Honey Bee Colony Losses Research Articles

Varroa destructor in Portugal: an exploratory assessment of pyrethroids resistance status

The drastic and abrupt loss of honey bee colonies around the world has long unsettled the beekeeping community, and although the phenomenon is far from being solved, there is a relative consensus regarding the detrimental effect the mite Varroa destructor exerts over Apis mellifera populations. In Portugal, this parasite was first recorded in the late 1980s and since then, the beekeepers’ method of choice for controlling the mite are synthetic acaricides, most notably the pyrethroids tau-fluvalinate and flumethrin. Unsurprisingly, resistance to these active ingredients quickly surfaced. Here, we report the first PCR-RFLP resistance assessment in Portuguese apiaries, where 96 V. destructor mites, from different geographic regions, were genotyped between April and August of 2019. The results showed that 47% of the sampled mites exhibit the mutation correlated with resistance. These findings stress the need for a current characterization of the acaricides being used and a description of how the treatments are been applied.

Spatial clusters of Varroa destructor control strategies in Europe

Beekeepers have various options to control the parasitic mite Varroa destructor in honey bee colonies, but no empirical data are available on the methods they apply in practice. We surveyed 28,409 beekeepers maintaining 507,641 colonies in 30 European countries concerning Varroa control methods. The set of 19 different Varroa diagnosis and control measures was taken from the annual COLOSS questionnaire on honey bee colony losses. The most frequent activities were monitoring of Varroa infestations, drone brood removal, various oxalic acid applications and formic acid applications. Correspondence analysis and hierarchical clustering on principal components showed that six Varroa control options (not necessarily the most used ones) significantly contribute to defining three distinctive clusters of countries in terms of Varroa control in Europe. Cluster I (eight Western European countries) is characterized by use of amitraz strips. Cluster II comprises 15 countries from Scandinavia, the Baltics, and Central-Southern Europe. This cluster is characterized by long-term formic acid treatments. Cluster III is characterized by dominant usage of amitraz fumigation and formed by seven Eastern European countries. The median number of different treatments applied per beekeeper was lowest in cluster III. Based on estimation of colony numbers in included countries, we extrapolated the proportions of colonies treated with different methods in Europe. This suggests that circa 62% of colonies in Europe are treated with amitraz, followed by oxalic acid for the next largest percentage of colonies. We discuss possible factors determining the choice of Varroa control measures in the different clusters.

Effect of honeybee venom and Egyptian propolis on the honeybee (Apis mellifera L.) health in vivo

BackgroundHoneybees are one of the most important pollinators in the world, and their products are nowadays included in most anticancer, antiallergic, antimicrobial drugs and are included in cosmetic treatments. In the present study, honeybee venom and Egyptian ethanolic propolis extract (EP) were focused to test their effect on health and some genes for honeybee workers (defensin2, abaecin, hymenoptaecin, vitellogenin, and juvenile hormone esterase).ResultsHoneybee venom and Egyptian propolis extract (EP) were used as supplements in the nutrition with different concentrations in Varroa mites-infected colonies to measure the colonies' activities after treatment. The immune-related genes and antimicrobial peptides (AMPs) were evaluated by using qRT-PCR. Treated colonies with HBV and EP showed up-regulation of immune and immune-related genes' expressions and increased the life span, activities and their density of bee workers. The data illustrated that the highest gene expression fold of juvenile hormone esterase was detected in the treated colonies with Egyptian ethanolic propolis extract (EP), while the highest vitellogenin expression fold in treated colonies was with honeybee venom. The up-regulation of antimicrobial peptides occurred in colonies with both treatments.ConclusionThe findings suggest that honeybee venom and Egyptian ethanolic propolis extract (EP) could be used as potential supplements, even at the lowest concentration to develop the immunity of worker bees to increase their efficiency and prevent loss of honeybee colonies due to several diseases closely associated with Varroa mites' infections that cause sudden death.

Social microbiota and social gland gene expression of worker honey bees by age and climate

Winter forage dearth is a major contributor to honey bee colony loss and can influence disease susceptibility. Honey bees possess a secretory head gland that interfaces with the social environment on many levels. During winter or forage dearth, colonies produce a long-lived (diutinus) worker phenotype that survives until environmental conditions improve. We used a known-age worker cohort to investigate microbiome integrity and social gene expression of workers in early and late winter. We provide additional context by contrasting host-microbial interactions from warm outdoor and cold indoor environments. Our results provide novel evidence that social immune gene expression is associated with worker longevity, and highlight the midgut as a target of opportunistic disease during winter. Host microbial interactions suggest opportunistic disease progression and resistance in long-lived workers, but susceptibility to opportunistic disease in younger workers that emerged during the winter, including increases in Enterobacteriaceae, fungal load and non-core bacterial abundance. The results are consistent with increased social immunity, including host associations with the social microbiota, and a social immune response by long-lived workers to combat microbial opportunism. The cost/benefit ratio associated with limited expression of the diutinus phenotype may be a strong determinant of colony survival during winter forage dearth.

Conflicting selection on workers underlies global honey bee colony losses

There is clear evidence for global and unsustainable high losses of the managed Western honey bee, Apis mellifera, colonies raising major concerns about the sustainability of pollination services and food security. Here, we address a conflicting selection scenario in workers to better understand life-history trade-offs underlying colony losses. Due to developmental plasticity, annual fluctuations in selection pressures result in long-living winter bees and short-living summer bees as adaptive responses to lack of food and ceased brood rearing in winter, or ample food and rapid brood turnover in spring and summer. Since trait evolution is governed by a balance of conflicting fitness advantages, trade-offs between longevity and other traits are inevitable (e.g. immune defense or detoxification). As worker longevity is essential to ensure colony functionality, these trade-offs render long-living workers more susceptible to the same stressors compared to short-lived ones. It seems as if trade-offs in workers play a previously overlooked key role, and the incorporation of long-living workers in research efforts is long overdue if our aim is to effectively mitigate declines and losses of social insect colonies globally. Indeed, managed honey bee colony losses in temperate regions predominantly occur throughout winter, but research efforts are almost exclusively conducted with short-lived summer bees, thereby sustaining the danger of false negative results. Thus, we should not shy away from meeting the respective logistic challenges. Studies of conflicting selection on workers will be informative about mechanisms underlying life history trade-offs, thereby fostering conservation efforts in the social insects.

Identification of the Nosema spp., a microsporidian parasite isolated from the honey bees (Apis mellifera) and its association with honey bee colony losses in apiaries of Iran

The aim of this study was to determine the Nosema species by microscopic and molecular method and its association with honeybee colony losses (Colony Collapse Disorder) in apiaries of Urmia, Northwest of Iran. For this purpose, honeybee samples were collected from 840 colonies kept in 120 apiaries in five different location of Urmia. The specimens were examined for the presence of Nosema spores. After DNA isolation, the 16S rRNA gene was evaluated using multiplex PCR. Total infection prevalence with the microscopic evaluation was 32% while in PCR test was 58.2%. Nosema positive samples were evaluated by PCR sequencing. Based on the results of PCR, all identified cases were N. ceranae. The obtained sequences were transferred to GenBank/NCBI (samples accession numbers MT001887 and MT001893). The results showed the prevalence of Colony Collapse Disorder like symptoms in the studied honeybee colonies were 13.33%. N. ceranae was detected by PCR in 20.28 % of honeybee colonies with Colony Collapse Disorder like signs. Our findings showed that there was a significant relation between Colony Collapse Disorder and presence of N. ceranae. The results of this study concluded that N. ceranae is the only specie that affects the honeybees which may have an important role in the occurrence of collapse of bee families and depopulation of hives in this area.

Effect of Chronic Exposure to Sublethal Doses of Imidacloprid and Nosema ceranae on Immunity, Gut Microbiota, and Survival of Africanized Honey Bees.

Large-scale honey bee colony losses reported around the world have been associated with intoxication with pesticides, as with the presence of pests and pathogens. Among pesticides, neonicotinoid insecticides are the biggest threat. Due to their extensive use, they can be found in all agricultural environments, including soil, water, and air, are persistent in the environment, and are highly toxic for honey bees. In addition, infection by different pests and pathogens can act synergistically, weakening bees. In this study, we investigated the effects of chronic exposure to sublethal doses of imidacloprid alone or combined with the microsporidia Nosema ceranae on the immune response, deformed wing virus infection (DWV), gut microbiota, and survival of Africanized honey bees. We found that imidacloprid affected the expression of some genes associated with immunity generating an altered physiological state, although it did not favor DWV or N. ceranae infection. The pesticide alone did not affect honey bee gut microbiota, as previously suggested, but when administered to N. ceranae infected bees, it generated significant changes. Finally, both stress factors caused high mortality rates. Those results illustrate the negative impact of imidacloprid alone or combined with N. ceranae on Africanized honey bees and are useful to understand colony losses in Latin America.

Monitoring Study in Honeybee Colonies Stressed by the Invasive Hornet Vespa velutina.

Vespa velutina is an invasive species that is currently the main concern for beekeeping in some areas of northern Spain. The hornet hunts honeybees to feed its larvae, stressing and weakening the honeybee colonies. To avoid losses of honeybee colonies, it is essential to investigate the pressure that is exerted by the yellow-legged hornet on apiaries and its consequences. In the present study, hives were monitored in an apiary that was situated in a high-pressure area of V. velutina during the years 2020 and 2021. The monitoring of environmental conditions of the apiary, the internal conditions of the colonies, and a hunting camera were used to relate the presence of hornets in front of the hives to the weather conditions in the apiary and the consequences caused on the colonies. The relationships between weather conditions and the hornet’s activity showed two types of hornet behavior. In the months of July and August, the maximum number of hornets appeared in non-central hours of the day. Meanwhile, in the months of September and October, the highest pressure in the apiary occurred in the central hours of the day, coinciding with temperatures between 15 °C and 25 °C and a relative humidity that was higher than 60%. The honeybee colony with the highest thermoregulatory capacity was the strongest and it was the key factor for the colony survival even when the hornet pressure was high too. Therefore, strengthening the hives and improving beehive health status is essential to avoid colonies decline.

The Role of Nosema ceranae (Microsporidia: Nosematidae) in Honey Bee Colony Losses and Current Insights on Treatment.

Honeybee populations have locally and temporally declined in the last few years because of both biotic and abiotic factors. Among the latter, one of the most important reasons is infection by the microsporidia Nosema ceranae, which is the etiological agent of type C nosemosis. This species was first described in Asian honeybees (Apis cerana). Nowadays, domestic honeybees (Apis mellifera) worldwide are also becoming infected due to globalization. Type C nosemosis can be asymptomatic or can cause important damage to bees, such as changes in temporal polyethism, energy and oxidative stress, immunity loss, and decreased average life expectancy. It causes drastic reductions in workers, numbers of broods, and honey production, finally leading to colony loss. Common treatment is based on fumagillin, an antibiotic with side effects and relatively poor efficiency, which is banned in the European Union. Natural products, probiotics, food supplements, nutraceuticals, and other veterinary drugs are currently under study and might represent alternative treatments. Prophylaxis and management of affected colonies are essential to control the disease. While N. ceranae is one potential cause of bee losses in a colony, other factors must also be considered, especially synergies between microsporidia and the use of insecticides.

Critical View on the Importance of Host Defense Strategies on Virus Distribution of Bee Viruses: What Can We Learn from SARS-CoV-2 Variants?

Bees, both wild and domesticated ones, are hosts to a plethora of viruses, with most of them infecting a wide range of bee species and genera. Although viral discovery and research on bee viruses date back over 50 years, the last decade is marked by a surge of new studies, new virus discoveries, and reports on viral transmission in and between bee species. This steep increase in research on bee viruses was mainly initiated by the global reports on honeybee colony losses and the worldwide wild bee decline, where viruses are regarded as one of the main drivers. While the knowledge gained on bee viruses has significantly progressed in a short amount of time, we believe that integration of host defense strategies and their effect on viral dynamics in the multi-host viral landscape are important aspects that are currently still missing. With the large epidemiological dataset generated over the last two years on the SARS-CoV-2 pandemic, the role of these defense mechanisms in shaping viral dynamics has become eminent. Integration of these dynamics in a multi-host system would not only greatly aid the understanding of viral dynamics as a driver of wild bee decline, but we believe bee pollinators and their viruses provide an ideal system to study the multi-host viruses and their epidemiology.

Integrative Analysis of lncRNA-mRNA Co-expression Provides Novel Insights Into the Regulation of Developmental Transitions in Female Varroa destructor

Varroa destructor is a major pathogenic driver of the Western honeybee colony losses globally. Understanding the developmental regulation of V. destructor is critical to develop effective control measures. Development is a complex biological process regulated by numerous genes and long non-coding RNAs (lncRNAs); however, the underlying regulation of lncRNAs in the development of V. destructor remains unknown. In this study, we analyzed the RNA sequencing (RNA-Seq) data derived from the four stages of female V. destructor in the reproductive phase (i.e., egg, protonymph, deutonymph, and adult). The identified differentially expressed mRNAs and lncRNAs exhibited a stage-specific pattern during developmental transitions. Further functional enrichment established that fat digestion and absorption, ATP-binding cassette (ABC) transporters, mitogen-activated protein kinase (MAPK) signaling pathway, and ubiquitin-proteasome pathway play key roles in the maturation of female V. destructor. Moreover, the lncRNAs and mRNAs of some pivotal genes were significantly upregulated at the deutonymph stage, such as cuticle protein 65/6.4/63/38 and mucin 5AC, suggesting that deutonymph is the key stage of metamorphosis development and pathogen resistance acquisition for female V. destructor. Our study provides novel insights into a foundational understanding of V. destructor biology.

Repeated short-term exposure to diesel exhaust reduces honey bee colony fitness

Production of insect-pollinated crops is often reliant on honey bee (Apis mellifera) pollination services. Colonies can be managed and moved to meet the demands of modern intensified monoculture farming systems. Increased colony mortalities have been observed, which are thought be caused by interacting factors including exposure to pesticides, parasites, viruses, agricultural intensification, and changes in global and regional climate. However, whilst common tropospheric air pollutants (e.g. NOx, particulate matter etc) are known to cause a range of negative effects on human health, there is little evidence of their impact on the health of A. mellifera. This study investigates the effects of exposure to diesel exhaust on A. mellifera, both at the level of individual foragers and on the whole colony. We exposed a series of colonies to diesel exhaust fumes for 2 h a day over the course of three weeks and contrasted their performance to a series of paired control colonies located at the same field site. We investigated markers of neuronal health in the brains of individual foragers and measured the prevalence of common viruses. Electronic counters monitored daily colony activity patterns and pollen samples from returning foragers were analysed to investigate plant species richness and diversity. The amounts of honey, brood and pollen in each colony were measured regularly. We demonstrated an upregulation of the synapse protein Neurexin 1 in forager brains repeatedly exposed to diesel exhaust. Furthermore, we found that colonies exposed to diesel exhaust lost colony weight after the exposure period until the end of the summer season, whereas control colonies gained weight towards the end of the season. Further investigations are required, but we hypothesise that such effects on both individual foragers and whole colony fitness parameters could ultimately contribute to winter losses of honey bee colonies, particularly in the presence of additional stressors.

Prevalence and pathogen detection of Varroa and Tropilaelaps mites in Apis mellifera (Hymenoptera, Apidae) apiaries in South Korea

The honey bee is an important pollinator of wild plants and crops and provides various useful products for humans. Infestations by honey bee mites damage the honey bees’ health, decrease their lifespan, and increase their viral susceptibility. In this study, surveys were conducted throughout South Korea in 2019 to investigate the status of honey bee mite infestation. Mite samples were collected for species identification, and estimation of infestation levels from 47 apiaries in 12 regions was conducted. Mite species were identified by morphological characteristics and genetic analysis using cytochrome c oxidase subunit I (COX1). The results showed that 93.6% of the apiaries were infested by honey bee mites, of which 85.1% and 76.6% of the apiaries were infested by Varroa spp. and Tropilaelaps spp., respectively. Furthermore, 68.0% were co-infested by both honey bee mites. Additionally, 82.5% of the apiaries with Varroa spp. showed infestation rate with >3 mites per 100 bees, the infestation level could result in winter losses of honey bee colonies. Species identification revealed that all mites from the apiaries in South Korea were Varroa destructor and Tropilaelaps mercedesae. Importantly, these two mite species were determined to be vectors of one to nine honey bee pathogens in real-time polymerase chain reaction detection. The most prevalent pathogen was the deformed wing virus, followed by the Israeli acute paralysis virus and chronic bee paralysis virus. The results of the surveys are important for estimating the economic losses caused by honey bee mites and establishing a possible strategy for controlling mites and mite-borne transmissible pathogens in South Korea.

Perdas de colônias de abelhas no Brasil em 2018-2019

A research was conducted to assess honey bee colony losses in Brazil, including their likely causes. Beekeepers responded to two complete annual questionnaires (n=268 in 2018 and n=254 in 2019). There was a total of 175,003 hives of Africanized honey bees (Apis mellifera Linnaeus), (µ=335 hives per beekeeper, min=9 and Max=3,600), of which 27.2% were lost. A Generalized Linear Model (GLM) for total loss (TL) and a Wald method for average loss (AL) were used to estimate 95% confidence intervals (CI) for loss rates based on year: 2018, TL=30.5%, CI (28.5-32.4), AL=39.5, CI (37.0-41.9); and 2019, TL=23.8%, CI (22.5-25.2), AL=31.3%, CI (29.5-33.1). Pesticides were speculated to be the leading cause of colony losses (47.3%), followed by climate (drought, flood, rain: 11.6%), malnutrition (lack of flowering, lack of energy and/or protein source, wrong nutrition: 9.7%), absconding (10.2%), mismanagement (wrong migratory activity, migration to mangrove, beekeeper’s personal problems: 7.9%), predators (3.9%), queen problems (2.8%), and varroa (1.6%). Other parasites, theft, toxic pollen (Brazilian sacbrood) and bushfires accounted for the remaining 5% of losses. Due to tropical temperatures, there is no substantial winter loss. In contrast, the highest incidence of losses occurred from September to January, coinciding with the intense agricultural activity. In summary, according to participants, there were significantly higher losses in 2018 compared to 2019, with pesticides alleged to be the main cause of honey bee colony losses in Brazil. However, beekeepers usually multiply colonies during the following season, sustaining pollination and honey production, thereby supporting agricultural activity.

Evaluating the Efficacy of 30 Different Essential Oils against Varroa destructor and Honey Bee Workers (Apis mellifera).

Simple SummaryWorldwide, mass losses of honey bee colonies are being observed more frequently due to Varroa mite infestation. Therefore, varroosis is considered a major problem in beekeeping participating to a large extent in colony collapse disorder. Except for direct damage of bees and suppressing their immune system caused by parasitism, Varroa mites transfer viral particles straight to bee hemolymph which can have a fatal impact. To control the mite population, several acaricidal treatments are used. Commonly used treatments are synthetic acaricides with a high risk of developing Varroa resistance population and contamination of bee products by acaricidal residues. Other commonly used treatments are organic acids, which are increasingly associated with damage of brood, adult bees, and premature deaths of queens. Therefore, in this study, we evaluated the varroacidal effect of 30 individual essential oils. The toxicity of the most effective oils selected by screening was subsequently tested on Varroa mites and adult honey bee workers simultaneously. In addition, the main components of these essential oils were specified. Several essential oils were proven to be effective against the adult female of Varroa mites and at the same dose safe for adult honey bee workers under laboratory conditions, especially manuka, peppermint, oregano, litsea, and cinnamon.Essential oils and their components are generally known for their acaricidal effects and are used as an alternative to control the population of the Varroa destructor instead of synthetic acaricides. However, for many essential oils, the exact acaricidal effect against Varroa mites, as well as the effect against honey bees, is not known. In this study, 30 different essential oils were screened by using a glass-vial residual bioassay. Essential oils showing varroacidal efficacy > 70% were tested by the complete exposure assay. A total of five bees and five mites were placed in the Petri dishes in five replications for each concentration of essential oil. Mite and bee mortality rates were assessed after 4, 24, 48, and 72 h. The LC50 values and selectivity ratio (SR) were calculated. For essential oils with the best selectivity ratio, their main components were detected and quantified by GC-MS/MS. The results suggest that the most suitable oils are peppermint and manuka (SR > 9), followed by oregano, litsea (SR > 5), carrot, and cinnamon (SR > 4). Additionally, these oils showed a trend of the increased value of selective ratio over time. All these oils seem to be better than thymol (SR < 3.2), which is commonly used in beekeeping practice. However, the possible use of these essential oils has yet to be verified in beekeeping practice.

Synergistic and Antagonistic Interactions Between Varroa destructor Mites and Neonicotinoid Insecticides in Male Apis mellifera Honey Bees

Pressures from multiple, sometimes interacting, stressors can have negative consequences to important ecosystem-service providing species like the western honey bee (Apis mellifera). The introduced parasite Varroa destructor and the neonicotinoid class of insecticides each represent important, nearly ubiquitous biotic and abiotic stressors to honey bees, respectively. Previous research demonstrated that they can synergistically interact to negatively affect non-reproductive honey bee female workers, but no data exist on how concurrent exposure may affect reproductive honey bee males (drones). This is important, given that the health of reproductive females (queens), possibly because of poor mating, is frequently cited as a major driver of honey bee colony loss. To address this, known age cohorts of drones were obtained from 12 honey bee colonies—seven were exposed to field-relevant concentrations of two neonicotinoids (4.5 ppb thiamethoxam and 1.5 ppb clothianidin) during development via supplementary pollen patties; five colonies received patties not spiked with neonicotinoids. Artificially emerged drones were assessed for natural V. destructor infestation, weighed, and then allocated to the following treatment groups: 1. Control, 2. V. destructor only, 3. Neonicotinoid only, and 4. Combined (both mites and neonicotinoid). Adult drones were maintained in laboratory cages alongside attendant workers (1 drone: 2 worker ratio) until they have reached sexual maturity after 14 days so sperm concentration and viability could be assessed. The data suggest that V. destructor and neonicotinoids interacted synergistically to negatively affect adult drone survival, but that they interacted antagonistically on emergence mass. Although sample sizes were too low to assess the effects of V. destructor and combined exposure on sperm quality, we observed no influence of neonicotinoids on sperm concentration or viability. Our findings highlight the diverse effects of concurrent exposure to stressors on honey bees, and suggest that V. destructor and neonicotinoids can severely affect the number of sexually mature adult drones available for mating.

A MICROSCOPY AND MOLECULAR STUDIES OF NOSEMA CERANAE INFECTION IN MAZANDARAN PROVINCE OF IRAN

Nosema ceranae as a fungal parasite has been reported from the Apis mellifera in all continents. It causes reduced longevity, depopulation, decreased production, and colony losses in honeybee colonies. This study aimed to determine the prevalence of N.ceranae in the apiaries of Mazandaran province. In this study, we randomly selected 320 hives from thirty-two apiaries and collected twenty old honeybees from the apiaries. The collected samples were examined by microscopy and molecular methods. The results of the microscopic examinations showed that 78.12% of apiaries were infected with Nosema spp. In addition, N. ceranae was identified 84.37% of apiaries by PCR, while no samples were infected by N. apis. Blast analysis of the sequenced samples confirmed the presence of N. ceranae infection in the apiaries. Based on the obtained results, a high frequency of N.ceranae was detected in apiaries in Mazandaran province.

Chemical Stimulants and Stressors Impact the Outcome of Virus Infection and Immune Gene Expression in Honey Bees (Apis mellifera).

Western honey bees (Apis mellifera) are ecologically, agriculturally, and economically important plant pollinators. High average annual losses of honey bee colonies in the US have been partially attributed to agrochemical exposure and virus infections. To examine the potential negative synergistic impacts of agrochemical exposure and virus infection, as well as the potential promise of phytochemicals to ameliorate the impact of pathogenic infections on honey bees, we infected bees with a panel of viruses (i.e., Flock House virus, deformed wing virus, or Sindbis virus) and exposed to one of three chemical compounds. Specifically, honey bees were fed sucrose syrup containing: (1) thyme oil, a phytochemical and putative immune stimulant, (2) fumagillin, a beekeeper applied fungicide, or (3) clothianidin, a grower-applied insecticide. We determined that virus abundance was lower in honey bees fed 0.16 ppb thyme oil augmented sucrose syrup, compared to bees fed sucrose syrup alone. Parallel analysis of honey bee gene expression revealed that honey bees fed thyme oil augmented sucrose syrup had higher expression of key RNAi genes (argonaute-2 and dicer-like), antimicrobial peptide expressing genes (abaecin and hymenoptaecin), and vitellogenin, a putative honey bee health and age indicator, compared to bees fed only sucrose syrup. Virus abundance was higher in bees fed fumagillin (25 ppm or 75 ppm) or 1 ppb clothianidin containing sucrose syrup relative to levels in bees fed only sucrose syrup. Whereas, honey bees fed 10 ppb clothianidin had lower virus levels, likely because consuming a near lethal dose of insecticide made them poor hosts for virus infection. The negative impact of fumagillin and clothianidin on honey bee health was indicated by the lower expression of argonaute-2, dicer-like, abaecin, and hymenoptaecin, and vitellogenin. Together, these results indicate that chemical stimulants and stressors impact the outcome of virus infection and immune gene expression in honey bees.

How COLOSS Monitoring and Research on Lost Honey Bee Colonies Can Support Colony Survival

Formation of This Group Since the mid-2000s beekeepers began to report cases of widespread, elevated mortalities of honey bee colonies (Figure 1) in different parts of the world. Today, international scientific monitoring of honey bee colony losses is organised as one of three ‘Core Projects’ of the non-profit honey bee research association COLOSS (prevention of honey bee COlony LOSSes). The topic of this Core Project, colony losses, is reflected in the acronym COLOSS, underlining its importance to the association! Since the very beginning of COLOSS as an EU COST-funded action in 2008, a working group has been dedicated to collect standardised data on honey bee colony losses. This group was termed “monitoring & diagnosis” and was first led and largely shaped by Romee van der Zee from the Netherlands. It is important also to note the involvement of other members who have been very active from the early days until today. These include Flemming Vejsnaes from the Danish Beekeepers Association, Victoria Soroker from Israel, Franco Mutinelli from Italy, and recently retired Preben Kristiansen from Sweden. No other international and long-lasting effort on honey bee colony health and mortality was established in Europe prior to this effort.

Combined effects of oxalic acid sublimation and brood breaks on Varroa mite (Varroa destructor) and deformed wing virus levels in newly established honey bee (Apis mellifera) colonies

Annual losses of honey bee colonies are high in the United States, with losses often attributed to the effects of the ectoparasitic mite, Varroa destructor, and its associated viruses (e.g., Deformed Wing Virus, DWV). In the spring, beekeepers rely on package bees to replace lost colonies. However, these packages often come with high levels of mites and are treated with miticides upon installation. Oxalic acid (OA) is a popular miticide used in spring, but little is known about its long-term efficacy for mite control. On the other hand, natural behavior that helps with mite control is swarming, which results in a break in the production of brood in a colony. In this study, we investigated the effect of spring OA sublimation and summer swarming on colony health and productivity. We found that OA sublimation is an effective method to increase mite drop from the colony in the first three days after treatment. However, mite populations recovered quickly leading to high mite levels in the fall for colonies that did not swarm during the summer. OA applications had a marginally significant negative effect on honey yield. Mid-season swarming was correlated with lower levels of Varroa mites suggesting that implementing a brood break in the middle of the summer could play an important role in reducing mite populations for colonies originating from packages. However, the combination of OA applications to packages in the spring and summer brood break had a significant effect on reducing mite levels for colonies entering the winter. We conclude that treating packages with OA in the spring in combination with summer mite treatments are powerful tools for beekeepers to keep colonies with lower pest loads entering the winter.