Apis dorsata

Apis dorsata

The rock bee or giant honey bee (Apis dorsata Fabricius, 1793) is an insect belonging to the Apidae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Animalia,
Subkingdom Eumetazoa,
Bilateria branch,
Phylum Arthropoda,
Subphylum Tracheata,
Superclass Hexapoda,
Class Insecta,
Subclass Pterygota,
Endopterygota cohort,
Superorder Oligoneoptera,
Section Hymenopteroidea,
Order Hymenoptera,
Suborder Apocrita,
Aculeated Section,
Superfamily Apoidea,
Family Apidae,
Subfamily Apinae,
Apini tribe,
Genus Apis,
Species A. dorsata.
The terms are synonyms:
– Apis bicolor Klug, 1807;
– Apis dorsata subsp. indica Sharma & Thakur, 1999;
– Apis dorsata subsp. torsada Engel, 2003;
– Apis nigripennis Latreille, 1804;
– Apis testacea Smith, 1857;
– Apis zonata Smith, 1859;
– Megapis dorsata (Fabricius, 1793);
– Megapis zonata (Smith, 1859).

The following subspecies are recognized within this species:
– Apis d. dorsata; mainly present in India;
– Apis d. binghami Cockerell; originally from Malaysia and Indonesia;
– Apis d. breviligula Maa; originally from the Philippines;
– Apis d. laboriosa Fabricius; present in India, Nepal, Bhutan, Myanmar, Laos, Vietnam and southern China.

Geographic Distribution and Habitat –
Apis dorsata is a bee widespread in South Asia and Southeast Asia.
The largest populations of Apis dorsata are found in China, Malaysia, Indonesia, India, Pakistan and Sri Lanka. In the Philippines, which once had one of the largest populations of Apis dorsata, populations have now become relatively rare, largely due to deforestation.
Their habitat is mainly on tall trees in dense forests, but they also build nests on urban buildings. These bees are tropical and migrate seasonally to most places. Individual colonies migrate between nest sites during the transition from wet to dry seasons and occupy each nest site for about 3 to 4 months at a time. Some recent evidence indicates that these bees return to the same site, although most, if not all, of the original worker bees could be replaced in the process because the workers usually live less than two months. Furthermore, these bees build small combs that serve as temporary nests during their long migrations.
In the rainforests of Borneo, Apis koschevnikovi and Apis dorsata are the only bees that frequently appear on flowering trees or honey bees. Even though they share much of the same rainforest habitat, they are still able to coexist. Their difference in size and tongue length helps differentiate resource usage.

Morphology –
Apis dorsata is a South and Southeast Asian honey bee, with workers typically about 17–25 mm long and the queen being even larger.
These bees build their nests mainly in exposed places away from the ground, such as on tree branches, under cliff ledges and under buildings. However, they rarely build nests on old or weak buildings for safety reasons. These social bees are known for their aggressive defense strategies and vicious behavior when disturbed. Although they have not been domesticated, indigenous peoples have traditionally used this species as a source of honey and beeswax, a practice known as honey hunting.
Each colony consists of a single vertical honeycomb made of worker wax suspended from above, and the honeycomb is typically covered with a dense mass of bees in multiple layers. The nests vary in size, reaching up to 1 meter. Each cell within the comb is hexagonal in shape.
These bees store honey in an upper corner of the nest. Cells of the same size and type are used to rear the larvae.
Apis dorsata can form dense aggregations at a nest site, sometimes with up to 200 colonies on one tree.
Each colony can contain up to 100,000 bees and is separated by only a few centimeters from the other aggregating colonies. Some colonies also exhibit nest recognition patterns, where they return to the same nest sites after migration.

Attitude and biological cycle –
As said, the Apis dorsata nests in a single honeycomb like Apis florea, suspending it from the branches of the trees or from the cliffs. The height of the nests varies from three to twenty-five meters from the ground.
In the tropical forests of Thailand, many colonies hang over twelve to twenty-five meters tall Dipterocarpus trees: this tree is probably preferred as a nesting place because it is relatively safe, because its bark is smooth and its trunk rises four- five meters before branching out making access to terrestrial predators very difficult.
However, about three-quarters of the worker bees in the population defend the colony, just as is the case for Apis florea. Although birds are common predators of Apis dorsata, the large body size of the workers protects them quite well from the invasion of ants, as they do not have bands of propolis on the branches to protect the honeycomb as in Apis florea, while their nests are very exposed in the large branches of these trees, presenting no camouflage of the foliage.
As regards the reproduction phase, it is noted that some drones and the queen fly away from the nest and mate in flight. This is called a wedding flight. The flights are relatively shorter than those of other Asian bee species. The flights of Apis dorsata take place around sunset for an average of 13 minutes. Apis dorsata exhibit high degrees of polyandry, with many drones mating with the queen. In fact, Apis dorsata is known to exhibit the highest levels of polyandry among all social insects. In general, this bee population experiences extreme multiple matings. This can be attributed to the short duration of flight times for mating.
In many localities, the arrival of colonies of Apis dorsata is an annual event, which occurs at the end of the rainy season or at the beginning of the dry season, when various species of nectariferous plants are in bloom. This phenomenon leads us to hypothesize that Apis dorsata has a fixed pattern in its annual migratory route.
As for their communication systems, this bee uses what is known as a dance language, also known as a wave dance, to communicate the location of food sources to other bees in the colony. The language of the dance indicates the distance, profitability and direction of the food source. These social bees dance outdoors and their dances produce high-pitched sound signals in the air. The orientation of the wagtail’s body points in the direction of the food source and the frequency of the sound indicates the profitability of the food source.
Apis dorsata produces silent dances, usually involving visual cues during the day. They also make sounds with their nocturnal dances, as they are the only bees of its kind that exhibit nocturnal foraging activity. Furthermore, there is evidence that Apis dorsata also dances for migratory purposes. Bees that have returned from the new nest site perform dances that alert the colony of information such as the direction of the new nest site.

Ecological Role –
Apis dorsata is closely related to Apis mellifera, Apis cerana and Apis florea.
There are some hypotheses as to when Apis dorsata diverged from both Apis florea and Apis cerana, as it is unclear which divergence occurred first. Currently, the hypothesis that finds greater consensus assigns a genealogical tree according to which the Apis dorsata diverged from both the Apis cerana and the Apis florea at the same time.
Regarding swarming, there are two methods of reproductive swarming where Apis dorsata starts new colonies, which usually happens in October or November.
The most common method occurs when a queen flies slowly away from her original nest and a swarm of workers follows her. This new group of bees can be temporary, or they can move to a new nesting site permanently. The distance these bees travel is unknown, but some have been observed to travel approximately 500 meters from their original nest. The second, rarer method is called “sprouting”. In budding, a group of workers leave the natal nest to form a new colony at a nest site about 1 meter away from the original.
A non-reproductive method of colony initiation is escape. Escape refers to when an entire colony moves to a new location. When a colony forms, multiple curtains, essentially layers, of bees form around the developing nest. The initiation of the colony is linked to the migratory patterns of these bees.
When a colony is established, migration depends on foraging resources and predation risks. These bees travel to different places depending on the flower blooming season. There are approximately 100,000 individuals in each colony and each colony resides at a nesting site for approximately 3-4 months at a time. Colonies tend to decrease when resources, such as food, honey, and pollen, are depleted. Colonies decrease during the rainy and summer seasons due to the instability of forage sources due to climate change.
Foraging bees can travel farther than A. cerana and A. florea, which travel up to 500 meters; however, 72% of observed A. dorsata foragers traveled no more than 400 meters.
With regards to kin selection, unlike the breeding patterns of other species of the Apis genus, the worker and drone broods of Apis dorsata are dispersed in the same area and even share cells, and are not differentiated into separate nest locations. It would appear that the worker police often make mistakes in properly removing the drone brood as the drone brood is interspersed with worker brood, but each male reared comes from a queen-laid egg (not a worker-laid egg) . This shows us that worker control actually works within populations of these bees. In these cases, worker control is through “egg eating” or oophagy, but in the case of these bees, worker control is directed at female workers with ovaries as oophagy is difficult to obtain, as eggs laid by Workers and queens are nearly identical in shape and size.
Furthermore, as Apis dorsata is known for its highly polyandrous activity, these bees exhibit large numbers of colonies close to each other. Although the colonies within an aggregation are close together, these colonies are not closely related.
Colony queens in an aggregation are not closely related, but the aggregation itself is more genetically related than one would expect by chance. There may be higher-than-expected genetic links between colonies because they migrate together on their long-distance migration routes to the same nesting sites in the new location. This can also be attributed to short distance reproductive swarming methods and also short mating periods. Since it has been observed that there is rarely a queen-daughter relationship within aggregations, the “sprout” hypothesis of colony initiation rarely occurs. Because of their long-distance migration patterns, bees cause sufficient gene flow between colonies of different aggregations. There is distinct genetic differentiation between aggregations. In turn, the genetic relatedness between colonies within a single aggregation decreases.
In reference instead to the recognition and fidelity of the nest, this bee is more careful than many of its relatives in avoiding the drift, that is the event that occurs when the bees return to the wrong colonies after having foraged.
Apis dorsata tends to form dense aggregations, contributing to high nest fidelity and recognition among these bees. These bees usually return to their native nests because this behavior results in increased fitness. If drift were common, predatory bees and parasites could spread rapidly through colonies. The high fidelity to the natal nests also leads to the aggressive behavior of these bees. In fact, they aggressively attack workers from colonies that are not theirs. If the workers and queens do not return to the same colony, they have a high probability of being killed because the other colony sees them as potential thieves or disease carriers. Some colonies even return to exactly the same nesting sites after seasonal migrations.
Furthermore, since Apis dorsata nests are quite exposed and accessible to predators, these giant bees exhibit strong and aggressive defense strategies. Their predators are mainly wasps, hornets, birds and humans.
Their defense strategies typically include physical contact, especially when faced with wasp attacks. These giant bees use a method called “heat balling,” in which they heat their thorax to a temperature of 45°C, which is deadly to wasps.
Another method used by Apis dorsata against wasps is called “glittering” or “defense shaking” behavior. The bees in the outer layer push the abdomen up 90° and shake it synchronously. This can be accompanied by fluttering wings. The signal is transmitted to nearby workers who also adopt the posture, thus creating a visible and audible “ripple” effect on the face of the comb, almost identical to an audience surge in a crowded stadium. These wavy patterns repel wasps that get too close to these bees’ nests and serve to confuse the wasp. In turn, the wasp cannot concentrate on catching a bee or taking food from the bees’ nest, so it will try to find easier prey and leave the nest in peace.
Glittering appears to be an evolutionarily successful behavior for group living among social bees.
Some research has been able to ascertain that bee colonies aggregate to defend themselves. If part of the nest is directly threatened by a bird, a signal (which is as yet unknown) is broadcast to the rest of the colony so that they all help in the defense, even if they are not directly threatened.
These bees, like other similar bees, are regularly affected by parasitic mites. The parasitic mite associated with Apis dorsata is Tropilaelaps clareae which requires brood to reproduce and is found predominantly in the male brood of the colony. Apis dorsata is believed to be the original host of this parasite. Since Apis dorsata migrates broodless, as is true for all other Apis species, this reduces infestation by this parasitic mite.
Finally, the relationship between this bee and man is important.
Since large quantities of honey (up to 45 kilograms) can be stored in the nests of Apis dorsata, many people often harvest their nests. For some of these people, honey is a livelihood as it can provide them with an important source of income. However, deforestation, urbanization, pesticides and honey hunting have threatened local bee populations and their honey. These bees are known to be aggressive and have the potential to sting humans viciously. At least one fatal defensive attack against a human has been reported.
In southern Vietnam, people use a traditional method to collect honey and wax from colonies of A. dorsata. This is a “bee-beekeeping” method that was first reported in 1902. A similar method is practiced in Songkhla province in Thailand.
According to Vietnamese sociologists, in the early 19th century, honey hunting or rafting was the most important occupation of people living in the Melaleuca forest swamp. At that time, people paid taxes to the government in exchange for living in the forest. Beeswax was used to pay taxes and to make candles, and was sold to visiting ships from Hainan, China.
Unfortunately between 1945 and 1975 the woods were devastated first by wars and then by deforestation for woodland and agricultural purposes. As a result, beam beekeeping has declined dramatically in the area. The technique is still used today at Song Trem State Farm in U Minh District. According to a survey, there are around 96 beekeepers in the area. In 1991, they collected 16,608 liters of honey and 747 kg of wax.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Russo G., 1976. Agricultural entomology. Special Part. Liguori Publisher, Naples.
– Pollini A., 2002. Handbook of applied entomology. Edagricole, Bologna.
– Tremblay E., 1997. Applied entomology. Liguori Publisher, Naples.

Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/258914179/original.jpg