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Recapping of Varroa destructor-infested brood cells is a trait that has recently attracted interest in honey bee breeding to select mite-resistant Apis mellifera colonies. To investigate the genetic architecture of this trait, we evaluated a sample of A. mellifera mellifera colonies (N = 155) from Switzerland and France and performed a genome-wide association study, using a pool of 500 workers per colony for next-generation sequencing. The results revealed that two QTL were significantly (P < 0.05) associated with recapping of V. destructor-infested brood cells. The best-associated QTL is located on chromosome 5 in a region previously found to be associated with grooming behaviour, a resistance trait against V. destructor, in A. mellifera and Apis cerana. The second best-associated QTL is located on chromosome 4 in an intron of the Dscam gene, which is involved in neuronal wiring. Previous research demonstrated that genes involved in neuronal wiring are associated with recapping and varroa sensitive hygiene. Therefore, our study confirms the role of a gene region on chromosome 5 in social immunity and simultaneously provides novel insights into genetic interactions between common mite resistance traits in honey bees.

Suppressed mite reproduction (SMR) is an important trait for the selection of Varroa resistant honey bee colonies. It has repeatedly been assumed that SMR is an effect of varroa sensitive hygiene (VSH) when hygienic bees preferably remove those brood cells where the mite has reproduced. We here compare the VSH behaviour of honey bees toward brood cells artificial infested with a varroa mite. By infesting half of the brood cells directly after the cell capping and the other half only 24 h later, we established two groups with high (> 75%) and low (

International audience; The invasive miteVarroa destructor is identified as the main biotic cause of European honey bee colony losses in many regions, leading to systematic treatments of colonies every year in order to prevent colonies from collapsing. However, some colonies have been reported to survive in the absence of treatment. The ability of honey bee colonies to survive varroa mite infestations has been associated with the development of Varroa Sensitive Hygiene (VSH) behavior. Colonies displaying VSH are able to detect the presence of varroa through the cap of developing brood cells and to remove the parasitized brood. To improve breeding programs for varroa resistance in apiculture, detailed knowledge of the mechanisms that enable bees to survive mite infestation and environmental conditions that can influence the expression and phenotyping of VSH behavior are needed. This study evaluated the influence of the genetic origin of the colony, the colony population dynamics, varroa density, and food supply on the ability of colonies to express the VSH trait. First, we found that varroa-selected colonies displayed lower varroa population growth rate. We also revealed that the genetic origin of the colonies and the month during which the test was performed had a significant impact on VSH behavior, with varroa-selected colonies showing higher VSH abilities than unselected colonies, and especially at the end of summer. Finally, we showed that sedentary varroa-selected colonies expressed higher VSH activity than colonies placed on lavender fields during active honey flow. Such findings are particularly important to standardize testing for varroa resistant colonies in different locations, a feature that is essential to ensure the success of breeding efforts.

Transmission routes impact pathogen virulence and genetics, therefore comprehensive knowledge of these routes and their contribution to pathogen circulation is essential for understanding host-pathogen interactions and designing control strategies. Deformed wing virus (DWV), a principal viral pathogen of honey bees associated with increased honey bee mortality and colony losses, became highly virulent with the spread of its vector, the ectoparasitic mite Varroa destructor. Reproduction of Varroa mites occurs in capped brood cells and mite-infested pupae from these cells usually have high levels of DWV. The removal of mite-infested pupae by worker bees, Varroa Sensitive Hygiene (VSH), leads to cannibalization of pupae with high DWV loads, thereby offering an alternative route for virus transmission. We used genetically tagged DWV to investigate virus transmission to and between worker bees following pupal cannibalisation under experimental conditions. We demonstrated that cannibalization of DWV-infected pupae resulted in high levels of this virus in worker bees and that the acquired virus was then transmitted between bees via trophallaxis, allowing circulation of Varroa-vectored DWV variants without the mites. Despite the known benefits of hygienic behaviour, it is possible that higher levels of VSH activity may result in increased transmission of DWV via cannibalism and trophallaxis.

Simple Summary Parasitic mites, Varroa destructor, are a major threat for Western honey bees, Apis mellifera, colonies globally. Nevertheless, some honey bee populations can survive infestations with this mite, probably due to behaviors that suppress parasite reproduction. However, possible changes in mites associated with these surviving bees and the potential variations of bee behavior over time are poorly understood. Here, we show that mites can change their reproduction when associated with surviving hosts and that the bee behaviors suppressing mite reproduction can vary over time. In a fully-crossed field experiment on Dutch surviving colonies (Amsterdam Water Dunes (AWD) selection), worker brood cell recapping and varroa sensitive hygiene (VSH) performed by bees and mite reproductive parameters were investigated. Neither recapping nor VSH were significantly expressed even though a previous study showed VSH in these AWD bees. A larger proportion of mites that co-evolved with AWD surviving bees reproduced compared to mites in routinely treated colonies, but had lower fecundity. Overall, our study suggests that honeybee colonies can survive infestations with these mites by not yet understood means and shows for the first time adaptive changes in the reproduction of their coevolved mites. Abstract Co-evolution is a major driving force shaping the outcome of host-parasite interactions over time. After host shifts, the lack of co-evolution can have a drastic impact on novel host populations. Nevertheless, it is known that Western honey bee (Apis mellifera) populations can cope with host-shifted ectoparasitic mites (Varroa destructor) by means of natural selection. However, adaptive phenotypic traits of the parasites and temporal variations in host resistance behavior are poorly understood. Here, we show that mites made adaptive shifts in reproductive strategy when associated with resistant hosts and that host resistance traits can change over time. In a fully-crossed field experiment, worker brood cells of local adapted and non-adapted (control) A. mellifera host colonies were infested with mites originating from both types of host colonies. Then, mite reproduction as well as recapping of cells and removal of infested brood (i.e., Varroa Sensitive Hygiene, VSH) by host workers were investigated and compared to data from the same groups of host colonies three years earlier. The data suggest adaptive shifts in mite reproductive strategies, because mites from adapted hosts have higher probabilities of reproduction, but lower fecundity, when infesting their associated hosts than mites in treated colonies. The results confirm that adapted hosts can reduce mite reproductive success. However, neither recapping of cells nor VSH were significantly expressed, even though the latter was significantly expressed in this adapted population three years earlier. This suggests temporal variation in the expression of adaptive host traits. It also appears as if mechanisms not investigated here were responsible for the reduced mite reproduction in the adapted hosts. In conclusion, a holistic view including mite adaptations and studies of the same parasite/host populations over time appears overdue to finally understand the mechanisms enabling survival of V. destructor-infested honey bee host colonies.

Hygienic behavior in honey bees, Apis mellifera, has been studied for over 80 years with the aim of understanding mechanisms of pathogen and parasite resistance and colony health. This review emphasizes the underlying behavioral mechanisms of hygienic behavior in honey bees and when known, in other social insects. We explore the relationship between honey bee hygienic behavior toward diseased brood and Varroa-parasitized brood (Varroa-sensitive hygiene, VSH); the timing of hygienic removal of diseased, Varroa-infested, and virus-infected brood relative to risk of transmission that can affect colony fitness; and the methods, utility, and odorants associated with different assays used to select colonies for resistance to diseases and Varroa. We also provide avenues for future research that would benefit honey bee health and survivorship.

In traditional bee breeding, the honeybee queen is chosen for breeding based on the performance of the colony produced by its mother. However, we cannot be entirely certain that a specific queen will produce offspring with desirable traits until we observe the young queen's new colony. Collecting the queen&rsquo, s genetic material enables quick and reliable determination of the relevant information. We sampled exuviae, feces, and wingtips for DNA extraction to avoid fatally injuring the queen when using tissue samples. Quantity and purity of extracted DNA were measured. Two mitochondrial markers were used to determine the lineage affiliation and exclude possible contamination of DNA extracts with non-honeybee DNA. dCAPS (derived Cleaved Amplified Polymorphic Sequences) markers allowed detection of single nucleotide polymorphisms (SNPs) in nuclear DNA regions presumably associated with Varroa sensitive hygiene and set the example of successful development of genotyping protocol from non-destructive DNA sources. One of the logical future steps in honeybee breeding is introducing genomic selection and non-destructive sampling methods of genetic material may be the prerequisite for successful genotyping. Our results demonstrate that the extraction of DNA from feces and exuviae can be introduced into practice. The advantage of these two sources over wingtips is reducing the time window for processing the samples, thus enabling genotyping directly after the queen&rsquo, s emergence.

Simple Summary : Honey bees, Apis mellifera, are currently facing drastic colony losses, some of which lies partially on the infestation by a parasite, varroa destructor. To maintain healthy honey bee colonies breeding for resistance to this infestation seems promising. However, measuring resistance is a tedious task as it is a complex process. One can consider a honey bee colony resistant to varroa infestation when the parasite fails reproducing and thus its population does not grow in the colony, this is called mite non reproduction. In this study we dissected the performance of a scoring method for mite non reproduction and compared it to other known methods to measure resistance. Although the mite non reproduction method is preferred for field studies because of its relative simplicity it appears to lack correspondence with other methods and it should be interpreted cautiously because it is variable. Even though resistance to varroa infestation is desired for breeding decision it should be done carefully when the way to measure such resistance is using the mite non reproduction method.Abstract : In the current context of worldwide honey bee colony losses, among which the varroa mite plays a major role, the hope to improve honey bee health lies in part in the breeding of varroa resistant colonies. To do so, methods used to evaluate varroa resistance need better understanding. Repeatability and correlations between traits such as mite non-reproduction (MNR), varroa sensitive hygiene (VSH), and hygienic behavior are poorly known, due to practical limitations and to their underlying complexity. We investigate (i) the variability, (ii) the repeatability of the MNR score, and (iii) its correlation with other resistance traits. To reduce the inherent variability of MNR scores, we propose to apply an empirical Bayes correction. In the short-term (ten days), MNR had a modest repeatability of 0.4, whereas in the long-term (a month), it had a low repeatability of 0.2, similar to other resistance traits. Within our dataset, there was no correlation between MNR and VSH. Although MNR is amongst the most popular varroa resistance estimates in field studies, its underlying complex mechanism is not fully understood. Its lack of correlation with better described resistance traits and low repeatability suggest that MNR needs to be interpreted cautiously, especially when used for selection.

International audience; Varroa destructor is a key contributor to honey bee (Apis mellifera L.) colony losses that threaten global economies. Some colonies, especially those displaying high levels of hygiene behaviour targeted towards V. destructor -infested cells, survive mite infestation. Worker bees displaying varroa sensitive hygiene (VSH) open infested brood cells and remove the contents, thereby suppressing mite reproduction. This study identifies features that distinguish cells uncapped by bees performing VSH from infested cells that VSH bees ignore. Brood cells targeted and uncapped by VSH bees were found to be more likely to contain multiple foundress females than nontargeted cells. They also contained higher numbers of mite offspring, and lay within brood cell patches that were more highly infested with V. destructor than were the surrounds of infested cells ignored by VSH bees. This study is the first to identify cell surrounds as a potential source of signals influencing the behaviour of bees performing VSH.

Social insects have evolved colony behavioral, physiological and organizational adaptations (social immunity) to reduce the risks of parasitization and/or disease transmission. The collection of resin from various plants and its use in the hive as propolis, is a clear example of behavioral defense. For Apis mellifera, an increased propolis content in the hive may correspond to variations in the microbial load of the colony and to a down-regulation of an individual bee's immune response. However, many aspects of such antimicrobial mechanism still need to be clarified. Assuming that bacterial and fungal infection mechanisms differ from the action of a parasite, we studied the resin collection dynamics in Varroa destructor infested honeybee colonies. Comparative experiments involving hives with different mite infestation levels were conducted in order to assess the amount of resin collected and propolis quality within the hive, over a two year period (2014 and 2015). Our study demonstrates that when A. mellifera colonies are under stress because of Varroa infestation, an increase in the number of resin foragers is recorded, even if a general intensification of the foraging activity is not observed. A reduction in the total polyphenolic content in propolis produced in infested vs uninfested hives was also noticed. Considering that different propolis types show varying levels of inhibition against a variety of honey bee pathogens in vitro, it would be very important to study the effects against Varroa of two diverse types of propolis: from Varroa free and from Varroa infested hives. This article is protected by copyright. All rights reserved.

The genetic diversity of Varroa destructor (Anderson and Trueman) is limited outside its natural range due to population bottlenecks and its propensity to inbreed. In light of the arms race between V. destructor and its honey bee (Apis mellifera L.) host, any mechanism enhancing population admixture of the mite may be favored. One way that admixture can occur is when two genetically dissimilar mites co-invade a brood cell, with the progeny of the foundresses admixing. We determined the relatedness of 393 pairs of V. destructor foundresses, each pair collected from a single bee brood cell (n = five colonies). We used six microsatellites to identify the genotypes of mites co-invading a cell and calculated the frequency of pairs with different or the same genotypes. We found no deviation from random co-invasion, but the frequency of cells infested by mites with different genotypes was high. This rate of recombination, coupled with a high transmission rate of mites, homogenized the allelic pool of mites within the apiary. This article is protected by copyright. All rights reserved

Feral bees colonizing large forest habitats without human intervention are also affected by diseases. Infected bees that survive several seasons constitute an interesting object of scientific inquiry. Little is known about the health and status of feral honey bee populations. The pathogens infesting/infecting bee colonies and the biochemical status of unhealthy bees need to be studied to prevent the global decline in bee populations. Honey bees inhabiting hollow trees in forest reserves of north-eastern Poland, infected with Nosema ceranae or infested with Varroa destructor and/or infected with the deformed wing virus (DWV), were analyzed. Differences in the analyzed biochemical parameters were noted in groups infected/infested with various pathogens relative to the control group. The most significant variations were observed in antioxidant parameters: lower total antioxidant status (TAS) (excluding group N. ceranae), lower activity of superoxide dismutase (SOD) and peroxidase (POX) (excluding group N. ce...

Varroa Sensitive Hygiene (VSH) is a useful resistance trait that honey bee (Apis mellifera) breeders could increase in different populations with cost-effective and reliable tests. We investigated ...

The honey bee (Apis mellifera) is an important pollinator of agricultural and horticultural crops, but also of wild flowers. The species has been facing declines in many areas of the world, the causes being identified as multifactorial. Recently, it has been theorised that some plant-dwelling animals may develop a dependence on the medicinal properties of their hots plant’s secondary metabolites. Here, the question of honey bee self-medication using organic materials, namely propolis, nectar, honey, honeydew, pollen, wood, and algae for self-medication is addressed. Self-medication in honey bees is a largely unexplored area and thus a comprehensive overview of the field is provided. Prior studies suggest that recent honey bee colony declines are driven by decreased forage plant availability. The problem is expanded and it is suggested, that if honey bees developed a dependence on medical properties of some disappearing plants or materials, this could explain a part of the colony losses observed around the world. To date, convincing evidence points towards self-medication with honey and propolis. Bees also contact plant secondary metabolites, fatty acids, essential oils, and microorganisms that are active against the causative agents of American foulbrood, European foulbrood, nosemosis, chalkbrood, stonebrood, and varroasis. In the future, selected taxa of plants with medicinal properties may be planted to boost honey bee health without chemotherapy. Future directions of research are discussed.

Parasites and pathogens of the honey bee (Apis mellifera) are key factors underlying colony losses, which are threatening the beekeeping industry and agriculture as a whole. To control the spread and development of pathogen infections within the colony, honey bees use plant resins with antibiotic activity, but little is known about the properties of other substances, that are mainly used as a foodstuff, for controlling possible diseases both at the individual and colony level. In this study, we tested the hypothesis that pollen is beneficial for honey bees challenged with the parasitic mite Varroa destructor associated to the Deformed Wing Virus. First, we studied the effects of pollen on the survival of infested bees, under laboratory and field conditions, and observed that a pollen rich diet can compensate the deleterious effects of mite parasitization. Subsequently, we characterized the pollen compounds responsible for the observed positive effects. Finally, based on the results of a transcriptomic analysis of parasitized bees fed with pollen or not, we developed a comprehensive framework for interpreting the observed effects of pollen on honey bee health, which incorporates the possible effects on cuticle integrity, energetic metabolism and immune response.

Varroa mite is the most destructive pest to bee colonies worldwide. In Saudi Arabia, preliminary data indicated high infestation levels in the exotic honeybee colonies; such as Apis mellifera carnica and Apis mellifera ligustica, compared to native honeybee subspecies Apis mellifera jemenitica, which may imply higher tolerance to Varroasis. In this study, fertility and reproductive rate of Varroa mite, Varroa destructor, in capped brood cells of the native honeybee subspecies were investigated and compared with an exotic honeybee subspecies, A. m. carnica. Mite fertility was almost alike (87.5% and 89.4%) in the native and craniolan colonies respectively. Similarly, results did not show significant differences in reproduction rate between both subspecies (F = 0.66, Pr > F = 0.42). Number of adult Varroa daughters per fertile mother mite was 2.0 and 2.1 for native and craniolan honeybee subspecies respectively. This may indicate that mechanisms of keeping low infestation rates in the native honeybee colonies are not associated with Varroa reproduction. Therefore, potential factors of keeping lower Varroa infestation rates in native honey bee subspecies should be further investigated.

The hygienic behavior of honey bee workers contributes to the social immunity of colonies. The ability of workers to detect and remove unhealthy or dead brood prevents the transmission of brood diseases inside the colony. Over the last five decades, this trait has been extensively studied and improved in several research and breeding programs. Given the strong interest for hygienic behavior, we here review the costs and benefits associated with this trait, extending preceding reviews on this subject from the late 1990s. Since the 1990s, there have been no major new insights on the efficiency of this behavior against American foulbrood and chalkbrood. However, the number of publications on hygienic behavior against the mite Varroa destructor has considerably increased, fueling the debate regarding the efficiency of hygienic behavior against this parasite. Breeding programs have shown that selection for a specific trait might also impact other traits. Thus, we also review the cost of trade-offs between hygi...

We refute a recent claim that parallel evolution in four European populations of honeybees has resulted in a not previously reported behavioural defence mechanism of the bees against the parasitic mite Varroa destructor, i.e. the ability of uncapping/recapping to reduce mite reproductive success. There are no data to support this claim, while there is a more plausible alternative interpretation of the reduced mite reproduction, i.e. reduction of mites through Varroa Sensitive Hygiene. We provide evidence why the former mechanism cannot explain resistance against Varroa in honeybees and the latter is instrumental in reducing Varroa populations.

Honey bees reproduce by colony fission, or swarming. The swarming process begins when worker bees initiate queen rearing in response to a suite of demographic factors within the colony, a reduction in the effectiveness of queen pheromones that inhibit worker reproduction, successful foraging, and other factors. Several aspects of Africanized bee biology appear to be very different from the attributes of European honey bees. Polygyny during swarming and of the parental colony before queen mating could provide immunity from queen loss, as apparently occurs in several North African races of honey bees. However, polygynous afterswarms of Africanized bees at the time of issuance are relatively uncommon. Honey bee colonies are affected by predation, loss of queens following swarming, and absconding. When swarming has been completed, Africanized bee colonies quickly return to a monogynous condition prior to mating by the new resident queen.

A robust trade in honey bee queens from different European countries began around 1870, in close association with the adoption of moveable frame hives in Germany. Within a few decades, the country ...

Honey bee-mite-pathogen associations have led to the widespread collapse of Apis mellifera colonies in various parts of the world. The global trade in bees continues to expose honey bees to new pests and pathogens. Here we highlight to the beekeeping community a potential new mite-pathogen association. In South America, ecto-parasitic Leptus mite larvae have been recorded parasitizing adult honey bees and these mites are known to transmit Spiroplasma bacteria, the causative agent of “Mays disease” in bees. Here we provide new data and review past studies on Leptus mites, and discuss the potential risk to A. mellifera that this mite may pose in the future.

The first record of tracheal mites, Acarapis woodi, in Japan was made in 2010. These mites have since caused serious damage to the colonies of Japanese honey bees, Apis cerana japonica. In the present study, to control the mites on Japanese honey bees with l-menthol, an agent used for European honey bees, Apis mellifera, we investigated (1) the seasonality of menthol efficacy, (2) the overwintering mortality of menthol-treated colonies, and (3) the menthol residue in honey under field conditions in cooperation with private beekeepers of Japanese honey bees. Seasonal menthol efficacy was tested by applying 30 g of l-menthol for 1 month in different seasons. Mite prevalence was measured by dissecting the honey bee thorax. Overwintering mortality was monitored during winter after checking the mite prevalence in autumn, and was compared with that of untreated colonies reported in our previous study. The residual level of menthol in honey was measured by GC-MS. The results showed that the menthol-treated colonies had a smaller rate of increase in mite prevalence than the untreated colonies. The effects of menthol were highest in March and April. The winter mortality was depressed by menthol treatment. Honey samples extracted from the menthol-treated colonies included 0.4 ppm of menthol residue on average. Our findings suggest that menthol treatment is effective for controlling the tracheal mites on Japanese honey bees.

Varroa destructor has been identified as a major culprit responsible for the losses of millions of honeybee colonies. Varroa sensitive hygiene (VSH) is a suite of behaviors from adult bees to suppress mite reproduction by uncapping and/or removing mite infested pupae from a sealed brood. Despite the efforts to elucidate the molecular underpinnings of VSH, they remain largely unknown. We investigated the proteome of mushroom bodies (MBs) and antennae of adult bees with and without VSH from a stock selected for VSH based on their response to artificially Varroa-infected brood cells by near-infrared camera observation. The pupal hemolymph proteome was also compared between the VSH-line and the line that was not selected for VSH. The identified 8609 proteins in the hemolymph, MBs, and antennae represent the most depth coverage of the honeybee proteome (55%) to date. In the hemolymph, the VSH-line adapts a unique strategy to boost the social immunity and drive pupal organogenesis by enhancing energy metabolism and protein biosynthesis. In MBs, the up-regulated proteins implicated in neuronal sensitivity suggest their roles to promote the execution of VSH by activation of synaptic vesicles and calcium channel activities. In antennae, the highly expressed proteins associated with sensitivity of olfactory senses and signal transmissions signify their roles by inputting a strong signal to the MBs for initiating VSH. These observations illustrate that the enhanced social immunities and olfactory and neuronal sensitivity play key roles in the combat against Varroa infestation. The identified candidate markers may be useful for accelerating marker-associated selection for VSH to aid in resistance to a parasite responsible for decline in honeybee health.

Varroa destructor is a parasitic mite of the Western honey bee. The activity of five antioxidant enzymes of V. destructor were analysed. Glutathione content and total antioxidant status was also evaluated. Our results suggest that antioxidant enzymes constitute the main line of defense against ROS in V. destructor, whereas low-molecular-weight antioxidants play a limited role in the antioxidant system of mites.

There has been growing concern over declines in populations of honey bees and other pollinators which are a vital part to our food security. It is imperative to identify factors responsible for accelerated declines in bee populations and develop solutions for reversing bee losses. While exact causes of colony losses remain elusive, risk factors thought to play key roles are ectoparasitic mites Varroa destructor and neonicotinoid pesticides. The present study aims to investigate effects of a neonicotinoid pesticide Imidacloprid and Varroa mites individually on survivorship, growth, physiology, virus dynamics and immunity of honey bee workers. Our study provides clear evidence that the exposure to sublethal doses of Imidacloprid could exert a significantly negative effect on health and survival of honey bees. We observed a significant reduction in the titer of vitellogenin (Vg), an egg yolk precursor that regulates the honey bees development and behavior and often are linked to energy homeostasis, in bees exposed to Imidacloprid. This result indicates that sublethal exposure to neonicotinoid could lead to increased energy usage in honey bees as detoxification is a energy-consuming metabolic process and suggests that Vg could be a useful biomarker for measuring levels of energy stress and sublethal effects of pesticides on honey bees. Measurement of the quantitative effects of different levels of Varroa mite infestation on the replication dynamic of Deformed wing virus (DWV), an RNA virus associated with Varroa infestation, and expression level of immune genes yields unique insights into how honey bees respond to stressors under laboratory conditions.

Recent efforts to evaluate the contribution of neonicotinoid insecticides to worldwide pollinator declines have focused on honey bees and the chronic levels of exposure experienced when foraging on crops grown from neonicotinoid-treated seeds. However, few studies address non-crop plants as a potential route of pollinator exposure to neonicotinoid and other insecticides. Here we show that pollen collected by honey bee foragers in maize- and soybean-dominated landscapes is contaminated throughout the growing season with multiple agricultural pesticides, including the neonicotinoids used as seed treatments. Notably, however, the highest levels of contamination in pollen are pyrethroid insecticides targeting mosquitoes and other nuisance pests. Furthermore, pollen from crop plants represents only a tiny fraction of the total diversity of pollen resources used by honey bees in these landscapes, with the principle sources of pollen originating from non-cultivated plants. These findings provide fundamental information about the foraging habits of honey bees in these landscapes., The extent to which non-crop plants may be contaminated by insecticides is not known. Here, the authors show that pollen collected by honey bees living in areas of intensive maize production is contaminated by a wide range of pesticides throughout the growing season, with the principle pollen source being non-crop plants.

Varroa mite (Varroa destructor Anderson and Trueman) is a major global threat to the western honey bee (Apis mellifera L.). The ectoparasite has been implicated in the spread of honeybee viruses. Beekeeping plays a major role in transmission of the mite. The study aimed at assessing levels of Varroa infestation, bee viruses and bacteria incidences in domesticated honeybee colonies. Samples of adult honey bees, bee brood and Varroa mites were collected from Baringo, Narok, Kwale, Magarini, Voi, Ijara, Busia and Siaya in Kenya. Ten hives in each site were inspected for the presence of Varroa mites on adult bees using the icing sugar technique and forceps in sealed brood cells. The number of mites observed were recorded per site. Ribonucleic acid was extracted from the mites, brood and adult bees and a polymerase chain reaction was performed to detect the black queen cell virus. Pooled RNA samples of brood and adult bees were used in next generation sequencing on a 454 GS FLX platform to detect bee v...

Honey bee colony decline in major parts of the world represents a severe risk to global food and nutritional security (Potts et al., 2010). This trend has been attributed to a plethora of biotic, a...

Varroa destructor, originally a parasite of the Eastern honey bee, Apis cerana, switched hosts and became a very serious parasite of the Western honey bee, Apis mellifera, and a major contributor t...

The Carniolan honey bee, Apis mellifera carnica, is a Slovenian autochthonous subspecies of honey bee. In recent years, the country has recorded an annual loss of bee colonies through mortality of up to 35%. One possible reason for such high mortality could be the exposure of honey bees to xenobiotic residues that have been found in honey bee and beehive products. Acaricides are applied by beekeepers to control varroosis, while the most abundant common agricultural chemicals found in honey bee and beehive products are fungicides, which may enter the system when applied to nearby flowering crops and fruit plants. Acaricides and fungicides are not intrinsically highly toxic to bees but their action in combination might lead to higher honey bee sensitivity or mortality. In the present study we investigated the molecular immune response of honey bee workers at different developmental stages (prepupa, white-eyed pupa, adult) exposed to the acaricide coumaphos and the fungicide prochloraz individually and in combination. Expression of 17 immune-related genes was examined by quantitative RT-PCR. In treated prepupae downregulation of most immune-related genes was observed in all treatments, while in adults upregulation of most of the genes was recorded. Our study shows for the first time that negative impacts of prochloraz and a combination of coumaphos and prochloraz differ among the different developmental stages of honey bees. The main effect of the xenobiotic combination was found to be upregulation of the antimicrobial peptide genes abaecin and defensin-1 in adult honey bees. Changes in immune-related gene expression could result in depressed immunity of honey bees and their increased susceptibility to various pathogens.

Grooming behavior of honey bees can be considered in two major categories: autogrooming or self-grooming and inter-bee grooming, called allogrooming. Allogrooming can be one-on-one, or social, involving several nestmates acting collaboratively. In addition, some house bees become allogrooming specialists, and for them grooming their nestmates can be a full-time occupation for most of their lives. Early observations on the Eastern honey bee, Apis cerana, recorded autogrooming, one-on-one, and social allogrooming, all of which result in dead, visibly mutilated varroa mites falling to the hive floor. Similar behavior has been sought in the Western honey bee. Apis mellifera, with variant observations for the different subspecies. Most descriptions relate to A. m. carnica, some to A. m. ligustica, but with one notable exception, almost none to A. m. mellifera. The most impressive findings are from “Africanized” bees, which provide some of the best cases of natural, long-lasting tolerance to varroa mites in A. ...

International audience; AbstractGuaranteeing high acaricide efficacy to control Varroa destructor is fundamental for colony survival. In this study, we verified the efficacy and impact of a commercial thymol-based veterinary product (Apiguard®) on colony honey bee populations when used alone or combined with the biotechnical method of caging honey bee queens to create an artificial brood interruption period in the colony. Apiguard® killed 76.1% of the mites while queen caging killed 40.6% of the mites. The combination of Apiguard® administration with queen caging killed 96.8% of the mites. Comparing bee numbers before and after treatment, Apiguard® treated colonies with caged queens had 48.7% fewer bees compared to before treatment, while Apiguard® alone reduced the number of adult bees by 13.6%. None of the treatments in the different groups resulted in elevated queen mortality.

Honey bees manifest a rich repertoire of behavioral traits. These traits contribute to the successful establishment of a highly evolved social organization in the honey bee. In this study, we describe a novel observational methodology using infrared camera technology for the long-term, undisturbed investigation of behavioral traits of honey bee. An illustration of this methodology is provided through observations of hygienic behavior in response to varroa infestation. Using our method, we show that honey bee workers exhibit a systematic sequence of behavioral activities during the performance of hygienic behavior. The results of this study support the hypothesis that the uncapping of varroa-parasitized brood cells is driven by abnormal odors from the parasitized pupae.

A survival field test was initiated in 1999 to observe the effects of no treatment against Varroa destructor on European honey bee colony survival. After losses of over two-thirds of the 268 original colonies, new colonies were made from the survivors. In 2002, genetic material from these survivors was bred into an independent group of 60 colonies. In 2013, 519 non-treated colonies from both groups were being used for commercial beekeeping, and mite populations were very low. This indicates that under commercial beekeeping conditions, simple methods can be used to select for reduced mite populations.

Varroa mites are important honey bee ecto-parasites that have caused disaster to the beekeeping industry in Europe and America. The extent of spread of these mites in Africa is not clearly known, but several sub-Saharan African countries including Uganda have been on the varroa-suspect list. We surveyed 16 districts falling in eight agroecological zones in Uganda with the aim of establishing the presence of varroa mites. Within each district, at least two subcounties were visited for honey bee sample collection and varroa detection between September 2011 and April 2013. Honey bee samples collected were screened for varroa mites by dusting with thymol. Farmers and beekeeping extension workers were interviewed on their knowledge of varroa. The results indicate that varroa mites were present in all the districts and agroecological regions sampled. Bee farmers and beekeeping extension workers were completely unaware of the presence of the varroa mites. The farmers reported no changes in honey production and h...

Nosema spp. and Varroa destructor are common parasites of honey bee colonies. Beekeepers routinely treat colonies with the fungicide fumagillin to control Nosema and an array of miticides to control V. destructor. Interactions between these parasites and chemical treatments are poorly understood. We allocated honey bee colonies to distinct chemical treatment regimes and monitored parasite intensities in the subsequent year. Infections of Nosema and infestations of V. destructor were positively correlated. Fumagillin was effective at mitigating Nosema intensities only over the short term, suggesting that biannual application is essential. V. destructor intensities were higher in colonies that had been previously treated with miticides, reasons for this warrant further investigation.

The ectoparasitic mite Varroa destructor is one of the main plagues of honey bees Apis mellifera. Grooming behavior is a resistance mechanism through which parasitized bees can dislodge mites by th...

The aim of this study was to assess infestation levels of Varroa destructor in some honey bee colonies from the National breeding program in the central part of Iran, and the relationship between mite infestation levels and postcapping period (PCP) of worker brood cells. Shortening the PCP is an important parameter limiting the success of varroa mite reproduction in honey bee colonies. In the present study, four pure-bred line colonies from isolated areas were selected to investigate the brood capping durations and mite infestation levels. Cages were used to synchronize egg laying of the queens and the time of capping and emerging of the brood cells was recorded at two-hour intervals. The results did not show any significant differences on the average of PCP of brood cells and mite infestation levels among test colonies. In addition, non-significant correlations were found between mite infestation and the capping period during the experiment. A relatively shorter capping period of brood cells was observed...

Two important traits that contribute to honey bee (Apis mellifera) colony survival are resistance to varroa and longevity of worker bees. We investigated the relationship between a panel of single nucleotide polymorphism markers and three phenotypic measurements of colonies: (a) percentage of mites in brood (MIB); (b) proportion of fallen injured mites; and (c) longevity of workers. We used single marker analysis to identify genetic intervals that may confer resistance and increased lifespan. One gene related to memory and learning, Ddc was identified for MIB, as was acj6, which functions for olfactory perception. These genes may contribute to elevated levels of mite detection and removal. Three genes were identified with high relevance for mite injury. CYP315A1 and Ptp69D function in motor neuron axon guidance in response to chemical stimuli. RabGAP11 is also involved in sensory function, specifically sensory organ development. Evidence for the longevity quantitative trait locus was also strong and one g...

In temperate climates, honey bees (Apis mellifera) survive the winter by entering a distinct physiological and behavioral state. In recent years, beekeepers are reporting unsustainably high colony losses during the winter, which have been linked to parasitization by Varroa mites, virus infections, geographic location, and variation across honey bee genotypes. Here, we review literature on environmental, physiological, and social factors regulating entrance, maintenance, and exit from the overwintering state in honey bees in temperate regions and develop a testable model to explain how multiple factors may be acting synergistically to regulate this complex transition. We also review existing knowledge of the factors affecting overwintering survival in honey bees and providing suggestions to beekeepers aiming to improve their colonies' overwintering success.

The Varroa mite (Varroa destructor) is implicated as a major disease factor in honey bee (Apis mellifera) populations worldwide. Honey bees are extensively relied upon for pollination services, and in countries such as New Zealand and Australia where honey bees have been introduced specifically for commercial pollinator services, the economic effects of any decline in honey bee numbers are predicted to be profound. V. destructor established in New Zealand in 2000 but as yet, Australia remains Varroa-free. Here we analyze the history of V. destructor invasion and spread in New Zealand and discuss the likely long-term impacts. When the mite was discovered in New Zealand, it was considered too well established for eradication to be feasible. Despite control efforts, V. destructor has since spread throughout the country. Today, assessing the impacts of the arrival of V. destructor in this country is compromised by a paucity of data on pollinator communities as they existed prior to invasion. Australia’s Varroa-free status provides a rare and likely brief window of opportunity for the global bee research community to gain understanding of honey bee-native pollinator community dynamics prior to Varroa invasion.