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タイトル: セイヨウミツバチ Apis melliferaにおける低温条件下の蜂群の動態
その他のタイトル: Behavior of bee clusters under low-temperature condition in honey bees (Apis mellifera)
著者: 渡邉, 雅美
発行日: 12-May-2017
抄録: During winter, honeybees (Apis mellifera) crowd together and accomplish thermogenesis by consuming stored honey. It has been assumed that the arrangement of honey cells influences the clustering of bees in the hive, but it remains unclear how bees that are tightly aggregated move to feed on the stored honey. The aim of this study was to identify the key behaviors of bee groups and individual workers under low-temperature conditions. Two kinds of experiments were performed. In the first (the cluster formation experiment), a cluster of workers that formed as a result of stimulation by low-temperature conditions was investigated to determine the influence of the arrangement of the honey cells. In the second (the long cool period experiment), the behavior of worker bees during a long cool period was tracked, with a focus on locomotion, feeding, and body temperature. Worker bees were collected from the hive maintained at Rakuno Gakuen. Each of the test groups, 300-500 workers in the first experiment and 1700 in the second, was introduced into the experimental cage with a comb in a 5°C temperature-controlled cabinet, and the behavior of the workers was monitored with a web camera and infrared thermography. In the cluster formation experiment, three comb patterns were prepared: (1) empty cells (E comb), (2) all cells containing honey (H comb), and (3) a central area of empty cells and a peripheral region with honey cells (E+H comb). In the long cool period experiment, a comb with sealed honey cells was used. The experiment initiated on December 4, 2016, and an LED light was switched on at 6:50, sunrise on that day, and switched off at 16:00 (sunset). A light/dark cycle of 9L/15D was maintained during the experiment. Monitoring continued for about a month until all the bees were dead. In the cluster formation experiment, the five replicates for each comb showed a similar process and final disposition of the aggregated bees in about 1 h. In the E combs, workers in small groups walked on the frame and, clustered around the position where a few honey cells were arranged, but not around the empty cells. In the H combs and H+E combs, workers walked on the honey cells and clustered on non-sealed honey cells. The temperature dropped more quickly in the empty cells than in the honey-filled cells. These results show that bees preferentially move to honey cells, prefer unsealed honey cells over sealed honey cells, never select cool empty cells, and move to join the large group. In the long cool period experiment, the bee group formed a cluster near the upper right where the seal of the honey cells had been artificially torn before the experiment. Five days after the bees formed a cluster, the location of the cluster shifted in such a way as to move from the region where the honey was exhausted toward the honey-filled cells. The temperature in the cage increased during the light period and decreased during the dark period, changing within a range of 5-8℃. Worker movement was observed under the light condition and was not detected under the dark condition. Under the light condition, some core workers moved to the periphery of the cluster and then entered the core again. The thorax temperature of the active workers was steady at 30-40℃. As the number of active workers increased after the light was switched on, the contour of the bee cluster changed. The active workers became unrecognizable after the light was switched off, and then the contour of the cluster returned to its earlier state. The workers on the surface of the cluster did not move spontaneously under either light or dark conditions. The body temperature of the surface bees remained steady from 14-20℃. When the number of active workers increased, the temperature of the surface bees rose to 20-25℃. The bees on the surface were not observed entering the core. From observations in the long cool period experiment, the position of bee cluster appears to have changed as follows: (1) as the core workers became active and moved to the cluster periphery, spaces arose inside the cluster, (2) some of the inner workers moved to fill these spaces, (3) the contour of the cluster changed, and as a result the central position of the cluster shifted. The outer bees functioned as a mantle over the cluster, and consequently provided heat insulation. The present experiment revealed the activities of the inner and outer bees of the cluster. These bees, however, made a flat cluster on one side of a single comb. In real bee nests, bees aggregate to form clusters that range over several combs. It will thus be necessary to conduct experiments on natural bee clusters to determine how bees divide work in natural settings.
URI: http://hdl.handle.net/10659/4909
学位授与年月日: 2016
学位名: 酪農学
学位授与機関: 酪農学園大学


このアイテムの引用には次の識別子を使用してください: http://hdl.handle.net/10659/4909


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