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1.
Monitoring of honey bee colony losses : A special issue
Aleš Gregorc, 2020, drugi znanstveni članki

Opis: In recent decades, independent national and international research programs have revealed possible reasons for the death of managed honey bee colonies worldwide. Such losses are not due to a single factor, but instead are due to highly complex interactions between various internal and external influences, including pests, pathogens, honey bee stock diversity, and environmental change. Reduced honey bee vitality and nutrition, exposure to agrochemicals, and quality of colony management contribute to reduced colony survival in beekeeping operations. Our Special Issue (SI) on ‘’Monitoring of Honey Bee Colony Losses’’ aims to address specific challenges facing honey bee researchers and beekeepers. This SI includes four reviews, with one being a meta-analysis that identifies gaps in the current and future directions for research into honey bee colonies mortalities. Other review articles include studies regarding the impact of numerous factors on honey bee mortality, including external abiotic factors (e.g., winter conditions and colony management) as well as biotic factors such as attacks by Vespa velutina and Varroa destructor.
Ključne besede: honey bee diseases, stressors, pathology, honey bee mortalities, colonies management
Objavljeno v DKUM: 23.01.2025; Ogledov: 0; Prenosov: 3
.pdf Celotno besedilo (202,36 KB)
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2.
Hydroxymethylfurfural affects caged honey bees (Apis mellifera carnica)
Aleš Gregorc, Snežana Jurišić, Blair Sampson, 2020, izvirni znanstveni članek

Opis: A high concentration of hydroxymethylfurfural (HMF) (e.g., 15 mg HMF per kg honey) indicates quality deterioration for a wide range of foods. In honey bee colonies, HMF in stored honey can negatively affect bee health and survival. Therefore, in the laboratory, we experimentally determined the effects of HMF on the longevity and midgut integrity of worker Apis mellifera carnica by feeding bees standard diets containing five concentrations of HMF (100, 500, 1000, and 1500 ppm). Simultaneously, we also examined HMF%s effect on Nosema ceranae spore counts within infected honey bees. We performed an immunohistochemical analysis of the honey bee midgut to determine possible changes at the cellular level. No correlation was established between HMF concentration and N. ceranae spore counts. Negative effects of HMF on bees were not observed in the first 15 days of exposure. However, after 15 to 30 days of exposure, HMF caused midgut cells to die and an increased mortality of honey bee workers across treatment groups.
Ključne besede: hydroxymethylfurfural, honey bee, cell death, immunohistochemistry, Nosema ceranae
Objavljeno v DKUM: 21.01.2025; Ogledov: 0; Prenosov: 2
.pdf Celotno besedilo (2,02 MB)
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3.
Vpliv prehranskih dodatkov na vitalnost čebeljih družin : diplomsko delo
Valentina Videčnik, 2024, diplomsko delo

Opis: V raziskovalnem delu smo od konca marca do sredine aprila leta 2023 čebelje družine v čebelnjaku v Lovrencu na Pohorju hranili s prehranskimi dodatki. Po vzorčenju čebel so bile analize opravljene na Fakulteti za kmetijstvo in biosistemske vede v Pivoli, Hoče. Za naš poskus smo uporabili 10 panjev. Panje smo razdelili v 5 skupin. Vsaka skupina je vsebovala 2 družini, ki sta bili vizualno zdravi, brez simptomov bolezni in škodljivcev. Označili smo jih z navedbo datum hranjenja in vrsto dodatka v hrani. 4 skupine panjev smo hranili z vnaprej pripravljenimi raztopinami izvlečka gob. Hranili smo jih ob ponedeljkih, sredah in petkih, približno ob istem času. Kontrolo družin in vzorčenje čebel smo izvajali vsak ponedeljek. Hranjenje čebel je potekalo s pomočjo sirupa, ki je bil sestavljen iz 50 % vode in 50 % sladkorja ter dodatka (izvlečka gob). Kontrolni družini smo hranili z raztopino sladkorja v vodi (1:1; w:w). Za krmljenje z izvlečki gob smo uporabili sirup, ki je vseboval 4 % izvlečka iz gob. Uporabili smo izvlečke iz gob Ganoderma lucidum, Hericium erinaceus, Inonotus obliquus in Trametes versicolor. Družine so bile hranjene tri tedne, trikrat na teden. Skupno je v poskusu vsaka družina prejela 3 litre hrane. Končna analiza kaže, da imajo izvlečki gob značilen vpliv na antioksidativne lastnosti pri čebelah. Največje učinke smo ugotovili po krmljenju izvlečka gobe Inonotus obliquus. Izvlečki gob so povzročili povečanje koncentracije encimov (ALP, ALT in AST) od 14. dne krmljenja dalje, v primerjavi s kontrolno skupino družin, ki so bile hranjene samo s sladkornim sirupom. Najvišje vrednosti encimov in zato najboljše indikatorje vitalnosti čebel je dal izvleček gob Inonotus obliquus saj je vplival na dolgoživost čebel in izboljšal zdravstveno stanje čebel.
Ključne besede: medonosna čebela, čebelje družine, prehranski dodatki, glive, varoza
Objavljeno v DKUM: 07.10.2024; Ogledov: 0; Prenosov: 13
.pdf Celotno besedilo (2,39 MB)

4.
Authoritative subspecies diagnosis tool for European honey bees based on ancestry informative SNPs
Jamal Momeni, Melanie Parejo, Rasmus O. Nielsen, Jorge Langa, Iratxe Montes, Laetitia Papoutsis, Leila Farajzadeh, Christian Brendixen, Eliza Cǎuia, Aleš Gregorc, 2021, izvirni znanstveni članek

Opis: Background: With numerous endemic subspecies representing four of its five evolutionary lineages, Europe holds a large fraction of Apis mellifera genetic diversity. This diversity and the natural distribution range have been altered by anthropogenic factors. The conservation of this natural heritage relies on the availability of accurate tools for subspecies diagnosis. Based on pool-sequence data from 2145 worker bees representing 22 populations sampled across Europe, we employed two highly discriminative approaches (PCA and FST) to select the most informative SNPs for ancestry inference. Results: Using a supervised machine learning (ML) approach and a set of 3896 genotyped individuals, we could show that the 4094 selected single nucleotide polymorphisms (SNPs) provide an accurate prediction of ancestry inference in European honey bees. The best ML model was Linear Support Vector Classifier (Linear SVC) which correctly assigned most individuals to one of the 14 subspecies or different genetic origins with a mean accuracy of 96.2% ± 0.8 SD. A total of 3.8% of test individuals were misclassified, most probably due to limited differentiation between the subspecies caused by close geographical proximity, or human interference of genetic integrity of reference subspecies, or a combination thereof. Conclusions: The diagnostic tool presented here will contribute to a sustainable conservation and support breeding activities in order to preserve the genetic heritage of European honey bees.
Ključne besede: Apis mellifera, European suspecies, conservation, machine learning, prediction, biodiversity
Objavljeno v DKUM: 01.10.2024; Ogledov: 0; Prenosov: 2
.pdf Celotno besedilo (1,06 MB)
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5.
What has been done in the fight against Varroa destructor : from the past to the present
Aleš Gregorc, Caio Eduardo da Costa Domingues, Hidayet Tutun, Sedat Sevin, 2022, pregledni znanstveni članek

Opis: Bees are the major pollinators in natural ecosystems and in the agricultural production of several crops used for human consumption. However, they are exposed to multiple stressors that are causing a serious decline in their population. We highlight a major one among them, the Varroa destructor mite (Varroa) that causes severe impacts on the health of honey bee colonies, transmitting a variety of viruses that can affect the survival ability of individual bees and entire colonies. Diagnosis and mite control methods have been intensively studied in recent decades, with many studies in different areas of knowledge having been conducted. This overview summarizes these studies with a focus on colony defense systems, biological characteristics of the parasite Varroa, diagnostic methods used to establish the infestation level of colonies, and currently used control methods.
Ključne besede: diagnosis, honey bee disease, mite, parasite, Varroa destructor
Objavljeno v DKUM: 18.07.2024; Ogledov: 151; Prenosov: 10
.pdf Celotno besedilo (641,50 KB)
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6.
Sustainable varroa mite (Varroa destructor) control in field conditions
Aleš Gregorc, Ivo Planinc, 2022, izvirni znanstveni članek

Opis: Experiments assessed the comparative efficacy of oxalic acid solution (OA) and combination of formic acid (FA) evaporation and trickling OA to control the honey bee mite, Varroa destructor, at two apiary locations. Queen caging, consecutive OA treatments of broodless colonies, or combined treatments using OA and FA in colonies with brood increased mite mortality (P < 0.05) in comparison to the pre-treatment period. FA application in colonies with brood in September and October resulted in an average mite mortality of 18% in the first apiary and subsequent FA applications in the same period in the second apiary killed, on average, 73% and 71% of mites; respectively. OA treatment of broodless colonies after queen caging at two apiaries resulted in 18% and 47% mite mortality. Caging the queens and OA treatments in broodless colonies or subsequently use consecutive OA or FA treatments ensure adequate mite reduction before wintering the colonies. Synergistic control methods of Varroa mites using OA and FA along with queen caging is discussed.
Ključne besede: beekeeping, mite control, oxalic acid, formic acid, queen caging
Objavljeno v DKUM: 10.07.2024; Ogledov: 107; Prenosov: 5
.pdf Celotno besedilo (819,18 KB)
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7.
Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid drones
David Wragg, Sonia E. Eynard, Benjamin Basso, Kamila Canale-Tabet, Emmanuelle Labarthe, Olivier Bouchez, Kaspar Bienefeld, Małgorzata Bieńkowska, Cecilia Costa, Aleš Gregorc, Per Kryger, Melanie Parejo, Alice M. Pinto, Jean-Pierre Bidanel, Bertrand Servin, Yves Le Conte, Alain Vignal, 2022, izvirni znanstveni članek

Opis: Honey bee subspecies originate from specific geographical areas in Africa, Europe and the Middle East, and beekeepers interested in specific phenotypes have imported genetic material to regions outside of the bees' original range for use either in pure lines or controlled crosses. Moreover, imported drones are present in the environment and mate naturally with queens from the local subspecies. The resulting admixture complicates population genetics analyses, and population stratification can be a major problem for association studies. To better understand Western European honey bee populations, we produced a whole genome sequence and single nucleotide polymorphism (SNP) genotype data set from 870 haploid drones and demonstrate its utility for the identification of nine genetic backgrounds and various degrees of admixture in a subset of 629 samples. Five backgrounds identified correspond to subspecies, two to isolated populations on islands and two to managed populations. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long and represents 21% of chromosome 11, with two major haplotypes corresponding to the two dominant genetic backgrounds identified. This large naturally phased data set is available as a single vcf file that can now serve as a reference for subsequent populations genomics studies in the honey bee, such as (i) selecting individuals of verified homogeneous genetic backgrounds as references, (ii) imputing genotypes from a lower-density data set generated by an SNP-chip or by low-pass sequencing, or (iii) selecting SNPs compatible with the requirements of genotyping chips.
Ključne besede: genome, haplotype, honey bee, population genetics, SNP
Objavljeno v DKUM: 08.07.2024; Ogledov: 109; Prenosov: 13
.pdf Celotno besedilo (3,07 MB)
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8.
Sensitivity to imidacloprid insecticide varies among some social and solitary bee species of agricultural value
Blair Sampson, Aleš Gregorc, Mohamed Alburaki, Chris Werle, Shahid Karim, John Adamczyk, Patricia R. Knight, 2023, izvirni znanstveni članek

Opis: Pollinator health risks from long-lasting neonicotinoid insecticides like imidacloprid has primarily focused on commercially managed, cavity-nesting bees in the genera Apis, Bombus, and Osmia. We expand these assessments to include 12 species of native and non-native crop pollinators of differing levels of body size, sociality, and floral specialization. Bees were collected throughout 2016 and 2017 from flowering blueberry, squash, pumpkin, sunflower and okra in south Mississippi, USA. Within 30–60 minutes of capture, bees were installed in bioassay cages made from transparent plastic cups and dark amber jars. Bees were fed via dental wicks saturated with 27% (1.25 M) sugar syrup containing a realistic range of sublethal concentrations of imidacloprid (0, 5, 20, or 100 ppb) that are often found in nectar. Bees displayed no visible tremors or convulsions except for a small sweat bee, Halictus ligatus, and only at 100ppb syrup. Imidacloprid shortened the captive longevities of the solitary bees. Tolerant bee species lived ~10 to 12 days in the bioassays and included two social and one solitary species: Halictus ligatus, Apis mellifera and Ptilothrix bombiformis (rose mallow bees), respectively. No other bee species tolerated imidacloprid as well as honey bees did, which exhibited no appreciable mortality and only modest paralysis across concentration. In contrast, native bees either lived shorter lives, experienced longer paralysis, or endured both. Overall, longevity decreased with concentration linearly for social bees and non-linearly for solitary species. The percentage of a bee’s captive lifespan spent paralyzed increased logarithmically with concentration for all species, although bumble bees suffered longest. Of greatest concern was comparable debilitation of agriculturally valuable solitary bees at both low and high sublethal rates of imidacloprid.
Ključne besede: bee culture, agricultural value
Objavljeno v DKUM: 02.04.2024; Ogledov: 208; Prenosov: 17
.pdf Celotno besedilo (1,72 MB)
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9.
Spatial clusters of Varroa destructor control strategies in Europe
Robert Brodschneider, Johannes Schlagbauer, Iliyana Arakelyan, Aleš Gregorc, 2022, izvirni znanstveni članek

Opis: Beekeepers have various options to control the parasitic mite Varroa destructor in honey bee colonies, but no empirical data are available on the methods they apply in practice. We surveyed 28,409 beekeepers maintaining 507,641 colonies in 30 European countries concerning Varroa control methods. The set of 19 different Varroa diagnosis and control measures was taken from the annual COLOSS questionnaire on honey bee colony losses. The most frequent activities were monitoring of Varroa infestations, drone brood removal, various oxalic acid applications and formic acid applications. Correspondence analysis and hierarchical clustering on principal components showed that six Varroa control options (not necessarily the most used ones) significantly contribute to defining three distinctive clusters of countries in terms of Varroa control in Europe. Cluster I (eight Western European countries) is characterized by use of amitraz strips. Cluster II comprises 15 countries from Scandinavia, the Baltics, and Central-Southern Europe. This cluster is characterized by long-term formic acid treatments. Cluster III is characterized by dominant usage of amitraz fumigation and formed by seven Eastern European countries. The median number of different treatments applied per beekeeper was lowest in cluster III. Based on estimation of colony numbers in included countries, we extrapolated the proportions of colonies treated with different methods in Europe. This suggests that circa 62% of colonies in Europe are treated with amitraz, followed by oxalic acid for the next largest percentage of colonies. We discuss possible factors determining the choice of Varroa control measures in the different clusters.
Ključne besede: Apis mellifera, COLOSS, beekeeping, acaricide, varroa control, survey results
Objavljeno v DKUM: 18.08.2023; Ogledov: 793; Prenosov: 36
.pdf Celotno besedilo (2,17 MB)
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10.
Virus prevalence in egg samples collected from naturally selected and traditionally managed honey bee colonies across Europe
David Claeys Bouuaert, Lina De Smet, Marleen Brunain, Bjørn Dahle, Tjeerd Blacquière, Anne Dalmon, Daniel S. Dezmirean, Dylan Elen, Janja Filipi, Alexandru Giurgiu, Aleš Gregorc, 2022, izvirni znanstveni članek

Opis: Monitoring virus infections can be an important selection tool in honey bee breeding. A recent study pointed towards an association between the virus-free status of eggs and an increased virus resistance to deformed wing virus (DWV) at the colony level. In this study, eggs from both naturally surviving and traditionally managed colonies from across Europe were screened for the prevalence of different viruses. Screenings were performed using the phenotyping protocol of the ‘suppressed in ovo virus infection’ trait but with qPCR instead of end-point PCR and a primer set that covers all DWV genotypes. Of the 213 screened samples, 109 were infected with DWV, 54 were infected with black queen cell virus (BQCV), 3 were infected with the sacbrood virus, and 2 were infected with the acute bee paralyses virus. It was demonstrated that incidences of the vertical transmission of DWV were more frequent in naturally surviving than in traditionally managed colonies, although the virus loads in the eggs remained the same. When comparing virus infections with queen age, older queens showed significantly lower infection loads of DWV in both traditionally managed and naturally surviving colonies, as well as reduced DWV infection frequencies in traditionally managed colonies. We determined that the detection frequencies of DWV and BQCV in honey bee eggs were lower in samples obtained in the spring than in those collected in the summer, indicating that vertical transmission may be lower in spring. Together, these patterns in vertical transmission show that honey bee queens have the potential to reduce the degree of vertical transmission over time.
Ključne besede: honey bee, suppressed in ovo virus infection, vertical transmission, virus resistance
Objavljeno v DKUM: 18.08.2023; Ogledov: 457; Prenosov: 48
.pdf Celotno besedilo (837,65 KB)
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