1. The adverse impacts of a single exposure to the fungicide picoxystrobin during the larval stage on africanized Apis melliferaCaio Eduardo da Costa Domingues, Leticia Salvioni Ansaloni, Aleš Gregorc, Elaine C. Mathias da Silva, 2024, izvirni znanstveni članek Opis: Pesticide use remains a problem in agriculture, contaminating natural ecosystems and affecting bees. Fungicides have been widely used worldwide, and honey bees can bring contaminated pollen and nectar to the colony, exposing the larvae. Studies on larval exposure to fungicides are still rare. Therefore, this work aimed to evaluate the effects of larval exposure to the fungicide picoxystrobin on biological parameters and cellular stress in the fat body. The larvae were single exposure on the fourth day (D4) to picoxystrobin at concentrations of 5 ng a.i./μL (PCX5), 45 ng a.i./μL (PCX45), 135 ng a.i./μL (PCX135), and 400 ng a.i./μL (PCX400). The effects on larval and pupal mortality, pupation rate, and emergence were evaluated. Additionally, cellular stress in the fat body was assessed in newly emerged bees. Exposure to PCX400 increased larval mortality by 26% and reduced the emergence of adult bees. The other concentrations did not affect larval and pupal mortality, or pupation and emergence rates. A cytotoxicity effect was observed in newly emerged bees from PCX400, indicated by positive immunolabeling of HSP70. Thus, a single exposure to picoxystrobin can impair larval development, induce a cellular stress response, and may interfere with colony dynamics. Ključne besede: development, honey bee, non-target organism, strobilurin, toxicity Objavljeno v DKUM: 23.04.2025; Ogledov: 0; Prenosov: 0
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2. Eggs sampling as an effective tool for identifying the incidence of viruses in honey bees involved in artificial queen rearingCaio Eduardo da Costa Domingues, Laura Šimenc Kramar, Ivan Toplak, D.C. de Graaf, Lina De Smet, Wim Verbeke, Luc Peelman, Leticia Salvioni Ansaloni, Aleš Gregorc, 2024, izvirni znanstveni članek Objavljeno v DKUM: 18.04.2025; Ogledov: 0; Prenosov: 1
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3. Ultrastructural changes in the midgut of Brazilian native stingless bee Melipona scutellaris exposed to fungicide pyraclostrobinCaio Eduardo da Costa Domingues, Lais Vieira Bello Inoue, Aleš Gregorc, Leticia Salvioni Ansaloni, Osmar Malaspina, Elaine C. Mathias da Silva, 2023, izvirni znanstveni članek Opis: Melipona scutellaris is a Brazilian stingless bee that is important for pollinating wild flora and agriculture crops. Fungicides have been widely used in agriculture, and floral residues can affect forager bees. The goal of our study was to evaluate the effects of sublethal concentrations of pyraclostrobin on the midgut ultrastructure of M. scutellaris forager workers. The bees were collected from three non-parental colonies and kept under laboratory conditions. The bees were orally exposed continuously for five days to pyraclostrobin in syrup at concentrations of 0.125 ng a.i./µL (FG1) and 0.005 ng a.i./µL (FG2). The control bees (CTL) were fed a no-fungicide sucrose solution, and the acetone solvent control bees (CAC) received a sucrose solution containing acetone. At the end of the exposure, the midguts were sampled, fixed in Karnovsky solution, and routinely processed for transmission electron microscopy. Ultrastructural analysis demonstrated that both the fungicide concentrations altered the midgut, such as cytoplasmic vacuolization (more intense in FG1), the presence of an atypical nuclear morphology, and slightly dilated mitochondrial cristae in the bees from the FG1 and FG2 groups (both more intense in FG1). Additionally, there was an alteration in the ultrastructure of the spherocrystals (FG1), which could be the result of cellular metabolism impairment and the excretion of toxic metabolites in the digestive cells as a response to fungicide exposure. The results indicate that ingested pyraclostrobin induced cytotoxic effects in the midgut of native stingless bees. These cellular ultrastructural responses of the midgut are a prelude to a reduced survival rate, as observed in previous studies. Ključne besede: digestive tract, Meliponini, mitochondria, morphology, strobilurin, sublethal effects Objavljeno v DKUM: 07.04.2025; Ogledov: 0; Prenosov: 2
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4. Monitoring of honey bee colony losses : A special issueAleš 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: 8
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5. 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: 4
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6. Vpliv prehranskih dodatkov na vitalnost čebeljih družin : diplomsko deloValentina 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: 23
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7. Authoritative subspecies diagnosis tool for European honey bees based on ancestry informative SNPsJamal 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
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8. What has been done in the fight against Varroa destructor : from the past to the presentAleš 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: 11
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9. Sustainable varroa mite (Varroa destructor) control in field conditionsAleš 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
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10. Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid dronesDavid 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: 15
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