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Honey bee (Apis mellifera) colonies usually survive less than 16 months if populations of parasitic mite (Varroa destructor) are not controlled. The timing of when to control Varroa populations is aided by using methods that estimate the number of Varroa in hives. The relative efficacy of eight methods used to calculate the number of Varroa in samples of 300 adult bees was established: icing sugar shake (78%), low-suds detergent wash (86%), ethanol wash (72%), 10-min exposure to Apistan® (42%), ether roll (42%), a 30-s exposure to grapefruit leaf smoke (5%), a 30-s exposure to fluvalinate smoke (0%), and a 30-s exposure to tobacco leaf smoke (0%). A range of approaches were investigated to improve the efficacy and reliability of some of the methods. The following approaches improved the efficacy of four methods so that more than 95% of the Varroa were recovered: two 15-s shakes with at least 10 g of icing sugar; three 15-s washes with low-suds detergent; three 30-s washes with ethanol; and a 35-min exposure to an Apistan® strip. [ABSTRACT FROM AUTHOR]

Background: The mite Varroa destructor is the most serious pest of the western honey bee (Apis mellifera) and a major factor in the global decline of colonies. Traditional control methods, such as chemical pesticides, although quick and temporarily effective, leave residues in hive products, harming bees and operators' health, while promoting pathogen resistance and spread. As a sustainable alternative, RNA interference (RNAi) technology has shown great potential for honey bee pest control in laboratory assays, but evidence of effectiveness in the field has been lacking. Methods: We investigated the efficacy and feasibility of a RNAi treatment to improve bee health under natural beekeeping conditions by integrating a honey bee diet with a mixture of dsRNA targeting V. destructor acetyl-CoA carboxylase, Na+/K+ ATPase and endochitinase genes. Results: In treated hives, we observed that the average infestation rate of phoretic Varroa mite was reduced by 33% and 42% relative to control bees fed with sucrose and GFP-dsRNA, respectively. The dsRNA treatment did not affect bee survival, and the beekeepers involved in the project found the method manageable in the apiary and non-intrusive to production activities. Conclusions: Our findings demonstrate the feasibility and effectiveness of RNAi technology in reducing Varroa mite infestations under natural rearing conditions. This study supports the potential of RNAi as a promising alternative to chemical pesticides, offering a targeted, efficient and sustainable solution for managing V. destructor in honey bee populations. [ABSTRACT FROM AUTHOR]

Background: Deformed wing virus (DWV) is a major honey bee pathogen that is actively transmitted by the parasitic mite Varroa destructor and plays a primary role in Apis mellifera winter colony losses. Despite intense investigation on this pollinator, which has a unique environmental and economic importance, the mechanisms underlying the molecular interactions between DWV and honey bees are still poorly understood. Here, we report on a group of honey bee proteins, identified by mass spectrometry, that specifically co-immunoprecipitate with DWV virus particles. Results: Most of the proteins identified are involved in fundamental metabolic pathways. Among the co-immunoprecipitated proteins, one of the most interesting was arginine kinase (ArgK), a conserved protein playing multiple roles both in physiological and pathological processes and stress response in general. Here, we investigated in more detail the relationship between DWV and this protein. We found that argK RNA level positively correlates with DWV load in field-collected honey bee larvae and adults and significantly increases in adults upon DWV injection in controlled laboratory conditions, indicating that the argK gene was upregulated by DWV infection. Silencing argK gene expression in vitro, using RNAi, resulted in reduced DWV viral load, thus confirming that argK upregulation facilitates DWV infection, likely through interfering with the delicate balance between metabolism and immunity. Conclusions: In summary, these data indicate that DWV modulates the host ArgK through transcriptional regulation and cooptation to enhance its fitness in honey bees. Our findings open novel perspectives on possible new therapies for DWV control by targeting specific host proteins. [ABSTRACT FROM AUTHOR]

Simple Summary: A major threat to honey bees is the Varroa destructor mite, a parasite that feeds on bee fat bodies and transmits viruses, leading to significant colony losses. Detecting the level of Varroa infestation in the apiary is crucial for defining appropriate intervention strategies and preventing irreparable damage to the colonies. Traditional methods based on manual counting are time-consuming and require meticulous attention. In this study, we tested an AI-based portable scanner for Varroa destructor detection. The device operates through image analysis of a sticky sheet placed under the beehive for several days, capturing the Varroa mites that naturally fall. Over 17 weeks, the scanner was tested with sheets from five beehives each week, assessing the accuracy, reliability, and speed of the method compared to conventional human visual inspection. Results show that the system can consistently repeat measurements with high precision, with an error rate in detecting Varroa mites consistently below 1% when there are more than 10 mites per sheet. Given its repeatability and reliability, the device can be considered a valuable tool for beekeepers and scientists, offering the opportunity to monitor many beehives in a short time. Beekeeping is a crucial agricultural practice that significantly enhances environmental health and food production through effective pollination by honey bees. However, honey bees face numerous threats, including exotic parasites, large-scale transportation, and common agricultural practices that may increase the risk of parasite and pathogen transmission. A major threat is the Varroa destructor mite, which feeds on honey bee fat bodies and transmits viruses, leading to significant colony losses. Detecting the parasite and defining the intervention thresholds for effective treatment is a difficult and time-consuming task; different detection methods exist, but they are mainly based on human eye observations, resulting in low accuracy. This study introduces a digital portable scanner coupled with an AI algorithm (BeeVS) used to detect Varroa mites. The device works through image analysis of a sticky sheet previously placed under the beehive for some days, intercepting the Varroa mites that naturally fall. In this study, the scanner was tested for 17 weeks, receiving sheets from 5 beehives every week, and checking the accuracy, reliability, and speed of the method compared to conventional human visual inspection. The results highlighted the high repeatability of the measurements (R2 ≥ 0.998) and the high accuracy of the BeeVS device; when at least 10 mites per sheet were present, the device showed a cumulative percentage error below 1%, compared to approximately 20% for human visual observation. Given its repeatability and reliability, the device can be considered a valid tool for beekeepers and scientists, offering the opportunity to monitor many beehives in a short time, unlike visual counting, which is done on a sample basis. [ABSTRACT FROM AUTHOR]

Olfaction mediated by the antennae is a vital sensory modality for arthropods and could be applied as a tool in pest control. The ectoparasitic mite Varroa destructor poses a significant threat to the health of the honey bee Apis mellifera worldwide and has garnered global attention. To better understand the chemical ecology of this host–parasite relationship, we collected and characterized the volatile organic compounds (VOCs) from V. destructor and used electroantennography (EAG) to record the responses of honey bee (A. c. cerana and A. m. ligustica) antennae to the different VOCs. Fifteen VOCs were detected from V. destructor using gas chromatography–mass spectrometry (GC-MS), which mainly contained ethyl palmitate, followed by isoamyl alcohol, nonanal, and ethyl oleate. The EAGs for ethyl palmitate were higher at the lowest stimulus loading (5 μg/μL in liquid paraffin) in A. c. cerana compared to A. m. ligustica, suggesting that A. c. cerana may have acute sensitivity to low concentrations of some VOCs from V. destructor. After exposure to ethyl palmitate for 1 h, the relative expression levels of AcerCSP1 and AcerOBP21 in A. c. cerana significantly increased, as well as the level of AmelCSP1 in A. m. ligustica, while AmelOBP8 showed no significant changes. The results indicate that the EAG response was influenced by the VOC composition and concentration. A. c. cerana tended to be more responsive than A. m. ligustica to the VOCs of V. destructor. Our findings offer a deeper understanding of how bees recognize V. destructor, potentially using ethyl palmitate as a chemical cue. [ABSTRACT FROM AUTHOR]

A survey was conducted of microbes and arthropods associated with Varroa destructor (Acari: Varroidae) mites (hereafter, Varroa) collected from honey bee colonies in Maryland, USA. Live Varroa were challenged with samples of both microbes and arthropods and assessed for their potential as biocontrol agents against the mites. To our knowledge, this is the first survey of natural enemies of Varroa conducted in North American honey bee colonies. The survey revealed 21 fungi, 25 bacteria, one nematode, and 8 arthropod species associated with Varroa in honey bee colonies, and from challenge assays using 11 of these, including 4 species of fungi, 2 species of bacteria, a parasitic nematode, 2 insects (Hemiptera and Hymenoptera), and 2 arachnids (Pseudoscorpiones) were capable of killing Varroa. This assemblage of Varroa natural enemies was similar to taxa identified from surveys conducted elsewhere globally, suggesting there is a core assemblage of organisms capable of killing Varroa that are best suited to tolerate the sometimes-hostile abiotic and biotic conditions of the hive environment. Generally, entomopathogenic fungi and bacteria assessed in our study showed the highest efficacy against Varroa, and for some, efficacy was comparable to that determined by other researchers, suggesting entomopathogenic fungi and bacteria appear to be the most promising candidates for development into commercially viable varroicides. A novel parasitic nematode identified from our survey killed greater than 90% of infected hosts. In addition, the behaviours of some arthropods toward Varroa observed in our study were indicative of predation on the mites. [ABSTRACT FROM AUTHOR]

ABSTRACT Honeybees, Apis mellifera, have experienced the full impacts of globalisation, including the recent invasion by the parasitic mite Varroa destructor, now one of the main causes of colony losses worldwide. The strong selection pressure it exerts has led some colonies to develop defence strategies conferring some degree of resistance to the parasite. Assuming these traits are partly heritable, selective breeding of naturally resistant bees could be a sustainable strategy for fighting infestations. To characterise the genetic determinism of varroa resistance, we conducted the largest genome wide association study performed to date on whole genome sequencing of more than 1500 colonies on multiple phenotypes linked to varroa resistance of honeybees. To take into account some genetic diversity of honeybees, colonies belonging to different ancestries representing the main honeybee subspecies in Western Europe were included and analysed both as separate populations and combined in a meta‐analysis. The results show that varroa resistance is substantially heritable and polygenic: while 60 significant associations were identified, none explain a substantial part of the trait genetic variance. Overall our study highlights that genomic selection for varroa resistance is promising but that it will not be based on managing a few strong effect mutations and rather use approaches that leverage the genome wide diversity of honeybee populations. From a broader perspective, these results point the way towards understanding the genetic adaptation of eusocial insects to parasite load. [ABSTRACT FROM AUTHOR]

The nutritional physiology of parasites is often overlooked although it is at the basis of host-parasite interactions. In the case of Varroa destructor, one of the major pests of the Western honey bee Apis mellifera, the nature of molecules and tissues ingested by the parasite is still not completely understood. Here, the V. destructor feeding biology was explored through artificial feeding, dissection of the mite's gut and proteomic analyses. More specifically, the proteome of guts extracted from starved mites and honey bee-fed mites was compared to highlight both the parasite proteins likely involved in food processing and the honey bee proteins actually ingested by the mite. We could identify 25 V. destructor candidate proteins likely involved in the parasite digestion. As the host developmental stages infested by the mite are diverse, we also focused on the identity and on the origin of honey bee proteins ingested by the mite when it feeds on larvae, pupae or adults. We highlighted profiles of consumed honey bee proteins and their variations throughout the V. destructor life cycle. These variations matched the ones observed in the honey bee hemolymph, showing that this tissue is an important part of the mite's diet. Based on the variations of abundance of the most consumed honey bee proteins and on their functions, the potential implication of these key candidate nutrients in V. destructor reproduction is also discussed. Author summary: Varroa destructor is one of the major parasitic pests in modern beekeeping worldwide. Since it shifted host from Eastern to Western honey bees, it was shown to weaken colonies by feeding on both immature and adult stages while transmitting several deadly viruses in the process. Nutrition, an overlooked aspect of parasite biology, is thus a key to comprehend the V. destructor life cycle and its impacts on its honey bee host. We explored the feeding physiology of this ectoparasite by analysing the protein content of its isolated gut to compare it with the protein composition of the honey bee tissues ingested. We highlighted several mite proteins probably involved in digestion and many honey bee derived proteins acquired during the feeding. Honey bee hemolymph is an important part of the mite's diet although the diet could vary throughout the cycle, especially when mites feed on adult bees. The abundance of the most regularly ingested honey bee proteins such as Vitellogenin or Hexamerin varies throughout the bee development and could directly impact the parasite physiology. The analysis and identification of key proteins required for the mite's survival and reproduction will pave the way for the development of more specific control strategies. [ABSTRACT FROM AUTHOR]

The Tropilaelaps spp. (Mesostigmata: Laelapidae), an ectoparasitic mite originally associated with such Asian giant honey bees as Apis dorsata, A. breviligula and A. laboriosa, has increasingly become a focus of global concern due to its severe effects on Western honey bee colonies (Apis mellifera) and its recent geographic expansion. This study documents the first reported presence of Tropilaelaps mercedesae in Western Georgia's Samegrelo-Zemo Svaneti region, specifically in seven honey bee colonies (A. mellifera caucasica) from three apiaries. We conducted brood sample inspections, DNA barcoding and morphological measurements to confirm mite identification. Our findings revealed high infestation rates of T. mercedesae, co-infestation with Varroa destructor and notable mite reproductive success. These results underscore the threat posed by T. mercedesae to Georgian apiculture and highlight the potential for further spread across Europe. Immediate action and vigilant monitoring by national and international authorities are crucial to mitigate the impact on beekeeping and agriculture. [ABSTRACT FROM AUTHOR]

Honey bees, Apis mellifera L. (Hymenoptera: Apidae), are the most important pollinators of agricultural products and plants in the natural environment. Honeybees are an important ecosystem component due to their role in nature and agricultural production. Bacterial, fungal, viral, and parasitic factors in bee farms are among the most important causes of honey bee colony losses. Honey bee diseases (bacterial, fungal and viral) and parasites are among the most important factors limiting beekeeping development and production efficiency in Türkiye. In addition to diseases caused by bacterial and fungal agents, diseases caused by viral agents are very diverse. Viruses, especially mixed infections, cause colony losses and are the most important factors in the decline of honey bee colonies. In this study the presence and prevalence of honey bee pathogens (Varroa destructor, Nosema ceranae, Paenibacillus larvae, and nine viruses) in suspicious samples with colony losses were investigated in Sivas province. For this purpose, microscopic, microbiological, and molecular methods were investigated on larvae and adult bee. The results showed that the most common viral pathogens in samples from Sivas province were Deformed Wing Virus (70%), Apis mellifera Filamentous Virus (60%), Black Queen Cell Virus (60%), Sacbrood Virus (55%) and Varroa destructor virus-1 (40%), respectively. In some samples, it was observed that there was a double (17.5%), triple (30%), quadruple (22.5%), or even quintuple (17.5%) association of viral agents. The viral infection/varroa coexistence rate was determined to be 50%. It was determined that 22.5% of the samples examined contained Nosema spores, while 12.5% were positive for P. larvae. Revealing the distribution of bee diseases will help beekeepers in disease-fighting and taking measures. This study showed the presence of the AmFV and the Varroa destructor virüs-1 in the Sivas province of Türkiye for the first time. [ABSTRACT FROM AUTHOR]

Simple Summary: One of the main culprits of honey bee colony losses is the parasitic mite, Varroa destructor, which is primarily controlled with acaricides, which lose efficacy due to resistance and can contaminate honey. An alternative is to breed bees that are resistant to Varroa, which was conducted in this study by bidirectional selection for mite fall to obtain colonies with low (resistant) or high (susceptible) Varroa population growth (LVG and HVG, respectively). Selection for three generations resulted in greatly reduced Varroa population growth in LVG compared to HVG colonies. In addition, Varroa infestation rates of bees were lower in LVG colonies, and they had lower Deformed Wing Virus (DWV) infection levels. Survival of Varroa-parasitized bees was higher for LVG bees compared to HVG bees, which may help explain why colony winter survivorship was higher for LVG colonies than for HVG colonies. Selecting colonies of bees for LVG resulted in better individual and colony bee health, demonstrating its effectiveness as a means of breeding for controlling Varroa mites. Honey bee (Apis mellifera) population declines have been associated with the parasitic mite, Varroa destructor, which is currently primarily controlled by the use of acaricides. An alternative is to breed for resistance to Varroa, which was conducted in this study by bidirectional selection for mite fall to obtain colonies with low (resistant) or high (susceptible) Varroa population growth (LVG and HVG, respectively). Selection for three generations resulted in approx. 90% lower Varroa population growth in LVG than in HVG colonies. In addition, late summer Varroa infestation rates of brood and adults were both significantly lower in LVG colonies (p < 0.01), which was also significantly associated with lower Deformed Wing Virus (DWV) infection levels (p < 0.01). Survival of Varroa-parasitized bees was almost 50% higher for LVG bees compared to HVG bees (p < 0.01). Also, colony winter survivorship was significantly higher for LVG colonies than for HVG colonies (p < 0.05). However, the higher colony populations observed for LVG colonies were not significantly different from those of HVG colonies. Overall, individual and colony health was improved by selecting colonies for LVG, demonstrating its effectiveness as a means of breeding for controlling Varroa populations in honey bee colonies. [ABSTRACT FROM AUTHOR]

Varroa mite threatens honey bees worldwide by affecting larvae and adults and causing viral diseases associated with colony collapse. This study investigates its prevalence and infestation level, and morphometric traits in Southern Sudanese (SS) and Northern Sudanese (NS) phytogeographical zones of Burkina Faso. We visited 238 hives from 48 apiaries in 9 provinces. Phoretic varroa mites were detected through a 70% alcohol wash on approximately 300 worker bees. Once in the laboratory, 7 morphometric characters were measured on 1 to 10 varroa mites per hive. According to these measurements, the mites were identified as Varroa destructor,Anderson & Trueman, 2000. Data analysis reveals that 91.6% of colonies of the whole sample are infested with varroa. In NS zone, the provinces of Bazega and Zoundweogo show high infestation level (5.93% and 7.18% respectively), while in the SS zone, Nahouri and Ziro exhibit the highest level (8.19% and 9.00%) respectively. In terms of body length and body width (BL and BW), varroa mites from SS zone display averages of 1176.04 ± 40.1 µm and 1765.14 ± 49.2 µm, while those from the NS zone have average values of 1167.44 ± 40.8 µm and 1755.36 ± 53.42 µm. These morphological differences are statistically significant (P ≤ 0.05), highlighting variability that may result from local adaptations or genetic variations. The morphological diversity of this parasite has implications for its biology, dispersion, and virulence towards bees. Future studies should explore genetic factors influencing parasitic dynamics and bee resistance for effective management strategies. [ABSTRACT FROM AUTHOR]

Lactic acid is an alternative treatment to hard chemicals against Varroa destructor, the parasitic mite of the Western honey bee Apis mellifera. This soft acaricide is used only for small apiaries due to its laborious administration. However, the mode of action of this honey bee medication remains unknown. Previous studies showed that a direct contact between the arolia of V. destructor and lactic acid altered their morphology and led to an impairment of grip. Yet, there is no evidence for the way of action of lactic acid in a realistic in-hive scenario, i.e. after an indirect exposure of the mite through honey bees. We investigated the nature of lactic acid activity in the hive treatment context. The local and/or systemic way of action of this honey bee treatment against V. destructor was studied through a behavioural and toxicological approach at the individual level. On one hand, we confirmed the altered morphology for the arolia of mites and studied the evolution of the process over time. On the other hand, we found that haemolymph contaminated with lactic acid did not kill the feeding parasitic mite. These findings support a local mode of action. In order to unravel the sequence of events leading to the local contact between the acid and the mite on bees, we also documented the olfactory valence of lactic acid for A. mellifera and V. destructor. This work provides a new comprehension of lactic acid activity against the parasitic mite through honey bee exposure and gives new opportunities for control strategies against V. destructor. [ABSTRACT FROM AUTHOR]

Six Corsican essential oils (EOs) from Humulus lupulus were studied for their activity against Varroa destructor adults and Apis mellifera pupae. The GC/MS analysis of EOs showed that the major compounds of all accessions were α-Humulene, Myrcene, α-Selinene, β-Selinene, (E)-β-Farnesene, and (E)-β-Caryophyllene. Bioassays showed that EOs from each accession acted as toxins and repellents against V. destructor adults, with lower toxicity towards A. mellifera pupae. In terms of efficacy against V. destructor adults, Smaragd 2020 oil displayed the highest performance, with LC50 and LC90 values of 2.33 and 7.83 µL/L air, respectively. Meanwhile, Smaragd 2019 and Tettnanger EOs showed moderate toxicity, with LC50 values of 3.101 and 3.66 µL/L air, along with LC90 values of 11.67 and 19.89µL/L air, respectively. The oils from Biguglia and Ajaccio were strongly repellent to Varroa adults. At the lowest concentration (2 µL/mL), these EOs exhibited percentage of repellence greater than 70% after 2h exposure, with RC50 values of 1.66 and 1.26 µL/L air, respectively. Concerning their insecticidal effects, EOs demonstrate reduced toxicity towards bee pupae when compared to Varroa mites. Notably, Ajaccio stands out for inducing lower mortality among bee pupae, with a selectivity ratio below 2 and LC50 of 11.25 µL/L air. [ABSTRACT FROM AUTHOR]

The western honey bee (Apis mellifera) is severely impacted by the parasitic Tropilaelaps mercedesae mite, which has the capacity to outcompete Varroa destructor mites (the current leading cause of colony losses) and more rapidly overwhelm colonies. While T. mercedesae is native to Asia, it has recently expanded its geographic range and has the potential to devastate beekeeping worldwide if introduced to new regions. Our research exploited the dependence of T. mercedesae on developing honey bees (brood) by combining a cultural technique (brood break) with U.S. registered chemical products (oxalic acid or formic acid) to manage T. mercedesae infestation. To evaluate this approach, we compared four treatment groups: (1) Brood Break; (2) Brood Break + Formic Acid (FormicPro®); (3) Brood Break + Oxalic Acid dribble (Api-Bioxal®); and (4) untreated Control. We found that the mite infestation rate of worker brood in Control colonies rose from 0.4 to 15.25% over 60 days, whereas all other treatment groups had infestation rates under 0.11% on Day 60. Mite fall assessments showed similar results, whereby Control colonies had 15.48 mites fall per 24 h on day 60 compared to less than 0.2 mites for any other treatment group. Evaluation of colony strength revealed that Brood Break + Formic Acid colonies had slightly reduced adult honey bee populations. No treatment eliminated all mites, so additional measures may be needed to eradicate T. mercedesae if detected in countries that do not currently have T. mercedesae. [ABSTRACT FROM AUTHOR]

The honey bee ectoparasite Varroa destructor is the main cause of honey bee colony losses worldwide. Over the last decades, several projects have focused on improving the robustness of Apis mellifera against this parasitic mite. Selection traits, such as mite non-reproduction (MNR) and Varroa sensitive hygiene (VSH), are favored selection factors in Varroa resistance projects. VSH is a trait where adult honey bees remove the Varroa-infested brood. During this process, the female mites are arrested in their reproductive cycle leading to a reduction of the Varroa population within the bee colony. From 2019 to 2022, 1402 queens were instrumentally inseminated with single or multiple drones in a breeding program. Colonies headed by these queens were established annually, and the MNR and VSH levels were analyzed. VSH was evaluated in response to cells artificially infested with Varroa, and colonies with high VSH values were used to generate our selected VSH stock. Despite crossing high VSH drones and queens, we measured a remarkable heterogeneity of MNR and VSH in the next generation(s), most likely due to the well-described, high recombination rate in the honey bee genome. When assessed multiple times in the same colony, great variance between measurements was observed. Detailed evaluations of daughter colonies are thus required if selection programs want to breed colonies with reliable VSH traits. This constant need to evaluate all offspring to ensure the desirable resistance traits are present results in high workloads and great expenses in selection programs. Furthermore, such large-scale breeding programs are inefficient due to high fluctuations between measurements and generations, indicating we need to develop new approaches and improved methods for assessing Varroa resistance. [ABSTRACT FROM AUTHOR]

Deformed wing virus (DWV), which is an important honey bee virus transmitted by Varroa destructor (V. destructor) , causes colony losses in honey bee colonies. This study aimed to investigate the prevalence and genetic diversity of DWV in honey bees in Türkiye and to determine the role of V. destructor in the transmission of the genetic variants of DWV. Honey bee samples were collected from 62 apiaries, by simple random sampling, during March 2022 and April 2023. The presence of V. destructor in collected bee samples was examined using a stereo microscope. Real-time RT-PCR was used for the detection of DWV-A and DWV-B (Varroa destructor virus-1 (VDV-1)) viruses. Genetic characterisation of the positive samples was conducted by sequencing polyprotein genomic region. Considering the V. destructor infestation rate of 3% as relevant, out of the 62 apiaries examined, 17 (27.4%) were positive. However, DWV-A and VDV-1 specific RNA was not detected in V. destructor samples. VDV-1 specific RNA was detected in 6.5% (4/62) of the apiaries, whereas DWV-A was not detected in the sampled apiaries. Phylogenetic analysis showed that isolates detected in this study were located in a separate cluster from previously characterised DWV-A and VDV-1 isolates. According to RDP4 and GARD analyses, DWV-VDV-1 recombination breakpoints were detected in field isolates. To the best our knowledge, this is the first report of the presence of VDV-1-DWV recombinants in Türkiye. Further studies are needed to determine the impact of VDV-1-DWV recombinants and their virological and antigenic properties. [ABSTRACT FROM AUTHOR]

Simple Summary: The mite Varroa destructor is the most damaging parasite of honey bees (Apis mellifera) worldwide. When necessary, mite control is mainly accomplished with acaricides. Optimal parasite control is achieved when the acaricide is applied during times of little or no brood in honey bee colonies, which varies by region. Therefore, in this study we analyzed the population dynamics of the mite in honey bee colonies established in a temperate semi-arid climate in Mexico by periodically sampling brood and adult bees, as well as by counting mites falling to the bottom board of hives over 10 months. We also measured brood and adult bee populations and food stores. It was found that the sampling period influences the population of V. destructor in the colonies. The mite population increased by 26% in the 10 months of sampling. It was observed that as the worker brood population increased, the mite infestation rate in adult bees decreased, and the opposite occurred when the amount of brood in the colonies was reduced. Monitoring V. destructor populations by recording fallen mites is more reliable than determining mite infestation rates in adult bees and brood. The best period to apply an acaricide treatment in the region of study is between November and December. This study aimed to analyze the population dynamics of the mite Varroa destructor in honey bee (Apis mellifera) colonies in a temperate semi-arid climate in Mexico. Ten colonies homogeneous in population, food stores, and levels of mite infestation were used. The mite infestation rate in brood and adult bees, total number of mites, daily mite fall, brood and adult bee population, and food stores were determined periodically for 10 months. There was a significant effect (p < 0.05) of sampling period on the population of V. destructor in adult bees, brood, total mite population, and daily fallen mites. The total mite population increased by 26% on average per colony. The increase in brood amount reduced the mite infestation rate in adult bees, and the opposite occurred when the brood decreased. Monitoring V. destructor populations by recording fallen mites is more reliable than determining mite infestation rates in bees, as mite fall has a dynamic pattern similar to that of the total mite population. The best period to apply an acaricide treatment in the region of study is between November and December because most mites were in the phoretic phase, since there was less brood in the colonies compared to other times. [ABSTRACT FROM AUTHOR]

Simple Summary: Varroa destructor is a significant global honey bee parasite and the primary threat to bee health. Due to its latent lifestyle, detecting the mite in a brood requires invasive techniques. Enhancing detection methods is critical for advanced research on mite population dynamics, spread, selection efforts, and control methodologies. In this study, we employed infrared thermal imaging, a less-explored technique in apicultural studies, to detect parasitism in Apis mellifera broods. Our findings indicate that handheld infrared thermal cameras can generate adequately detailed heat maps of the hive. These maps distinctly separate cells containing honey, pollen, and brood, with stable, reproducible temperature measurements observable in late autumn. Notably, mite parasitism induces a sustained temperature increase in developing honey bee pupae, consistently detected regardless of mite numbers in the cell. This study reveals an advanced thermoregulatory behavior in the honey bee colony, manifesting as a social fever phenomenon. Further research is necessary to explore the health benefits of this behavior for bees and the negative effects on the mite. Our method, combined with the development of AI-based image evaluation software, could provide beekeepers and researchers with a valuable tool for Varroa research and bee biological studies. The Varroa destructor is the most significant bee parasite and the greatest threat to bee health all around the world. Due to its hidden lifestyle, detection within the brood cell is only possible through invasive techniques. Enhancing detection methods is essential for advancing research on population dynamics, spread, selection efforts, and control methodologies against the mite. In our study, we employed infrared imaging to measure the thermal differences in parasite and intact Apis mellifera worker broods. Experiments were conducted over two years at the MATE Kaposvár Campus in Hungary involving five beehives in 2022 and five beehives in 2023. A FLIR E5-XT WIFI handheld infrared camera was used to create a heat map of capped brood frames. Our results indicate that the resolution of these cameras is sufficient to provide detailed IR images of a bee colony, making them suitable to detect temperature differences in intact and Varroa parasitized capped brood cells. Mite parasitism causes a time-dependent and sustained temperature increase in developing bee pupae, observable regardless of mite number. Our work demonstrates two different heating patterns: hotspot heating and heating cells that are responsible for the elevated temperature of the Varroa-infested cells as a social fever response by the worker bees. Based on our results, future research combined with AI-based image evaluation software could offer beekeepers and researchers practical and valuable tools for high-throughput, non-invasive Varroa detection in the field. [ABSTRACT FROM AUTHOR]

The combined effects of mite infestation and viral transmission can lead to a rapid decline in colony health. There is growing concern about the decline of Western honey bees (Apis mellifera) caused by an emerging pathogen, Tropilaelaps mercedesae. So far, it is unclear whether T. mercedesae transmits viruses and which viruses might facilitate increased transmission. Here, we found that T. mercedesae harbored six common honey bee viruses. Furthermore, viral proliferation analysis by RT-qPCR showed that viral loads in T. mercedesae was higher than in A. mellifera, especially for deformed wing virus (DWV). Subsequently, we verified that DWV can be transferred between A. mellifera and T. mercedesae during the mite parasitism process by employing an infectious clone of DWV with Green fluorescent protein (GFP). Our findings not only contribute to the understanding of the bee-mite-virus interplay but also highlight the potential role of T. mercedesae as a vector for DWV, similar to Varroa destructor. Due to their ability to transmit viral infections, coupled with their direct parasitic effects, more research is needed for effective management strategies to protect honey bees and ensure the sustainability of apiculture and agriculture. [ABSTRACT FROM AUTHOR]

Despite the major role that insect pollinators play in crop production, agricultural intensification drives them into decline. Various conservation measures have been developed to mitigate the negative effects of agriculture on insect pollinators.In a novel comparison of the efficacy of three conservation measures on honeybee colony growth, we monitored experimental honeybee colonies in 16 landscapes that comprised orthogonal gradients of organic agriculture, annual flower strips and perennial semi‐natural habitats. Using structural equation modelling, we assessed the effects of conservation measures on the prevalence of 11 parasites, Varroa destructor loads and their collective impact on colony growth.Increasing area coverage of perennial semi‐natural habitat related to higher V. destructor load and indirectly to lower colony growth.Increasing area of annual flower strips was associated with lower V. destructor load and indirectly with higher colony growth.Increasing area of organic farming related to lower parasite richness and also directly to improved colony growth.Synthesis and applications: Landscape features can affect pollinators directly through the provision of food resources and indirectly through modulation of parasite prevalence. To promote honeybee colony health in agro‐ecosystems, our results suggest that organic agriculture and annual flower strips should be prioritized conservation measures. Landscape management should consider the merits and demerits of different measures to sustain healthy populations of pollinators in agro‐ecosystems. [ABSTRACT FROM AUTHOR]

Winter is the season of main concern for beekeepers since the temperature, humidity, and potential infection from mites and other diseases may lead the colony to death. As a consequence, beekeepers perform invasive checks on the colonies, exposing them to further harm. This paper proposes a novel design of an instrumented beehive involving color cameras placed inside the beehive and at the bottom of it, paving the way for new frontiers in beehive monitoring. The overall acquisition system is described focusing on design choices towards an effective solution for internal, contactless, and stress-free beehive monitoring. To validate our approach, we conducted an experimental campaign in 2023 and analyzed the collected images with YOLOv8 to understand if the proposed solution can be useful for beekeepers and what kind of information can be derived from this kind of monitoring, including the presence of Varroa destructor mites inside the beehive. We experimentally found that the observation point inside the beehive is the most challenging due to the frequent movements of the bees and the difficulties related to obtaining in-focus images. However, from these images, it is possible to find Varroa destructor mites. On the other hand, the observation point at the bottom of the beehive showed great potential for understanding the overall activity of the colony. [ABSTRACT FROM AUTHOR]

Varroa destructor is a dangerous pest directly for beekeeping and indirectly for crops that require insect pollination. In recent years, the application of chemical pesticides has led to the occurrence of mite resistance and contamination of hive products. Plant extracts are considered as a suitable alternative to chemical acaricides for the Varroa mite control. Therefore, the present study aimed to investigate the acaricidal and insecticidal activity of extract of Prangos ferulacea plant against the Varroa mite and its host in the honey bee colonies in the climatic conditions of Kurdistan province from 2022 to 2024. The P. ferulacea plant was collected in June 2022 from different regions of Kurdistan province in the flowering stage, extracted and then its chemical compounds were identified using GC-MS. The present study was conducted in the form of a factorial experiment based on a completely random basic design with four treatments and seven replications. Before conducting the bioassay experiments, the experimental colonies were homogenized in terms of queen age, population (adults and brood), and honey storage. Also, the initial infestation rate of colonies with Varroa mites was evaluated for adult and brood. The results showed that the extract of 50% of P. ferulacea was relatively favorable acaricidal properties. So that, there was no significant difference with oxalic acid and Apistan treatments in terms of mite mortality percentage in the first time of spraying. Also, the result showed that the bee's mortality percentage was not more than 7% in any of the times of spraying with the 50% extract of the P. ferulacea, and there was observed a significant difference compared to the oxalic acid and Apistan treatments in terms of bee's mortality percentage (P<0.01). The queen superseding was not observed in any of the experimental treatments. According to the findings of the present research, the concentration of 50% of the extract P. ferulaceous can be suggested as a suitable alternative to synthetic acaricides and organic acids to control the Varroa mite in honey bee colonies. [ABSTRACT FROM AUTHOR]

Varroa destructor is the main health problem in the honey bee colonies. Regular monitoring of the Varroa load plays an essential role in determining the right time for treatment of the colony and evaluating the effectiveness of the treatment method. This research aimed at comparative evaluation of the efficacy of alcohol wash and powdered sugar methods to dislodge the Varroa mite from the adult bees' body. Our findings revealed that wash the bees with 75% ethanol dislodged 81.14±3.56% of the mites from their body. In contrast, powdered sugar could dislodge only 54.53±3.56% of the mites from the body of the bees. Therefore, alcohol wash method is more accurate for determining the infestation intensity of the adult honey bees to the Varroa mite. [ABSTRACT FROM AUTHOR]

Simple Summary: Honeybees are vital pollinators, essential for maintaining ecosystems and biodiversity, but there is rising concern about the health of managed honey bee colonies, especially in heavily human-influenced ecosystems. Multiple factors contribute to this decline, including environmental conditions, forage quality, and pesticide use. These elements have a complex effect on the health and nutritional status of honeybee colonies and influence their response to disease and various stressors. In this study, the authors propose a new approach to assess colony health by correlating common measures of colony strength such as honey and pollen reserves, the number of bees, and brood with hemolymph proteins, common bee pathogens (Varroa destructor and Nosema spp.), and essential trace elements (iron, zinc, and copper). Significant correlations were found between hemolymph proteins and colony performance measures, and between V. destructor and hemolymph proteins and iron content. In conclusion, this study confirms the need for a more holistic approach to honeybee health considering all the relevant aspects and critical points that may affect colony survival. 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. [ABSTRACT FROM AUTHOR]

The mite Varroa destructor Anderson 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. [ABSTRACT FROM AUTHOR]

Bees are the most important insect pollinators of the crops humans grow, and Apis mellifera, the Western honey bee, is the most commonly managed species for this purpose. In addition to providing agricultural services, the complex biology of honey bees has been the subject of scientific study since the 18th century, and the intricate behaviors of honey bees and ants, fellow hymenopterans, inspired much sociobiological inquest. Unfortunately, honey bees are constantly exposed to parasites, pathogens, and xenobiotics, all of which pose threats to their health. Despite our curiosity about and dependence on honey bees, defining the molecular mechanisms underlying their interactions with biotic and abiotic stressors has been challenging. The very aspects of their physiology and behavior that make them so important to agriculture also make them challenging to study, relative to canonical model organisms. However, because we rely on A. mellifera so much for pollination, we must continue our efforts to understand what ails them. Here, we review major advancements in our knowledge of honey bee physiology, focusing on immunity and detoxification, and highlight some challenges that remain. [ABSTRACT FROM AUTHOR]

Simple Summary: There is a global need for targeted, environmentally friendly, sustainable alternatives to pesticides. In the apicultural industry, the parasitic mite Varroa destructor poses a serious threat to honey bee health. Like many other agricultural pests, Varroa are primarily managed via pesticides. Whilst these pesticides can effectively control mites, they can also harm bee health, contaminate bee products and pose toxicity risks to beekeepers during application. As a first step to assessing public support for a new biotechnology that could provide a non-toxic alternative to pesticides, beekeepers' perspectives on a novel Varroa control method designed to inhibit protein production, called RNA interference (RNAi), were investigated. The majority of beekeepers surveyed were open to using RNAi treatments against Varroa, particularly as it provided a non-toxic alternative to current pesticide options. The major concerns raised were the unknown long-term effects of the RNAi treatment on bee health, potential effects on non-target species that interact with beehives and concern that an uninformed public that might prevent them from accessing a new tool to combat Varroa. Surveys such as ours can inform scientists and regulatory authorities on how best to introduce novel biotechnologies for commercial use. 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. [ABSTRACT FROM AUTHOR]

Varroosis is a disease that can be observed in all life stages of honey bees and causes serious clinical findings in infested hives. This study aimed to investigate and compare the efficiency of thyme oil, Cinnamomum verum, Melaleuca viridiflora, Syzygium aromaticum essential oils, and amitraz against Varroosis in the field. After the essential oils were dissolved in glycerin, they were impregnated on strips and applied by placing them between frames. Amitraz was applied by fumigation. Positive and phoretic Varroa negative control groups were also included. Treatments were applied once a week for four weeks during the autumn season. The rates of acaricide efficacy and weekly mite count per bottom frame were determined for each of the treatments. According to the results, the highest effectiveness against Varroosis was detected in the amitraz treatment group at 81.3%. The C. verum treatment group had the highest efficacy of all the essential oil treatment groups at 73.5%. The efficacies in thyme oil, M. viridiflora, and S. aromaticum essential oils treatment groups were 71.9%, 71.3%, and 67.4%, respectively. According to the findings of the study, natural extracts can be used instead of chemical drugs in the fight against Varroosis. No toxicity or unnatural death was observed in honey bees throughout the study. [ABSTRACT FROM AUTHOR]

The worldwide dispersal of the ectoparasitic mite Varroa destructor from its Asian origins has fundamentally transformed the relationship of the honey bee (Apis mellifera) with several of its viruses, via changes in transmission and/or host immunosuppression. The extent to which honey bee-virus relationships change after Varroa invasion is poorly understood for most viruses, in part because there are few places in the world with several geographically close but completely isolated honey bee populations that either have, or have not, been exposed long-term to Varroa, allowing for separate ecological, epidemiological, and adaptive relationships to develop between honey bees and their viruses, in relation to the mite's presence or absence. The Azores is one such place, as it contains islands with and without the mite. Here, we combined qPCR with meta-amplicon deep sequencing to uncover the relationship between Varroa presence, and the prevalence, load, diversity, and phylogeographic structure of eight honey bee viruses screened across the archipelago. Four viruses were not detected on any island (ABPV-Acute bee paralysis virus, KBV-Kashmir bee virus, IAPV-Israeli acute bee paralysis virus, BeeMLV-Bee macula-like virus); one (SBV-Sacbrood virus) was detected only on mite-infested islands; one (CBPV-Chronic bee paralysis virus) occurred on some islands, and two (BQCV-Black queen cell virus, LSV-Lake Sinai virus,) were present on every single island. This multi-virus screening builds upon a parallel survey of Deformed wing virus (DWV) strains that uncovered a remarkably heterogeneous viral landscape featuring Varroa-infested islands dominated by DWV-A and -B, Varroa-free islands naïve to DWV, and a refuge of the rare DWV-C dominating the easternmost Varroa-free islands. While all four detected viruses investigated here were affected by Varroa for one or two parameters (usually prevalence and/or the Richness component of ASV diversity), the strongest effect was observed for the multi-strain LSV. Varroa unambiguously led to elevated prevalence, load, and diversity (Richness and Shannon Index) of LSV, with these results largely shaped by LSV-2, a major LSV strain. Unprecedented insights into the mite-virus relationship were further gained from implementing a phylogeographic approach. In addition to enabling the identification of a novel LSV strain that dominated the unique viral landscape of the easternmost islands, this approach, in combination with the recovered diversity patterns, strongly suggests that Varroa is driving the evolutionary change of LSV in the Azores. This study greatly advances the current understanding of the effect of Varroa on the epidemiology and adaptive evolution of these less-studied viruses, whose relationship with Varroa has thus far been poorly defined. Author summary: Honey bees are plagued by many enemies, and the Varroa mite is one of the most important of these. Varroa hurts bees by feeding on their haemolymph, but more importantly, by facilitating the transmission and development of many viruses. The impact of Varroa on most honey bee viruses remains poorly understood. Here, we capitalized on the exceptional Azores setting, which contains islands with and without Varroa, to gain unprecedented insights into the complex mite-virus interactions. We uncovered a very heterogenous viral landscape, with one virus (SBV) occurring only on mite-infested islands, two (CBPV and DWV) on some islands, and two (BQCV and LSV) on every single island. While Varroa influenced the prevalence and/or diversity of all four viruses, its strongest effect was observed for LSV, with the mite leading to elevated LSV prevalence, loads, and diversity (number of variants and their relative abundance). Furthermore, we discovered a novel LSV strain and showed for the first time that the epidemiology of LSV-2, a major strain of LSV, is unambiguously linked to the presence of Varroa. Our findings not only deepen current scientific understanding of the mite-virus relationships but are also of value for assisting veterinary authorities in decision-making regarding the movement of bees across territories. [ABSTRACT FROM AUTHOR]

β-Costic acid is a sesquiterpene phytoalexin with acaricidal activity against Varroa destructor and antitrypanosomal activity. A concise and efficient method was developed for the synthesis of β-costic acid via the allylic oxidation of β-selinene, a component of celery seed oil. [ABSTRACT FROM AUTHOR]

Since the global invasion of the ectoparasitic mite Varroa destructor (Anderson and Trueman), selection of mite-resistant honey bee (Apis mellifera L.) colonies appears challenging and has to date not broadly reduced colony mortality. The low published estimated heritability values for mite infestation levels could explain the limited genetic progresses obtained so far. We hypothesize that intercolonial horizontal mite transmission could differentially affect the single colonies located in a given apiary and therefore invisibly bias colony infestation phenotypes. This bias may be lower in regions with lower colony density, providing suitable conditions to set up evaluation apiaries. To verify these hypotheses, we monitored mite infestation and reinvasion in experimental colonies, as well as infestation in neighboring colonies belonging to beekeepers in three areas with variable colony densities in the canton of Bern, Switzerland during three consecutive beekeeping seasons. Mite immigration fluctuated between apiaries and years and significantly contributed to colony infestation level. Depending on apiary and year, 17–48% of the mites present in the experimental colonies at the time of the summer oxalic acid final treatment potentially derived from mite immigration that had occurred since mid-spring. Mite immigration was not linked to local colony density or the infestation levels of beekeepers' colonies located within 2 km. Our results do not prove that apiaries for colony evaluation should necessarily be established in areas with low colony density. However, they highlight the high impact of beekeeping management practices on mite colony infestation levels. [ABSTRACT FROM AUTHOR]

Apis mellifera filamentous virus (AmFV) is a double-stranded DNA virus that infects Apis mellifera bees. To our knowledge, this is the first comprehensive study aiming to detect and analyse the genetic diversity and prevalence of AmFV in Korean honeybee colonies. Phylogenetic analysis based on baculovirus repeat open reading frame–N gene (Bro–N) sequences revealed that AmFV isolates from the Republic of Korea (ROK) fell into two distinct lineages, with genetic origins in Switzerland and China, with nucleotide similarities of 98.3% and 98.2%, respectively. Our prevalence analysis demonstrated a noteworthy infection rate of AmFV in 545 honeybee colonies, reaching 33.09% in 2022 and increasing to 44.90% by 2023. Intriguingly, we also detected AmFV in Varroa destructor mites, highlighting their potential role as vectors and carriers of AmFV. The presence of AmFV was correlated with an increased infection rate of sacbrood virus, deformed wing virus, Lake Sinai virus 2, black queen cell virus, and Nosema ceranae in honeybee colonies. These findings provide valuable insight into the prevalence and potential transmission mechanisms of AmFV in honeybee colonies in the ROK. The results of this study may be instrumental in the effective management of viral infections in honeybee apiaries. [ABSTRACT FROM AUTHOR]

A sustainable solution to the global threat of the Varroa destructor mite is the selection of varroa‐resistant honey bee (Apis mellifera) colonies. Both "mite non‐reproduction" (MNR) and "varroa sensitive hygiene" (VSH) appear to be promising selection traits for achieving the goal of a resistant honey bee. MNR describes colonies that have a high number of non‐reproductive mites (no offspring, no males, or delayed development of mite offspring). High numbers of non‐reproductive mites have been observed in selected colonies, but the mechanism behind this trait has not yet been identified. The specialized hygienic behavior of selected honey bees, called VSH, is the removal of varroa‐infested brood. These traits were thought to be linked by VSH bees preferentially removing reproductive varroa females leaving only non‐reproductive mites behind in cells and thus creating colonies with high levels of MNR. To further investigate this link, we used an experimental setup and data sets from a four‐year selection project designed to breed for MNR and VSH colonies. In addition, we sought to answer the question of whether non‐reproductive mites are a direct consequence of worker removal behavior. To test this, we artificially induced removal behavior, and after providing the mite with enough time to re‐enter another cell, we opened all capped cells, relocated the mites, and evaluated their reproduction. As shown in previous studies and in this study, VSH had no effect on MNR levels. Also, the induced removal behavior did not lead to non‐reproduction in the subsequent reproductive cycle post interruption. We thus concluded that breeding for non‐reproductive mites does not automatically breed for VSH behavior and worker removal behavior does not cause subsequent reproductive failure of the mites forced to flee and find a new cell for reproduction. [ABSTRACT FROM AUTHOR]

Varroa mites, scientifically identified as Varroa destructor, pose a significant threat to beekeeping and cause one of the most destructive diseases affecting honey bee populations. These parasites attach to bees, feeding on their fat tissue, weakening their immune systems, reducing their lifespans, and even causing colony collapse. They also feed during the pre-imaginal stages of the honey bee in brood cells. Given the critical role of honey bees in pollination and the global food supply, controlling Varroa mites is imperative. One of the most common methods used to evaluate the level of Varroa mite infestation in a bee colony is to count all the mites that fall onto sticky boards placed at the bottom of a colony. However, this is usually a manual process that takes a considerable amount of time. This work proposes a deep learning approach for locating and counting Varroa mites using images of the sticky boards taken by smartphone cameras. To this end, a new realistic dataset has been built: it includes images containing numerous artifacts and blurred parts, which makes the task challenging. After testing various architectures (mainly based on two-stage detectors with feature pyramid networks), combination of hyperparameters and some image enhancement techniques, we have obtained a system that achieves a mean average precision (mAP) metric of 0.9073 on the validation set. [ABSTRACT FROM AUTHOR]

The virulence patterns observed in viruses transmitted by Varroa destructor implied a potential association of these honey bee pests in Poland with the Korean haplotype. Nevertheless, it is noteworthy that this hypothesis lacked direct verification. Therefore, the aim of the study was to determine the haplotype affiliation of V. destructor mites infesting bees in Poland and Ukraine. Adult females were collected from drone brood from honey bee colonies maintained in the apiary at the University of Life Sciences in Lublin, Poland, and the apiary in Synevyr National Park in Ukraine. The haplotype affiliation was determined through the sequencing of the cytochrome oxidase subunit I gene (CO I; 929 bp) fragment. Based on the phylogenetic comparison with 84% bootstrap support, the V. destructor females from both locations were confirmed to represent three haplotypes: Korean 1 (AmK1-1), Korean 2 (AmK1-2), and Chinese 4 (AmK1-4). They are the most virulent types of this parasite worldwide and in Poland. Concurrently, the present study confirms that the Synevyr National Park in Ukraine is isolated from alien bee subspecies, but is not free from alien parasites. [ABSTRACT FROM AUTHOR]

Simple Summary: Since the mid-20th century, the parasitic Varroa mite has become a major threat for honey bee health worldwide. However, mature female mites are only able to reproduce in the honey bee colony's brood cells, which are the hexagonal wax cells in which early bee larvae and pupae develop. By abundantly feeding on the larvae and pupae's fat body tissues and hemolymph, the mites weaken the bees and act as an important vector for many honey bee viruses. Worldwide, distinct natural mite-surviving colonies have already been observed, which often show a range of Varroa resistance traits suppressing the mite's population growth. One such trait is characterized by the suppression of mite reproduction in the brood cells of the developing bees. However, accounting for this trait in selection programs to improve resilience is hard, as the trait is labor- and time-intensive to evaluate. In this study, we propose an alternative, more holistic way of evaluating this Varroa resistance trait, reducing labor without impairing precision, which ultimately allows more colonies to be included in honey bee selection or breeding programs. The mechanisms of action behind decreased mite reproduction (DMR) are still unknown, but current hypotheses state that DMR is the result of brood-intrinsic and/or external disturbances in the V. destructor—honey bee pupa signal interactions. For accurate and precise DMR phenotyping, sufficient single infested honey bee brood cells are required (e.g., 35), which requires extensive labor and time and may exclude many samples not reaching the threshold. We defined a new comprehensive trait called the 'mean V. destructor reproduction rate' (mVR), which describes the mean number of offspring mites per infested cell in the sample while compensating for the reduced number of offspring with increasing multiple infested cells. We found a significant correlation between mVR and DMR, allowing for an estimation of DMR based on the mVR only. When the mVR was calculated with 10 infested cells, we found an average variation in mVR of 16.8%. For the same variation in DMR determination, 40 single infested cells are required. This broader look at V. destructor resistance phenotyping can improve the applicability and effectiveness of traits related to V. destructor reproduction in honey bee breeding programs. [ABSTRACT FROM AUTHOR]

The grooming behavior of honeybees serves as a crucial auto-protective mechanism against Varroa mite infestations. Compared to Apis mellifera, Apis cerana demonstrates more effective grooming behavior in removing Varroa mites from the bodies of infested bees. However, the underlying mechanisms regulating grooming behavior remain elusive. In this study, we evaluated the efficacy of the auto-grooming behavior between A. cerana and A. mellifera and employed RNA-sequencing technology to identify differentially expressed genes (DEGs) in bee brains with varying degrees of grooming behavior intensity. We observed that A. cerana exhibited a higher frequency of mite removal between day 5 and day 15 compared to A. mellifera, with day-9 bees showing the highest frequency of mite removal in A. cerana. RNA-sequencing results revealed the differential expression of the HTR2A and SLC17A8 genes in A. cerana and the CCKAR and TpnC47D genes in A. mellifera. Subsequent homology analysis identified the HTR2A gene and SLC17A8 gene of A. cerana as homologous to the HTR2A gene and SLC17A7 gene of A. mellifera. These DEGs are annotated in the neuroactive ligand–receptor interaction pathway, the glutamatergic synaptic pathway, and the calcium signaling pathway. Moreover, CCKAR, TpnC47D, HTR2A, and SLC17A7 may be closely related to the auto-grooming behavior of A. mellifera, conferring resistance against Varroa infestation. Our results further explain the relationship between honeybee grooming behavior and brain function at the molecular level and provide a reference basis for further studies of the mechanism of honeybee grooming behavior. [ABSTRACT FROM AUTHOR]

A sustainable solution to the global threat of the Varroa destructor mite is the selection of varroa‐resistant honey bee (Apis mellifera) colonies. Both "mite non‐reproduction" (MNR) and "varroa sensitive hygiene" (VSH) appear to be promising selection traits for achieving the goal of a resistant honey bee. MNR describes colonies that have a high number of non‐reproductive mites (no offspring, no males, or delayed development of mite offspring). High numbers of non‐reproductive mites have been observed in selected colonies, but the mechanism behind this trait has not yet been identified. The specialized hygienic behavior of selected honey bees, called VSH, is the removal of varroa‐infested brood. These traits were thought to be linked by VSH bees preferentially removing reproductive varroa females leaving only non‐reproductive mites behind in cells and thus creating colonies with high levels of MNR. To further investigate this link, we used an experimental setup and data sets from a four‐year selection project designed to breed for MNR and VSH colonies. In addition, we sought to answer the question of whether non‐reproductive mites are a direct consequence of worker removal behavior. To test this, we artificially induced removal behavior, and after providing the mite with enough time to re‐enter another cell, we opened all capped cells, relocated the mites, and evaluated their reproduction. As shown in previous studies and in this study, VSH had no effect on MNR levels. Also, the induced removal behavior did not lead to non‐reproduction in the subsequent reproductive cycle post interruption. We thus concluded that breeding for non‐reproductive mites does not automatically breed for VSH behavior and worker removal behavior does not cause subsequent reproductive failure of the mites forced to flee and find a new cell for reproduction. [ABSTRACT FROM AUTHOR]

For decades, the honeybee, Apis mellifera, has suffered from severe colony losses due to the ectoparasitic mite Varroa destructor. Various strategies based on chemicals fail to adequately control varroa mite populations, and often comprise side-effects on the host, parasite resistance and residues in hive products. Reduced temperature tolerance of V. destructor compared to its host has long been recognised and accordingly, the potential of hyperthermia to disrupt mite reproduction within honeybee brood cells or even kill adult parasites. Yet, earlier studies on hyperthermia remain largely anecdotal, and readily implementable solutions have so far been lacking. This study investigates autonomously controlled interval heating from within brood combs throughout the season compared to control colonies maintained according to good apicultural practice. We documented treatment-dependent colony growth dynamics and honey production at three apiaries, complemented by regular monitoring of varroa mite levels and comprehensive digital assessments of brood development over time. Our one-year field trial suggests the evaluated hyperthermia device efficiently suppresses mite populations below critical thresholds until autumn. Whilst a general winter reference-curing revealed similar mite infestations of colonies previously treated with hyperthermia versus formic acid (control), only the latter imposed substantial overwintering burdens indirectly through frequent late-season queen supersedure. However, relative to targeted pupae, increased mortality particularly of heat-treated non-target brood stages (eggs and larvae) appeared to trigger compensatory colony-level responses, translating into temporarily decreased numbers of adult workers coupled with increased pollen foraging and overall lower honey harvests. Valuable insights into previously unrecognised side-effects of hyperthermia and mitigation thereof may ultimately permit successful routine applications of this chemical-free approach to combat the major threat to honeybees worldwide. [ABSTRACT FROM AUTHOR]

Invasive species require adequate reliable detection methods to mitigate their further spread and impact. However, the reliability of molecular detection methods is often hampered by both false positives (Error type I) and false negatives (Error type II). At present, the reliability of the four published molecular detection methods for small hive beetles (SHB), Aethina tumida, has not been rigorously evaluated considering their extensive genetic diversity. Here, we performed intra- and interlaboratory comparisons of the four available methods using SHB samples representing 78 regions from 27 countries on five continents, beetles from the same genus (Aethina concolor, A. inconspicua, A. flavicollis and A. major), as well as western honey bees, Apis mellifera, and ectoparasitic mites Varroa destructor. The data show that the Idrissou et al. (2018) and Li et al. (2018) methods avoid both false positives and false negatives probably due to lower sensitivity to nucleotide mismatches on the primer and probe's target sequences. Further, the Li et al. (2018) method can be considered more sensitive because the fluorescent amplification curve crosses the threshold at lower Cq values compared to the Idrissou et al. (2018) one. In light of our data, the Li et al. (2018) method is the most reliable molecular diagnostic tool for SHB. We therefore recommend using this method as it will contribute to management efforts of this invasive species. [ABSTRACT FROM AUTHOR]

The survival of the honey bee (Apis mellifera), which has a crucial role in pollination and ecosystem maintenance, is threatened by many pathogens, including parasites, bacteria, fungi and viruses. The ectoparasite Varroa destructor is considered the major cause of the worldwide decline in honey bee colony health. Although several synthetic acaricides are available to control Varroa infestations, resistant mites and side effects on bees have been documented. The development of natural alternatives for mite control is therefore encouraged. The study aims at exploring the effects of cinnamon and oregano essential oils (EOs) and of a mixed fruit cocktail juice on mite infestation levels and bee colony health. A multi-method study including hive inspection, mite count, molecular detection of fungal, bacterial and viral pathogens, analysis of defensin-1, hymenoptaecin and vitellogenin immune gene expression, colony density and honey production data, was conducted in a 20-hive experimental apiary. The colonies were divided into five groups: four treatment groups and one control group. The treatment groups were fed on a sugar syrup supplemented with cinnamon EO, oregano EO, a 1:1 mixture of both EOs, or a juice cocktail. An unsupplemented syrup was, instead, used to feed the control group. While V. destructor affected all the colonies throughout the study, no differences in mite infestation levels, population density and honey yield were observed between treatment and control groups. An overexpression of vitellogenin was instead found in all EO-treated groups, even though a significant difference was only found in the group treated with the 1:1 EO mixture. Viral (DWV, CBPV and BQCV), fungal (Nosema ceranae) and bacterial (Melissococcus plutonius) pathogens from both symptomatic and asymptomatic colonies were detected. [ABSTRACT FROM AUTHOR]

Simple Summary: Diseases are a major cause of honeybee colony weakness and death. An effective and fast way to diagnose subclinical infections is by sampling and analyzing debris from hive bottom boards. Molecular tests, like PCR and qPCR can be used to identify disease-causing agents quickly. In this study, we analyzed hive debris samples from Croatian apiaries to check the presence of pathogens, such as Paenibacillus larvae, Melissococcus plutonius, Crithidia mellificae, Lotmaria passim, Vairimorpha spp. (Nosema spp.), Aethina tumida, Acute Bee Paralysis Virus (ABPV), Black Queen Cell Virus (BQCV), Deformed Wing Virus (DWV) and Sacbrood Virus (SBV). Debris samples were also examined to quantify Varroa destructor mites, and natural mite fall was observed in spring. Many honeybee colonies were infected with four to six agents, which is probably why some colonies failed to survive winter. Honeybee diseases are one of the most significant and most common causes of honeybee colonies' weakness and death. An early diagnosis of subclinical infections is necessary to implement precautionary and control measures. Sampling debris from hive bottom boards is simple, non-invasive, and cheap. In this study, we collected winter debris samples in apiaries located in the continental part of Croatia. We used molecular methods, PCR and qPCR, for the first time to analyze those samples. Laboratory results were compared with the health condition and strength of honeybee colonies at an apiary in spring. Our study successfully identified the presence and quantity of various pathogens, including the presence of Vairimorpha spp. (Nosema spp.), quintefied Paenibacillus larvae, Acute Bee Paralysis Virus (ABPV), Black Queen Cell Virus (BQCV), Deformed Wing Virus (DWV), and Sacbrood Virus (SBV). However, our analysis did not detect Melissococcus plutonius, Crithidia mellificae, Lotmaria passim, and Aethina tumida. Samples of winter debris were also examined for the presence and quantification of the V. destructor mites, and their natural mite fall was observed in spring. Honeybee colonies were simultaneously infected by an average of four to six pathogens. Some observed honeybee colonies developed characteristic symptoms, while others did not survive the winter. [ABSTRACT FROM AUTHOR]

Honey bees use grooming to defend against the devastating parasite Varroa destructor Anderson and Trueman. We observed the grooming responses of individual bees from colonies previously chosen for high- and low-grooming behavior using a combination of mite mortality and mite damage. Our aim was to gain insight into specific aspects of grooming behavior to compare if high-grooming bees could discriminate between a standardized stimulus (chalk dust) and a stimulus of live Varroa mites and if bees from high-grooming colonies had greater sensitivity across different body regions than bees from low-grooming colonies. We hypothesized that individuals from high-grooming colonies would be more sensitive to both stimuli than bees from low-grooming colonies across different body regions and that bees would have a greater response to Varroa than a standardized irritant (chalk dust). Individuals from high-grooming colonies responded with longer bouts of intense grooming when either stimulus was applied to the head or thorax, compared to sham-stimulated controls, while bees from low-grooming colonies showed no differences between stimulated and sham-stimulated bees. Further, high-grooming bees from colonies with high mite damage exhibited greater grooming to Varroa than high-grooming colonies with only moderate mite damage rates. This study provides new insights into Varroa -specific aspects of grooming, showing that although a standardized stimulus (chalk dust) may be used to assess general grooming ability in individual bee grooming assays, it does not capture the same range of responses as a stimulus of Varroa. Thus, continuing to use Varroa mites in grooming assays should help select colonies with more precise sensitivity to Varroa. [ABSTRACT FROM AUTHOR]

Honey bees are the most important managed insect pollinators in the US and Canadian crop systems. However, the annual mortality of colonies in the past 15 years has been consistently higher than historical records. Because they are eusocial generalist pollinators and amenable to management, honey bees provide a unique opportunity to investigate a wide range of questions at molecular, organismal, and ecological scales. Here, the American Association of Professional Apiculturists (AAPA) and the Canadian Association of Professional Apiculturists (CAPA) created 2 collections of articles featuring investigations on micro and macro aspects of honey bee health, sociobiology, and management showcasing new applied research from diverse groups studying honey bees (Apis mellifera) in the United States and Canada. Research presented in this special issue includes examinations of abiotic and biotic stressors of honey bees, and evaluations and introductions of various stress mitigation measures that may be valuable to both scientists and the beekeeping community. These investigations from throughout the United States and Canada showcase the wide breadth of current work done and point out areas that need further research. [ABSTRACT FROM AUTHOR]

The negative effects of Varroa and pesticides on colony health and survival are among the most important concerns to beekeepers. To compare the relative contribution of Varroa , pesticides, and interactions between them on honey bee colony performance and survival, a 2-year longitudinal study was performed in corn and soybean growing areas of Iowa. Varroa infestation and pesticide content in stored pollen were measured from 3 apiaries across a gradient of corn and soybean production areas and compared to measurements of colony health and survival. Colonies were not treated for Varroa the first year, but were treated the second year, leading to reduced Varroa infestation that was associated with larger honey bee populations, increased honey production, and higher colony survival. Pesticide detections were highest in areas with high-intensity corn and soybean production treated with conventional methods. Pesticide detections were positively associated with honey bee population size in May 2015 in the intermediate conventional (IC) and intermediate organic (IO) apiaries. Varroa populations across all apiaries in October 2015 were negatively correlated with miticide and chlorpyrifos detections. Miticide detections across all apiaries and neonicotinoid detections in the IC apiary in May 2015 were higher in colonies that survived. In July 2015, colony survival was positively associated with total pesticide detections in all apiaries and chlorpyrifos exposure in the IC and high conventional (HC) apiaries. This research suggests that Varroa are a major cause of reduced colony performance and increased colony losses, and honey bees are resilient upon low to moderate pesticide detections. [ABSTRACT FROM AUTHOR]

Agrochemical exposure is a major contributor to ecological declines worldwide, including the loss of crucial pollinator species. In addition to direct toxicity, field-relevant doses of pesticides can increase species' vulnerabilities to other stressors, including parasites. Experimental field demonstrations of potential interactive effects of pesticides and additional stressors are rare, as are tests of mechanisms via which pollinators tolerate pesticides. Here, we controlled honey bee colony exposure to field-relevant concentrations of 2 neonicotinoid insecticides (clothianidin and thiamethoxam) in pollen and simultaneously manipulated intracolony genetic heterogeneity. We showed that exposure increased rates of Varroa destructor (Anderson and Trueman) parasitism and that while increased genetic heterogeneity overall improved survivability, it did not reduce the negative effect size of neonicotinoid exposure. This study is, to our knowledge, the first experimental field demonstration of how neonicotinoid exposure can increase V. destructor populations in honey bees and also demonstrates that colony genetic diversity cannot mitigate the effects of neonicotinoid pesticides. [ABSTRACT FROM AUTHOR]

Despite the use of various integrated pest management strategies to control the honey bee mite, Varroa destructor , varroosis remains the most important threat to honey bee colony health in many countries. In Canada, ineffective varroa control is linked to high winter colony losses and new treatment options, such as a summer treatment, are greatly needed. In this study, a total of 135 colonies located in 6 apiaries were submitted to one of these 3 varroa treatment strategies: (i) an Apivar® fall treatment followed by an oxalic acid (OA) treatment by dripping method; (ii) same as in (i) with a summer treatment consisting of formic acid (Formic Pro™); and (iii) same as in (i) with a summer treatment consisting of slow-release OA/glycerin pads (total of 27 g of OA/colony). Treatment efficacy and their effects on colony performance, mortality, varroa population, and the abundance of 6 viruses (acute bee paralysis virus [ABPV], black queen cell virus [BQCV], deformed wing virus variant A [DWV-A], deformed wing virus variant B [DWV-B], Israeli acute paralysis virus [IAPV], and Kashmir bee virus [KBV]) were assessed. We show that a strategy with a Formic Pro summer treatment tended to reduce the varroa infestation rate to below the economic fall threshold of 15 daily varroa drop, which reduced colony mortality significantly but did not reduce the prevalence or viral load of the 6 tested viruses at the colony level. A strategy with glycerin/OA pads reduced hive weight gain and the varroa infestation rate, but not below the fall threshold. A high prevalence of DWV-B was measured in all groups, which could be related to colony mortality. [ABSTRACT FROM AUTHOR]

The parasitic mite Varroa destructor (Anderson and Trueman) is one of the greatest stressors of Apis mellifera (L.) honey bee colonies. When Varroa infestations reach damaging levels during fall, rapid control is necessary to minimize damage to colonies. We performed a field trial in the US Southeast to determine if a combination of registered treatments (Apivar, amitraz-based; and Apiguard, thymol-based) could provide rapid and effective control of Varroa. We compared colonies that received this combination treatment against colonies that received amitraz-based positive control treatments: (i) Apivar alone; or (ii) amitraz emulsifiable concentrate ("amitraz EC"). While not registered, amitraz EC is used by beekeepers in the United States in part because it is thought to control Varroa more rapidly and effectively than registered products. Based on measurements of Varroa infestation rates of colonies after 21 days of treatment, we found that the combination treatment controlled Varroa nearly as rapidly as the amitraz EC treatment: this or other combinations could be useful for Varroa management. At the end of the 42-day trial, colonies in the amitraz EC group had higher bee populations than those in the Apivar group, which suggests that rapid control helps reduce Varroa damage. Colonies in the combination group had lower bee populations than those in the amitraz EC group, which indicates that the combination treatment needs to be optimized to avoid damage to colonies. [ABSTRACT FROM AUTHOR]

The life cycle of Varroa destructor , the ectoparasitic mite of honey bees (Apis mellifera), includes a dispersal phase, in which mites attach to adult bees for transport and feeding, and a reproductive phase, in which mites invade worker and drone brood cells just prior to pupation to reproduce while their bee hosts complete development. In this study, we wanted to determine whether increased nurse bee visitations of adjacent drone and worker brood cells would increase the likelihood of Varroa mites invading those cells. We also explored whether temporarily restricting the nurses' access to sections of worker brood for 2 or 4 h would subsequently cause higher nurse visitations, and thus, higher Varroa cell invasions. Temporarily precluding larvae from being fed by nurses subsequently led to higher Varroa infestation of those sections in some colonies, but this pattern was not consistent across colonies. Therefore, removing highly infested sections of capped worker brood could be further explored as a potential mechanical/cultural method for mite control. Our results provide more information on how nurse visitations affect the patterns of larval cell invasion by Varroa. Given that the mite's successful reproduction depends on the nurses' ability to visit and feed developing brood, more studies are needed to understand the patterns of Varroa mite invasion of drone and worker cells to better combat this pervasive honey bee parasite. [ABSTRACT FROM AUTHOR]