Apis+dorsata

//Apis (Megapis) dorsata// Fabricius, 1793 Common Giant Honey Bee (Hymenoptera: Apidae: Apini) Figure 1. //Apis dorsata// foraging at Punggol Wasteland. Photo: [|Federick Ho] from Flickr flat =1. Overview = //Apis dorsata// is the largest honey bee species in Singapore. Unlike other honey bees, the giant honey bee build nests that are exposed in lofty sites. Although being the largest species of the //Apis//, the giant honey bees do not tend to hide themselves as a large number of individuals can be seen forming a protective curtain around the nest at once. Colonies of giant honey bees have a strong tendency to aggregate on a single structure, creating a remarkably magnificent sight to behold. Nevertheless, it is always best to admire them from afar as colonies of //A. dorsata// are known to be aggressive, where up to three-quarters of the workers are engaged in colony defense. This page aims to educate one on the identification of //A. dorsata//, the social structure of honey bees, and the difference in behaviour of the giant honey bees from the dwarf and cavity-nesting honey bees. More interestingly, the conflict over species status of certain species in the subgenus //Megapis// will be discussed. =2. Morphology =

2.1. Identification Key (Worker)
To spot a honey bee in general, one could look out for a black flying insect with black and yellow stripes on its abdomen. However, if visual identification is too difficult, one could always go to the extreme by catching the bee and getting stung by it - stinger of honey bee workers get dislodged (embedded in skin) after stinging. This is due to the barbed nature of the honey bee worker's stinger. The largest honey bee species in Singapore, //A. dorsata// can be easily differentiated from the other honey bee species by virtue of size (fig. 4). Another key identification to the //A. dorsata// is the contrasting hairs on the thorax. The scutum is covered with black hairs which contrast strongly with tan hairs of the scutellum, metanotum and propodeum (fig. 5). Figure 4. Comparison of four honey bees (worker) in Singapore. From left: //A. dorsata, A. cerana, A. florea, A. andreniformis//. © 2016 Z. Y. Tan Figure 5. Top view of //A. dorsata // worker. © 2016 Z. Y. Tan A key to each species of //Apis// in Singapore was provided by J. S. Ascher: =3. Organization of a Colony = Each colony is made up of three castes: the queen, workers and drones. Castes are behaviourally, physiologically, and morphologically different to perform specific tasks. The caste system of honey bees results in an inevitable interdependence of all individuals. Each caste is irreplaceable and is vital for the survival of the colony.
 * [[image:Id key apis.png width="647" height="416"]] ||
 * Figure 6. A key to species of //Apis// in Singapore. Contributed by: J. S. Ascher ||

3.1. Queen
A colony normally has a single queen bee. Being the only individual of the female reproductive caste, the queen’s primary function is reproduction. The queen engages in nuptial flight one week after emergence from a queen cell to mate with multiple drones 1]. The adaptation to being the only egg-laying female relates to the queen’s greatly enlarged ovaries and spermatheca 2]. Other than reproduction, the queen also takes up the role of maintaining the organisation of her colony by producing pheromones using her mandibular glands 3]4]5]6]7]. Figure 7. Comparison of sting between //A. dorsata// queen (left) and worker (right). © 2016 Z. Y. Tan Photo: Queen sting by [|Hilary Kearney] (pending permission) The queen can be easily distinguished from the workers and drones by a more tapered and wasp-like abdomen, and the lack of corbiculae 2]. Moreover, the sting of a queen is smooth, unlike the barbed sting of the workers (fig. 7). This allows the queen to sting other rival queens multiple times without dislodging her stinger along with her internal organs 2].

3.2. Worker
The worker population is made up entirely females. These females arise from the fertilized eggs (just like the queen), however are treated differently in terms of rearing conditions (refer to Section 4). Workers retain functional vestigial ovaries, but lack the full reproductive capacity of a queen and are effectively sterile. Although the workers are capable of producing fully functional male offspring, they actually gain more reproductive success by helping to rear their sisters rather than their offspring (refer to Section 5). Roles of the worker bees are age-specific and self-organizing 8]. The endocrine system of the worker changes over her lifetime to enable her to have the right toolkit to perform each task. The younger workers, having active hypopharangeal glands, perform hive-related tasks such as feeding the larvae and the queen. As they mature, their wax and poison glands become active, enabling them to build and guard the hive. The older workers forage for nectar and pollen. However, roles of workers can differ based on the needs of the hive. Workers bees have modified parts that are not found in the queens. They possess the corbiculae (fig. 8) for gathering pollen, glands that produce wax or brood food, crop for nectar and barbed stings (fig. 7). These derived modifications are essential for the workers to perform their daily tasks. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 8. Foreleg of //A. dorsata// worker. © 2016 Z. Y. Tan

<span style="font-family: Arial,Helvetica,sans-serif;">3.3. Drone
The drones make up the male reproductive caste and their sole purpose is to find mate. Drones are attracted to the sex pheromones produced by flying virgin queens 9]. Each mating flight can attract a swarm of up to 100 drones 10]. Although competition in mating with the virgin queens is high, no apparent sign of contest between the drones was observed 11]. The honey bee penis, a large, fragile and membranous structure, is unique to its genus 12]. Each species of honey bee has their own unique male genitalia, which match the female genitalia like a ‘lock and key’ mechanism, to prevent interspecific mating (fig. 9) 13]. Figure 9: Everted penises of the genus //Apis//. Source: Koeniger et al (1991) <span style="font-family: Arial,Helvetica,sans-serif;">The video below shows how a drone grasps the queen’s thorax with his front legs and everts his penis into the queen sting chamber. The process of everting his penis instantaneously paralyzes the drone, causing it to dislodge its penis and falling away from the queen. The drone dies eventually. media type="youtube" key="FaJ3K9qRVwo" width="560" height="315" align="center" Video: Mating flight of honey bees. Source: [|YouTube] <span style="font-family: Arial,Helvetica,sans-serif;">Drones are easily recognizable by their huge eyes and short tongues (fig. 10). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 10. Side view of //A. dorsata// drone. © 2016 Z. Y. Tan

<span style="font-family: Arial,Helvetica,sans-serif;">4.1. Life Cycle
//Apis dorsata// share similar life cycle with the other honey bees. Honey bees are holometabolous insects which life cycle consists of four life stages – egg, larva, pupa and adult. The life cycle of a honey bee generally starts when a queen bee lays an egg in an individual brood cell. The time taken for an egg to develop into an adult differs between different castes (table 1) 15]. Table 1: Development time (days) of the brood of A. dorsata. Laval development means the time from an egg hatch to cell capping, pupal development the time from cell capping to adult emergence. Source: Qayyum & Nabi (1968) <span style="font-family: Arial,Helvetica,sans-serif;">There are three different trajectories to how an individual egg can develop – a queen, a worker or a drone (fig. 14). The outcome of an egg is based solely on whether it has been fertilized, and its feeding and treatment as a larva.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10.4px;">Figure 14. Developmental pathways for a honey bee egg. © 2016 Z. Y. Tan

<span style="font-family: Arial,Helvetica,sans-serif;">4.2. Reproductive Swarm
<span style="font-family: Arial,Helvetica,sans-serif;">Before the emergence of the new queens, the old queen and about half of the worker population take flight to establish a new colony elsewhere. Colonies of //A. dorsata// that are ready for reproductive swarm are seen to be characterized by a “cone” of young bees hanging down from the lower edge of the nest 16].

<span style="font-family: Arial,Helvetica,sans-serif;">4.3. Nest
<span style="font-family: Arial,Helvetica,sans-serif;">The nest of //A. dorsata// is easily distinguished apart from the other three Apis in Singapore. Combs are massive (up to 1.5m wide and 1m long) and are built beneath a branch or overhang (fig. 15). //A. andreniformis// and //A. florea// build their combs around small branches while //A. cerana// build their combs in cavities. Figure 15. Aggregation of giant honey bee Nests. (with permission) Photo: [|Will Burrard-Lucas]

<span style="font-family: Arial,Helvetica,sans-serif;">4.4. Nest Defence
Nests consist of highly nutritious food source and valuable broods, and it is critical for //A. dorsata// to defend their hives from predators. By building their nests in lofty sites, //A. dorsata// are able to deter terrestrial predators. However, they are still susceptible to attack from flying organisms such as hornets and birds. A variety of defense mechanisms are employed to deter these predators. Shimmering behaviour is one of the defense mechanisms to deter flying insects, and sometimes birds 17]. The shimmer begins when an intruder approaches too near to the hive. Initially, a few workers will rapidly raise (towards the intruder) and lower their abdomens, often accompanied with a ‘buzz’ made by a single wing beat. This act then passes on to the adjacent workers, leading to a form of ripple across the surface of the hive (imagine a “kallang wave”). This behaviour tends to startle the predator, causing it to change its direction of flight. media type="youtube" key="6JUZiKuUzo0" width="560" height="315" align="center" Video: Shimmering behaviour of //A. dorsata// against hornet Source: [|YouTube] //A. dorsata// is known to be one of the most aggressive stinging insects 18]. The approach of a large organism within 10m of their colony triggers a defense mechanism where workers loosen their protective curtain which ‘enlarges’ the comb size 2]. This also allows many workers (400-600 workers in a second) to unleash an attack on the predator simultaneously if threatened further 19]. <span style="font-family: Arial,Helvetica,sans-serif;">Although the defense mechanisms of //A. dorsata// may seems intimidating, there are predators that are still able to acquire the sweet, nutritious rewards within the hives.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10.4px;">Figure 16. Honey buzzard feeding on //A. dorsata// comb. © 2011 S. X. Chui =<span style="font-family: Arial,Helvetica,sans-serif;">5. Kin Selection =

<span style="font-family: Arial,Helvetica,sans-serif;">5.1. Haplodiploidy
<span style="font-family: Arial,Helvetica,sans-serif;">//Apis//, like other aculeate Hymenopteras, has a unique genetic system called haplodiploidy – males are haploid and females are diploid (fig. 11). This allows the female reproductive caste to fully control the sex of her offspring by deciding whether the eggs are to be fertilized – a fertilized egg is diploid and, thus, develops into a female while an unfertilized egg develops into a male. Haplodiploid species live in an interesting social structure where the queens are surrounded by sterile workers that help to raise the young. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 11. Illustration of haplodiploidy. © 2016 Z. Y. Tan <span style="font-family: Arial,Helvetica,sans-serif;">Haplodiploidy creates “supersister” where sterile workers are more closely related to the female offspring (supersisters) of their mother than their own daughters. Workers share 75% of their genetic materials (25% from the mother and 50% from the father) among themselves while only sharing 50% of their genetic materials with their own offspring (fig. 12). Thus, the workers gain more reproductive success by refraining from personal reproduction of daughters and helping to raise their supersisters. However, reproduction of male offspring by workers are often tolerated as workers are more related to each other (r=0.75) and their male offspring (r=0.5) than to the queen’s sons (r=0.25). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 12. Haplodiploidy in monogamous species. © 2016 Z. Y. Tan

<span style="font-family: Arial,Helvetica,sans-serif;">5.2. Polyandry & Worker Policing
<span style="font-family: Arial,Helvetica,sans-serif;">In a polyandrous haplodiploid species like the honey bees, where queen mates with several males in one mating flight, the queens produce workers with asymmetrical relatedness. The worker population is made up of groups of half-sisters that are divided by their paternities (fig. 13). Workers of the same paternity are supersisters while workers of different paternities are half-sisters. This asymmetrical relatedness of the workers brings about worker policing where workers are favoured to suppress reproduction by other workers of different paternities 14]. Workers are more related to the queen’s sons (r=0.25) than to another worker’s sons (r=0.125). Ultimately, the queen will be the only one with reproductive success. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 13. Haplodiploidy in polyandrous species. © 2016 Z. Y. Tan =<span style="font-family: Arial,Helvetica,sans-serif;">6. Communication & Foraging =

<span style="font-family: Arial,Helvetica,sans-serif;">6.1. Waggle Dance
<span style="font-family: Arial,Helvetica,sans-serif;">Honey bees have an interesting way to communicate and convey information on productive foraging sites – dance! The dance runs in a figure-of-eight pattern (fig. 17). The honey bee starts off by striding forward while waggling her body side to side. This is termed the ‘waggle run’. At the end of the waggle run, the bee will make a sharp turn to either the left or right and return to the starting position to retrace the waggle run. At the end of the second waggle run, she will make another sharp turn to the opposite direction and return to the starting position. Thus, with every two waggle runs, the bee has gone through a figure of eight. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 17: Waggle dance of honey bees. © 2016 Z. Y. Tan The waggle dance codes information such as distance, direction and richness of a foraging site. Distance to the site is through the duration of the dance, while richness is by the excitement of the dance 20]. The way each group of honey bees conveys the direction to the foraging site differ due to difference in location of the dance floor. The dance floor, where the waggle dance is performed, of //A. dorsata// is located on the vertical plane of the comb. In order to convey the direction, the forager has to first estimate the angle deviation of the Sun’s current azimuth to the food source. After which, the forager will perform a waggle dance where direction of the waggle run and the vertical will deviate to the same degree as the Sun’s azimuth to the food source (fig. 18) 21]. It has been observed that the waggle runs of //A. dorsata// are accompanied by wing buzz sounds 22]23]24]. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 18: How direction information is conveyed by the waggle run in //A. dorsata//. © 2016 Z. Y. Tan =<span style="font-family: Arial,Helvetica,sans-serif;">7. Distribution =

<span style="font-family: Arial,Helvetica,sans-serif;">7.1. Global
<span style="font-family: Arial,Helvetica,sans-serif;">//A. dorsata// has a widespread distribution throughout southern Asia (fig. 2).
 * [[image:distribution of dorsata.png]] ||
 * Figure 2: Global distribution of //A. dorsata//. (with permission) Data & Map: [|Discover Life] ||

<span style="font-family: Arial,Helvetica,sans-serif;">7.2. Local
Data: NUS Bee Lab || =<span style="font-family: Arial,Helvetica,sans-serif;">8. Taxonomy & Systematics =
 * [[image:Screen Shot 2016-11-08 at 22.59.14.png align="center"]] ||
 * Figure 3: Local distribution of //A. dorsata//.

<span style="font-family: Arial,Helvetica,sans-serif;">8.1. Classification
<span style="font-family: Arial,Helvetica,sans-serif;">Kingdom: Animalia <span style="font-family: Arial,Helvetica,sans-serif;">Phylum: Arthropoda <span style="font-family: Arial,Helvetica,sans-serif;">Class: Insecta <span style="font-family: Arial,Helvetica,sans-serif;">Order: Hymenoptera <span style="font-family: Arial,Helvetica,sans-serif;">Superfamily: Apoidea <span style="font-family: Arial,Helvetica,sans-serif;">Family: Apidae <span style="font-family: Arial,Helvetica,sans-serif;">Subfamily: Apinae <span style="font-family: Arial,Helvetica,sans-serif;">Tribe: Apini <span style="font-family: Arial,Helvetica,sans-serif;">Genus: //Apis// <span style="font-family: Arial,Helvetica,sans-serif;">Subgenus: //Megapis// <span style="font-family: Arial,Helvetica,sans-serif;">Species: //dorsata//

<span style="font-family: Arial,Helvetica,sans-serif;">Data from [|ITIS]

<span style="font-family: Arial,Helvetica,sans-serif;">8.2. Type Information
<span style="font-family: Arial,Helvetica,sans-serif;">Type locality: India orientali <span style="font-family: Arial,Helvetica,sans-serif;">Type sex: Worker <span style="font-family: Arial,Helvetica,sans-serif;">Type repository: [|Natural History Museum of Denmark – Zoological Museum]

<span style="font-family: Arial,Helvetica,sans-serif;">8.3. Phylogeny
<span style="font-family: Arial,Helvetica,sans-serif;">The phylogeny of the honey bees, through molecular, behavioural, and morphological data, has come to a consensus that the genus //Apis// is separated into three subgenera: //Micrapis//, //Megapis// & //Apis.// In figure 19, major clades were supported with high bootstrap values (fig. 19). It can be seen that open nesting is a more plausible basal character trait than cavity nesting. Cavity nesting being lost twice during evolution leading to the open nesting honey bees is less probable than cavity nesting being derived once. <span style="font-family: Arial,Helvetica,sans-serif;">Although much studies have been done on //Apis// in general, there have been no comprehensive morphometric or DNA studies conducted on giant honey bees. Thus, species status within //Megapis// are suggestive.



Fig 19: Bootstrap 50% majority-rule consensus tree of six equally parsimonious trees, from ND2 sequence data (361 steps, CI = 0.726, RI = 0.832). Bootstrap frequencies (2000 replicates) are indicated for each node. <span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 10.4px; text-align: center;">Adapted from Arias & Sheppard (2005) <span style="display: block; font-family: Arial,Helvetica,sans-serif; text-align: justify;">In the subgenus //Megapis//, the widely debated argument would be the species status of //A. laboriosa// (author’s opinion; //A. d. laboriosa// would be used if regarded as subspecies) that is distinct from //A. dorsata//. //Apis laboriosa//, the Himalayan honey bee, is only found above 1500m in the Himalayas. It is obvious why many taxonomists do not recognize //A. laboriosa// as a species on its own (fig. 20). Other than the slight difference in overall size and the colour of the hair on the scutum, the two species of giant honey bees are morphologically similar 25]. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 80%;">Figure 20: Comparison between //A. dorsata// (left) and //A. laboriosa// (right). © 2016 Z. Y. Tan <span style="font-family: Arial,Helvetica,sans-serif;">There are many evidence suggesting species status of //A. laboriosa//: <span style="font-family: Arial,Helvetica,sans-serif;">1) Difference in time of mating flight – //A. laboriosa// takes flight between 12:30 and 14:30 26] while //A. dorsata// takes flight just after dusk 27]28]. <span style="font-family: Arial,Helvetica,sans-serif;">2) Difference in dance language – waggle run of //A. dorsata// is accompanied with wing buzz sounds while //A. laboriosa// does not 29]. <span style="font-family: Arial,Helvetica,sans-serif;">3) There is a significant difference (10.6-11.5%) in DNA sequences of the two species 30]. 4) In figure 19, samples of //A. laboriosa// form a unique well-defined cluster with high bootstrap value. <span style="font-family: Arial,Helvetica,sans-serif;">However, species status of //A. laboriosa// is still extensively discussed and more observations or DNA work studies have to be done.

<span style="font-family: Arial,Helvetica,sans-serif;">As previously mentioned that species status are suggestive, below are two widely recognised subspecies of //A. dorsata://

<span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 10.4px; text-align: center;">Figure 21: Side view of ////A. d. binghami.//// © 2016 Z. Y. Tan || <span style="display: block; font-family: Arial,Helvetica,sans-serif; font-size: 10.4px; text-align: center;">Figure 21: Side view of //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10.4px;">A. d. breviligula. //© 2016 Z. Y. Tan ||
 * [[image:binghami_65mm_1.5x.jpg width="355" height="270" align="center"]]

=<span style="font-family: Arial,Helvetica,sans-serif;">9. References = <span style="font-family: Arial,Helvetica,sans-serif;">1 Tan, N. Q., M. Mardan, P. H. Thai, and P. H. Chinh. 1999. Observations on multiple mating flights of Apis dorsata queens. Apidologie. 30: 339-346.

<span style="font-family: Arial,Helvetica,sans-serif;">2 Oldroyd, B. P., and Wongsiri, S. 2006. Asian honey bees: biology, conservation, and human interactions. 7-8.

<span style="font-family: Arial,Helvetica,sans-serif;">3 Free, J. B. 1987. Pheromones of social bees. Chapman and Hall: London.

<span style="font-family: Arial,Helvetica,sans-serif;">4 Plettener, E., K. N. Slessor, M. L. Winston, G. E. Robinson, and R. E. Page. 1993. Mandibular gland components and ovarian development as measures of caste differentiation in the honey bee (Apis mellifera L.). Journal of Insect Physiology 39: 235-240.

<span style="font-family: Arial,Helvetica,sans-serif;">5 Plettener, E., G. W. Otis, D. C. Wimalaratne, M. L. Winston, K. N. Slessor, T. Pankiw, and P. W. K. Punchihewa. 1997. Species- and caste-determined mandibular gland signals in honeybees (Apis). Journey of Chemical Ecology 23: 363-377.

<span style="font-family: Arial,Helvetica,sans-serif;">6 Winston, M. L., and K. N. Slessor. 1998. Honey bee primer pheromones and colony organization: gaps in our knowledge. Apidologie 29: 81-95.

<span style="font-family: Arial,Helvetica,sans-serif;">7 Wossler, T. C., and R. M. Crewe. 1999. Honeybee queen tergal gland secretion affects ovarian development in caged workers. Apidologie 30: 311-320.

<span style="font-family: Arial,Helvetica,sans-serif;">8 Lindauer, M. 1967. Communication among social bees. Harvard University Press: Cambridge.

<span style="font-family: Arial,Helvetica,sans-serif;">9 Gary, N. E. 1962. Chemical mating attractants in the queen honey bee. Science 136: 773-774.

<span style="font-family: Arial,Helvetica,sans-serif;">10 Gries, M., and N. Koeniger. 1996. Straight forward to the queen: pursuing honeybee drones (Apis mellifera L.) adjust their body axis to the direction of the queen. Journal of Comparative Physiology A 179: 539-544.

<span style="font-family: Arial,Helvetica,sans-serif;">11 Koeniger, G. 1990. The role of the mating sign in honey bees, Apis mellifera L.: does it hinder or promote multiple mating? Animal Behaviour 39: 444-449.

<span style="font-family: Arial,Helvetica,sans-serif;">12 Ruttner, F. 1988. Biogeography and taxonomy of honeybees. Springer-Verlag: Berlin.

<span style="font-family: Arial,Helvetica,sans-serif;"> 13 Koeniger, G., N. Koeniger, M. Mardan, G. Otis, and S. Wongsiri. 1991. Comparative anatomy of male genital organs in the genus Apis. Apidologie 22: 539-522. <span style="font-family: Arial,Helvetica,sans-serif;"> []

<span style="font-family: Arial,Helvetica,sans-serif;"> 14 Ratnieks, F. L. W. 1988. Reproductive harmony via mutual policing by workers in eusocial Hymenoptera. American Naturalist 132: 217-236.

<span style="font-family: Arial,Helvetica,sans-serif;">15 Qayyum, H. A., and A. Nabi. 1968. Biology of Apis dorsata. Pakistan Journal of Science 19: 109-113.

<span style="font-family: Arial,Helvetica,sans-serif;">16 Woyke, J., J. Wilde, and M. Wilde. 2000. Swarming, migrating, and absconding of Apis dosata colonies. In Seventh international conference on tropicalbees: management and diversity and fifth Asian Apicultural Association conference, Chiang Mai; Thailand, ed. S. Wongsiri, pp. 183-188. International Bee Research Association: Cardiff.

<span style="font-family: Arial,Helvetica,sans-serif;">17 Seeley, T. D., R. H. Seeley, and P. Akratanakul. 1982. Colony defense strategies of the honeybees in Thailand. Ecological Monographs 52: 43-63.

<span style="font-family: Arial,Helvetica,sans-serif;">18 Morse, R. A, and F. M. Laigo. 1969. Apis dorsata in the Philippines. Philippines Association of Entomologists: Laguna.

<span style="font-family: Arial,Helvetica,sans-serif;">19 Kastberger, G., and D. K. Sharma. 2000. The predator-prey interaction between blue-bearded bee eaters (Nyctyornis athertoni Jardine and Selby 1830) and giant honey bees (Apis dorsata Fabricius 1798). Apidologie 31: 727-736.

<span style="font-family: Arial,Helvetica,sans-serif;"> 20 Seeley, T. D., A. S. Mikheyev, and G. J. Pagano. 2000. Dancing bees tune both duration and rate of waggle-run production in relation to nectar source profitability. Journal of Comparative Physiology A 186: 813-819.

<span style="font-family: Arial,Helvetica,sans-serif;">21 Lindauer, M. 1954. Temperaturregulierung und Wasserhaushalt im Bienenstaat. Zeitschrift fur Vergleichende Physiologie 36: 391-432.

<span style="font-family: Arial,Helvetica,sans-serif;">22 Dreller, C., and W. H. Kirchner. 1994. Hearing in the Asian honeybees Apis dorsata and Apis florea. Insectes Sociaux 41: 291-299.

<span style="font-family: Arial,Helvetica,sans-serif;">23 Kirchner, W. H. 1993. Acoustical communication in honeybees. Apidologie 24: 297-307.

<span style="font-family: Arial,Helvetica,sans-serif;">24 Kirchner, W., and C. Dreller. 1993. Acoustical signals in the dance language of the giant honeybee, Apis dorsata. Behavioral Ecology and Sociobiology 33: 67-72.

<span style="font-family: Arial,Helvetica,sans-serif;">25 Engel, M. S. 1999. The taxonomy of recent and fossil honey bees (Hymenoptera: Apidae; Apis). Journal of Hymenopteran Research 8: 165-196.

<span style="font-family: Arial,Helvetica,sans-serif;">26 Underwood, B. A. 1990b. Time of drone flight in Apis laboriosa Smith in Nepal. Apidologie 21: 501-504.

<span style="font-family: Arial,Helvetica,sans-serif;">27 Koeniger, N., and H. N. P. Wijayagunesekera. 1976. Time of drone flight in three Asian honeybee species (Apis cerana, Apis florea, Apis dorsata). Journal of Apicultural Research 15:67-71.2

<span style="font-family: Arial,Helvetica,sans-serif;">28 Rinderer, T. E., B. P. Oldroyd, S. Wongsiri, S. Potichot, W. S. Sheppard, and S. Buchmann. 1993. Time of drone flight in four bee species in south-eastern Thailand. Journal of Apicultural Research 32: 27-33.

<span style="font-family: Arial,Helvetica,sans-serif;">29 Kirchner, W. H., C. Dreller, A. Grasser, and D. Baidya. 1996. The silent dances of the Himalayan honeybee, Apis laboriosa. Apidologie 27: 331-339.

<span style="font-family: Arial,Helvetica,sans-serif;">30 Arias, M. C., and W. S. Sheppard. 2005. Phylogenetic relationships of honey bees (Hymenoptera: Apinae: Apini) inferred from nuclear and mitochondrial DNA sequence data. Molecular Phylogenetics and Evolution 37: 25-33.