Genetic variability of the honey bee mite, Varroa destructor, from a humid continental climatic region of Canada, and temperate and tropical climatic regions of Mexico.

Varroa destructor is a damaging mite of Western honey bees (Apis mellifera). Genetic variability of the mite in different regions of the world could be related to the movement of infested bees or other factors, such as climate. In this study, V. destructor samples were collected from tropical and temperate climate regions of Mexico, and a humid continental climate region of Canada. COX-1 AFLPs showed that all the mites were the Korean haplotype. Four microsatellites revealed nine haplogroups from the continental climate region of Canada, compared to three haplogroups from the tropical and temperate climate regions of Mexico. CytII-ATP sequences showed seven haplogroups from the humid continental climate region vs. two haplogroups from the temperate region and one haplogroup from the tropical region. CytB sequences revealed seven haplogroups from Canada vs. three from Mexico. A comparison of the cytB sequences of the samples from Canada and Mexico to those from a worldwide collection showed that one sequence, designated the cytB1 type, predominated, comprising 57% of the 86 sequences; it clustered with similar sequences that comprised 80% of the sequences, designated family A. CytB1 was predominant in Mexico, but not in Canada. The other 20% of sequences were in families B and C, and all those samples originated from East and Southeast Asia. The microsatellite, cytII-ATP, and cytB markers, all showed higher variability in mites collected in Canada than in Mexico, which could be related to the cooler climate or an earlier invasion and/or multiple mite invasions in Canada.

Prevalence of Adult Honey Bee (Apis mellifera L.) Pests and Pathogens in the Five Beekeeping Regions of Mexico.

Mexico is a major honey producer, but not much information exists about the health status of honey bees (Apis mellifera L.) in the country. This study was conducted to determine the sanitary status of adult honey bees in Mexico's five beekeeping regions. Samples from 369 apiaries were diagnosed to identify pathogens such as Varroa destructor, which was quantified, Acarapis woodi, Nosema spp., and five viruses. Colonies were also inspected for the presence of the small hive beetle (SHB), Aethina tumida. Varroa destructor was found in 83.5% of the apiaries, with the Pacific Coast region having the highest prevalence (>95%) and rates (4.5% ± 0.6). Acarapis woodi was detected in only one apiary from the Pacific Coast, whereas Nosema spp. were prevalent in 48.5% of the apiaries, with the highest and lowest frequencies in the Yucatan Peninsula and North regions (64.6% and 10.2%, respectively). For viruses, deformed wing virus (DWV) was detected in 26.1% of the apiaries, with the highest frequency in the Pacific Coast region (44.7%). Israeli acute paralysis virus (IAPV) was diagnosed in 3.2% of the samples and sacbrood bee virus (SBV) in 23.3% of them, with the highest frequency in the High Plateau region (36.4%). Chronic bee paralysis and Kashmir bee viruses were not detected. SHB prevalence was 25.2% nationwide, with the highest frequency in the Yucatan Peninsula (39.2%). This study shows that the most common parasites of adult honey bees in Mexico are V. destructor and Nosema spp., and that the most prevalent virus is DWV, whereas SHB is highly prevalent in the Yucatan Peninsula. This information could be useful to design disease control strategies for honey bee colonies in different regions of Mexico.

Varroa Destructor Classification Using Legendre-Fourier Moments with Different Color Spaces.

Bees play a critical role in pollination and food production, so their preservation is essential, particularly highlighting the importance of detecting diseases in bees early. The Varroa destructor mite is the primary factor contributing to increased viral infections that can lead to hive mortality. This study presents an innovative method for identifying Varroa destructors in honey bees using multichannel Legendre-Fourier moments. The descriptors derived from this approach possess distinctive characteristics, such as rotation and scale invariance, and noise resistance, allowing the representation of digital images with minimal descriptors. This characteristic is advantageous when analyzing images of living organisms that are not in a static posture. The proposal evaluates the algorithm's efficiency using different color models, and to enhance its capacity, a subdivision of the VarroaDataset is used. This enhancement allows the algorithm to process additional information about the color and shape of the bee's legs, wings, eyes, and mouth. To demonstrate the advantages of our approach, we compare it with other deep learning methods, in semantic segmentation techniques, such as DeepLabV3, and object detection techniques, such as YOLOv5. The results suggest that our proposal offers a promising means for the early detection of the Varroa destructor mite, which could be an essential pillar in the preservation of bees and, therefore, in food production.

Hydrolats from Humulus lupulus and Their Potential Activity as an Organic Control for Varroa destructor.

Varroa destructor is a parasitic mite, which is considered a severe pest for honey bees causing serious losses to beekeeping. Residual hydrolats from steam extraction of hop essential oils, generally considered as a waste product, were tested for their potential use as acaricides on V. destructor. Four hop varieties, namely Cascade, Spalt, Victoria, and Mapuche, showed an interesting performance as feasible products to be used in the beekeeping industry. Some volatile oxidized terpenoids were found in the hydrolats, mainly ß-caryophyllene oxide, ß-linalool, and isogeraniol. These compounds, together with the presence of polyphenols, flavonoids, and saponins, were probably responsible for the promissory LC50 values obtained for mites after hydrolat exposition. Victoria hydrolat was the most toxic for mites (LC50: 16.1 µL/mL), followed by Mapuche (LC50 value equal to 30.1 µL/mL), Spalt (LC50 value equal to 114.3 µL/mL), and finally Cascade (LC50: 117.9 µL/mL). Likewise, Spalt had the highest larval survival, followed by Victoria and Mapuche. Cascade was the variety with the highest larval mortality. In addition, none of the extracts showed mortality higher than 20% in adult bees. The Victoria hydrolat presented the best results, which makes it a good compound with the prospect of an acaricide treatment against V. destructor.

A Reciprocal Transplant Experiment Confirmed Mite-Resistance in a Honey Bee Population from Uruguay.

In the past few years there has been an increasing interest for the study of honey bee populations that are naturally resistant to the ectoparasitic mite Varroa destructor, aiming to identify the mechanisms that allow the bees to limit the reproduction of the mite. In eastern Uruguay there are still bees resistant to mites that survive without acaricides. In order to determine if the differential resistance to V. destructor was maintained in other environments, a reciprocal transplant experiment was performed between the mite-resistant bee colonies and the mite-susceptible bee colonies from the east and the west of the country, respectively, infesting bees with local mites. In both regions, the mite-resistant colonies expressed a higher hygienic behavior and presented a higher phoretic mites/reproductive mites and mites in drone cells/mites in worker cells ratio than the mite-susceptible colonies. All the mite-susceptible colonies died during fall-winter, while a considerable number of mite-resistant colonies survived until spring, especially in the east of the country. This study shows that the bees in the east of the country maintain in good measure the resistance to V. destructor in other regions and leaves open the possibility that the mites of the two populations have biases in the reproductive behavior.

Genotype, but Not Climate, Affects the Resistance of Honey Bees (Apis mellifera) to Viral Infections and to the Mite Varroa destructor.

This study was conducted to analyze the effect of genotype and climate on the resistance of honey bee (Apis mellifera) colonies to parasitic and viral diseases. The prevalence and intensity of parasitism by Varroa destructor, or infection by Nosema spp., and four honey bee viruses were determined in 365 colonies of predominantly European or African ancestry (descendants of A. m. scutellata) in subtropical and temperate regions of Mexico. Varroa destructor was the most prevalent parasite (95%), whilst N. ceranae was the least prevalent parasite (15%). Deformed wing virus (DWV) and black queen cell virus (BQCV) were the only viruses detected, at frequencies of 38% and 66%, respectively. Varroa destructor was significantly more prevalent in colonies of European ancestry (p < 0.05), and the intensity of parasitism by V. destructor or infection by DWV and BQCV was also significantly higher in colonies of European descent than in African descent colonies (p < 0.01), although no genotype−parasite associations were found for N. ceranae. Additionally, significant and positive correlations were found between V. destructor and DWV levels, and the abundance of these pathogens was negatively correlated with the African ancestry of colonies (p < 0.01). However, there were no significant effects of environment on parasitism or infection intensity for the colonies of both genotypes. Therefore, it is concluded that the genotype of honey bee colonies, but not climate, influences their resistance to DWV, BQCV, and V. destructor.

Hygienic Behavior of Apis mellifera and Its Relationship with Varroa destructor Infestation and Honey Production in the Central Highlands of Ecuador.

The aim of this research was to analyze the relationship among hygienic behavior (HB), Varroa destructor infestation, and honey production in the central highlands of Ecuador. Overall, 75 honey bee colonies were evaluated before, during, and after production at three altitude levels (2600-2800, 2801-3000, and >3000 m.a.s.l.). The hygienic behavior percentage of the colonies was determined by the pin-killing method, and the colonies were classified into three groups: high HB (>85%), mid HB (60.1-85%), and low HB (≤60%). Varroa infestation was diagnosed as well, and honey production was evaluated only during production. HB was high and heterogeneous, averaging 80% ± 9.7%. Its highest expression was observed at lower altitudes. The infestation degree was low (3.47% ± 1.56%), although the mite was detected in all colonies upon sampling. A negative correlation was observed between HB and Varroa infestation in the first sampling (-0.49 **), suggesting that the high- and mid-altitude HB colonies underwent the lowest infestation rates, regardless of sampling. The correlations between HB and production were significant (0.26 *), indicating a positive effect of HB on production, meaning that colonies with high HB obtained the highest honey production (25.08 ± 4.82 kg/hive). The HB of bees showed an inverse relationship with altitude and it tended to reduce the effect of Varroa infestation, favoring honey production and, thus, suggesting the feasibility of selecting colonies with high HB.

Field evaluation of Varroa-resistance traits in surviving Apis mellifera colonies in Argentina.

Varroa destructor is one of the most important sanitary threats for the beekeeping industry and so far disease control is based mainly on chemical treatment. However, a long-term solution may arise from studying natural surviving colonies of Apis mellifera. We compared the Varroa infestation rate in six commercial colonies that received annual treatment against mites and six non-treated colonies that survived in absence of any treatment for the last 6 years. In addition, we evaluated two potential mechanisms that might be involved in colony survival: hygienic (HYG) and Varroa-sensitive hygiene behavior (VSH) by means of pin-killed and mite artificial infestation, respectively. HYG and VSH were negatively correlated with mite infestation independently of the colony group (treated or non-treated). Furthermore, colonies expressing high levels of pupae removal (≥ 80%) showed higher %HYG and lower mite infestation compared to colonies showing low pupae removal (< 80%). The analysis of reproductive status of mites from the non-removed infested cells evidenced that more infertile mites are found in colonies with more than 80% of pupae removal. To study non-treated colonies that survive for several years, it is a suitable approach for identifying the underlying mechanisms related to Varroa-resistance.

Genome-wide identification of miRNAs and target regulatory network in the invasive ectoparasitic mite Varroa destructor.

Varroa destructor is an ectoparasite mite that attacks bees leading to colony disorders worldwide. microRNAs (miRNAs) are key molecules used by eukaryotes to post-transcriptional control of gene expression. Nevertheless, still lack information aboutV. destructor miRNAs and its regulatory networks. Here, we used an integrative strategy to characterize the miRNAs in the V. destructor mite. We identified 310 precursors that give rise to 500 mature miRNAs, which 257 are likely mite-specific elements. miRNAs showed canonical length ranging between 18 and 25 nucleotides and 5' uracil preference. Top 10 elements concentrated over 80% of total miRNA expression, with bantam alone representing ~50%. We also detected non-templated bases in precursor-derived small RNAs, indicative of miRNA post-transcriptional regulatory mechanisms. Finally, we note that conserved miRNAs control similar processes in different organisms, suggesting a conservative role. Altogether, our findings contribute to the better understanding of the mite biology that can assist future studies on varroosis control.

Morphotype and haplotype identification of Varroa destructor (Acari: Varroidae), and its importance for apiculture in Nicaragua.

The ectoparasite Varroa (Acari: Varroidae) is considered to be the main pest of honey bees (Apis mellifera L.) in Nicaragua. The aim of this study was to determine morphotypes and mitochondrial haplotypes of the Varroa mites, related to infestation levels in A. mellifera hives in Nicaragua in a cross-sectional study (2013-2016). Samples were taken from 34 sentinel apiaries in five geographical zones; from 713 Varroa females collected during the study, 153 were selected for measurement of various morphometric characters for further classification into morphotypes. The mitochondrial haplotype was assigned to one of the two (Korean or Japanese), using the restriction by SacI of the PCR product of a fragment of the gene CO-I. Morphometric measurement and sequencing revealed the affiliation to the species Varroa destructor with a mean (± SD) body width of 1699.1 ± 60.2 µm and a body length of 1161.1 ± 34.9 µm. Body characters were significantly different among the 34 apiaries. Varroa destructor samples were classified into four morphotypes, with no significant differences in the geographical zones. As GAGCTC SacI enzyme cleavage sequences were not observed, all PCR products were identified as V. destructor Korean haplotype. The CO-I gene nucleotide sequences from two samples V. destructor showed both 100% similarity with the Korean haplotype and 99.8% similarity to the Japanese haplotype. Although the V. destructor mite was identified as a Korean haplotype, host-parasite association in 2 decades has led into a balance without entering into severe losses in the Nicaraguan apiculture.

Deformed wing virus type a and b in managed honeybee colonies of Argentina.

Apis mellifera is infected by more than 24 virus species worldwide, mainly positive-sense, single-stranded RNA viruses of the Dicistroviridae and Iflaviridae families. Among the viruses that infect honey bees, Deformed wing virus is the most prevalent and is present as three master variants DWV-A, B, and C. Given that the ectoparasitic mite Varroa destructor vectors these virus variants, recombination events between them are expected, and variants and their recombinants can co-exist in mites and honeybees at the same time. In this study, we detect, through RT-qPCR, the presence of DWV-A and B in the same samples of adult bees from colonies of Argentina. Total RNA was extracted from pools of ten adult bees from 45 apiaries distributed across the main beekeeping Provinces of Argentina (Buenos Aires, Santa Fe, Córdoba, Santiago del Estero, Río Negro, and Mendoza); then RT-qPCR reactions were performed to detect DWV-A and B, with specific primer pairs. After the amplifications, PCR products (204 and 660 bp amplicons for DWV-B, and ~250 bp for DWV-A) were purified and sequenced to verify that they corresponded to reported sequences, analyzing them using the Blast software. Of the 45 samples analyzed by RT-qPCR, over 90% were infected with DWV-A and 47% were also positive for DWV-B, where it was found in high prevalence specifically in colonies of A. mellifera of the Buenos Aires Province. Future studies will determine the impact of this type of the virus and its ability to recombine with the other DWV types in the apiaries of our country.

Influence of physicochemical factors on environmental availability and distribution of semiochemicals that affect Varroa destructor and phylogenetically close organisms: classification by VHWOC PCA-clustering.

Varroa destructor parasites Apis mellifera larvae following the interception of the semiochemicals involved in bee communication; thus, the semiochemical availability and distribution pathways take place within different physicochemical environments. The structure of 172 molecules with semiochemical activity on Varroa destructor was used to compute the representative physicochemical descriptors of the thermodynamic partition among different physicochemical environments: vapor pressure (V), Henry's coefficient (H), water solubility constant (W), octanol-water partition coefficient (O) and organic carbon partition coefficient (C); VHWOC. The principal component analysis (PCA) and hierarchical clustering of VHWOC descriptors allowed us to establish the trend in availability and distribution of the semiochemicals resulting in a 4 classes model of physicochemical environments: Class 1, Soluble/Volatile; Class 2, Soluble; Class 3, Contact; Class 4, Adsorbed/Volatile. Our results suggest that semiochemicals can transit between different thermodynamic equilibrium phases depending on environment conditions. The classification prediction of the model was tested on 6 new molecules obtained from ketonic extracts of L5 Apis mellifera drone larvae; locating them in class 4, which was consistent with their molecular structure. This study can be the starting point for the design of synthetic semiochemicals or for the control of Varroa destructor. In addition, the method can be used in the analysis of other semiochemical groups.

Impact of Varroa destructor and deformed wing virus on emergence, cellular immunity, wing integrity and survivorship of Africanized honey bees in Mexico.

The ectoparasitic mite Varroa destructor is the primary health problem of honey bees (Apis mellifera) worldwide. Africanized honey bees in Brazil have demonstrated tolerance to the mite, but there is controversy about the degree of mite tolerance of Africanized bees in other countries. This study was conducted to quantify the effect of V. destructor parasitism on emergence, hemocyte concentration, wing integrity and longevity of Africanized honey bees in Mexico. Africanized bee brood were artificially infested with V. destructor mites and held in an incubator until emergence as adults and compared to non-infested controls. Deformed wing virus (DWV) presence was determined in the mites used to infest the bees. After emergence, the bees were maintained in an incubator to determine survivorship. The percentage of worker bees that emerged from parasitized cells (69%) was significantly lower than that of bees emerged from non-infested cells (96%). Newly-emerged parasitized bees had a significantly lower concentration of hemocytes in the hemolymph than non-parasitized bees. Additionally, the proportion of bees with deformed wings that emerged from V. destructor-parasitized cells was significantly higher (54%) than that of the control group (0%). The mean survival time of bees that emerged from infested and non-infested cells was 8.5 ±â€¯0.3 and 14.4 ±â€¯0.4 days, respectively, and the difference was significant. We conclude that V. destructor parasitism and DWV infections kill, cause deformities and inhibit cellular immunity in developing Africanized honey bees, and significantly reduce the lifespan of adult bees in Mexico. These results suggest that the tolerance of Africanized bees to V. destructor is related to adult bee mechanisms.

Detection of Lotmaria passim in Africanized and European honey bees from Uruguay, Argentina and Chile.

Trypanosomatids affecting honey bees, Crithidia mellificae and Lotmaria passim, have been poorly studied in South America. We therefore analyzed their presence in Africanized and European honeybees from Uruguay, Argentina and Chile collected between 1990 and 2011 and assessed their association with other bee parasites and pathogens. Crithidia mellificae was not detected while L. passim was wide-spread. This report shows that L. passim has been present in this region at least since 2007 and it infects both Africanized and European honey bees. L. passim infected colonies showed high V. destructor parasitization levels, suggesting an association between them.

Heat shock proteins in Varroa destructor exposed to heat stress and in-hive acaricides.

Varroa destructor is one of the major pests that affect honeybees around the world. Chemical treatments are common to control varroosis, but mites possess biochemical adaptive mechanisms to resist these treatments, enabling them to survive. So far, no information is available regarding whether these pesticides can induce the expression of heat shock protein (Hsp) as a common protective mechanism against tissue damage. The aims of this study were to determine differences in heat shock tolerance between mites collected from brood combs and phoretic ones, and to examine patterns of protein expression of Hsp70 that occur in various populations of V. destructor after exposure to acaricides commonly employed in beekeeping, such as flumethrin, tau-fluvalinate and coumaphos. Curiously, mites obtained from brood cells were alive at 40 °C, unlike phoretic mites that reached 100% mortality, demonstrating differential thermo-tolerance. Heat treatment induced Hsp70 in mites 4 × more than in control mites and no differences in response were observed in phoretic versus cell-brood-obtained mites. Dose-response assays were carried out at increasing acaricide concentrations. Each population showed a different stress response to acaricides despite belonging to the same geographic region. In one of them, coumaphos acted as a hormetic stressor. Pyrethroids also induced Hsp70, but mite population seemed sensitive to this treatment. We concluded that Hsp70 could represent a robust biomarker for measuring exposure of V. destructor to thermal and chemical stress, depending on the acaricide class and interpopulation variability. This is relevant because it is the first time that stress response is analyzed in this biological model, providing new insight in host-parasite-xenobiotic interaction.

Potential associations between the mite Varroa destructor and other stressors in honeybee colonies (Apis mellifera L.) in temperate and subtropical climate from Argentina.

The presence of Varroa destructor in colonies of Apis mellifera is explained by the interaction among a number of factors including beekeeping practices and surrounding environment features. The aim of this study was to evaluate the relative impact of environment geographical region and beekeeping management on Varroa infestation levels throughout a year. A monitoring study was carried out during 2015 in north-central regions from Argentina, consisting of three sampling dates: 1) autumn survey before autumn acaricide treatment; 2) autumn survey after autumn acaricide treatment and 3) spring survey. During these visits, we collected samples for Varroa mites and Nosema sp. presence assessment and information concerning the apiary management practices during each period. Both regional location and beekeeping practices impact on V. destructor infestation level during the course of the year, but relative importance depend partially on the time of year when this was observed. Varroa infestation level is driven simultaneously by a wide-range of environmental factors (regional effect) and honeybee population dynamics. Additionally, colony life histories are also strongly affected by the management practices employed by beekeepers, especially regarding the Varroa mites control and the supplementary feeding. Complexity involving multiple factors interaction in socio-ecological systems like beekeeping is discussed.

Prevalence of honey bee (Apis mellifera) viruses in temperate and subtropical regions from Argentina / Prevalencia de virus en abejas melíferas (Apis mellifera) en ambientes templados y subtropicales de Argentina

In Argentina, bee virus studies are still incipient, and there are no studies regarding the climatic effect. The aim of this study was to assess and compare the presence of honeybee viruses in different climatic regions from Argentina. A total of 385 colonies distributed in five Argentinean eco-regions were examined to evaluate the percentage of infestation with Varroa destructor and the presence of seven virus species (Deformed wing virus, DWV; Acute bee paralysis virus, ABPV; Chronic bee paralysis virus, CBPV; Black queen cell virus, BQCV; Kashmer bee virus, KBV; Israeli acute bee paralysis virus, IAPV; and Sacbrood bee virus, SBV) after honey yield. Two viruses, KBV and IAPV, were not detected. The other five viruses were found in different prevalences: DWV (35%), ABPV (21.5%), BQCV (8.0%), CBPV (2.2%), and SBV (1.1%). We found double and triple viral associations in approximately 25% of the sampled colonies. The mean V. destructor infestation in the colonies prior to the acaricide treatment was 7.12% ± 8.7%. The knowledge of the prevalence of these viruses in the region and their relation with the mite and other possible influencing factors is important for preventing colony losses. Further studies are necessary to identify the risk factors associated with virus presence and its relationship with other pathogens such as V. destructor.

En Argentina, los estudios sobre prevalencia de virus en abejas continúan siendo incipientes y no existen reportes acerca de cómo inciden sobre dicha prevalencia las variables climáticas. El objetivo de este estudio fue evaluar y comparar la presencia de virus en abejas melíferas en diferentes regiones agroecológicas de Argentina. A tal fin se evaluaron 385 colmenas distribuidas en 5 regiones agroecológicas de las provincias de Chaco y Santa Fe; en ellas se analizó el porcentaje de infestación con Varroa destructor (ácaro patógeno de abejas) y la presencia de 7 especies de virus (DWV, virus de las alas deformadas; ABPV, virus de la parálisis aguda de la abeja; CBPV, virus de la parálisis crónica de la abeja; BQCV, virus de celda negra de la reina; KBV, virus de la abeja de Cachemira; IAPV, virus israelí de la parálisis aguda y SBV, virus de la cría ensacada). luego de la cosecha de miel. Dos virus (KBV y IAPV) no fueron detectados. Las otras 5 especies de virus se encontraron con prevalencias variables: DWV (35%), ABPV (21,5%), BQCV (8%), CBPV (2,2%) y SBV (1,1%). Fue posible identificar la presencia de 3 y hasta 3 virus simultáneamente en el 25% de las colmenas evaluadas. El promedio de infestación por V. destructor en las colmenas luego de la cosecha de miel y antes del tratamiento con acaricidas fue de 7,12% (±8,7). Conocer la prevalencia de virus en las diferentes regiones agroecológicas y su relación con la presencia del ácaro V. destructor e identificar otros posibles factores que podrían influir en su presencia es relevante para definir estrategias que reduzcan la mortandad de colmenas. Es necesario realizar estudios adicionales para identificar los factores de riesgo asociados a la presencia de virus en las colmenas y su relación con otros patógenos, como V. destructor.

Risk factors for the presence of Deformed wing virus and Acute bee paralysis virus under temperate and subtropical climate in Argentinian bee colonies.

Beekeepers all across the world are suffering important losses of their colonies, and the parasitic mites Varroa destructor and Nosema sp, as well as several bee viruses, are being pointed out as the possible causes of these losses, generally associated with environmental and management factors. The objective of the present study was to evaluate the presence of seven virus species (Deformed wing virus -DWV-, Acute bee paralysis virus -ABPV-, Chronic bee paralysis virus -CBPV-, Black queen cell virus -BQCV-, Kashmir bee virus -KBV-, Israeli acute bee paralysis virus -IAPV-, and Sacbrood bee virus -SBV), as well as the prevalence of Nosema sp. and Varroa destructor, and their possible associated factors, under temperate and subtropical climate conditions in Argentinean colonies. A total of 385 colonies distributed in five Argentinean eco-regions were examined after honey harvest. The final multivariable model revealed only one variable associated with the presence of DWV and two with the presence of ABPV. The apiary random effect was significant in both cases (P=0.018; P=0.006, respectively). Colonies with a Varroa infestation rate >3% showed higher presence of DWV than colonies with <3% of Varroa infestation level (OR=1.91; 95% CI: 1.02-3.57; P<0.044). The same pattern was observed for the presence of ABPV (OR=2.23; 95% CI: 1.04-4.77; P<0.039). Also, colonies where replacement of old combs was not a common practice had higher presence of ABPV (OR=6.02; 95% CI: 1.16-31.25; P<0.033). Regardless of the location of the colonies, virus presence was strongly associated with V. destructor level. Therefore, all the factors that directly or indirectly influence the levels of mites will be also influencing the presence of the viruses.

Prevalence of honey bee (Apis mellifera) viruses in temperate and subtropical regions from Argentina.

In Argentina, bee virus studies are still incipient, and there are no studies regarding the climatic effect. The aim of this study was to assess and compare the presence of honeybee viruses in different climatic regions from Argentina. A total of 385 colonies distributed in five Argentinean eco-regions were examined to evaluate the percentage of infestation with Varroa destructor and the presence of seven virus species (Deformed wing virus, DWV; Acute bee paralysis virus, ABPV; Chronic bee paralysis virus, CBPV; Black queen cell virus, BQCV; Kashmer bee virus, KBV; Israeli acute bee paralysis virus, IAPV; and Sacbrood bee virus, SBV) after honey yield. Two viruses, KBV and IAPV, were not detected. The other five viruses were found in different prevalences: DWV (35%), ABPV (21.5%), BQCV (8.0%), CBPV (2.2%), and SBV (1.1%). We found double and triple viral associations in approximately 25% of the sampled colonies. The mean V. destructor infestation in the colonies prior to the acaricide treatment was 7.12%±8.7%. The knowledge of the prevalence of these viruses in the region and their relation with the mite and other possible influencing factors is important for preventing colony losses. Further studies are necessary to identify the risk factors associated with virus presence and its relationship with other pathogens such as V. destructor.

Environment or beekeeping management: What explains better the prevalence of honey bee colonies with high levels of Varroa destructor?

Varroa destructor is one of the major threats to honey bee colonies. The mite abundance in the colonies is affected by environmental conditions as well as by beekeeping management. The aim of this study was to recognize the main drivers associated with autumn V. destructor infestation in honey bee colonies when different regions from Argentina are compared. A total of 361 colonies distributed in five Argentinean eco-regions were examined to evaluate Varroa mite infestation rate during autumn and Nosema sp. presence. Regions were different regarding annual temperature, precipitation and especially vegetation landscape. In addition, beekeeping management practices were obtained from a checklist questionnaire answered by the beekeepers. The prevalence of colonies with high infestation level was lower in semi-arid Chaco followed by humid and transition Chaco regions. Also, colonies that were positive for Nosema sp. showed a higher Varroa infestation rate. The "environmental" effect was stronger compared with the influence of secondary drivers associated with beekeeping activities. As well, a significant association between V. destructor infestation rates and Nosema presence was identified. Under contrasting natural conditions, environment seems a predominant driver on Varroa destructor infestation level in honey bee colonies.