Chronic bee paralysis as a serious emerging threat to honey bees

This work was funded jointly by BBSRC grants BB/R00482X/1 (Newcastle University) and BB/R00305X/1 (University of St Andrews) in partnership with The Bee Farmers’ Association and the National Bee Unit of the Animal and Plant Health Agency.Chronic bee paralysis is a well-defined viral disease of honey bees with a global distribution that until recently caused rare but severe symptomatology including colony loss. Anecdotal evidence indicates a recent increase in virus incidence in several countries, but no mention of concomitant disease. We use government honey bee health inspection records from England and Wales to test whether chronic bee paralysis is an emerging infectious disease and investigate the spatiotemporal patterns of disease. The number of chronic bee paralysis cases increased exponentially between 2007 and 2017, demonstrating chronic bee paralysis as an emergent disease. Disease is highly clustered spatially within most years, suggesting local spread, but not between years, suggesting disease burnt out with periodic reintroduction. Apiary and county level risk factors are confirmed to include scale of beekeeping operation and the history of honey bee imports. Our findings offer epidemiological insight into this damaging emerging disease.Publisher PDFPeer reviewe

Utilizing "Omic" technologies to identify and prioritize novel sources of resistance to the oomycete pathogen <i>Phytophthora infestans</i> in potato germplasm collections

The biggest threat to potato production world-wide is late blight, caused by the oomycete pathogen Phytophthora infestans. A screen of 126 wild diploid Solanum accessions from the Commonwealth Potato Collection (CPC) with P. infestans isolates belonging to the genotype 13-A2 identified resistances in the species S. bulbocastanum, S. capsicibaccatum, S. microdontum, S. mochiquense, S. okadae, S. pinnatisectum, S. polyadenium, S. tarijense and S. verrucosum. Effector-omics, allele mining and diagnostic RenSeq (dRenSeq) were utilized to investigate the nature of resistances in S. okadae accessions. dRenSeq in resistant S. okadae accessions 7129, 7625, 3762 and a bulk of 20 resistant progeny confirmed the presence of full-length Rpi-vnt1.1 under stringent mapping conditions and corroborated allele mining results in the accessions 7129 and 7625 as well as Avr-vnt1 recognition in transient expression assays. In contrast, susceptible S. okadae accession 3761 and a bulk of 20 susceptible progeny lacked sequence homology in the 5’ end compared to the functional Rpi-vnt1.1 gene. Further evaluation of S. okadae accessions with late blight isolates that have a broad spectrum of virulence demonstrated that, although S. okadae accessions 7129, 7625 and 7629 contain functional Rpi-vnt1.1, they also carry a novel resistance gene. We provide evidence that existing germplasm collection are important sources of novel resistances and that ‘omic’ technologies such as dRenSeq-based genomics and effector-omics are efficacious tools to rapidly explore the diversity within these collections

Chronic bee paralysis as a serious emerging threat to honey bees

Chronic bee paralysis is a well-defined viral disease of honey bees with a global distribution that until recently caused rare but severe symptomatology including colony loss. Anecdotal evidence indicates a recent increase in virus incidence in several countries, but no mention of concomitant disease. We use government honey bee health inspection records from England and Wales to test whether chronic bee paralysis is an emerging infectious disease and investigate the spatiotemporal patterns of disease. The number of chronic bee paralysis cases increased exponentially between 2007 and 2017, demonstrating chronic bee paralysis as an emergent disease. Disease is highly clustered spatially within most years, suggesting local spread, but not between years, suggesting disease burnt out with periodic reintroduction. Apiary and county level risk factors are confirmed to include scale of beekeeping operation and the history of honey bee imports. Our findings offer epidemiological insight into this damaging emerging disease

YFP fusions to R3a* variants re-localize to vesicles after the perception of both of AVR3a^KI and AVR3a^EM, whereas YFP-R3a remains cytoplasmic in the presence of AVR3a^EM.

<p>Two days after infiltration of mixtures of <i>Agrobacterium</i> cultures designed to express AVR3a^KI, AVR3a^EM, YFP-R3a or YFP fusions to the R3a* variants, infiltrated <i>N. benthamiana</i> leaf tissue was examined under a confocal laser scanning microscope. Scale bar  = 50 µm.</p

HR responses resulting from R3a* recognition of AVR3a^EM and AVR3a^KI, like those caused by wild-type R3a recognition of AVR3a^KI, are dependent on SGT1 and HSP90.

<p>SGT1- and HSP90-silenced plants were produced using TRV-based vectors. These plants and control plants inoculated with TRV:<i>eGFP</i> were infiltrated with different combinations of <i>Agrobacterium</i> cultures designed to express R3a, R3a* variants, AVR3a^KI (KI) or AVR3a^EM (EM). The percentage of sites (N = 12) showing HR responses six days after infiltration was recorded. The graph shows the mean percentages from three independent experiments with the exception that the dependence on HSP90 of Rd4-1 responses was only tested in a single experiment. The non-host bacterial pathogen <i>Erwinia amylovora</i> was used as a control for an SGT1- and HSP90-independnet HR response. Error bars show +/− standard error. Zero values have been transformed to 1% to facilitate their observation.</p

R3a and R3a* variants expressed via the <i>R3a</i> promoter in transgenic plants protect the susceptible cultivar Ranger Russet from <i>P. infestans</i> strain P6752, which is heterozygous for AVR3a^KI and AVR3a^EM, but not from strain US-8 BF-6, which is homozygous for AVR3a^EM.

<p>Non-transgenic plants were used as a control for susceptibility. Transgenic plants expressing R3a or Rpi-vnt1 were used as positive controls for resistance to P6752 or US-8 BF-6, respectively. Representative plants were photographed at 11dpi.</p

Both YC-AVR3a^KI and YC-AVR3a^EM when co-expressed with YN-R3a* fusions give vesicle associated YFP fluorescence like YC-AVR3a^KI and YN-R3a, whereas YC-AVR3a^EM and YN-R3a do not.

<p>Two days after infiltration of mixtures of <i>Agrobacterium</i> cultures designed to express YC-AVR3a^KI, YC-AVR3^EM, YN-R3a or YN fusions to the R3a* variants, infiltrated <i>N. benthamiana</i> leaf tissue was examined under a confocal laser scanning microscope. Representative images from two experiments. Scale bar  = 50 µm.</p

R3a and R3a* variants expressed from <i>Agrobacterium</i> reduce the spread of a <i>P. infestans</i> strain expressing AVR3a^KI, but not the spread of a strain expressing only AVR3a^EM.

<p>(a) Means of lesion diameters measured 12 days after drop inoculation of agro-infiltrated areas with strain 7804.b (KI/KI). (b) Means of lesion diameters measured 8 days after drop inoculation of agro-infiltrated areas with strain 88069 (EM/EM). (a) and (b) show representative experiments from sets of three and five repeated experiments, respectively. For both (a) and (b), error bars show +/− standard errors, N = 30. EVC indicates empty vector control.</p