6 research outputs found

    Number of attacking bees for each of the five colonies displayed separately.

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    <p>Discs were displayed in 1.5 m a distance to the nests. Box plots in white with red scatter plot overlay represent number of attacking bees during downward movement of discs. Box plots in grey with cyan scatter plot overlay represent number of attacking bees during upward movement of discs respectively. The total number of observations were 69 for colony 1, 13 for colony 2, 13 for colony 3, 12 for colony 4, 12 for colony 5 respectively.</p

    Number of attacking bees in response to up and downwards movement in three different disc sizes (8 cm, 25 cm, 50 cm).

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    <p>Discs were displayed in a 1.5 m distance to the nests. Box plots in white with red scatter plot overlay represent number of attacking bees during downward movement of discs. Box plots in grey with cyan scatter plot overlay represent number of attacking bees during upward movement of discs respectively. The total number of observations were 15 for 8 cm (colony 1 only), 34 for 25 cm (colonies 1 and 3) and 70 for 50 cm (colonies 1, 2, 4 and 5) disc sizes respectively.</p

    Relative expression (mean ± s.e.) of candidate genes important for apoptosis in <i>Nosema</i> infected honeybees.

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    <p><i>Nosema</i> sensitive (SN, solid circles) and tolerant (TN, solid squares) honeybees infected with 10<sup>5</sup><i>N</i>. <i>ceranae</i> spores, and their controls uninfected (SC, open circles and TC, open squares), were sampled at 1 day (green) and 6 days (blue) after inoculation. The genes JNK/<i>bsk</i> (Jun N–terminal kinase/ <i>basket</i>), <i>p53</i> (<i>tumor protein p53-like</i>), <i>iap–2</i> (<i>inhibitor of apoptosis protein 2;</i> predicted homologous gene to <i>Diap–1</i> in <i>D</i>. <i>melanogaster</i>), <i>casp–2</i> (<i>caspase–2–like; homologous gene to Dcp–1</i>), <i>casp–10</i> (<i>caspase–10–like; homologous gene to Dredd</i>) were predicted from <i>Drosophila melanogaster</i>. Sample sizes are ranging between six and ten pools of three individual honeybee midguts (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140174#pone.0140174.s003" target="_blank">S3 Table</a>). Significance between treatment groups ***, <i>P</i> < 0.001.</p

    “Envelope” of bees shielding the comb (schematic cross section).

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    <p>“Envelope” of bees shielding the comb (schematic cross section).</p

    <i>A</i>. <i>dorsata</i> colony nests high up under a thick horizontal branch.

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    <p><i>A</i>. <i>dorsata</i> colony nests high up under a thick horizontal branch.</p

    “Up” or “down” that makes the difference. How giant honeybees (<i>Apis dorsata</i>) see the world

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    <div><p><i>A</i>. <i>dorsata</i> builds its large exposed comb high in trees or under ledges of high rocks. The “open” nest of <i>A</i>. <i>dorsata</i>, shielded (only!) by multiple layers of bees, is highly vulnerable to any kind of direct contact or close range attacks from predators. Therefore, guard bees of the outer layer of <i>A</i>. <i>dorsata’s</i> nest monitor the vicinity for possible hazards and an effective risk assessment is required. Guard bees, however, are frequently exposed to different objects like leaves, twigs and other tree litter passing the nest from above and falling to the ground. Thus, downward movement of objects past the nest might be used by <i>A</i>. <i>dorsata</i> to classify these visual stimuli near the nest as “harmless”. To test the effect of movement direction on defensive responses, we used circular black discs that were moved down or up in front of colonies and recorded the number of guard bees flying towards the disc. The size of the disc (diameter from 8 cm to 50 cm) had an effect on the number of guard bees responding, the bigger the plate the more bees started from the nest. The direction of a disc’s movement had a dramatic effect on the attraction. We found a significantly higher number of attacks, when discs were moved upwards compared to downward movements (GLMM (estimate ± s.e.) 1.872 ± 0.149, P < 0.001). Our results demonstrate for the first time that the vertical direction of movement of an object can be important for releasing defensive behaviour. Upward movement of dark objects near the colony might be an innate releaser of attack flights. At the same time, downward movement is perceived as a “harmless” stimulus.</p></div
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