Five fixed isoenzyme selections, within the white clover (Trifolium repens) cultivar S100, were used as genetic markers in a study of the effectiveness of bees of different genera as pollen vectors. ...Five plants of each of the five selections were cloned to provide two identical plots of 25 plants with equal proportions of the five different pollen donor plants. Pollen flow within each plot, mediated by honey bees, Apis mellifera, and bumble bees, Bombus spp., was determined on an individual inflorescence basis in plots containing the different pollinator species. The movement between plants of the various pollen types was monitored by determining the paternity of the seedlings that resulted following pollination and fertilization using starch gel electrophoresis. Variation was found in the proportions of the different paternal donors to sire seed within pods. Following pollination by Apis, c. 50% of pods contained seed from ovules fertilized by pollen from two different selections, c. 25% with that from three or four selections and none with that from only one. Following pollination by Bombus, c. 30% of pods contained seed from ovules fertilized by pollen from two selections, c. 50% with that from three selections and c. 10% with that from one or four. Within an inflorescence, pollination by both Apis and Bombus resulted in c. 70% of seed having the same paternity. Within individual pods, one paternal selection dominated; in pods containing seeds of two, three or four paternities the dominant paternal selection accounted for 75%, 60% and 60%, respectively, following pollination by Apis, and 75%, 64% and 63%, respectively, following pollination by Bombus. The results are discussed in relation to the foraging behaviour of bees, pollen carryover and gene flow.
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Provider: - Institution: - Data provided by Europeana Collections- Halle (Saale), Martin-Luther-Universität Halle-Wittenberg, Diss., 2015- All metadata published by Europeana are available free of ...restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Istraživanje prikazuje posjećenost suncokreta medonosnom pčelom (Apis mellifera carnica) a obavljeno je na poljskom pokusu u slučajnom blok rasporedu koji je obuhvatio 6 hibrida merkantilnog ...suncokreta (Helianthus annuus L.), najviše zastupljenih na poljima kontinentalne Hrvatske. Mjerenje se provodilo na 100, 200 i 300 metara od košnica. Tijekom mjerenja uočena je različita atraktivnost pojedinog hibrida u pokusu za medonosnu pčelu. Statističkom je analizom utvrđena signifikantna razlika između hibrida H2, kod kojeg je utvrđena najmanja posjećenost, i hibrida H4 kod kojeg je ona bila najveća. Nadalje, analiza podataka je pokazala da je najmanja posjećenost pčelom bila na udaljenosti 200 m od košnica. Na udaljenostima 100 i 300 metara nije bilo veće razlike. Ujedno je bio uočen vrlo mali broj prirodnih oprašivača, što je indikator znatnog smanjenja njihove populacije u agro-eko sustavu Baranje. Tijekom cvatnje suncokreta medonosna pčela zabilježena je kao najzastupljeniji oprašivač. Evidentirana je u 99,53 % mjerenja obavljenih tijekom pokusa, bumbari (Bombus spp.) su evidentirani u 0,32 % mjerenja, dok je muha Volucella zonaria (Poda, 1761) evidentirana u 0,15 % mjerenja. Klimatske prilike tijekom cvatnje suncokreta bile su pogodne za aktivnost pčele (temp. 19,9 - 27,5 °C, relativna vlažnost zraka 65-88% i 16,1 mm oborina tijekom tri dana).
Evaluating the potential for genetically modified (GM) crops to have a negative impact on pollinating insects has long been recognized as an important part of risk assessment of such plants. ...Extensive field experience with commercial GM crops, bred for herbicide tolerance or insect resistance using ( ) crystal (Cry) toxin genes, has shown no deleterious effects on pollinators. Many other insecticidal GM plants, not yet commercialized, have been studied to see if they could be hazardous to bees. Of these, only some of the protease inhibitors and lectins could present dose-dependent hazards to bees if there were realistic routes for sufficiently high exposure. A good understanding of crop pollination biology is essential for adequately assessing risks of GM plants to pollinators. In addition, information on crop pollination will aid the study of transgene flow since pollinators could play a role in the transfer of transgenes from GM plants to non-GM crops or wild relatives.
Provider: - Institution: - Data provided by Europeana Collections- Halle (Saale), Martin-Luther-Universität Halle-Wittenberg, Diss., 2010- All metadata published by Europeana are available free of ...restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
