Thermoregulation in the Asiatic giant honey bee Apis dorsata (Hymenoptera:

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" Thermoregulation in the Asiatic giant honey bee Apis dorsata (Hymenoptera: "
M. B. Mardan

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112362
Doc. No	:	TLpq303775348
Main Entry	:	M. B. Mardan
Title & Author	:	Thermoregulation in the Asiatic giant honey bee Apis dorsata (Hymenoptera:\ M. B. Mardan
College	:	University of Guelph (Canada)
Date	:	1989
student score	:	1989
Degree	:	Ph.D.
Page No	:	1
Abstract	:	A field study on the thermoregulation of A. dorsata F. at the individual and colonial levels was conducted in Peninsular Malaysia. To determine whether or not the bees thermoregulate and why they must thermoregulates, experiments were made on broodright colonies of A. dorsata. The experiments showed that A. dorsata maintains brood temperature at ca. 33.5C, the range being 27 to 37C. Temperatures greater than 38C were found to increase the water demand for evaporative cooling and caused death in caged adult bees and brood. Brood maintained at ambient temperatures ranging from 26 to 29 C suffered sublethal effects, e.g. adults emerged with deformed wings. At the level of individual bee, the presence of fluid in the honeycrop had a temperature reducing effect on the average temperature excesses in the body parts of the bee. This effect was observed in the comparisons between (1) fluid foragers (water or nectar), (2) pollen foragers that carried negligible amount or no fluid in their honeycrops, (3) and between those curtain bees (forming the protective screen covering/enveloping the colony) with and without fluids in their honeycrops. Gobbetting (the sequential formation of fluid droplets at the mouthparts) curtain bees and fluid foragers were deduced to extrude honeycrop contents for evaporative cooling as evidenced by (a) increased gobbetting rate in response to directed air currents and (b) the moisture loss of honeycrop contents in fluid foragers returning from foraging. During fluid gobbetting by curtain bees, the head acts as a heat sink and the abdomen as a thermal window. At thoracic temperature excesses less and greater than 4.4C (Thermal Compensation Point) in these bees, the abdomen lost and gained heat from the metabolic heat in the thorax, respectively. The structure of the circulatory system appears to play a dynamic role in thermoregulation. At the colony level, young bees which form the majority of the bee curtain were found to thermoregulate the colony by: performing colony en masse airborne (CEMA) behaviour; mass defecation during CEMA; fluid gobbetting; fanning in response to solar radiation; varying the density of bees at various ambient temperatures; and probably by wing comportment. By performing CEMA and mass defecation prior to the maximum temperature of the day, the colony can lose heat immediately by convection and dump heat and mass through fecal droppings during mass flight. Consequently, the reduction of abdominal mass by ca. 40 per cent enables faster cooling which can be achieved by fluid gobbetting. Extensive fluid gobbetting by the curtain bees on the colony during high ambient temperatures (>28C) probably cools the brood by evaporative cooling. Clustering or fanning behaviours are usually the obvious immediate responses to a sudden drop or increase in ambient temperature, respectively.
Subject	:	Biological sciences
	:	Entomology