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  • 1
    ISSN: 1420-9098
    Keywords: Stingless bees ; Plebeia remota ; social evolution ; division of labour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The genusPlebeia has a special significance for the study of social evolution of stingless bees: morphologically primitive, its species display a wealth of behavioural evolution, especially with respect to the oviposition process. We comparePlebeia remota with the few other members of the genus studied so far. Related to its subtropical geographical range, brood production is seasonal (there is no brood in the colony in colder months), and adult workers occur as summer and winter bees. The nest is in tree cavities, and the involucrum is absent or restricted to the winter period. Brood cells are arranged in horizontal combs, and new cells are built completely synchronously. Each series consists of up to 50 cells, their number being mainly dependent on colony size. Construction speed is remarkably constant, allowing 4–6 batches per 24 hours. Cell building and provisioning are activities of a small group of specialized workers. The oviposition cycle follows the classical subdivisions for stingless bees. During the patrolling phase a worker may “offer” a trophic egg in a most remarkable way: while retreating backward from the queen she bends the abdomen under thorax and head, and lays an egg on the comb. This egg is eaten by the queen or a worker. The provisioning, oviposition and operculation of all cells occur simultaneously, each cell is provisioned by 4–9 workers. Localization of a cell by the queen may be facilitated by its characteristic guard, which “defends” the cell against the approaching queen. The degree of synchronization within a batch is very high: the duration per cell lasts 420–950 sec, the batch of up till 50 cells needs only 557–1160 sec. Operculation is done by a worker that was not involved in the previous steps. Males are generally produced by the queen. Several male producing cycles per year occur. In orphan colonies laying workers give rise to males, and in queenright colonies workers may occasionally reproduce as well. Division of labour follows the general pattern for stingless bees; however, cell building and provisioning are activities of a specialized group of workers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Insectes sociaux 45 (1998), S. 231-233 
    ISSN: 1420-9098
    Keywords: Key words: Multiple mating, stingless bees, Tetragonisca angustula, Meliponinae.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: In several stingless bee species many males aggregate in the vicinity of a nest when a virgin queen is present in the colony and is preparing for the nuptial flight. We report such male assemblage for Tetragonisca angustula. The departure of a virgin queen from the colony and the subsequent mating could be video-recorded, because the queen and the males that had mounted her fell to the ground. Since at least two males had lost their genitalia, multiple mating seems to have occurred. This is in contrast with the prevailing view found in literature concerning the mating biology of stingless bees.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1420-9098
    Keywords: Key words: Stingless bees, Melipona subnitida, worker reproduction, male production, queen dominance.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: In stingless bees brood cells are sequentially filled with liquid larval food (mass-provisioning), upon which the queen lays an egg. Thereafter the cell is closed by a worker. This study showed that during these processes workers of Melipona subnitida regularly laid eggs that served as food for the queen. Occasionally cells were oviposited in and immediately closed by a worker. These cells always rendered males. Some of these reproductive workers were seen to lay a trophic egg as well. Cells which were exclusively oviposited in by the physogastric queen gave rise to workers and queens only. In one colony it could be verified that three workers alone, which differed in age by one day, laid 15 male-producing eggs within a period of two successive weeks. Among them the number of ovipositions was positively related to the order in which workers eclosed - the oldest worker laying most eggs - and inversely related to the number of times they closed cells oviposited in exclusively by the queen. Apparently the physogastric queen was not able to stop certain workers from reproducing. We therefore conclude that some workers in M. subnitida temporarily dominated their queens in egg-laying.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 263 (1998), S. 377-380 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The HEGRA experiment investigates the relativistic (non thermal) universe by measuring air showers initiated in the atmosphere by photons and charged particles from the cosmos, using the imaging atmospheric Cherenkov light technique (〉 500 GeV) and the showerfront sampling technique (〉 20 TeV). New results concerning the search and study of gamma ray sources above 500 GeV, the measurement of the energy spectrum and chemical composition of cosmic rays above 1 PeV and the search of TeV counterparts of Gamma Ray Bursts are briefly described.
    Type of Medium: Electronic Resource
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