| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 10 / 10
Na začetekNa prejšnjo stran1Na naslednjo stranNa konec
1.
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)
Gradivo ima več datotek! Več...

2.
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)
Gradivo ima več datotek! Več...

3.
4.
COLOSS survey: global impact of COVID-19 on bee research
Raffaele Dall’Olio, Tjeerd Blacquiere, Maria Bouga, Robert Brodschneider, Norman L Carreck, Panuwan Chantawannakul, Vincent Dietemann, Lotta Fabricius Kristiansen, Anna M. Gajda, Aleš Gregorc, Asli Ozkirim, Christian Pirk, Victoria Soroker, Geoffrey R. Williams, Peter Neumann, pregledni znanstveni članek

Opis: The socio-economic impacts of COVID-19 on society have yet to be truly revealed; there is no doubt that the pandemic has severely affected the daily lives of most of humanity. It is to be expected that the research activities of scientists could be impacted to varying degrees, but no data exist on how COVID-19 has affected research specifically. Here, we show that the still ongoing COVID-19 pandemic has already diversely and negatively affected bee research at a global level. An online survey disseminated through the global COLOSS honey bee research association showed that every participant (n = 230 from 56 countries) reported an impact on one or more of their activities. Activities that require travelling or the physical presence of people (meetings and conferences, teaching and extension) were affected the most, but also laboratory and field activities, daily operations, supervision and other activities were affected to varying degrees. Since the basic activities are very similar for many research fields, it appears as if our findings for bee research can be extrapolated to other fields. In the light of our data, we recommend that stakeholders such as governments and funding bodies who support research should facilitate the wide implementation of web-based information technology required for efficient online communication for research and education, as well as adequately loosened restriction measures with respect to field and laboratory work. Finally, increased flexibility in administration and extension of research grants and fellowships seem to be needed. It is apparent that adequate responses by all stakeholders are required to limit the impact of COVID-19 and future pandemics on bee science and other research fields.
Ključne besede: COLOSS, Apis mellifera, coronavirus, COVID-19, honey bee, pandemic, research, extension
Objavljeno v DKUM: 12.11.2020; Ogledov: 1029; Prenosov: 212
.pdf Celotno besedilo (2,26 MB)
Gradivo ima več datotek! Več...
Gradivo je zbirka in zajema 1 gradivo!

5.
Combating Varroa destructor in honeybee colonies using flumethrin or fluvalinate
Aleš Gregorc, Maja Ivana Smodiš Škerl, 2007, izvirni znanstveni članek

Opis: Mite mortality in two apiaries, one with 32 and the other with 15 honeybee (Apis mellifera carnica) colonies, was recorded prior to and after flumethrin or fluvalinate treatments and after a control, oxalic-acid application. During the 42- and 51-day pre-treatment periods, the average daily natural mite drop was 0.04 (± 0.04) and 2.82 (± 2.19), respectively, which represents 1.09% (± 1.06) and 3.84% (± 3.04) of the total number of mites found during the experiment. The flumethrin or fluvalinate applications resulted in an average mite mortality at the two apiaries of 214.46 (± 260.02) and 4,098.64 (± 2,508.31). The treatments resulted in a 19.11% (± 14.62) and a 39.28% (± 10.47) reduction in the number of mites in slightly infested colonies and 94.30% (± 4.26) and 96.24% (± 3.14) in highly infested colonies. The difference in treatment efficacy between both apiaries was significant (P < 0.001) and indicates that fluvalinate and flumethrin are highly efficacious in dealing with highly infested honeybee colonies with sealed brood. The importance of effective mite control in colonies with a high level of natural mite mortality is discussed in this study.
Ključne besede: Acaricides, control methods, Apis mellifera, oxalic acid, mite infestation
Objavljeno v DKUM: 04.08.2017; Ogledov: 2183; Prenosov: 352
.pdf Celotno besedilo (149,12 KB)
Gradivo ima več datotek! Več...

6.
Chronic bee paralysis virus and Nosema ceranae experimental co-infection of winter honey bee workers (Apis mellifera L.)
Ivan Toplak, Urška Jamnikar Ciglenečki, Katherine Aronstein, Aleš Gregorc, 2013, izvirni znanstveni članek

Opis: Chronic bee paralysis virus (CBPV) is an important viral disease of adult bees which induces significant losses in honey bee colonies. Despite comprehensive research, only limited data is available from experimental infection for this virus. In the present study winter worker bees were experimentally infected in three different experiments. Bees were first inoculated per os (p/o) or per cuticle (p/c) with CBPV field strain M92/2010 in order to evaluate the virus replication in individual bees. In addition, potential synergistic effects of co-infection with CBPV and Nosema ceranae (N. ceranae) on bees were investigated. In total 558 individual bees were inoculated in small cages and data were analyzed using quantitative real time RT-PCR (RT-qPCR). Our results revealed successful replication of CBPV after p/o inoculation, while it was less effective when bees were inoculated p/c. Dead bees harbored about 1,000 times higher copy numbers of the virus than live bees. Co-infection of workers with CBPV and N. ceranae using either method of virus inoculation (p/c or p/o) showed increased replication ability for CBPV. In the third experiment the effect of inoculation on bee mortality was evaluated. The highest level of bee mortality was observed in a group of bees inoculated with CBPV p/o, followed by a group of workers simultaneously inoculated with CBPV and N. ceranae p/o, followed by the group inoculated with CBPV p/c and the group with only N. ceranae p/o. The experimental infection with CBPV showed important differences after p/o or p/c inoculation in winter bees, while simultaneous infection with CBPV and N. ceranae suggesting a synergistic effect after inoculation.
Ključne besede: Apis mellifera, experimental infection, Chronic Bee Paralysis Virus, CBPV, Nosema ceranae, interaction
Objavljeno v DKUM: 22.06.2017; Ogledov: 1270; Prenosov: 365
.pdf Celotno besedilo (541,74 KB)
Gradivo ima več datotek! Več...

7.
Palinološka analiza in primerjava peloda jesenske paše domače čebele (Apis mellifera) na različnih lokacijah Prekmurja
Lea Dominko, 2016, diplomsko delo

Opis: Namen diplomske naloge je bil analizirati in medsebojno primerjati vzorce peloda jesenske paše domače čebele iz različnih lokacij, izbranih v regiji Prekmurje. Izbrane lokacije so bile Dokležovje, Dobrovnik in Prosečka vas. Pelod smo na vseh lokacijah pobirali v istem časovnem obdobju, in sicer od 1. 9. do 30. 9. 2016. Pobranega smo zamrznili, posušili in shranili do analize. Hkrati s pobiranjem vzorcev smo po vseh lokacijah v radiju petih kilometrov od stojišča čebelnjaka popisovali rastline. Pri mikroskopski analizi peloda sta nas zanimala predvsem vrstna sestava vzorcev in deleži posameznih pelodnih vrst v vzorcih. Iz rezultatov smo lahko razbrali atraktivnost posamezne jeseni cvetoče rastline za čebele, vsakemu vzorcu pa smo določili tudi Shannon-Weaverjev diverzitetni indeks in indeks vrstne poravnanosti. Rezultati so lahko odlično vodilo pri izbiri lokacije stojišča čebelnjaka v Prekmurju. Ugotovili smo, da so se vzorci v določenem obsegu vrstno prekrivali. Deleži posameznih vrst peloda so se od lokacije do lokacije razlikovali, v vseh vzorcih pa smo opazili prevlado pelodnih zrn navadne ajde (Fagopyrum esculentum) in rumene gorjušice (Sinapis arvensis). Čebelam najatraktivnejše vrste rastlin so bile, poleg navedenih dveh, še plazeča detelja (Trifolium repens), žlezava nedotika (Impatiens glandulifera), polajeva materina dušica (Thymus pulegioides), navadni potrošnik (Cichorium intybus) in navadni regrat (Taraxacum officinale). Na podlagi vseh zbranih rezultatov in vrednosti obeh indeksov smo ugotovili, da je bila v času našega vzorčenja peloda najprimernejša lokacija za postavitev čebelnjaka Prosečka vas.
Ključne besede: domača čebela, Apis mellifera, pelod, analiza peloda, vrstna sestava peloda, deleži posameznih vrst peloda, Shannon-Weaverjev indeks, indeks vrstne poravnanosti, Prekmurje
Objavljeno v DKUM: 26.09.2016; Ogledov: 1632; Prenosov: 122
.pdf Celotno besedilo (3,58 MB)

8.
Spremembe v srednjem črevesu in goltnih žlezah po okužbi medonosne čebele (Apis mellifera carnica) s sporami Nosema spp.
Mateja Soklič, 2016, doktorsko delo/naloga

Opis: Medonosna čebela (A. mellifera) spada med najpomembnejše, vsekakor pa tudi najštevilčnejše opraševalce kmetijskih pridelkov. Živi v specifični socialni združbi z izrazitim kastnim sistemom. Troti in matica predstavljajo reproduktivne osebke v družini za razliko od delavk, ki so sociološko sterilne. V družini opravljajo naloge oskrbovanja zalege, matice in mladih čebel z matičnim mlečkom ali drugo hrano, gradijo satje, varujejo panj pred vsiljivci in nabirajo mano, nektar, cvetni prah in vodo. Delavke lahko zaradi prezgodnje smrtnosti ali subletalnih učinkov, zaradi katerih niso sposobne opravljati katere od naštetih nalog, družini ne koristijo več. Kadar je število takšnih delavk veliko, ta izguba prizadene celotno čebeljo družino. Zato smo v pričujoči nalogi preverili, kakšni so subletalni vplivi okužbe s pogostima parazitoma iz družine Nosema spp. na srednje črevo in goltne žleze čebel delavk. S pomočjo tehnike TUNEL za zaznavanje celične smrti smo ugotavljali pojavnost odmiranja celic na tkivnih rezinah srednjega črevesa in goltnih žlez, neokuženih ali z N. apis oziroma N. ceranae okuženih čebel. Poleg tega smo ocenili vpliv okužbe na morfologijo obeh organov. Premer goltnih žlez smo uporabili kot indikator razvitosti žlez in analizirali njegovo povezanost s težo glave. Ugotovili smo, da okužba z N. apis povzroča povečano smrtnost celic epitela srednjega črevesa. Delež TUNEL pozitivnih jeder pri neokuženih delavkah se je ves čas gibal okoli desetih odstotkov, kar je približno petina pozitivnih jeder, ugotovljenih pri z N. apis okuženih delavkah. Po 15. dnevu je število upadlo na raven prvih. V črevesju z N. ceranae okuženih delavk je bilo število apoptotičnih jeder znatno višje od kontrol tretji. dan, po 12. dnevu pa je povsem upadlo na z neokuženimi delavkami primerljivo raven. Pri čebelah, okuženih z Nosema spp., so bile spore 15. dan prisotne v večini epitelnih celic, zgradba srednjega črevesa je bila močno spremenjena in je kazala znake degeneracije. Okužba z Nosema spp. je negativno delovala na razvoj goltnih žlez in njihovo sekretorno aktivnost. Pri okužbi z N. ceranae smo zabeležili signifikanten (P < 0,05) negativen vpliv okužbe na razvitost goltnih žlez na vse dni testiranja in na 12. ter 21. dan za okužbo z N. apis. Na histološki ravni smo pri okuženih delavkah v hipofaringealnih žlezah ugotovili zmanjšanje količine citoplazme in sekretornih veziklov, ki so znak aktivnosti žlez. Povišan je bil tudi delež celične smrti v sekretornih celicah goltnih žlez okuženih čebel. Ker v nobenem izmed preiskovanih vzorcev goltnih žlez nismo ugotovili spor Nosema spp. sklepamo, da žleze niso primarno mesto okužbe. Atrofija žlez pri okuženih delavkah je tako verjetno posledica slabšega izkoriščanja hrane zaradi poškodb, ki jih povzroči razmnoževanje parazitskih gliv v črevesnem epiteliju. Premeri goltnih žlez so bili v neposredni korelaciji s težo glave pri delavkah iz vseh treh skupin. Okužba z N. ceranae se je širila z okuženih na neokužene delavke, ne pa tudi na matice v poskusnih plemenilnikih. Razvoj okužbe pri neokuženih delavkah je z zamikom sledil poteku pri sočasno naseljenih delavkah, ki so prejele 80.000 spor N. ceranae.
Ključne besede: Apis mellifera, srednje črevo, goltne žleze, Nosema spp., celična smrt
Objavljeno v DKUM: 05.08.2016; Ogledov: 3035; Prenosov: 168
.pdf Celotno besedilo (5,33 MB)

9.
10.
Poznosezonska bera pri domači čebeli (Apis mellifera) in pri čmrljih (Bombus)
Tadej Törnar, 2015, diplomsko delo

Opis: Najpogostejši opraševalci žužkocvetnih rastlin so domače čebele (Apis mellifera), ki jih navadno gojimo v panjih. Zelo pomembni in ogroženi opraševalci žužkocvetnih rastlin so tudi čmrlji (Bombus). Čebele in čmrlji skozi leto nabirajo nektar, pelod ter nekatere rastlinske izločke, ki vsebujejo sladkorje, kot hrano za odrasle osebke kot tudi za zarod ter za preživetje celotne čebelje kolonije v dolgotrajnejših zimskih obdobjih. Vsak med nima hranilne vrednosti oz. je za čebele kot hrana včasih nedostopen. Naravni med lahko pod določenimi pogoji kristalizira, nekatere vrste prej, druge pozneje in ga v taki obliki čebele ne morejo zaužiti. Tako lahko čebele pozimi stradajo, kljub obilici nabranih zalog hrane. Zato je za obstoj čebelje kolonije izjemnega pomena kakšen tip medičine čebele delavke naberejo v pozni vegetacijski sezoni. V pozni vegetacijski sezoni opraševalci nimajo veliko možnosti za nabiranje zimske zaloge hrane. Zato se v tem obdobju čebelarji zanašajo na obilno cvetenje nekaterih rastlinskih vrst, ki pa so z naravovarstvenega vidika lahko zelo problematične. Pri tem imamo v mislih invazivne tujerodne vrste. V poznem letnem času za čebele pomemben vir hrane predstavljajo tudi nekatere kultivirane vrste. Pri poznosezonskih vrstah pa se lahko dogaja, da med takih rastlin hitro kristalizira in je s tem neprimeren za zimsko zalogo hrane čebelam. Mnoge invazivne vrste, kot sta žlezava nedotika in orjaška zlata rozga, izrazito siromašita biodiverziteto tako na ravni flore kot tudi habitatov. Ker pa gre za pomemben vir hrane za čebele in čmrlje, želimo v tej nalogi ugotoviti, katero rastlinsko vrsto čebele in čmrlji v poznem jesenskem času najpogosteje obiskujejo. Prav tako nas je zanimalo, ali čebele in čmrlji raje nabirajo hrano na gozdnih ali na odprtih površinah. Popisi čebel in čmrljev so se izvajali na štirih različnih lokalitetah ob treh različnih dnevnih časih (dopoldne, opoldne in popoldne). Ker so tudi čmrlji pomembni opraševalci v našem okolju, smo v našo študijo vključili tudi te vrste. Evidentiranih je bilo sedem vrst čmrljev na območju popisov, ki smo jih v tej študiji tudi podrobneje predstavili.
Ključne besede: domača čebela, Apis mellifera, čmrlji, Bombus, orjaška zlata rozga, žlezava nedotika, ajda, bršljan, opraševalci, med, poznosezonska bera, invazivne tujerodne rastline
Objavljeno v DKUM: 21.04.2015; Ogledov: 1760; Prenosov: 204
.pdf Celotno besedilo (3,15 MB)

Iskanje izvedeno v 0.31 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici