Varroa Destructor Research Articles

Honey bee populations surviving Varroa destructor parasitism in Latin America and their mechanisms of resistance

The honey bee (Apis mellifera) parasitic mite, Varroa destructor, is considered one of the main causes of colony losses in European honey bee (EHB) populations around the world. However, some EHB and Africanized honey bee (AHB) populations (derived from the African subspecies A. m. scutellata) that inhabit tropical and subtropical regions of the Americas, have survived varroa mite infestations in the absence of acaricide treatments. It is conceivable to expect that these honey bee populations, which have been subjected to natural selection over decades, would have developed resistance against V. destructor or possess pre-existing adaptations that allow them to survive mite parasitism. Here, we present a comprehensive literature review describing the spread of V. destructor and the honey bee populations occurring in Latin America (LA), and summarize the evidence of resistance of those populations to V. destructor. We also analyze reports describing the potential mechanisms of mite resistance and how they operate in those honey bee populations. Studies of a few EHB, as well as of numerous AHB populations exhibiting resistance to V. destructor in LA, unveil the existence of evolutionary adaptations that restrain V. destructor population growth and provide insight into the current host-parasite relationship. This review supports the notion that selective breeding of local honey bee populations from LA could be a viable strategy to manage varroa mite infestations in colonies.

Safety assessment of high doses of vaporized oxalic acid on honey bee worker health and queen quality

IntroductionThe honey bee ectoparasitic mite, Varroa destructor, is one of the main causes of honey bee colony loss worldwide. Synthetic acaricides are the most commonly used strategy for varroa control, however, resistance to these acaricides has emerged. Consequently, the use of organic acids for varroa control is gaining more interest among beekeepers. For example, oxalic acid (OA) is a natural compound that has been shown to be an effective acaricide against varroa mites, however, the potential toxicity of OA to adult bees and queens is poorly understood. The objective of the study was to evaluate the toxicity of incremental doses of vaporized OA on honey bee workers and queens.MethodsWe exposed 32 colonies to incremental doses (0, 5, 10 or 20 g per colony) of vaporized OA once per week over four consecutive weeks and we monitored the acute and long-term toxicity. We investigated the short-term effects of OA administration by evaluating adult bee mortality, brood production, and population size. Next, we evaluated the long-term effects of OA application on both worker bees and queens. Regarding workers, we investigated their ability to rear new queens. As for queens, we measured acceptance, performance, and sperm quality.ResultsWe found that colonies treated with 20 g OA (20 times the label dose) had a statistically significant increase in worker bee mortality, with a non-significant, 23% decrease in brood relative to controls. No significant differences were observed in queen performance nor sperm quality.DiscussionWe found that repeated application of vaporized OA, at up to 20 times the label dose, had no significant short-term nor long-term, negative effects on colony or queen health, with the exception of a short-term increase in adult bee mortality in the 20 g OA-treated group. The results of this study support the safety of higher-than-label doses of OA for honey bee colonies. The observed increase in adult bee mortality in the 20 g OA dose group in this study suggests that OA doses should be maintained below 20 g per brood chamber.

ProtectaBEE® and bee vectoring: innovating hive-based health with inspensing technology for sustainable apiculture

Apivectoring, or bee vectoring, employs managed bees to distribute powders containing disease and pest-fighting biocontrol agents during pollination flights to crops. Our research introduces a novel application of this concept, termed inspensing, which leverages bee vectoring for hive-based benefits. In inspensing, bees traverse through a carrier powder combined with products aimed at combating pathogens or pests within the hive. To facilitate this, we developed the ProtectaBEE® system, an innovative beehive-entrance technology that guides bees through a compartment inoculated with an inspensing powder. This system facilitates the application of beneficial agents into the hive without the need for beekeepers to open the hive, thereby streamlining the treatment process and reducing hive disturbance. To analyze the effectiveness of the system, we employed a fluorescent tracer in a powder formulation for tracking distribution throughout the hive. Complementing this, we inspensed a living dry powder-formulated biocontrol agent, Beauveria bassiana, an entomopathogenic fungus known to reduce Varroa mite populations, and detected its presence in the hive using PCR. The fluorescent powder was detected in 78.8% of the samples while B. bassiana was confirmed in up to 86.2% of larvae and 91.7% of mites. Our results underscore the system's efficacy in delivering material throughout the hive and affirm the potential for inspensing dry-powder-formulated biocontrol agents to manage Varroa destructor. Inspensing paves new paths for optimizing bee health and pest control strategies, streamlining disease management, simplifying hive maintenance, and minimizing beekeeper intervention, all contributing to sustainable apiculture.

Evaluation of a new plant-based formulation to control Varroa mite (Varroa destructor) in honey bee (Apis mellifera) colonies

Evaluation of a new plant-based formulation to control Varroa mite (Varroa destructor) in honey bee (Apis mellifera) colonies

Diagnostic study on major honeybee disease, pests and predators in North Western Ethiopia.

The study was conducted in Pawe district from Benishangul-Gumuz and Jawi and Fagita Lekoma districts from the Amhara region to investigate major honeybee pests, predators and diseases. Using a purposive sampling technique, 183 households were interviewed, and 240 samples were collected for laboratory analysis of bee disease; data were analysed using descriptive statistics. The share of hive types owned by sampled respondents was 88.6%; overall, 1.1% and 10.3% were traditional, transitional and modern beehives, respectively. About 92% of the sample respondents acquired their base colonies by catching swarm bees on the apex of trees. The majority of beekeepers executed external inspections of their colony, whereas only 50% carried out internal inspections. Based on the responses of beekeepers, around 48.9%, 56.3% and 23.1% of colonies absconded every year from Pawe, Jawi and Fagita Lekoma districts, respectively. Ants, wax moths, bee lice, beetles, spiders, birds, monkeys and honey badgers were the major honeybee pests and predators discovered in study areas in decreasing order. Concerning the incidence of Varroa mites, Nosema apis and amoeba disease, 27.5%, 60% and 71.6% of samples showed positive results in study locations, respectively. From this result, we observed that ants, wax moths, bee lice, beetles, spiders, birds, monkeys and honey badgers were the major honeybee pests and predators. The prevalence of amoeba disease was comparatively higher in highland areas and in the summer season. This finding suggests the need for the alertness of beekeepers in controlling bee disease and pests and strengthening bee colonies through seasonal colony management. There should be a strict quarantine, and check-up undertaken when a new colony is purchased from one region to another is essential.

Comparing the efficacy of alcohol wash and powdered sugar methods to dislodge the Varroa mite from the body of the adult honey bee

Comparing the efficacy of alcohol wash and powdered sugar methods to dislodge the Varroa mite from the body of the adult honey bee

Assessing the Efficacy of Organic and Chemical Treatments for Varroa Mite Control in Macedonian Apiaries

Varroa destructor infestations pose a significant global threat to honeybee colonies, affecting bee populations and honey production. The purpose of this study is to assess the performance of Apis mellifera L. honeybee colonies under various control methods with a particular focus on critical parameters like mite dewdrop, honey production and colony growth. The study took place in a normal apiary in the Pelister district for a year from April 2021 to March 2022. There were three treatment groups: Group A got Amitraz (a chemical treatment), group M got formic acid (an organic treatment) and group K got nothing (a control group) to see how the treatments affected the bees. Regular monitoring assessed parameters including dropped mites and Varroa infestation levels with honey production evaluated seasonally. The results showed that both chemical and organic treatments successfully decreased the levels of Varroa mite infestation compared to the control group, while also noting differences in colony growth and honey production. The Amitraz treatment did prevent the mites from dropping, but it also slowed down the young's development. On the other hand, the formic acid treatment kept the brood's development healthy, suggesting that it might be a better way to get rid of varroa. This study shows how important it is to think about how treatments affect important colony parameters. It also calls for more research like longterm observations, to fully understand how treatments affect the health, development and longevity of bee families which will eventually lead to the creation of more effective combined pest control methods.

Deformed wing virus genotypes A and B do not elicit immunologically different responses in naïve honey bee hosts.

Iflavirus aladeformis (Picornavirales: Iflaviridae), commonly known as deformed wing virus(DWV), in association with Varroa destructor Anderson and Trueman (Mesostigmata: Varroidae), is a leading factor associated with honey bee (Apis mellifera L. [Hymenoptera: Apidae]) deaths. The virus and mite have a near global distribution, making it difficult to separate the effect of one from the other. The prevalence of two main DWV genotypes (DWV-A and DWV-B) has changed over time, leading to the possibility that the two strains elicit a different immune response by the host. Here, we use a honey bee population naïve to both the mite and the virus to investigate if honey bees show a different immunological response to DWV genotypes. We examined the expression of 19 immune genes by reverse transcription quantitative PCR (RT-qPCR) and analysed small RNA after experimental injection with DWV-A and DWV-B. We found no evidence that DWV-A and DWV-B elicit different immune responses in honey bees. RNA interference genes were up-regulated during DWV infection, and small interfering RNA (siRNA) responses were proportional to viral loads yet did not inhibit DWV accumulation. The siRNA response towards DWV was weaker than the response to another honey bee pathogen, Triatovirus nigereginacellulae (Picornavirales: Dicistroviridae; black queen cell virus), suggesting that DWV is comparatively better at evading host antiviral defences. There was no evidence for the production of virus-derived Piwi-interacting RNAs (piRNAs) in response to DWV. In contrast to previous studies, and in the absence of V. destructor, we found no evidence that DWV has an immunosuppressive effect. Overall, our results advance our understanding of the immunological effect that DWV in isolation elicits in honey bees.

Field Application of an Innovative Approach to Assess Honeybee Health and Nutritional Status.

Environment, forage quality, management practices, pathogens, and pesticides influence honeybee responses to stressors. This study proposes an innovative approach to assess colony health and performance using molecular diagnostic tools by correlating hemolymph proteins with common measures of colony strength, prevalent honeybee pathogens (Varroa destructor and Nosema spp.), and essential trace elements (iron, zinc and copper). Colonies were selected from four apiaries located in different environmental and foraging conditions in the province of Bologna (Italy). Hemolymph samples were taken from June to October 2019. The Varroa infestation of the colonies was estimated by assessing the natural mortality of the mites, while the bees were tested for Nosema spp. spores using a microscopic method. Hemolymph proteins were quantified and separated using SDS-PAGE, and colony performance was assessed by determining adult bees, total brood, honey, and pollen reserves. The biomarkers measured proved to be useful for monitoring changes in performance and trophic conditions during summer and early autumn. Significant correlations were found between hemolymph proteins and colony performance measures. A positive correlation between pollen reserves, vitellogenin, and hexamerin 70a highlights the importance of these proteins for successful overwintering. In October, Varroa infestation was negatively correlated with total proteins, vitellogenin, apolipophorin II, transferrin, and hexamerin 70a, with negative implications for overwintering; furthermore, Varroa infestation was also negatively correlated with iron content, potentially affecting iron homeostasis.

Effects of landscape variation on thermoregulation and performance in Apis mellifera honey bee colonies: insights from mtDNA haplotypes

In a year-long research study, we delved into the thermoregulation and performance of twenty-one honey bee colonies situated in three distinct landscape settings: 1- Urban, 2- Agricultural (AG), and 3- Non-agricultural (Non-AG) environments. All colonies, consistent in size, were equipped with sensors designed to record inner hive temperature and humidity. Additionally, colonies were placed on precision electronic scales for weight monitoring. Varroa mite infestations were documented at seven different time points throughout the experiment. Colonies were genetically analyzed for subspecies and haplotype identification using the in silico DraI mtDNA COI-COII test. Our results unveiled an overall significant (p < 0.001) weight gain (5.76 kg) in colonies located within the urban setting, in stark contrast to both AG and Non-AG locations. Notably, colonies situated in the natural refuge center (Non-AG) experienced a weight loss of −0.05 kg, signaling a lack of sustainable forage resources in such a setting. Similarly, the inner hive temperature was significantly (p < 0.001) higher in the urban area (33.65 °C) with a significantly lower relative humidity (61.2%) compared to both other locations. Among the locations, the temperature variable displayed the strongest significant correlation (p < 0.001) with a positive correlation coefficient (r = 0.95). Two distinct mtDNA haplotypes were identified: C1 and C2j, characterizing the ligustica and carnica maternal origin, respectively. These haplotypes consistently demonstrated significant differences in their thermoregulation and weight gain, irrespective of the landscape compositions. The C1 haplotype displayed significantly higher weight gain alongside lower inner hive temperature and humidity levels compared to the C2j haplotype. No differences in mite infestation were observed between the various locations or haplotypes. Our data underscores the substantial impact of landscape composition on honey bee performance. It also unveils significant variations in thermoregulation and adaptation between haplotypes, shedding light on the multifaceted relationship between environmental factors, genetics, and bee colony dynamics.

The salivary gland transcriptome of Varroa destructor reveals suitable targets for RNAi-based mite control.

The mite Varroa destructorAnderson and Trueman (Mesostigmata: Varroidae) has a dramatic impact on beekeeping and is one of the main causes of honey bee colony losses. This ectoparasite feeds on honey bees' liquid tissues, through a wound created on the host integument, determining weight loss and a reduction of lifespan, as well as the transmission of viral pathogens. However, despite its importance, the mite feeding strategy and the host regulation role by the salivary secretions have been poorly explored. Here, we contribute to fill this gap by identifying the salivary components of V. destructor, to study their functional importance for mite feeding and survival. The differential expression analysis identified 30 salivary gland genes encoding putatively secreted proteins, among which only 15 were found to be functionally annotated. These latter include proteins with putative anti-bacterial, anti-fungal, cytolytic, digestive and immunosuppressive function. The three most highly transcribed genes, coding for a chitin-binding domain protein, a Kazal domain serine protease inhibitor and a papain-like cysteine protease were selected to study their functional importance by reverse genetics. Knockdown (90%-99%) by RNA interference (RNAi) of the transcript of a chitin-binding domain protein, likely interfering with the immune reaction to facilitate mite feeding, was associated with a 40%-50% decrease of mite survival. This work expands our knowledge of the host regulation and nutritional exploitation strategies adopted by ectoparasites of arthropods and allows the identification of potential targets for RNAi, paving the way towards the development of new strategies for Varroa mite control.

Complex dynamical behaviors of a honeybee-mite model in parameter plane

The honeybee has a significant impact on ecosystem stability, biodiversity conservation, and pollinating crops. However, during the past few years, there has been a sharp reduction in both the honeybee population and their colonies. It has been found that the parasitic mite Varroa destructor is responsible for the decline in honeybee colonies around the world, which in turn immensely affects the economic growth of a country. To investigate how the dynamics of a system is influenced by the growth of honeybees and the parasitism of mites, we study a nonlinear honeybee-mite population model in a discrete-time setup. We observe that an increase in the value of the queen’s egg-laying rate drives the system towards chaos. However, chaos can be controlled as well if the parasite attachment effect is increased. The intrinsic dynamical properties of the proposed system are investigated with the simultaneous variation of the queen’s egg-laying rate and the mite’s parasite attachment effect by constructing several largest Lyapunov exponent and isoperiodic diagrams. The investigation reveals the existence of several periodic structures in the quasiperiodic and chaotic regimes of the parameter plane, including Arnold tongues, saddle area, spring area, connected shrimp-shaped structure, and connected saddle area. We also find the appearance of a novel ‘jellyfish’-shaped periodic structure. One of the most fascinating findings of this study is the appearance of Arnold tongues along the inner boundary region of another Arnold tongue. In addition, this work also reveals different types of multistability, e.g., the coexistence of two, three, and even four attractors. What is more interesting is that the current analysis unveils the coexistence of five attractors as well, more specifically, four different periodic attractors coexist with the trivial fixed point attractor, which is quite rare in ecological systems. The structures of the basins of these coexisting attractors are either smooth or very complex in nature. Furthermore, the present study also discloses the fact that variation in the initial condition of the system can significantly change the appearance of the periodic structures in the parameter plane.

Beekeepers Support the Use of RNA Interference (RNAi) to Control Varroa destructor.

Current Varroa mite management strategies rely heavily on the use of pesticides, adversely affecting honey bee health and leaving toxic residues in hive products. To explore the likelihood of RNAi technology being utilised as an alternative control method for pests like Varroa, the opinions of beekeepers on the use of this new biotechnology were obtained using a mixed-methodology approach. In-person surveys and focus groups using the Q method were conducted to discover the willingness of beekeepers to utilise Varroa-targeting RNAi treatments in their hives, and to gain feedback to inform decisions before the implementation of this new technology. Overall, the beekeepers saw potential in RNAi being used to control Varroa in their hives and were eager to have access to an alternative to pesticide treatments. Participants raised concerns about unknown long-term effects on bees and other non-target species, and the potential of an uninformed public preventing them from accessing a new Varroa treatment. While further research and discussion is needed before RNAi treatments for Varroa become commercially available, RNAi technology presents a promising, species-specific and non-toxic solution for Varroa management.

From consumption to excretion: Lithium concentrations in honey bees (Apis mellifera) after lithium chloride application and time-dependent effects on Varroa destructor.

Owing to its systemic mode-of-action and ease of application, lithium chloride (LiCl) is an ideal varroacide for the control of Varroa destructor infestations in honey bee colonies. To better understand how LiCl functions within a colony, we screened different parts of honey bee anatomy for lithium accumulation. We wanted to elucidate the time-dependent effects of LiCl on V. destructor and its metabolism within honey bees when they were fed continuous LiCl treatments, as well as evaluate potential adverse effects such as accumulation in the hypopharyngeal glands of nurse bees, which could negatively impact queens and larvae. Cage experiments reveal rapid acaricidal onset, with >95% mite mortality within 48 h of treatment. Bee hemolymph analysis supports these observations, showing a rapid increase in lithium concentration within 12 h of treatment, followed by stabilization at a constant level. Lithium accumulates in the rectum of caged bees (≤475.5 mg kg-1 after 7 days of feeding 50 mm LiCl), reflecting the bees' metabolic and excretion process. Despite concerns about potential accumulation in hypopharyngeal glands, low lithium levels of only 0.52 mg kg-1 suggest minimal risk to the queen and 1st- and 2nd-instar larvae. Cessation of LiCl treatment results in a rapid decline in mite mortality in the first 5 days, which increases again thereafter, resulting in mite mortality of 77-90% after 10 days. These findings help optimize LiCl application in colonies to achieve high Varroa mortality without unwanted adverse effects and provide important baseline data for future registration. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The first complete mitochondrial genome of the genus Laelaps with novel gene arrangement reveals extensive rearrangement and phylogenetics in the superfamily Dermanyssoidea.

We collected 56 specimens ofLaelaps chini from the endemic Hengduan Mountain rat species (Eothenomys miletus) and obtained the first complete mitochondrial genome of L. chini by next-generation sequencing (NGS). The L. chini mitogenome is 16,507bp in size and contains 37 genes and a control region of 2380bp in length. The L. chini mitogenome has a high AT content and a compact arrangement with four overlapping regions ranging from 1 to 2bp and 16 spacer regions ranging from 1 to 48bp. We analyzed 13 protein-coding genes of L. chini mitogenome andfound that protein-coding genes in the L. chini mitogenome preferred codons ending in A/U and codon usage pattern was mainly influenced by natural selection. Cox1 has the slowest evolution rate and cox3 has the fastest evolution rate. We combined the mitochondrial genome of eight species ofgamasid mites in the superfamily Dermanyssoidea from Genbank and theL. chini mitochondrial genometo analyze its rearrangement patterns and breakpoint numbers. We found that the L. chini mitogenome showed a novel arrangement pattern and nine species ofgamasid mites in the superfamily Dermanyssoidea, which have been sequenced complete mitochondrial genomes to date, all showed different degrees of rearrangement. Laelaps chini, Echinolaelaps echidninus and Echinolaelaps fukinenensis were closely related species based on genetic distance and phylogenetic analyses. Notably they are clustered with Varroa destructor of the family Varroidae, suggesting that the family Varroidae is more closely related to the family Laelapidae, but more data are needed to test whether Varroa can be classified under the family Laelapidae. The L. chini mitogenome is the first complete mitochondrial genome for the genus Laelaps, and contributes to further exploration of the mitochondrial gene rearrangements and phylogeny for the superfamily Dermanyssoidea.

Origins, diversity, and adaptive evolution of DWV in the honey bees of the Azores: the impact of the invasive mite Varroa destructor.

Deformed wing virus (DWV) is a honey bee virus, whose emergence from relative obscurity is driven by the recent host-switch, adaptation, and global dispersal of the ectoparasitic mite Varroa destructor (a highly efficient vector of DWV) to reproduction on honey bees (Apis mellifera). Our study examines how varroa affects the continuing evolution of DWV, using the Azores archipelago, where varroa is present on only three out of the eight Islands, as a natural experimental system for comparing different evolutionary conditions and trajectories. We combined qPCR of 494 honey bee colonies sampled across the archipelago with amplicon deep sequencing to reveal how the DWV genetic landscape is altered by varroa. Two of the varroa-free Islands were also free of DWV, while a further two Islands were intriguingly dominated by the rare DWV-C major variant. The other four Islands, including the three varroa-infested Islands, were dominated by the common DWV-A and DWV-B variants. The varroa-infested Islands had, as expected, an elevated DWV prevalence relative to the uninfested Islands, but not elevated DWV loads, due the relatively high prevalence and loads of DWV-C on the varroa-free Islands. This establishes the Azores as a stable refuge for DWV-C and provides the most convincing evidence to date that at least some major strains of DWV may be capable of not just surviving, but actually thriving in honey bees in the absence of varroa-mediated transmission. We did not detect any change in DWV genetic diversity associated with island varroa status but did find a positive association of DWV diversity with virus load, irrespective of island varroa status.

Varroa destructor mite population dynamics in africanized honeybee (Apis mellifera) colonies in a semi-arid region.

Most published data on mite infestation rates in semi-arid regions have been collected over only 3 or 4 months during a specific period of the year. Therefore, the aim of this study was to observe parasite-host dynamics of hygienic and non-hygienic Africanized bee colonies considering environmental factors that may influence Varroa destructor mite infestation rates in a semi-arid region. To this end, the brood puncture method was applied to 37 colonies, forming two groups, namely G1, encompassing 16 hygienic colonies, and G2, comprising 21 non-hygienic colonies. After forming the groups, 300 worker bees from each colony were examined monthly for mite infestations and the data were correlated with climatological records. The monthly infestation average was considered low, below 10%, except in November, when it reached 12.19% ± 6.45. No statistically significant difference was observed for inter-group infestation rates (P > 0.05). When mite infestation rates were associated with climatic variables, they were linked to colony losses (32%) due to swarming. No significant correlations between hygienic behaviour and parasite infestation rates were noted. Nonetheless, these results support the idea that there is no need to apply acaricides for V. destructor control in Brazil.

Varroa Mite Counting Based on Hyperspectral Imaging.

Varroa mite infestation poses a severe threat to honeybee colonies globally. This study investigates the feasibility of utilizing the HS-Cam and machine learning techniques for Varroa mite counting. The methodology involves image acquisition, dimensionality reduction through Principal Component Analysis (PCA), and machine learning-based segmentation and classification algorithms. Specifically, a k-Nearest Neighbors (kNNs) model distinguishes Varroa mites from other objects in the images, while a Support Vector Machine (SVM) classifier enhances shape detection. The final phase integrates a dedicated counting algorithm, leveraging outputs from the SVM classifier to quantify Varroa mite populations in hyperspectral images. The preliminary results demonstrate segmentation accuracy exceeding 99% and an average precision of 0.9983 and recall of 0.9947 across all the classes. The results obtained from our machine learning-based approach for Varroa mite counting were compared against ground-truth labels obtained through manual counting, demonstrating a high degree of agreement between the automated counting and manual ground truth. Despite working with a limited dataset, the HS-Cam showcases its potential for Varroa counting, delivering superior performance compared to traditional RGB images. Future research directions include validating the proposed hyperspectral imaging methodology with a more extensive and diverse dataset. Additionally, the effectiveness of using a near-infrared (NIR) excitation source for Varroa detection will be explored, along with assessing smartphone integration feasibility.

Effective control of Varroa destructor mites with Juniperus excelsa, Juglans regia, Origanum onites, and Mentha spicata leaf extracts: a study of honey bee colonies

This study aimed to assess the efficacy of plant leaf extracts from Juniperus excelsa (J. excelsa), Juglans regia (J. regia), Origanum onites (O. onites), and Mentha spicata (M. spicata) in controlling Varroa destructor (V. destructor) mites, a major cause of honey bee colony loss. This research seeks to identify eco-friendly and sustainable alternatives for pest control in beekeeping practices. Forty honey bee colonies naturally infested with mites were selected. The colonies were divided into five groups, one control group and four treatment groups, which received varying concentrations of the plant leaf extracts. This study was conducted in two phases: determining the optimal dosage and conducting a field study during autumn and spring, during which the mite infestation levels were evaluated using the powdered sugar method. The powdered sugar method revealed that a 25% concentration of plant leaf extract was the most effective. In the autumn treatment, the efficacy rates were 87% for J. regia, 86% for J. excelsa, 83% for O. onites, and 68% for M. spicata. During spring treatment, rates were slightly reduced but remained promising, with 66% for O. onites, 63% for J. regia, 61% for J. excelsa, and 55% for M. spicata. This study highlights that plant leaf extracts offer a viable and eco-friendly alternative to traditional therapies for controlling Varroa in beekeeping when used at the appropriate dosage. This research provides valuable insights into sustainable pest management and the potential for innovative, environmentally friendly pest control solutions based on aromatic plant products.

The health of managed and wild-living Western honey bee colonies, Apis mellifera, on Guam

A survey conducted as part of the National Honey Bee Survey from 2013 to 2020 quantified the managed honey bee hives on Guam, sampled accessible wild-living colonies, and described associated diseases and pests. During this period the number of managed bee colonies increased from 20 to 121 which was associated with the formation of the Guam Beekeepers Association. Managed Apis mellifera colonies on Guam had significantly fewer parasites and diseases than reported in the USA. The Varroa mite, Varroa destructor, was detected in 2014 in a wild-living colony in southern Guam. The greater banded hornet, Vespa tropica, was first observed on Guam in 2016, with honey bee depredations observed in 2017. Nosema ceranae was initially detected in wild-living and managed colonies in 2013 and has been consistently observed since that time with little apparent effect on colony health as there have been no recorded colony losses in apiaries. No small hive beetle, Aethina tumida, Tropilaelaps mite, Tropilaelaps spp, American foulbrood, Paenibacillus larvae, European foulbrood, Melissococcus plutonius, chalkbrood, Ascosphaera sp. and 11 additional viral diseases of the 22 known to infest honey bees, including deformed wing virus, were observed.