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1.
Sci Rep ; 14(1): 7866, 2024 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-38570723

RESUMO

In 2019, a joint eight-variant model was published in which eight single nucleotide polymorphisms (SNPs) in seven Apis mellifera genes were associated with Varroa destructor drone brood resistance (DBR, i.e. mite non-reproduction in drone brood). As this model was derived from only one Darwinian Black Bee Box colony, it could not directly be applied on a population-overarching scale in the northern part of Belgium (Flanders), where beekeepers prefer the carnica subspecies. To determine whether these eight SNPs remained associated with the DBR trait on a Flemish colony-broad scope, we performed population-wide modelling through sampling of various A. mellifera carnica colonies, DBR scoring of Varroa-infested drone brood and variant genotyping. Novel eight-variant modelling was performed and the classification performance of the eight SNPs was evaluated. Besides, we built a reduced three-variant model retaining only three genetic variants and found that this model classified 76% of the phenotyped drones correctly. To examine the spread of beneficial alleles and predict the DBR probability distribution in Flanders, we determined the allelic frequencies of the three variants in 292 A. mellifera carnica queens. As such, this research reveals prospects of marker-assisted selection for Varroa drone brood resistance in honeybees.


Assuntos
Varroidae , Abelhas/genética , Animais , Varroidae/genética , Polimorfismo de Nucleotídeo Único , Frequência do Gene , Bélgica , Fenótipo
2.
Open Vet J ; 14(2): 692-698, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38549575

RESUMO

Background: Ecto-parasite, varroa mite, (Varroa destructor), is the primary pest affecting the apiculture sector globally in various regions. Aim: This study examined the toxicity of nine essential oils to Apis mellifera L. and the acaricidal impact of those oils against V. destructor. Methods: The acaricidal effects of nine essential oils, extracted from plant materials were used. In the screening experiment, 10 mg of the active ingredients of the plant material extracts were prepared in an alcohol solution with concentrations of 5%, 10%, and 15%. For each type of plant extract, five female V. destructor were transferred to a Petri dish with five worker bees incubated at 70% humidity and 33°-34° for 2 days, for each treatment four replicates were used compared to the control. Forty-eight hours following treatment, the number of dead and live mites was counted to determine the mortality rate. In the second assay experiment, the best five essential oils of the previous experiment were selected to re-assess their effectiveness on varroa mites and honeybee workers by using a concentration of 15%. Five females of V. destructor were transferred to a Petri dish with 10 adult bees and treated with the solution of the selected oils. Five replicates and control treatments were taken for each sample simultaneously. Dead and live bees were counted for each replicate at 48 hours after treatment. Results: There were no significant differences between the concentrations used of each oil on the rate of death of mites, and its effectiveness ranged between 70.0% and 53.3% compared to the control groups. In addition, the best oil used was bitter melon, with a death rate of 80% at a concentration of 15%, while peppermint oil showed the lowest death rate of 45% at a concentration of (5%). However, all these treatments were statistically highly significant compared with the natural death rate in control (2%). In the second test, the results of the statistical analysis indicated that there were highly significant differences (P0.05 <0.0001) in the average numbers of dead varroa mites compared to the control when using a 15% concentration of five selected oils. On the other hand, there was no statistically significant difference in the honey bee workers' mortality rate between the treatment and control groups (P0.05 <0.3390), and it was relatively low for all treatments except the basil oil, where the bee mortality rate was 16% compared to the control (10%). Conclusion: It is clear from this experiment that bitter melon oil can be used to control varroa mites and it can be considered safe for honey bees as well as for the environment.


Assuntos
Acaricidas , Óleos Voláteis , Varroidae , Feminino , Abelhas , Animais , Óleos Voláteis/farmacologia , Acaricidas/farmacologia
3.
Arch Virol ; 169(3): 43, 2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38334819

RESUMO

Acute bee paralysis virus (ABPV), Kashmir bee virus (KBV), and Israeli acute paralysis virus (IAPV) usually persist as covert infections in honey bee colonies. They can cause rapid bee mortality in cases of severe infection, often associated with high Varroa destructor infestation, by which they are transmitted. In various countries, these viruses have been associated with colony collapse. Despite their potential danger, these viruses are often disregarded, and little information is available on their occurrence in many countries, including Italy. In 2021, 370 apiaries representing all of the Italian regions were investigated in four different months (June, September, November, and March) for the presence of ABPV, KBV, and IAPV. IAPV was not found in any of the apiaries investigated, whereas 16.45% and 0.67% of the samples tested positive for ABPV and KBV, respectively. Most ABPV cases occurred in late summer-autumn in both northern and southern regions. We observed a scattered pattern of KBV-positive colonies that did not allow any seasonal or regional trends to be discerned. Differences observed among regions and months were potentially related to the dynamics of varroa infestation, viral genetic variations, and different climatic conditions resulting in variations in bee behaviour. This study improves our understanding of the circulation of bee viruses and will contribute to better disease prevention and preservation of bee health.


Assuntos
Dicistroviridae , Varroidae , Vírus , Abelhas , Animais , Dicistroviridae/genética , Estações do Ano
4.
PLoS One ; 19(2): e0297980, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38329992

RESUMO

The ectoparasitic mite, Varroa destructor is the most serious widespread pest of managed honeybees (Apis mellifera). Several acaricide products, which include essential oils, have been proposed for mite control. In this study, we aimed to apply atmospheric-pressure plasma to modify a cardboard piece surface in order to prolong the delivery of essential oils for controlling Varroa in honeybee colonies. Absorption capacity, release rates and evaporation rates of essential oils were determined. Cardboard piece showed a higher absorption capacity of cinnamon compared to citronella and clove. Surface modification of cardboard pieces using argon plasma at different gas flow rates and treatment durations, significantly affected the absorption of clove oil. Additionally, the release rate of cinnamon, citronella and clove was significantly enhanced after argon plasma treatments. Evaporation of cinnamon was dramatically increased by plasma treatment at 6-h of incubation. The highest evaporation rate was obtained by plasma-treated cardboard piece at a gas flow rate of 0.5 Lpm for 60 s (0.2175 ± 0.0148 µl/g•h). Efficiency of plasma-treated cardboard piece, impregnated with essential oils, was also investigated for Varroa control in honeybee colonies. In the first experiment, formic acid 65% (v/v) showed the highest efficiency of 90.60% and 81.59% with the percent of mite infestation was 0.23 ± 0.13% and 0.47 ± 0.19% at 21 and 35 days, respectively after treatment. The efficacy of cardamon oil (5% (v/v)) delivered using plasma-treated cardboard pieces was 57.71% (0.70 ± 0.16% of mite infestation) at day 21 of experiment. However, the delivery of cardamon oil at the concentration of 1% and 5% (v/v) by untreated cardboard piece had 16.93% and 24.05% of efficacy to control mites. In the 2nd experiment, the application of plasma-treated cardboard pieces impregnated with 5% (v/v) clove oil induced a 38.10% reduction in the population of Varroa mites followed by 5% (v/v) of cardamon with 30% efficiency. Although, the infestation rate of Varroa in colonies was not significant different between treatments, essential oils delivered using plasma-treated cardboard pieces tended to decrease Varroa population in the treated colonies. Hence, atmospheric-pressure plasma for the modification of other materials, should be further investigated to provide alternative control treatment applications against honeybee mites.


Assuntos
Acaricidas , Lamiaceae , Óleos Voláteis , Gases em Plasma , Escabiose , Varroidae , Abelhas , Animais , Acaricidas/farmacologia , Óleos Voláteis/farmacologia , Óleo de Cravo , Gases em Plasma/farmacologia
5.
Res Vet Sci ; 169: 105173, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38335895

RESUMO

Colony collapse disorder (CCD) has affected bees worldwide in recent decades, with southwestern Spain being no exception. This disorder is one of the main causes of Apis mellifera mortality and is believed to be caused by environmental, social and sanitary conditions. Dietary supplementation can help to improve some parameters of the general status and sanitary condition of bees, such as infestation by certain recurrent pathogens, including Varroa destructor and Nosema ceranae, by enhancing immune and social response. Thus, the aim of this study was to test a liquid hydrolysed protein supplement on the health and general status of the hive in several apiaries with access to the same natural food and under similar climatic conditions. We selected two groups of ten hives (supplemented by either placebo or protein) from five apiaries where the number of adult bees, amount of brood (open and operculated), honey and pollen reserves, infestation by V. destructor, N. ceranae, deformed wing virus (DWV) and chronic bee paralysis virus (CBPV) were measured. Additionally, we assess the expression of four immune system-related genes and a gene encoding vitellogenin. At the end of this work, treated hives showed a significant increase in open brood and a decrease in V. destructor infestation. Also, these hives showed a significant decrease in the mortality rate after the cold season. Therefore, supplementation with this product improved the health of the hive and could be a promising tool against bee colony loss.


Assuntos
Mel , Vírus de RNA , Urticária , Varroidae , Abelhas , Animais , Espanha/epidemiologia , Varroidae/fisiologia , Urticária/veterinária , Suplementos Nutricionais
6.
J Invertebr Pathol ; 203: 108068, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38272108

RESUMO

Host-parasite co-evolution is a reciprocal genetic change; however, the parasite may switch to a novel host, deviating from conventional co-evolution. Varroa destructor is a native parasite of the honey bee Apis cerana, and the mite has established infestation in another honey bee, Apis mellifera, causing colony failure. When mites switched to the novel host, they formed a distinct population from mites that remained on the native host. Consequently, this led to divergence in the microbiota associated with mites in two host populations. The microbes were conserved at the species level reflected by alpha diversity, with substantial relative abundance variance. Microbes found in mites were distinct from the bee microbiota. They mainly were pathogenic with antibiotic resistance, while a few bacterial taxa were previously found in honey bees, including Klebsiella pneumoniae and Pseudomanas aeruginosa. These symbionts may transfer between the mites and honey bees.


Assuntos
Ácaros , Parasitos , Varroidae , Abelhas , Animais
7.
Proc Biol Sci ; 291(2014): 20232293, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38196351

RESUMO

Deformed wing virus (DWV) is a resurgent insect pathogen of honeybees that is efficiently transmitted by vectors and through host social contact. Continual transmission of DWV between hosts and vectors is required to maintain the pathogen within the population, and this vector-host-pathogen system offers unique disease transmission dynamics for pathogen maintenance between vectors and a social host. In a series of experiments, we measured vector-vector, host-host and host-vector transmission routes and show how these maintain DWV in honeybee populations. We found co-infestations on shared hosts allowed for movement of DWV from mite to mite. Additionally, two social behaviours of the honeybee, trophallaxis and cannibalization of pupae, provide routes for horizontal transmission from bee to bee. Circulation of the virus solely among hosts through communicable modes provides a reservoir of DWV for naïve Varroa to acquire and subsequently vector the pathogen. Our findings illustrate the importance of community transmission between hosts and vector transmission. We use these results to highlight the key avenues used by DWV during maintenance and infection and point to similarities with a handful of other infectious diseases of zoonotic and medical importance.


Assuntos
Movimento , Varroidae , Animais , Abelhas , Pupa , Comportamento Social
8.
Nat Commun ; 15(1): 725, 2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38272866

RESUMO

Ectoparasitic mites of the genera Varroa and Tropilaelaps have evolved to exclusively exploit honey bees as food sources during alternating dispersal and reproductive life history stages. Here we show that the primary food source utilized by Varroa destructor depends on the host life history stage. While feeding on adult bees, dispersing V. destructor feed on the abdominal membranes to access to the fat body as reported previously. However, when V. destructor feed on honey bee pupae during their reproductive stage, they primarily consume hemolymph, indicated by wound analysis, preferential transfer of biostains, and a proteomic comparison between parasite and host tissues. Biostaining and proteomic results were paralleled by corresponding findings in Tropilaelaps mercedesae, a mite that only feeds on brood and has a strongly reduced dispersal stage. Metabolomic profiling of V. destructor corroborates differences between the diet of the dispersing adults and reproductive foundresses. The proteome and metabolome differences between reproductive and dispersing V. destructor suggest that the hemolymph diet coincides with amino acid metabolism and protein synthesis in the foundresses while the metabolism of non-reproductive adults is tuned to lipid metabolism. Thus, we demonstrate within-host dietary specialization of ectoparasitic mites that coincides with life history of hosts and parasites.


Assuntos
Ácaros , Varroidae , Abelhas , Animais , Proteômica , Pupa/parasitologia , Dieta , Reprodução
9.
Sci Rep ; 14(1): 1726, 2024 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-38242935

RESUMO

USDA-ARS Bee Research Laboratory received symptomatic honey bee (Apis mellifera L.) samples across the United States for disease diagnosis. Here, we present a retrospective study and cartography of ectoparasite Varroa destructor and intracellular microsporidia parasite Nosema spp. These two major parasites were identified in the diseased honey bee samples between 2015 and 2022. Varroa infestation level (VIL) was examined by a wash technique (Mites/100 bees) and calculated as a percentage, while Nosema infection was quantified by microscopical spore count (Million Spores/Bee). Data were analyzed by month, year, state, and by nine geographical climate regions described in the U.S. Of adult bee samples (n = 4039) that were analyzed for Varroa mite infestation, the overall VIL in the U.S. ranged between 0.4 and 30.85%, with an overall national VIL and Varroa prevalence of 8.21% and 85.14%, respectively. Overall monthly data showed VIL constantly exceeded the critical level of 4% except from June to September and reached a maximum of 15% in January and December. Nationwide, VIL significantly (p < 0.001) increased from 2015 to 2018 (1.1-4.7%), plateaued from 2018 to 2021 (4.7-4.5%), followed by a significant decrease in 2022 (3.6%). Significant VIL differences (p < 0.001) were recorded among climate regions, with the highest mite infestation levels in the Upper Midwest region (13.9%) and the lowest in the West region (5.1%). Of adult bee samples (n = 2,994) that were analyzed for Nosema infection, Nosema spore count ranged between (1-16.8) million spores per bee among states, with a national average of 6.8 and a prevalence of 99.7%. The lowest and highest Nosema loads were respectively recorded in the South region (3.1) and Upper Midwest (10.5), a significant difference (p < 0.001). No statistical differences were recorded among the six other climate regions. Overall, VIL and Nosema infection correlated significantly (p < 0.001) with a regression coefficient of (R2 = 0.6). Our data, which originated from ailing bee colonies, showed significantly higher rates of maladies compared to data from healthy colonies obtained by the USDA-APHIS National Honey Bee Survey, demonstrating the role of bee diseases caused by Varroa mite and Nosema in honey bee population declines.


Assuntos
Nosema , Escabiose , Varroidae , Abelhas , Animais , Estudos Retrospectivos , Prevalência
10.
Sci Rep ; 14(1): 1148, 2024 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-38212601

RESUMO

The Varroa destructor mite is a parasitic threat to managed and feral honey bee colonies around the world. Beekeepers use miticides to eliminate Varroa in commercial hives, but these chemicals can diminish bee health and increase miticide resistance. In contrast, feral honey bees have developed multiple ways to counteract mites without chemical treatment. We compared mite levels, grooming habits, and mite-biting behavior between feral Africanized honey bees (genomically verified Apis mellifera scutellata hybrids) and managed Italian honey bees (A. mellifera ligustica). Surprisingly, there was no difference in mite infestation levels between scutellata-hybrids and managed bees over one year despite the regular use of miticides in managed colonies. We also found no differences in the social immunity responses of the two groups, as measured by their hygienic habits (through worker brood pin-kill assays), self-grooming, and mite-biting behavior. However, we provide the first report that both scutellata-hybrids and managed honey bees bite off mite chemosensory forelegs, which the mites use to locate brood cells for reproduction, to a significantly greater degree than other legs (a twofold greater reduction in foreleg length relative to the most anterior legs). Such biting may impair mite reproduction.


Assuntos
Acaricidas , Escabiose , Varroidae , Abelhas , Animais , Varroidae/fisiologia , Reprodução/fisiologia , Hábitos
11.
Pest Manag Sci ; 80(3): 1577-1592, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37974358

RESUMO

BACKGROUND: Varroa mite, Varroa destructor, is a major threat for honey bee, Apis mellifera, colonies. Beekeepers have used synthetic Varroacides against Varroa mite for decades, but resistance to organophosphates, pyrethroids and formamidine has been reported in many locations worldwide. The goals of this study were to develop a reliable bioassay to assess efficacy and phenotypic resistance to commercial Varroacides. In this study, efficacy and Varroa resistance was evaluated using the Apiarium technique in comparison to the Mason jar method. RESULTS: Among tested Varroacides, a high efficacy (89%) for Apivar was identified when compared to Bayvarol (58%), Apistan (44%) and CheckMite (6%), in a 24 h assessment. We also found that CheckMite was toxic to bees in the Mason jar method. In addition, the Apiarium technique revealed a case of phenotypic resistance to Bayvarol, Apistan and CheckMite in the mite population evaluated. CONCLUSION: A laboratory protocol was developed using the Apiarium method to evaluate Apivar efficacy. Collectively, the findings indicated that the Apiarium methodology provided a reliable technique to measure Varroacide efficacy and determine the presence of phenotypic resistance in V. destructor. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Varroidae , Abelhas , Animais , Controle de Pragas
12.
J Insect Physiol ; 152: 104583, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37979771

RESUMO

Deformed wing virus (DWV) transmitted by the parasitic mite Varroa destructor is one of the most significant factors contributing to massive losses of managed colonies of western honey bee (Apis mellifera) subspecies of European origin reported worldwide in recent decades. Despite this fact, no antiviral treatment against honey bee viruses is currently available for practical applications and the level of viral infection can only be controlled indirectly by reducing the number of Varroa mites in honey bee colonies. In this study, we investigated the antiviral potential of the gypsy mushroom (Cortinarius caperatus) to reduce DWV infection in honey bees. Our results indicate that the alcohol extract of C. caperatus prevented the development of DWV infection in cage experiments as well as after direct application to honey bee colonies in a field experiment. The applied doses did not shorten the lifespan of honey bees. The reduced levels of DWV in C. caperatus-treated honey bees in cage experiments were accompanied by significant changes in the gene expression of Tep7, Bap1, and Vago. The C. caperatus treatment was not effective against the trypanosomatid Lotmaria passim. No residues of C.caperatus were found in honey harvested in the spring from colonies supplemented with the mushroom extract for their winter feeding. These findings suggest that C. caperatus alcohol extract could be a potential natural remedy to treat DWV infection in honey bees.


Assuntos
Agaricales , Vírus de RNA , Roma (Grupo Étnico) , Varroidae , Abelhas , Animais , Humanos , Vírus de RNA/genética
13.
Exp Appl Acarol ; 92(1): 87-107, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38015279

RESUMO

Varroosis induced by Varroa destructor Anderson and Trueman represents the most pathogenic and destructive disease affecting the western honey bee, Apis mellifera. In this study, we investigated the acaricidal activity against the Varroa mite using essential oils (EOs) from the aerial parts of four autochthonous Algerian herbal species, namely Artemisia herba alba, Artemisia campestris, Artemisia judaica and Ruta montana. EOs were obtained by means of hydrodistillation and their composition was characterized by gas chromatography-mass spectrometry. The toxicity of the selected EOs toward V. destructor and A. mellifera adult honey bees was evaluated using the complete exposure method. The results indicate the predominance of davanone (66.9%) in A. herba alba, ß-pinene (19.5%) in A. campestris, piperitone (68.7%) in A. judaica and 2-undecanone (70.1%) in R. montana EOs. Interestingly, the LC50 values coupled to bee mortality rates revealed that all tested oils exhibited significant acaricidal efficiency with selectivity ratio (SR) values of 10.77, 8.78, 5.62 and 3.73 for A. campestris, A. judaica, A. herba alba, and R. montana, respectively. These values were better than that of thymol (SR = 3.65), the positive control. These findings suggest that these EOs could be used as plant-derived veterinary acaricides to control varroosis in field conditions.


Assuntos
Acaricidas , Óleos Voláteis , Varroidae , Abelhas , Animais , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Acaricidas/farmacologia , Timol
14.
J Insect Sci ; 23(6)2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-38055939

RESUMO

A significant amount of researcher and practitioner effort has focused on developing new chemical controls for the parasitic Varroa destructor mite in beekeeping. One outcome of that has been the development and testing of "glycerol-oxalic acid" mixtures to place in colonies for extended periods of time, an off-label use of the otherwise legal miticide oxalic acid. The majority of circulated work on this approach was led by practitioners and published in nonacademic journals, highlighting a lack of effective partnership between practitioners and scientists and a possible failure of the extension mandate in beekeeping in the United States. Here, we summarize the practitioner-led studies we could locate and partner with a commercial beekeeper in the Southeast of the United States to test the "shop towel-oxalic acid-glycerol" delivery system developed by those practitioners. Our study, using 129 commercial colonies between honey flows in 2017 split into 4 treatment groups, showed no effectiveness in reducing Varroa parasitism in colonies exposed to oxalic acid-glycerol shop towels. We highlight the discrepancy between our results and those circulated by practitioners, at least for the Southeast, and the failure of extension to support practitioners engaged in research.


Assuntos
Mel , Varroidae , Estados Unidos , Animais , Abelhas , Ácido Oxálico/farmacologia , Glicerol/farmacologia , Sudeste dos Estados Unidos , Criação de Abelhas/métodos
15.
J Insect Sci ; 23(6)2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-38055944

RESUMO

Oxalic acid (OA) is a popular miticide used to control Varroa destructor (Mesostigmata: Varroidae) in western honey bee (Apis mellifera L.) (Hymenoptera: Apidae) colonies. Our aim was to investigate which method of OA application (dribbling, fogging, or vaporizing) was the most effective at reducing V. destructor infestations (Experiment 1) and to improve upon this method by determining the treatment interval that resulted in the greatest V. destructor control (Experiment 2). We used the product Api-Bioxal (97% OA) and maintained 40 honey bee colonies (10/treatment) in both experiments. In Experiment 1, the treatments included (i) dribbling 50 ml of 3% OA solution, (ii) vaporizing 4 g of solid OA, (iii) using an insect fogger supplied with 2.5% OA dissolved in ethyl alcohol, and (iv) an untreated control. After 3 weeks, only the vaporization method reduced V. destructor infestations (from 9.24 mites/100 bees pretreatment to 3.25 mites/100 bees posttreatment) and resulted in significantly increased brood amounts and numbers of adult bees over those of the controls. In Experiment 2, all colonies were treated with 4 applications of OA via vaporization at a constant concentration of 4 g OA/colony. In this experiment, the groups were separated by treatment intervals at either 3-, 5-, or 7-day intervals. We observed that 5- and 7-day treatment intervals significantly reduced V. destructor populations from pretreatment levels over that of the controls and 3-day intervals. Our data demonstrate the efficacy of OA in reducing V. destructor infestation, particularly vaporizing 4 g every 5-7 days as the most effective method of application.


Assuntos
Acaricidas , Himenópteros , Varroidae , Abelhas , Animais , Ácido Oxálico , Acaricidas/farmacologia , Volatilização
16.
J Insect Sci ; 23(6)2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-38055946

RESUMO

The ectoparasitic mite, Varroa destructor (Anderson and Trueman), is the leading cause of western honey bee colony, Apis mellifera (L.), mortality in the United States. Due to mounting evidence of resistance to certain approved miticides, beekeepers are struggling to keep their colonies alive. To date, there are varied but limited approved options for V. destructor control. Vaporized oxalic acid (OA) has proven to be an effective treatment against the dispersal phase of V. destructor but has its limitations since the vapor cannot penetrate the protective wax cap of honey bee pupal cells where V. destructor reproduces. In the Southeastern United States, honey bee colonies often maintain brood throughout the year, limiting the usefulness of OA. Prior studies have shown that even repeated applications of OA while brood is present are ineffective at decreasing mite populations. In the summer of 2021, we studied whether incorporating a forced brood break while vaporizing with OA would be an effective treatment against V. destructor. Ninety experimental colonies were divided into 2 blocks, one with a brood break and the other with no brood break. Within the blocks, each colony was randomly assigned 1 of 3 treatments: no OA, 2 g OA, or 3 g OA. The combination of vaporizing with OA and a forced brood break increased mite mortality by 5× and reduced mite populations significantly. These results give beekeepers in mild climates an additional integrated pest management method for controlling V. destructor during the summer season.


Assuntos
Acaricidas , Criação de Abelhas , Abelhas , Ácido Oxálico , Varroidae , Animais , Abelhas/efeitos dos fármacos , Abelhas/parasitologia , Himenópteros/efeitos dos fármacos , Himenópteros/parasitologia , Ácido Oxálico/farmacologia , Estações do Ano , Varroidae/efeitos dos fármacos , Volatilização , Acaricidas/farmacologia , Criação de Abelhas/métodos , Cruzamento/métodos
17.
Pestic Biochem Physiol ; 197: 105655, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38072530

RESUMO

The Varroa mite, Varroa destructor, is an ectoparasite that infests honey bees. The extensive use of acaricides, including fluvalinate, has led to the emergence of resistance in Varroa mite populations worldwide. This study's objective is to monitor fluvalinate resistance in field populations of Varroa mites in Korea through both bioassay-based and molecular marker-based methods. To achieve this, a residual contact vial (RCV) bioassay was established for on-site resistance monitoring. A diagnostic dose of 200 ppm was determined based on the bioassay using a putative susceptible population. In the RCV bioassay, early mortality evaluation was effective for accurately discriminating mites with the knockdown resistance (kdr) genotype, while late evaluation was useful for distinguishing mites with additional resistance factors. The RCV bioassay of 14 field mite populations collected in 2021 indicated potential resistance development in four populations. As an alternative approach, quantitative sequencing was employed to assess the frequency of the L925I/M mutation in the voltage-gated sodium channel (VGSC), associated with fluvalinate kdr trait. While the mutation was absent in 2020 Varroa mite populations, it emerged in 2021, increased in frequency in 2022, and became nearly widespread across the country by 2023. This recent emergence and rapid spread of fluvalinate resistance within a span of three years demonstrate the Varroa mite's significant potential for developing resistance. This situation further underscores the urgent need to replace fluvalinate with alternative acaricides. A few novel VGSC mutations potentially involved in resistance were identified. Potential factors driving the rapid expansion of resistance were further discussed.


Assuntos
Acaricidas , Ácaros , Piretrinas , Varroidae , Canais de Sódio Disparados por Voltagem , Animais , Abelhas , Ácaros/genética , Varroidae/genética , Acaricidas/farmacologia , Piretrinas/farmacologia , Bioensaio , Biomarcadores
18.
Sci Rep ; 13(1): 22484, 2023 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-38110489

RESUMO

Resistance traits of honeybees (Apis mellifera) against their major parasite Varroa destructor have fascinated scientists and breeders for long. Nevertheless, the mechanisms underlying resistance are still largely unknown. The same applies to possible interactions between host behaviours, mite reproduction and seasonal differences. Two resistance traits, reproductive failure of mites and recapping of brood cells, are of particular interest. High rates of recapping at the colony level were found to correspond with low reproductive success of mites. However, the direct effect of recapping on mite reproduction is still controversial and both traits seem to be very variable in their expression. Thus, a deeper knowledge of both, the effect of recapping on mite reproduction and the seasonal differences in the expression of these traits is urgently needed. To shed light on this host-parasite interaction, we investigated recapping and mite reproduction in full-grown colonies naturally infested with V. destructor. Measurements were repeated five times per year over the course of 3 years. The reproductive success of mites as well as the recapping frequency clearly followed seasonal patterns. Thereby, reproductive failure of mites at the cell level was constantly increased in case of recapping. Interestingly, this did not apply to the occurrence of infertile mites. In line with this, recapping activity in fertile cells was most frequent in brood ages in which mite offspring would be expected. Our results suggest that mite offspring is the main target of recapping. This, in turn, leads to a significantly reduced reproductive success of the parasite.


Assuntos
Varroidae , Abelhas , Animais , Estações do Ano , Reprodução , Fertilidade , Interações Hospedeiro-Parasita
19.
Viruses ; 15(12)2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-38140585

RESUMO

The deformed wing virus (DWV) belongs to the genus Iflavirus and the family Iflaviridae within the order Picornavirales. It is an important pathogen of the Western honey bee, Apis mellifera, causing major losses among honey bee colonies in association with the ectoparasitic mite Varroa destructor. Although DWV is one of the best-studied insect viruses, the mechanisms of viral replication and polyprotein processing have been poorly studied in the past. We investigated the processing of the protease-polymerase region at the C-terminus of the polyprotein in more detail using recombinant expression, novel serological reagents, and virus clone mutagenesis. Edman degradation of purified maturated polypeptides uncovered the C- and N-termini of the mature 3C-like (3CL) protease and RNA-dependent RNA polymerase (3DL, RdRp), respectively. Autocatalytic processing of the recombinant DWV 3CL protease occurred at P1 Q2118 and P1' G2119 (KPQ/GST) as well as P1 Q2393 and P1' S2394 (HAQ/SPS) cleavage sites. New monoclonal antibodies (Mab) detected the mature 3CL protease with an apparent molecular mass of 32 kDa, mature 3DL with an apparent molecular mass of 55 kDa as well as a dominant 3CDL precursor of 90 kDa in DWV infected honey bee pupae. The observed pattern corresponds well to data obtained via recombinant expression and N-terminal sequencing. Finally, we were able to show that 3CL protease activity and availability of the specific protease cleavage sites are essential for viral replication, protein synthesis, and establishment of infection using our molecular clone of DWV-A.


Assuntos
Vírus de RNA , Varroidae , Abelhas , Animais , Vírus de RNA/genética , Peptídeo Hidrolases , Poliproteínas
20.
J Insect Sci ; 23(6)2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-38098224

RESUMO

A major threat to honey bee (Apis mellifera Linnaeus, Hymenoptera: Apidae) health continues to be parasitism by the mite Varroa destructor, which has been linked to high colony losses worldwide. Besides feeding on developing and adult bees, Varroa is also a prolific vector of honey bee-associated viruses. Because they live in unmanaged conditions, wild honey bee colonies are not treated against Varroa, which has enabled the natural selection of more mite-tolerant bees. To date, few studies have explored the prevalence of viruses in unmanaged colonies. The Welder Wildlife Refuge (WWR) in Texas is a unique site to study the viral landscape of unmanaged honey bees in the United States. The goals of this study were to identify and quantify viruses in wild colonies at the WWR, to examine changes in the prevalence of viruses in these colonies over time, and to compare the presence and titers of viruses between wild colonies at the WWR and those from the nearest managed apiary. We collected bees from colonies at the WWR in 2013, 2016, and 2021, and analyzed selected viruses for their presence and titers via quantitative polymerase chain reaction. In 2021, we also sampled bees from the nearest managed apiary for comparison. We found low average virus titers in all wild colonies sampled, and no difference in virus titers between colonies at the WWR and those from the managed apiary. Our study indicates that virus titers in wild colonies at the WWR are similar to those found in nearby colonies, and that these titers fluctuate over time.


Assuntos
Vírus de RNA , Varroidae , Vírus , Abelhas , Animais , Carga Viral , Prevalência , Texas , Vírus de RNA/genética
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