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Giant Honey Bee - Apis dorsata
Topic Started: Mar 24 2013, 12:00 PM (2,706 Views)
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Giant Honey Bee - Apis dorsata

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Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Apidae
Genus: Apis
Subgenus: (Megapis)
Species: Apis dorsata

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Apis dorsata, the giant honey bee, is a honey bee of southern and southeastern Asia mainly in forested areas like the Terai of Nepal. The subspecies with the largest individuals is the Himalayan cliff honey bee — Apis dorsata laboriosa — but typical Apis dorsata workers from other subspecies are around 17–20 millimetres (0.7–0.8 in) long.
Nests are mainly built in exposed places far off the ground, on tree limbs and under cliff overhangs, and sometimes on buildings. Apis dorsata is a defensive bee and has never been domesticated (as it does not use enclosed cavities for nesting). Each colony consists of a single vertical comb (sometimes approaching a square metre) suspended from above, and the comb is typically covered by a dense mass of bees in several layers. When disturbed, the workers may exhibit a defensive behavior known as defense waving. Bees in the outer layer thrust their abdomens ninety degrees in an upward direction and shake them in a synchronous way. This may be accompanied by stroking of the wings. The signal is transmitted to nearby workers that also adopt the posture, thus creating a visible — and audible — "ripple" effect across the face of the comb, in an almost identical manner to an audience wave at a crowded stadium.
These bees are tropical and in most places they migrate seasonally. Some recent evidence indicates that the bees return to the same nest site, even though most, if not all, the original workers might be replaced in the process. The mechanism of memory retention remains a mystery. Despite its aggressive nature, indigenous peoples have traditionally used this species as a source of honey and beeswax, a practice known as honey hunting.

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Edited by Taipan, Apr 13 2013, 03:43 PM.
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Asian giant honeybees may move in synchrony to ventilate nests
Collective 'inhalation'-'exhalation' cycles may keep the interior of honeybee nests cool, fresh

Date: August 3, 2016
Source: PLOS
The Asian giant honeybee, Apis dorsata, builds its large single-comb nests out in the open, making them potentially vulnerable to extremes of temperature that may threaten survival. New research shows that these giant honeybees may use synchronized movements to ventilate and cool their nests.

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Identification of warm and cool zones at the surface of a giant honeybee nest.
Credit: Kastberger et al. (2016); CCAL

Asian giant honeybees may use synchronized movements to ventilate and cool their nests, according to a study published August 3, 2016 in the open-access journal PLOS ONE by Gerald Kastberger from the University of Graz, Austria, and colleagues.

The Asian giant honeybee, Apis dorsata, builds its large single-comb nests out in the open, making them potentially vulnerable to extremes of temperature that may threaten survival. Colonies are known to create an insulating 'bee curtain' of five to seven layers of bees covering the single central comb. Researchers had also previously observed 'cool nest regions,' small areas on the nest surface that are cooler than neighboring areas, appearing briefly in the bee curtain. To investigate colony cooling mechanisms, the authors monitored the changes in surface temperature and slow horizontal movements of the bee curtain throughout the day using an infrared camera and vibrometer in several bee nests in Nepal.

The researchers observed that certain bees in the curtain appeared to act as "fanners" during the hottest part of the day, seemingly aligning their bodies to funnel air towards the cool nest regions. They suggest that curtain bees may also move in synchrony to ventilate the nest with a mechanism analogous to mammalian inhalation.

The researchers hypothesize that the inner bees stretch their limbs against the comb, expanding the inner nest area, lowering internal pressure to draw cool fresh air through the funnels from the ambiance. When the curtain bees relax the nest interior contracts by gravity, pressing the warm stale air from the center out diffusely through the meshwork of the bee curtain, completing the ventilation cycle. While the authors did not directly observe the internal mechanism, this may be a previously unknown collective respiratory movement for nest cooling in giant honeybee colonies.

Story Source: PLOS. "Asian giant honeybees may move in synchrony to ventilate nests: Collective 'inhalation'-'exhalation' cycles may keep the interior of honeybee nests cool, fresh." ScienceDaily. www.sciencedaily.com/releases/2016/08/160803151101.htm (accessed August 8, 2016).

Journal Reference:
Gerald Kastberger, Dominique Waddoup, Frank Weihmann, Thomas Hoetzl. Evidence for Ventilation through Collective Respiratory Movements in Giant Honeybee (Apis dorsata) Nests. PLOS ONE, 2016; 11 (8): e0157882 DOI: 10.1371/journal.pone.0157882

The Asian giant honeybees (Apis dorsata) build single-comb nests in the open, which makes this species particularly susceptible to environmental strains. Long-term infrared (IR) records documented cool nest regions (CNR) at the bee curtain (nCNR = 207, nnests > 20) distinguished by marked negative gradients (ΔTCNR/d < -3°C / 5 cm) at their margins. CNRs develop and recede within minutes, predominantly at higher ambient temperatures in the early afternoon. The differential size (ΔACNR) and temperature (ΔTCNR) values per time unit correlated mostly positively (RAT > 0) displaying the Venturi effect, which evidences funnel properties of CNRs. The air flows inwards through CNRs, which is verified by the negative spatial gradient ΔTCNR/d, by the positive grading of TCNR with Tamb and lastly by fanners which have directed their abdomens towards CNRs. Rare cases of RAT < 0 (< 3%) document closing processes (for ΔACNR/Δt < -0.4 cm2/s) but also suggest ventilation of the bee curtain (for ΔACNR/Δt > +0.4 cm2/s) displaying “inhalation” and “exhalation” cycling. “Inhalation” could be boosted by bees at the inner curtain layers, which stretch their extremities against the comb enlarging the inner nest lumen and thus causing a pressure fall which drives ambient air inwards through CNR funnels. The relaxing of the formerly “activated” bees could then trigger the “exhalation” process, which brings the bee curtain, passively by gravity, close to the comb again. That way, warm, CO2-enriched nest-borne air is pressed outwards through the leaking mesh of the bee curtain. This ventilation hypothesis is supported by IR imaging and laser vibrometry depicting CNRs in at least four aspects as low-resistance convection funnels for maintaining thermoregulation and restoring fresh air in the nest.

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