Foulbrood Research Articles

Report of amoebic disease in a colony of Western honey bees (Apis mellifera).

The amoeba Malpighamoeba mellificae is the etiologic agent of amoebic (amoeba) disease of Western honey bees (Apis mellifera). M. mellificae damages the Malpighian tubules, which is believed to weaken and kill the host bee. Here, the authors describe the detection of this organism in a honey bee colony in the Yukon Territory, Canada. The Malpighian tubules of 14% (7/50) of the adult worker bees were discolored dark brown. Fifteen bees screened using conventional polymerase chain reaction for the 18S gene of M. mellificae were positive for the pathogen. Histologically, the lumens of Malpighian tubules were packed with amoebae, causing dilation of the tubules and attenuation and loss of the tubular epithelium. This phylogenetic analysis places M. mellificae in a new clade, a sister group to the Entamoebidae. This work provides a foundation for further investigation into the distribution, prevalence, and pathology associated with M. mellificae infection.

First identification of Tyrophagus curvipenis (Acari: Acaridae) and pathogen detection in Apis mellifera colonies in the Republic of Korea

Mites of the genus Tyrophagus (Acari: Acaridae) are among the most widely distributed mites. The species in this genus cause damage to stored products and crops, and pose a threat to human health. However, the influence of Tyrophagus spp. in apiculture remains unknown. In 2022, a study focusing on the identification of Tyrophagus species within five apiaries was conducted in Chungcheongnam Province, Republic of Korea. Its specific objective was to investigate the presence of Tyrophagus mites in response to the reported high mortality of honey bee colonies in this area. Morphological identification and phylogenetic analysis using the mitochondrial gene cytochrome-c oxidase subunit 1 (CO1) confirmed for the first time the presence of the mite species Tyrophagus curvipenis in a honey bee colony in the Republic of Korea. Two honey bee pathogens were detected in the mite, a viral pathogen (deformed wing virus, DWV) and a protozoal pathogen (Trypanosoma spp.). The presence of the two honey bee pathogens in the mite suggests that this mite could contribute to the spread of related honey bee diseases. However, the direct influence of the mite T. curvipenis on honey bee health remains unknown and should be further investigated.

Anti-Bacterial Activity of Four Distinct Propolis Extracts against P. larvae and M. plutonius; Etiological Agent of American and European Foulbrood Disease of Honeybees.

Four different propolis samples obtained from different regions of Iran were evaluated for their antibacterial effects against the bacterial agents responsible for two important honeybee diseases. Paenibacillus larvae (P. larvae) and Melissococcus plutonius (M. plutonius), as the etiological agents of American foulbrood (AFB) and European foulbrood (EFB) diseases, were subjected to propolis ethanolic extracts in the agar well diffusion assay. The minimum inhibitory concentrations (MIC) and the minimum bactericidal concentrations (MBC) of the antibacterial effects of the samples against the two indicator organisms were determined by the microdilution technique using different concentrations of the propolis extracts. Finally, the synergistic antibacterial actions of the mixed propolis samples were determined, and their MIC and MBC values were recorded. A two-way analysis of variance was used to evaluate correlations among the diameters of the inhibition zones, the bacterial agents, and the propolis extracts. Based on our results, three of the propolis samples showed significant antibacterial effects against P. larvae and M. plutonius during the agar well diffusion assay. Furthermore, the antibacterial capacity of the propolis samples, when mixed in equal proportions, was significantly enhanced, as indicated by the obtained MIC and MBC values. Approximately, 0.02 mg/mL of mixed propolis samples was required for inhibiting the growth of both pathogens. A direct correlation was observed between propolis concentrations and their antibacterial activity. The results of the study are conclusive of the significant antibacterial actions of Iranian propolis samples against the etiological agents of the mentioned honeybee diseases, suggesting their probable use as a safe biological agent to control AFB and EFB diseases.

MOLECULAR IDENTIFICATION OF MICROBIAL PATHOGENS IN HONEY BEES FROM AMASYA

Honey bees, Apis mellifera are highly beneficial insects that constitute both the livelihood of the producers and the food source of the consumers. However, there are some diseases that affect the yield of bees and cause the collapse of almost the entire colony. Most of these diseases are caused by microbial pathogens originating from viruses, bacteria, and fungi. Beekeeping is an important source of livelihood both in the center of Amasya and in almost all its districts. In this study, microbial pathogens that cause mass bee deaths and epidemics in Amasya province were determined using molecular methods. The results showed that the most common honey bee pathogens in Amasya are the Deformed wing virus, Chronic bee paralysis virus, and Aspergillus flavus fungus. Thus, the profile of bee diseases in Amasya province was determined for the first time with this study. In addition, this study guides other studies planned for the prevention of bee diseases and healthy beekeeping.

Antibacterial effects of propolis and brood comb extracts on the causative agent of European Foulbrood (Melissococcus plutonius) in honey bees (Apis mellifera)

Among a long list of parasites and pathogens that threaten the European honey bee (Apis mellifera), European Foulbrood (EFB) has become an urgent apiary disease, as epidemic outbreaks are becoming increasingly common. EFB is a bacterial disease of larval honey bees, caused by a gram-positive, anaerobic bacterium, Melissococcus plutonius. The most effective current treatment for EFB, oxytetracycline hydrochloride, can disrupt the bee microbiome, cause bee mortality and residues may persist in honey harvested for human consumption. In this study, we explore the efficacy of more sustainable bee-derived solutions, including propolis, honey comb, and brood comb ethanol extracts. Propolis has been shown to successfully inhibit the growth of a similar larval bee disease, American Foulbrood (AFB). Using a series of dilutions of these extracts, we determined the minimum inhibitory concertation (MIC) of each bee-derived product on M. plutonius, as well as two model bacterial species, Staphylococcus saprophyticus (gram-positive) and Escherichia coli (gram-negative). Overall, we found that propolis extract was most effective at inhibiting the growth of gram-positive bacteria, and that M. plutonius was also susceptible to honey comb (MIC = 16.00 mg/mL) and brood comb (MIC = 45.33 mg/mL) extracts, but at much higher concentrations than that of propolis (MIC = 1.14 mg/mL). As previously demonstrated for AFB, propolis is a promising natural defense against EFB, which could have important implications for hive management.

Oxytetracycline resistance of Melissococcus plutonius strains in Japan

European foulbrood caused by the Gram-positive lanceolate coccus, Melissococcus plutonius, is a major bacterial infection of honey bee brood. Oxytetracycline (OTC) has been used to combat this disease in some countries. Although OTC resistance was not previously reported despite its long-term use, the first case was finally detected in an M. plutonius strain isolated in Canada in 2019. In Japan, OTC has not been approved for use in the control of any honey bee diseases. However, after testing 77 M. plutonius strains isolated in Japan between the 1980s and 2010s, we identified four OTC-resistant strains with a minimum inhibitory concentration of OTC on agar medium of 16 µg/ml. The four strains were isolated in 2008 (1 strain), 2013 (1 strain), and 2015 (2 strains); i.e., before the Canadian OTC-resistant isolate. These results provide insights into the mechanisms underlying the development of OTC-resistant M. plutonius.

First molecular detection of the presence of honey bee viruses in insects, Varroa destructor mites, and pollinated plants in an isolated region of Armenia.

Recently, viral diseases of honey bees (Apis mellifera) have presented an increasing threat to beekeeping. This study aimed to examine the presence of honey bee viruses in Apis and non-Apis bee species, the mite Varroa destructor, and pollinated plants in Armenia. Sampling was performed in Tavush Province, in the northeast of the Republic of Armenia, from August to November 2019. Overall, 200 A. mellifera bees, 50 V. destructor mites, and 20 wasps were collected (corresponding to three bees, five mites, and 2-11 wasps in each investigated sample) and homogenized for RNA isolation and detection of viruses. Ten pollinated plants were taken from each plant, and 2 g of each sample was used for homogenization. In each investigated case Apis mellifera, Varroa destructor, Vespula germanica and plants received percentages of the virus presence. Six important honey bee viruses (acute bee paralysis virus [ABPV], deformed wing virus [DWV], A. mellifera norovirus [ANV], Lake Sinai virus-2 [LSV-2], Big Sioux River virus [BSRV], and A. mellifera filamentous virus [AmFV]) were detected in samples by polymerase chain reaction. Our results showed that DWV, ANV, and ABPV were the most common viruses in honey bees. All viruses were detected in wasps, but LSV-2 and ANV were present in almost all samples. Our results showed that almost all viruses were present in V. destructor. Although ANV is very common in honey bees, it did not appear in any mite samples. Our study indicates that viruses typically associated with honey bees were also actively infecting wasps. Our data suggest that the survival of viruses in plants can be an important source of seasonal transmission of viruses to bees. In addition, pollinated plants can potentially serve as reservoirs for honey bee viruses.

Prevalence of Nosemosis and Varroosis in Honeybees (Apis mellifera L., 1758) in Bolu Region

Bolu province has a potential to progress in beekeeping due to its rich flora and vegetation. However, the amount of honey production per beehive in the province of Bolu is 8-10 kg, which is below the average (14.4 kg) of Turkey. Honey bee diseases and parasites are among the most important factors that retard the development of beekeeping and limit production efficiency in Turkey. In this study, it was aimed to evaluate the presence of varroosis and nosemosis in honey bee samples in different districts of Bolu. The presence of nosemosis and varroosis diseases in bee colonies in Bolu province are documented for the first time. Nosemosis was the most common disease. 190 of the 3030 examined bee samples were infected by Nosema spp. Average of the nosemosis infection was 6.3%. On the other hand, Varroa infestation was observed in the six of nine localities examined in Bolu province. 118 of the 3753 examined bee samples were infected by Varroa mites. Total infection ranged from 0.6 to 19.2%. This study has shown a prevailing higher percentage of infested with Varroa mites and Nosema spp. in Bolu region and revealed that the beekeepers in the Bolu region should be informed in detail about the precautions to be taken in the monitoring and controlling varroosis and nosemosis.

Use of Dicranum polysetum extract against Paenibacillus larvae causing American Foulbrood under in vivo and in vitro conditions.

Recent research shows that Dicranum species can be used to ameliorate the negative effects of honeybee bacterial diseases and that novel compounds isolated from these species may have the potential to treat bacterial diseases. This study aimed to investigate the efficacy of Dicranum polysetum Sw. against American Foulbrood using toxicity and larval model. The effectiveness of D. polysetum Sw. ethanol extract in combating AFB was investigated in vitro and in vivo. This study is important in finding an alternative treatment or prophylactic method to prevent American Foulbrood disease in honey bee colonies. Spore and vegetative forms of Paenibacillus larvae PB31B with ethanol extract of D. polysetum were tested on 2040 honey bee larvae under controlled conditions. Total phenolic and flavonoid contents of D. polysetum ethanol extracts were determined as 80.72mg/GAE(Gallic acid equivalent) and 303.20µg/mL, respectively. DPPH(2,2-diphenyl-1-picrylhydrazyl) radical scavenging percent inhibition value was calculated as 4.32%. In Spodoptera frugiperda (Sf9) and Lymantria dispar (LD652) cell lines, the cytotoxic activities of D. polysetum extract were below 20% at 50µg/mL. The extract was shown to considerably decrease infection in the larvae, and the infection was clinically halted when the extract was administered during the first 24h after spore contamination. The fact that the extract contains potent antimicrobial/antioxidant activity does not reduce larval viability and live weight, and does not interact with royal jelly is a promising development, particularly regarding its use to treat early-stage AFB infection.

Ingestion of heat-killed pathogens confers transgenerational immunity to the pathogens via the vitellogenin–hypopharyngeal gland axis in honeybees

Honeybee diseases are a serious threat to beekeeping and pollination. Transgenerational immune priming (TGIP) has been attracting increasing attention as a promising strategy to protect honeybee colonies from infections. This study investigated whether feeding honeybees (Apis mellifera) with a heat-killed pathogen cocktail can provide them with transgenerational immunity to these pathogens. We found that vitellogenin (Vg) and defensin-1 were highly upregulated in nurse bees upon feeding them with a cocktail of heat-killed Ascosphaera apis and Paenibacillus larvae (A + P cocktail). Pathogen-pattern–recognition receptor genes in the Toll signaling pathway were upregulated in nurse bees upon ingestion of the A + P cocktail. In the nurse bees of the hives supplied with the A + P cocktail, Vg was upregulated in the fat body, and the defensin-1 expression and Vg uptake in the hypopharyngeal glands were induced. Consequently, the major proteins in royal jelly were upregulated. In addition, defensin-1 was upregulated in the queen larvae and young worker larvae in these hives. In correlation, the young worker larvae showed high pathogen resistance to P. larvae infection. Thus, our findings imply that introduction of a heat-killed pathogen cocktail into hives is an efficient strategy for conferring honeybees with social immunity through TGIP.

Sunflower plantings reduce a common gut pathogen and increase queen production in common eastern bumblebee colonies.

Community diversity can reduce the prevalence and spread of disease, but certain species may play a disproportionate role in diluting or amplifying pathogens. Flowers act as both sources of nutrition and sites of pathogen transmission, but the effects of specific plant species in shaping bee disease dynamics are not well understood. We evaluated whether plantings of sunflower (Helianthus annuus), whose pollen reduces infection by some pathogens when fed to bees in captivity, lowered pathogen levels and increased reproduction in free-foraging bumblebee colonies (Bombus impatiens). Sunflower abundance reduced the prevalence of a common gut pathogen, Crithidia bombi, and reduced infection intensity, with an order of magnitude lower infection intensity at high sunflower sites compared with sites with little to no sunflower. Sunflower abundance was also positively associated with greater queen production in colonies. Sunflower did not affect prevalence of other detected pathogens. This work demonstrates that a single plant species can drive disease dynamics in foraging B. impatiens, and that sunflower plantings can be used as a tool for mitigating a prevalent pathogen while also increasing reproduction of an agriculturally important bee species.

Challenges and Advances in Bee Health and Diseases

Understanding the health status of bees is crucial in assessing the epidemiology of pathogens that cause diseases in honey bee (Apis mellifera) colonies and wild bees [...].

Epizootic monitoring of contagious diseases of bees in Rivne region for the period of 2018–2022

The important role of honey bees has been known for a long time, as the successful work of Apis mellifera helps to maintain natural biogeocenoses and provides humanity with food and medicinal production. The massive loss of honeybee colonies in the southern and eastern border regions of Ukraine is putting a strain on beekeeping production in the north-western regions of Ukraine. To intensify apiaries, there is a need for systematic and regular monitoring research. Epizootic monitoring provides data on the health of honey bees in a specific geographical region that can be scientifically substantiated. To analyse the epizootic situation with contagious bee diseases in the Rivne region in 2017–2022, we used official data from the State Service of Ukraine on Food Safety and Consumer Protection in the Rivne region. In addition to epizootic monitoring, the aim of our study was to identify the most common bee diseases in this region. The analysis of the results shows that diagnostic tests for varroosis and nosema, acarapidosis, American and European foulbroods, and amoebiasis are planned and carried out systematically. From 2017 to 2021, the number of diagnostic tests for bacterial diseases of bees was increased. At the same time, in 2022, the activity of such research decreased by 6.4% in comparison to 2021. A different pattern was registered for parasitic diseases of bees. For example, there was an increase in the number of such studies from 2019 (1678 studies) to 2022 (3184 studies). It was found that the Rivne region has been safe from American and European foulbroods, acarapidosis, braulosis and amoebiasis for the last 6 years. Varoosis and nosema are registered annually in 2017–2022, with the infection rate for these diseases set at 11.06 % (2020) – 14.82 % (2022), respectively. This data is likely to indicate a change in the economic situation of beekeepers, which makes it impossible to prevent hives from being treated for certain diseases in a timely manner. Thus, the analysis of laboratory tests for contagious diseases of bees helps to detail the epizootic state of a particular region, which allows to determine the direction for veterinary and sanitary measures for a specific apiary.

Bioactive metabolites from autochthonous lactic acid bacteria inhibit the growth of Melissococcus plutonius, causal agent of European foulbrood disease in honey bees

AbstractEuropean foulbrood (EFB), a serious disease affecting honey bee larvae, Apis mellifera L. (Hymenoptera: Apidae), is caused by the Gram‐positive bacterium Melissococcus plutonius corrig. (ex White) Bailey & Collins. In this in‐vitro study, we evaluated the inhibitory potential of microbial metabolites produced by lactic acid bacteria (LAB), isolated from the honey bee gut, against M. plutonius. Several LAB species were identified by biochemical tests and 16S rRNA sequencing. Their filtered cell‐free supernatant (CFS) fluids were evaluated individually and in combination against growth and survival of three concentrations of M. plutonius (104–106 colony‐forming units mL−1), for various time intervals (24–96 h), in agar‐well diffusion and broth micro‐dilution assays. We also assessed whether the bioactive metabolites from selected LAB isolates consisted of acids, bacteriocins, and/or hydrogen peroxide, and quantified the presence of short‐chain fatty acids (SCFA; i.e., acetic, butyric, lactic, and propionic acid) by means of high‐performance liquid chromatography. Six LAB isolates inhibited M. plutonius growth: Lactobacillus acidophilus (Moro) Hansen & Mocquot, Lacticaseibacillus rhamnosus (Hansen) Zheng et al., Lactiplantibacillus plantarum (Orla‐Jensen) Zheng et al. (two isolates), Lactobacillus apis Killer et al., and Pediococcus acidilactici Lindner. The inhibitory effects on M. plutonius were larger at the lowest than at the highest M. plutonius concentration, and P. acidilactici showed the strongest antibacterial activity. Exposure to a mixture of CFS fluids of the four most potent isolates could reduce M. plutonius survival to 0% within 96 h. The antagonistic activity in the CFS of L. rhamnosus and L. apis appeared to be related to the presence of acids, whereas the antagonistic activity in L. plantarum and P. acidilactici appeared to be related to the presence of bacteriocins or bacteriocin‐like inhibitory substances (BLIS). Hydrogen peroxide did not seem to play a role. Total SCFA levels were highest in L. rhamnosus CFS fluid. These results can serve as a basis for in vivo studies on the use of LAB isolates as potential biocontrol agents against EFB in honey bees.

State epizootic monitoring of contagious diseases of bees in the territory of the Volyn region

The well-being of apiaries is a priority in the state's economic, social, and environmental aspects. There is a state monitoring system to ensure proper control over the prevalence of infectious, invasive, and viral diseases. This system systematically monitors the spread of diseases that cause significant economic problems. Solving these problems will further shape the state's favorability to ensure the export of beekeeping products to European countries. Data on the spread of infectious and invasive diseases of bees from official departments of the State Production and Consumer Services of particular regions. In work, such data were processed in the Volyn region from 2017 to 2022, including a plan for determining the incidence and incidence rates in this region. The results show that nosemosis and varroosis were the most common diseases in the Volyn region during the studied period. It was established that the indicator of bee colonies with the Varroa destructor mite in all analyzed years exceeds the incidence of nosemosis by 8.03 % (2020) – 24.49 % (2021). Moreover, the highest incidence of both diseases during the studied period was registered in 2021. In 2017, American foulbrood (AFB), created by a bacterium, was recorded in this region. The spread of bacterial diseases in bees is given. From the analyzed data, it is possible to note the imperfection of the monitoring system, as the research plans include a wide range of invasive diseases, but a small share is allocated to bacterial infections. Unplanned beekeeping studies include invasive and infectious diseases: bee bacteriosis and viral pathologies. The main problem is the low percentage of certified private farms. As a result, it is challenging to analyze damage to apiaries by contagious bee diseases. Thus, it is necessary to improve the state monitoring system, owing to which it will be possible to diagnose planned not only infectious and invasive diseases but also other diseases of bees that cause massive destruction of hives in apiaries of our state.

Small hive beetle (Aethina tumida) threat on the horizon

Beekeeping is an agricultural industry that deals with breeding bees, obtaining honey, wax, and other products. Bees are used for pollination of many types of crops to increase their harvest. Beekeeping products are also used in medicine, pharmacology, chemical, and food industries. One of the essential aspects of successful beekeeping development is ensuring sustainable epizootic well-being from infectious and invasive bee diseases in Ukraine. About 3 million bee colonies are owned by private farms and amateur beekeepers, which give approximately 50-60 thousand tons of commercial honey and 1.2–1.4 thousand tons of wax per year at the current stage of beekeeping development in Ukraine. Honey and bee products from Ukraine received 15 prestigious awards in various categories at the 77th National Honey Show, held in London among many countries in 2008. In recent years, there has been a constant increase in the threat of new little-known invasive and infectious diseases that pose a significant danger to beekeeping worldwide. The invasion of the small hive beetle Aethina tumida belongs to quarantine and hazardous invasive diseases, which have destroyed many bee colonies in several countries worldwide (USA, Canada, African countries, Australia, some European countries – Italy, and Portugal). There are no effective methods of preventing and controlling the small hive beetle. The only way to prevent the invasion of the small hive beetle in Ukraine is constant monitoring and control at the state border of the movement of bee packages and bee products, which may pose a threat to introducing this invasive species into Ukraine.

Colonization of Honey Bee Digestive Tracts by Environmental Yeast Lachancea thermotolerans Is Naturally Occurring, Temperature Dependent, and Impacts the Microbiome of Newly Emerged Bees.

Honey bees are critical pollinators in both agricultural and ecological settings. Recent declines in honey bee colonies in the United States have put increased strain on agricultural pollination. Although there are many environmental stressors implicated in honey bee disease, there has been intensifying focus on the role of microbial attacks on honey bee health. Despite the long-standing appreciation for the association of fungi of various groups with honey bees and their broader environment, the effects of these interactions on honey bee health are incompletely understood. Here, we report the discovery of colonization of the honey bee digestive tract by the environmental yeast Lachancea thermotolerans. Experimental colonization of honey bee digestive tracts by L. thermotolerans revealed that this yeast species maintains high levels in the honey bee midgut only at temperatures below the typical colony temperature. In newly eclosed bees, L. thermotolerans colonization alters the microbiome, suggesting that environmental yeasts can impact its composition. Future studies should be undertaken to better understand the role of L. thermotolerans and other environmental yeasts in honey bee health. IMPORTANCE Although many fungal species are found in association with honey bees and their broader environment, the effects of these interactions on honey bee health are largely unknown. Here, we report the discovery that a yeast commonly found in the environment can be found at high levels in honey bee digestive tracts. Experimentally feeding this yeast to honey bees showed that the yeast's ability to maintain high levels in the digestive tract is influenced by temperature and can lead to alterations of the microbiome in young bees. These studies provide a foundation for future studies to better understand the role of environmental yeasts in honey bee health.

Molecular Detection and Phylogenetic Analysis of Deformed Wing Virus and Sacbrood Virus Isolated from Pollen.

Among many pathogens and pests, honey bee viruses are known as one of the most common cause of diseases in honey bee colonies. In this study, we demonstrate that pollen grains and bee bread are potential sources of viral DNA. We extracted DNA from 3 types of pollen samples: directly provided by beekeepers (n = 12), purchased from trade markets (n = 5), and obtained from honeycombs (bee bread, n = 10). The extracted DNA was used for molecular detection (RT-PCR analysis) of six of the most widely distributed honey bee viruses: deformed wing virus, sacbrood virus, acute bee paralysis virus, black queen cell virus, Kashmir bee virus, Israeli acute paralysis virus, and chronic bee paralysis virus. We successfully managed to establish only the deformed wing virus (DWV) and the sacbrood virus (SBV), with different distribution frequencies depending on the territory of the country. The phylogenetic analyses of Bulgarian isolates were performed with the most similar sequences available in molecular databases from other countries. Phylogenies of Bulgarian viral strains demonstrated genetically heterogeneous populations of DWV and relatively homogenous populations of SBV. In conclusion, the results obtained from the current study have shown that pollen is a valuable source for molecular detection of honey bee pathogens. This allows epidemiological monitoring of honey bee diseases at a regional and a national level.

Conservation measures or hotspots of disease transmission? Agri-environment schemes can reduce disease prevalence in pollinator communities.

Insects are under pressure from agricultural intensification. To protect pollinators, conservation measures such as the EU agri-environment schemes (AES) promote planting wildflowers along fields. However, this can potentially alter disease ecology by serving as transmission hubs or by diluting infections. We tested this by measuring plant-pollinator interactions and virus infections (DWV-A, DWV-B and ABPV) across pollinator communities in agricultural landscapes over a year. AES had a direct effect on DWV-B, reducing prevalence and load in honeybees, with a tentative general dilution effect on load in early summer. DWV-A prevalence was reduced both under AES and with increasing niche overlap between competent hosts, likely via a dilution effect. By contrast, AES had no impact on ABPV, its prevalence driven by the proportion of bumblebees in the community. Epidemiological differences were also reflected in the virus phylogenies, with DWV-B showing recent rapid expansion, while DWV-A and ABPV showed slower growth rates and geographical population structure. Phylogenies indicate that all three viruses freely circulate across their host populations. Our study illustrates how complex interactions between environmental, ecological and evolutionary factors may influence wildlife disease dynamics. Supporting pollinator nutrition can mitigate the transmission of important bee diseases, providing an unexpected boost to pollinator conservation. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.

Prevalence of honey bee pathogens and parasites in South Korea: A five-year surveillance study from 2017 to 2021

Honey bees play an important role in the pollination of crops and wild plants and provide important products to humans. Pathogens and parasites are the main factors that threaten beekeeping in South Korea. Therefore, a nationwide detection of 14 honey bee pathogens, including parasites (phorid flies, Nosema ceranae, and Acarapis woodi mites), viruses, bacteria, and fungal pathogens, was conducted from 2017 to 2021 in the country. The infection rate and the trend of detection of each pathogenic agent were determined. A total of 830 honey bee samples from Apis cerana (n = 357) and A. mellifera (n = 473) were examined. N. ceranae (35.53%), deformed wing virus (52.63%), sacbrood virus (SBV) (52.63%), and black queen cell virus (55.26%) were the most prevalent honey bee pathogens, and their prevalence rapidly increased from 2017 to 2021. The prevalence of Paenibacillus larvae, Israeli acute paralysis virus, Ascosphaera apis, A. woodi, Melissococcus plutonius, and chronic bee paralysis virus remained stable during the surveillance period, with infection rates ranging from 5.26% to 16.45% in 2021. Other pathogens, including acute bee paralysis virus, phorid flies, Kashmir bee virus, and Aspergillus flavus, had low infection rates that gradually declined during the detection period. The occurrence of honeybee pathogens peaked in July. SBV was the most common pathogen in A. cerana, whereas N. ceranae was predominant in A. mellifera. This study provides information regarding the current status of honey bee pathogens and presents the trend of the occurrence of each pathogen in South Korea. These data are important for predicting outbreaks of honey bee diseases in the country.