those of
N. apis. Virulence data at both the individual bee and at the colony level are conflicting possibly because the impact of this parasite differs in different environments. The recent advancements in
N. ceranae genetics, with a draft assembly of the
N. ceranae genome available, are discussed and the need for increased research on the impacts of this parasite on European honey bees is emphasized.
Virulence variations of Paenibacillus larvae subsp. larvae, the causative agent of American foulbrood disease of honeybees, were investigated by analysis of 16 field isolates of this pathogen, ...belonging to three previously characterized genotypes, as well as the type strain (ATCC 9545) of P. larvae subsp. larvae, with exposure bioassays. We demonstrated that the strain-specific 50% lethal concentrations varied within an order of magnitude and that differences in amount of time for the pathogen to kill 100% of the infected hosts (LT₁₀₀) correlated with genotype. One genotype killed rather quickly, with a mean LT₁₀₀ of 7.8 ± 1.7 days postinfection, while the other genotypes acted more slowly, with mean LT₁₀₀s of 11.2 ± 0.8 and 11.6 ± 0.6 days postinfection.
1 Department of Molecular Microbiology, Institute for Bee Research, Friedrich-Engels-Str. 32, D-16540 Hohen Neuendorf, Germany
2 Department of Entomology, Swedish University of Agricultural Sciences, ...Box 7044, SE-75007 Uppsala, Sweden
3 National Veterinary and Food Research Institute, PL 92, FIN-70701 Kuopio, Finland
4 Staatliches Veterinäruntersuchungsamt Arnsberg, Zur Taubeneiche 10-12, D-59821 Arnsberg, Germany
Correspondence Elke Genersch elke.genersch{at}rz.hu-berlin.de
A polyphasic taxonomic study of the two subspecies of Paenibacillus larvae , Paenibacillus larvae subsp. larvae and Paenibacillus larvae subsp. pulvifaciens , supported the reclassification of the subspecies into one species, Paenibacillus larvae , without subspecies separation. Our conclusions are based on the analysis of six reference strains of P. larvae subsp. pulvifaciens and three reference strains and 44 field isolates of P. larvae . subsp. larvae . The latter originated from brood or honey of clinically diseased honey bee colonies or from honey of both clinically diseased and asymptomatic colonies from Sweden, Finland and Germany. Colony and spore morphology, as well as the metabolism of mannitol and salicin, did not allow a clear identification of the two subspecies and SDS-PAGE of whole-cell proteins did not support the subspecies differentiation. For genomic fingerprinting, repetitive element-PCR fingerprinting using ERIC primers and PFGE of bacterial DNA were performed. The latter method is a high-resolution DNA fingerprinting method proven to be superior to most other methods for biochemical and molecular typing and has not previously been used to characterize P. larvae . ERIC-PCR identified four different genotypes, while PFGE revealed two main clusters. One cluster included most of the P. larvae subsp. larvae field isolates, as well as all P. larvae subsp. pulvifaciens reference strains. The other cluster comprised the pigmented variants of P. larvae subsp. larvae . 16S rRNA gene sequences were determined for some strains. Finally, exposure bioassays demonstrated that reference strains of P. larvae subsp. pulvifaciens were pathogenic for honey bee larvae, producing symptoms similar to reference strains of P. larvae subsp. larvae . In comparison with the type strain for P. larvae subsp. larvae , ATCC 9545 T , the P. larvae subsp. pulvifaciens strains tested were even more virulent, since they showed a shorter LT 100 . An emended description of the species is given.
Abbreviations: AFB, American foulbrood; MRPs, macrorestriction profiles; rep-PCR, repetitive element-PCR fingerprinting
Published online ahead of print on 4 November 2005 as DOI 10.1099/ijs.0.63928-0.
The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of Paenibacillus larvae strains 03-525, 00-1163, 02-130 and 03-189 are DQ079620 DQ079623, respectively.
A table giving the CCUG accession numbers for the P. larvae field strains used in the study and figures showing colony and spore morphology are available as supplementary material in IJSEM Online.
The economically most important honey bee species,
Apis mellifera, was formerly considered to be parasitized by one microsporidian,
Nosema apis. Recently, Higes, M., Martín, R., Meana, A., 2006.
...Nosema ceranae, a new microsporidian parasite in honeybees in Europe, J. Invertebr. Pathol. 92, 93–95 and Huang, W.-F., Jiang, J.-H., Chen, Y.-W., Wang, C.-H., 2007. A
Nosema ceranae isolate from the honeybee
Apis mellifera. Apidologie 38, 30–37 used 16S (SSU) rRNA gene sequences to demonstrate the presence of
Nosema ceranae in
A. mellifera from Spain and Taiwan, respectively. We developed a rapid method to differentiate between
N. apis and
N. ceranae based on PCR–RFLPs of partial SSU rRNA. The reliability of the method was confirmed by sequencing 29 isolates from across the world (
N =
9 isolates gave
N. apis RFLPs and sequences,
N =
20 isolates gave
N. ceranae RFLPs and sequences; 100% correct classification). We then employed the method to analyze
N =
115 isolates from across the world. Our data, combined with
N =
36 additional published sequences demonstrate that (i)
N. ceranae most likely jumped host to
A. mellifera, probably within the last decade, (ii) that host colonies and individuals may be co-infected by both microsporidia species, and that (iii)
N. ceranae is now a parasite of
A. mellifera across most of the world. The rapid, long-distance dispersal of
N. ceranae is likely due to transport of infected honey bees by commercial or hobbyist beekeepers. We discuss the implications of this emergent pathogen for worldwide beekeeping.
We compared the mortality of honeybee (Apis mellifera) drone and worker larvae from a single queen under controlled in vitro conditions following infection with Paenibacillus larvae, a bacterium ...causing the brood disease American Foulbrood (AFB). We also determined absolute P. larvae cell numbers and lethal titres in deceased individuals of both sexes up to 8 days post infection using quantitative real-time PCR (qPCR). Our results show that in drones the onset of infection induced mortality is delayed by 1 day, the cumulative mortality is reduced by 10% and P. larvae cell numbers are higher than in worker larvae. Since differences in bacterial cell titres between sexes can be explained by differences in body size, larval size appears to be a key parameter for a lethal threshold in AFB tolerance. Both means and variances for lethal thresholds are similar for drone and worker larvae suggesting that drone resistance phenotypes resemble those of related workers.
A population of European honey bees (
Apis mellifera
) surviving
Varroa destructor
mite infestation in Sweden for over 10 years without treatment, demonstrate that a balanced host–parasite ...relationship may evolve over time. Colony-level adaptive traits linked to
Varroa
tolerance were investigated in this population to identify possible characteristics that may be responsible for colony survival in spite of mite infestations. Brood removal rate, adult grooming rate, and the mite distribution between brood and adults were not significantly different in the untreated population compared with treated control colonies. However, colony size and the reproductive success of the mite were significantly reduced in surviving colonies compared with control colonies. Our data suggest that colony-level adaptive traits may limit mite population growth by reducing mite reproduction opportunities and also by suppressing the mite reproductive success.
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