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Wilted Leaves and Honeybees

Text by Karin Sternberg   Photographs by Jenny Cullinan

There is a fascinating connection between Pephricus, a so-called ‘leaf-wilter’, and the honeybee…

Pephricus sp.

On a recent trip to one of our research sites in the Swartland region of the Cape Province, we came upon a Pephricus species of the Coreidae family. This True Bug, either Pephricus livingstonii or P. paradoxus (both species are very similar, but can be separated on the hind margin of the dorsal plate, the so called pronotum), belongs to a group of spiny bugs that feed on plants. Very little is known about the biology of these species, and colouration and shape can vary within the species. Other species of this genera are found sucking on Ipomoea, Maerua and cacao. One observation of Pephricus sp. in a patch of renosterveld vegetation was close to some Salvia africana-caerulea (pers comm S. Hall).

Salvia lanceolata on a rocky outcrop on the Cape Peninsula. Although also somewhat spiny and haired, the S. africana is softly hairy, sometimes with toothed leaves. One can see how Pephricus camouflage would work well on this plant.

Pephricus sp. protects itself through its leaf-like camouflage, moving jerkily like a leaf in the wind. Where this camouflage does not help, Pephricus uses a scent gland to ward off ants and other enemies.

Pephricus sp. moves jerkily like a leaf in the wind. Wind is common feature in the Western Cape.

How was Pephricus connected to the Cape honeybee (Apis mellifera capensis)? We found Pephricus on a wax comb on the ground at the base of a honeybee nest that had been poached – a rich and easy source of honey and pollen. This observation of Pephricus shows that these bugs obviously ingest pollen and nectar, as many other bugs do.

Pephricus sp. moving off wax comb

Pephricus sp.

(With many thanks to Dr Jürgen Deckert, Museum für Naturkunde Berlin, for his invaluable input.)

Bombardier Beetles and the Cape Honeybee

By Karin Sternberg    Photographs by Jenny Cullinan and Karin Sternberg (all photographs and videos are protected by copyright)

bee-eating beetle

When people hear the word honeybees, they usually think of bees in boxes and as the source of honey. Little does one know, that there is far more to honeybees than hives and honey. Here in the winter rainfall area of South Africa, the majority of honeybees occur in the wild where nesting sites are selected mainly under rocks or in rock crevices with the physical environment largely determining nesting behaviour. The dominant vegetation is fynbos (heathland) and the Cape honeybee (Apis mellifera capensis) is endemic to this region. The wild honeybees use a prolific amount of propolis to insulate the nest from temperature and humidity fluctuations, which also serves as an effective fire barrier (Tribe et al. 2017). The fynbos vegetation is adapted to fire which is essential for its perpetuation and preservation. An abundance of plant resins and waxes occur within these fynbos plants, largely as chemical defences against herbivory, which offers a diverse and unique source of resins for creating propolis. The propolis wall is therefore also an integral part of the bees‘ immunity with its alchemy of organic compounds offering important antibacterial and anti-fungal properties to the colony. Not only has the Cape honeybee adapted to living in this fire-prone region, but a number of animal species have adapted to living in association with the wild Cape honeybee, such as the Ten-spotted ground beetle, Anthia (Termophilum) decemguttata.

ten-spotted beetle, note-taking

Bees are the most important pollinators of flowering plants worldwide and are ecological keystone species. By co-evolving with angiosperms, bees have contributed decisively to the present phytodiversity and the structure of the terrestrial vegetation and ecosystems (Kuhlmann 2010). The Cape fynbos region is the smallest of the six floral kingdoms in the world, but the most diverse in terms of species’ richness. The existence of a small population of the Ten-spotted ground beetle is partially dependant, too, on the wild honeybee, as observed at a wild honeybee nest in the Table Mountain National Park, Cape of Good Hope Section. Once one starts observing the honeybee in its natural habitat, there is a fascinating array of interconnections waiting to be discovered.

Wild honeybee nest ’93’ located under rock and with a recovery area out of the prevailing SE and NW winds

Wild honeybee nests attract a diverse variety of other creatures, most notably lizards.

All year round we have observed this particular ground beetle on our walks across the Cape Peninsula while tracking honeybees in flight and searching for wild colonies. But, it was only while monitoring this nest that we realised the dependence of the beetle on the honeybee as a source of food. The nest was recently discovered and is at the highest elevation at 190m above sea level of the 93 nesting sites found to date in the Cape Point Section. The nesting site has a south west entrance orientation, with a protected landing area and the colony is deeply recessed under rock with a long and narrow propolis wall, measuring 1100mm (l) by 100mm (h). The nest entrance is surrounded by Metalasia, Syncarpha vestita, Hermas villosa, Restio patens and Diastella divaricata fynbos plants.

The beetle is elongate, roughly 50mm in total length, dull black in colour, has prominent brown eyes, the head is large and flattened and the jaw juts forward to facilitate the capture of prey. It has a reddish-brown heart-shaped thorax, each side marked with a small white spot. The antennae are thin and long and equipped with keen senses of touch and smell. The legs are strong and well suited for running (Scholtz & Holm 1985). The elytra, or wing cases, are sculptured with a number of longitudinal grooves. Each elytron has five spots of white down (The Naturalist’s Library, Vol. 2). They cannot fly as their wing cases (elytra) are fused, forming a strong covering for the abdomen; the membranous wings beneath the wing cases have disappeared (Skaife 1979). The colouration, spots and intensity of the white spots can vary, as we noted when we saw several of these beetles together at this nest location. Being black, they absorb heat which enables them to become active earlier in cold conditions.

A guard bee buzzes the mating pair.

At this particular location we watched as a single beetle warmed up under a rock overhang three metres from the ridge of rocks within which the honeybee colony is located. Between the beetle and the colony were low fynbos shrubs and exposed sandy patches; a controlled burn having taken place in April 2015 in this area. Its abdomen faced into the sun, its head slightly hidden from view under rock. At approximately 10:30am the beetle started moving towards the nest under the protective canopy of fynbos and restiads. At this time we noticed a convergence of at least two other beetles of the same species moving towards the nest. Directly at the nest entrance and in the path of the exiting and returning foragers, slightly hidden from our view by the tufted reed Restio patens, two individuals started mating. Guard bees continually monitored the two beetles, sometimes flying in close and almost buzzing the beetles, at other times flying into the beetles. On one occasion the male tried to kick out at the guard bee. Otherwise the beetles did not seem to be disturbed by the presence of the guard bees. The mating process was a long affair of 45min and we captured on video a foot-tapping display by the female.

A mating pair of T. decemguttatum. The larger female is eating a honeybee during the mating act.

Video: Mating beetles with female eating a honeybee

After mating was complete, 4 – 6 beetles were spotted in the vicinity of the nest, emerging from different directions. The activity at the nest was heightened, while the sound from the bees changed and became louder. Guard bees started zig-zagging close to the ground through the undergrowth and between the plants and restiads and patrols became more prolific. The beetles started hunting, running up the sandy clearing directly under the flight path of the foragers, sometimes in pairs, and sometimes at least three were close to the nest. One of the beetles ran up the rock face, along and down, only to drop into the nest entrance from the rock overhang above. Another beetle ran up a cluster of a grass-like plant and waited for an opportunity to hunt. Several returning and emerging bees became caught in the curly restiads protruding into the nest entrance. In addition, the bees of this colony were unusually clumsy, often landing upside down or falling sideways, a phenomena only otherwise seen at one other nest. In fact, this nest is the closest in proximity to the nest we had aptly named “Clumsy Nest” after this extraordinary behavioural trait. We considered whether these nests were directly related.

These beetles are formidable hunters and fast on foot. They quickly caught and subdued any forager (female worker bee) or drone (male bee) tangled in the restiads. The guard bees immediately chased the beetle predator, probably in response to the distress pheromone discharged by the trapped bee, but the guard bees had little impact on the beetles and their hunting activities. The beetles with their mouthparts adapted for biting and chewing (Skaife 1979) were quickly able to consume the bees under cover of the fynbos. After one beetle carried away a drone in its mandibles, another beetle came towards it, but there was no tussle and the oncoming beetle merely turned away. The beetles appear not to share their prey. On several other occasions we witnessed fighting amongst the beetles with attacks from behind and two males rolling as if in a skirmish.

Video: Ten spotted ground beetle using a scissor-like action of its mandibles to eat a honeybee

It did not appear as if the beetles known locally as “Oogpister” used their chemical defence mechanism to squirt formic acid in response to feeling threatened (Scholtz & Holm 1985) by the bees. The local name is derived from the squirting of this foul and irritating liquid into the eyes or mouth of predators such as lizards, toads, birds and various mammals. The chlorine or bleach-like odour is easily perceptible if the beetle feels threatened, causing it to squirt this liquid consisting of Benzoquinine compounds. The aposomatic or warning colouration of red and black is usually a deterrent to such predators.

ten-spotted beetle and southern rock agama eating bees

The heightened bee activity between 12:30 and 13:30 attracted not only the Ten-spotted beetles, but also Black girdled lizards and Southern rock agamas. Two smaller orientation flights took place during this period amidst loud buzzing sounds from the honeybee colony. There were a number of drones present. The beetles often took cover in a protected nook slightly inside the nest recovery area and close to where many of the bees clumsily landed. Particularly the drones would land, walk up and along the back wall and then down and through the nest entrance hole in the propolis wall.

Rock agama eating honeybees with scatterings of drones

Black girdled lizard after predating on a honeybee

Since documenting this behaviour at ‘Nest 93’, we have since seen it at other nests. By additionally preying on dead bees that have been removed from a nest, these beetles play a vital role in the wider hygiene of the nesting site. When a beetle thought itself overly formidable at ‘Hope Nest’ and ran in under the ball of bees hanging from their comb, a number of guard bees quickly engulfed it and grounded it indefinitely.

Ten spotted beetle upside down in the leaf litter below the colony and grounded indefinitely

The presence of this carabid beetle species is just one example of adaptation to the largely ground-nesting behaviour of the Cape honeybee in the fynbos biome. It highlights the importance of protecting natural habitats to foster species biodiversity; a biological diversity alive with a variety of living organisms and natural processes.

Male T. decemguttatum with evaginated internal sac of the aedaegus.

It is thought that the behaviour of the male ‘blowing bubbles’ with the internal sac spreads sexual pheromones to attract females for mating.

With many thanks to Dr Manfred Uhlig, Museum für Naturkunde Berlin, for his invaluable input.

The authors at work:

References

Kuhlmann, M. (2010). More than just honey.

Scholtz, C.H. & Holm, E. (1985). Insects of Southern Africa. Butterworths, Durban. 502 pgs.

Skaife, S.H. (1979). African Insect Life. Struik. 279 pgs.

Where Blue is a Rare Colour in Nature. Roella recurvata and its Blue Pollen.

By Karin Sternberg

Stepping into the fynbos brings untold surprises and beauty with it. Writing this now in mid-February, a difficult time for this floral kingdom in the face of mid-summer heat, extreme winds and very little to no rain, we are once again marvelling at nature’s intelligence and the interaction between plants and pollinators.

The Roella recurvata flowers are a South Peninsula endemic known from fewer than 5 sub-populations. They are a source of abundant pollen for bees. The pollen is mostly blue! Yet blue is a rare colour in nature, so what is the significance of this colour for pollen? Why of all the colours is it blue? Perhaps it has some ultra-violet colouration that we cannot see, but that might be a brilliant colour for the bees with their ultra-violet vision?

Presently there is very little forage for bees. January/February is always the most challenging time for bees to find forage in the winter rainfall regions and the colonies dwindle to a minimum. But the wild nest we are monitoring close to this sub-population of flowers is doing very well and they are busy, carrying in their heavy loads of pollen packed tightly into their pollen baskets. This means that they are able to stock up on their pollen stores, but also that they have brood (babies) to feed! Drones are also present, where they are absent at all the other nests being monitored. In fact, at most other nests there is very little activity and very little pollen going in. Most of the wild honeybee nests are literally just ticking over, trying desperately to survive this period of dearth.

One possible reason for this flower bearing blue pollen may lie in careful observation of the photo with the pollen-foraging bees entering the depths of the nest. The blue pollen almost has a fluorescence or luminescence like quality to it. We found the following paragraph in Science Magazine (08 Aug 1975: Vol. 189, Issue 4201, pp. 476-478):

‘Nectar, which fluoresces in the visible and absorbs in the ultraviolet spectrum when irradiated by ultraviolet light, occurs in many bee-pollinated plants. It is suggested that these characteristics function as direct visual cues by which bees can evaluate the quantities of nectar available. Thus, they assume an important role in pollination of the flowers and foraging efficiency of bees.’

These flowers with blue pollen, extraordinary as they are, possibly also have the capability to attract bees to it through a fluorescence, indicating their abundance of pollen, which possibly also has a high nutrient/protein content which is invaluable to the bees especially at this time of year.

So many questions arise when looking at nature and when trying to understand nature’s intelligence. One realises just how important the ecology and biodiversity is for the survival of both plant and pollinator. In this example, one cannot separate the flower from the bee. It has possibly evolved over time to develop this extraordinary visual cue not to be missed when pollinators are least expecting it.

A solitary bee on Roella recurvata

(All photos are copyrighted and are thus the property of the authors. If you wish to use any, please contact us at ujubeeconservation@gmail.com)

The author at work amongst the Roella flowers:

Karin Sternberg

Do drones accompany absconding and migrating swarms?

By Geoff Tribe, Jenny Cullinan and Karin Sternberg

Swarming bees departing for their new nesting site

Occasionally when a swarm issues from a nest and hangs from a branch a little way off, a few drones may be seen hovering around the swarm, possibly attracted to the pheromone secreted by the queen.  Drones are however not known to accompany a reproductive, absconding or migrating swarm, although drones have been recorded departing from clustered swarms around a tethered queen (Burgett, 1974). Yet this appears to have happened in a swarm which had arrived unseen in a natural nest under a rock no more than 30 days previously where multiple drones were immediately present – which would mean that drone comb would have had to have been constructed simultaneously with that of worker comb and brood rearing immediately begun.

But the duration of the life stage of a drone is 28 days and it is only sexually mature after 36 days on which it takes its first mating flight. Drones do not take part in any of the functions within a nest; their sole function is to mate with a queen, which happens in the air in drone congregation areas (DCA) a considerable distance from the nest. A virgin queen will mate with up to 40 drones and some sperm from each drone will be stored in her spermatheca. Thus over a period of time the nest will contain workers of various patrilines (paternal lines). Inbreeding, the mating of a queen with a related drone, is detrimental to a colony and DCAs containing hundreds or thousands of drones ensure that the chance of mating with a related drone is extremely remote.

Honeybee drones attracted to a strip of cloth attached to fishing gut and a helium filled balloon which had been lowered to near ground level within a drone congregation area in Pretoria.

How the drones find these DCAs is not fully known, but wind direction, landmarks and pheromones all appear to play a role. Both queens and drones find these DCAs independently and so respond to the same cues. Drones leave the nest independently on optimal days for flight, although at peak flying times the rush of drones to the exit and away may appear like a stampede. Flight usually begins at 12h00 and ends at 16h00 in which an average of three flights of varying duration by a single drone may take place. As the period for flight nears, drones appear to become ‘restless’ and begin combing their eyes with their forelegs, especially at the nest entrance just before take-off. In between flights the drones rush to open honey cells to replenish their energy – which takes 3 minutes on average.

Drone comb is built in an established colony when there is a surplus of pollen, and is built after that of the requirements in worker brood has been met. The drones tend to congregate in a remote part of the nest away from the brood nest when inactive and take no part in any of the functions within the nest. They never appear to follow the foraging or swarming dances of the workers or are located in the area where the dances take place. The interaction of workers with drones is limited largely to allowing them access to uncapped honey and of expelling them from the hive during times of dearth, mainly due to a shortage of pollen. The drones are either forcefully expelled from the nest by workers or are denied entrance to the nest on return from mating flights.

Swarms that issue from a nest may be reproductive or absconding (migrating) swarms, the latter induced by disturbance (predation, manipulation) or due to a dearth of resources (Winston et al. 1979). Congestion in the nest of a rapidly expanding population of bees results in the issuing of reproductive swarms where the old queen departs with young bees (Hogg 2006). 

During 2016 a wild honeybee colony that had constructed its nest under a boulder and enclosed the opening with a propolis wall absconded. This nest site remained empty for several months and was inspected at irregular intervals. On 28/6/2016 the nest was again inspected and found to be empty. The propolis wall was analyzed and removed as part of a research project, but on 29/7/2016 it was found to be inhabited by a new swarm which had immediately begun rebuilding any damaged comb. The most amazing discovery was that many drones were departing on mating flights and could only have accompanied the swarm on its migration because drone brood needs 28 days to develop from egg to adult and is only sexually mature after 36 days and is only produced after sufficient worker brood is present in the colony. It is unlikely that the drone presence could be the result of drift because of the numbers involved, the lack of honey stores and the nearest colony being located a considerable distance away.

Drones seen on the edge of the colony departing from the recently re-occupied nest

A swarm about to abscond sends out flight experienced bees which locate suitable nesting sites. On return to the nest they dance to indicate the direction and distance to the proposed nesting site. There may be dozens of dancers indicating a dozen or more sites, but over time only one dance will predominate (Seeley & Buhrman 1999). This means that all the scout bees have visited all the potential sites prior to the swarm issuing and have agreed by consensus on which site is the most suitable. Dancing scouts can be recognised in having no pollen on their legs and they do not stop at intervals to offer nectar to those following the dance.

Small swarm of Apis mellifera capensis hanging from a strand of barbed-wire during the flowering of canola near Caledon during which many swarms trek.

At the beginning of absconding, thousands of bees pour out of the nest and mill about in a swirling mass which begins after a period of time to coalesce into a swarm which alights on a branch or another such structure where they remain for several hours or even a day or two before they finally depart for the selected nesting site. Yet, the dance indicating their destination continues on the outside of the swarm of hanging bees, using the mass of bees as the substrate. Sometimes a few drones are seen with such swarms but, being so close to the original nest, they are usually regarded as having wandered on return to the nest by being attracted to the queen pheromone. Somehow the swarm manages to keep together despite individual bees flying in circles around the queen as they move rapidly through the air in a straight line while at the same time orienting towards a predetermined destination.

Drones however never appear to follow dances and therefore cannot be expected to understand them. Yet a large number presumably arrived at this new site and successfully migrated with the swarm. This could have been accomplished by one of three ways or a combination of all three – pheromones, sound (vibration) and sight.

A drone

A swirling swarm of bees on the move creates a distinct sound which is easily audible as it passes by; it can be followed by eye and although it moves at a pace, it could be followed by a runner if over level terrain; and both the queen and workers are releasing their pheromones as they fly to keep the bees together in the swarm. It has been established that in the case of reproductive swarms at least that there is a continual flight of worker bees between the old hive and the new site while swarming is in progress which steer them to the new site which may be several kilometres away (Wenner 1992; Seeley & Buhrman 1999). Hundreds of scout bees thus generate an aerial pathway by establishing an odour trail of Nasonov pheromone as they fly back and forth through the moving swarm (Wenner 1992; Schmidt et al. 1993). As explained by Lindauer (1955): While the swarm cloud is proceeding gradually along one sees a few hundred bees shooting ahead through the crowd in the direction towards the nesting place, then flying back at the margin of the swarm cloud, again pushing forward rapidly, and so on, until the goal is reached. Bees already at the site release Nasonov pheromone which serves to further attract the swarm and serves as a ‘settling’ or ‘orienting’ pheromone (Schmidt et al. 1993; Schmidt 1994; Wenner 1992). Because of the pivotal role played by pheromones, migrating swarms invariably issue only when weather conditions are favourable, especially the absence of strong winds.

What is also amazing is that swarming bees would tolerate so many drones which cannot forage for themselves and so have to rely on the workers to feed them. On arrival at the nest site, initial comb building relies on the honey stored in the honey-stomachs of the migrating workers which is of crucial importance for establishing a new colony. Perhaps drones are only able to accompany swarms in times of plenty of forage – drones regarded here as of value to the species even though they will not mate with a related queen from their own colony i.e. the workers tolerate/rear their drones for the benefit of another colony. 

Drones cannot live on their own and rely on the workers to provide them with sustenance and to heat the nest. An absconding swarm will therefore have severe repercussions for any drones in the nest unless they could depart with the swarm. Bees abscond due to various causes including pests, disease and disturbance, but the main reason is usually a dearth of nectar and pollen. Ordinarily the latter would mean few if any drones in the nest. For drones to leave with the swarm would presuppose that the drones were aware of this and, despite limited interaction with workers, would have recognised the cues as the nest started its relatively lengthy preparations to swarm. This would involve a drastic decrease in brood-rearing, few if any larvae present, all sealed worker brood having emerged and no stored pollen, nectar or honey (Winston et al. 1979). Brood rearing would have ceased, the queen would have been fed less lavishly to enable her to fly, the last capped brood would be emerging, and the honey stores would be depleted. Could distinctive sounds that are produced during the last few days before the swarm issues from its present colony, ‘a buzzing like that of an army setting out on the march’ (Wenner 1992) be recognized by drones as to what it portends? In the case of reproductive after-swarms the peculiar humming noise (Esch 1967) within the hive could also be augmented by the piping of queens. So the signs would be there but are drones able to recognise them?

When travelling with the swarm, do drones remain on the periphery or immerse themselves within the body of the swarm? Drones are strong flyers and able to fly as fast as or even faster than worker bees. The workers are aware of where they are going because they reach consensus before they depart to the new site they have selected, but the queen who had not taken part in following these dances would be as much a ‘passenger’ in the swarm as would be the drones. The queen would at all times be surrounded by, yet following the workers, as a safety precaution against predators. By releasing 9HDA pheromone, the queen would contribute to the clustering behaviour of the bees in the swarm (Winston et al. 1982). Thus both queen and worker pheromones would be integrated into facilitating the flight of the swarm, and possibly, together with sight and sound, enable the drones to attach themselves to the swarm.

Small hive beetle

A similar perplexing observation involving small hive beetles (Aethina tumida) by Dr Lundy in Pretoria where he witnesses a flailing ball travel through the air as if in a swarm directly to one of his garden hives where the beetles ‘melted’ inside (Tribe, 2000). Hours later the bees absconded due to the overwhelming numbers of beetles. How this ‘swarm’ of beetles emerged from one hive possibly a considerable distance away and were able to move en masse in a co-ordinated manner and to invade another hive is unknown.

References

Allen, M.D. 1965. The effect of a plentiful supply of drone comb on colonies of honeybees. Journal of Apicultural Research 4(2): 109-119.

Avitabile, A. and Kasinskas, J.R. 1977. The drone population of natural honeybee swarms. Journal of Apicultural Research 16(3): 145-149.

Burgett, D.M. 1974. Drone honey bee flight from clustered swarms. Annals of the Entomological Society of America 67: 683-684.

Esch, H. 1967. The sounds produced by swarming honey bees. Z. vergleich. Physiol. 56: 408-411.

Hogg, J.A. 2006. The anatomy of reproductive swarming. American Bee Journal 142(2): 131-135.

Lindauer, M. 1955. Schwarmbienen auf Wohnungssuche. Z. vergleich. Physiol. 37: 263-324.

Schmidt, J.O. 1994. Attraction of reproductive honey bee swarms to artificial nests by Nasonov pheromone. Journal of Chemical Ecology 20(5): 1053-1056.

Schmidt, J.O., Slessor, K.N. and Winston, M.L. 1993. Roles of Nasonov and queen pheromones in attraction of honeybee swarms. Naturwissenschaften 80: 573-575.

Seeley, T.D. and Buhrman, S.C. 1999. Group decision making in swarms of honey bees. Behavioral Ecology and Sociobiology 45: 19-31.

Tribe, G.D. 2000. A migrating swarm of small hive beetles (Aethina tumida Murray). South African Bee Journal 72(3): 121-122.

Wenner, A.M. 1992. Swarm movement: a mystery explained. American Bee Journal 132(1): 27-31.

Winston, M.L. and Otis, G.W. 1978. Ages of bees in swarms and afterswarms of Africanized honeybee. Journal of Apicultural Research 17(3): 123-129.

Winston, M.L., Otis, G.W. and Taylor, O.R. 1979. Absconding behaviour of the Africanized honeybee in South America. Journal of Apicultural Research 18 (2): 85-94.

Winston, M.L., Slessor, K.N., Smirle, M.J., and Kandil, A.A. 1982. The influence of a queen-produced substance, 9HDA, on swarm clustering behaviour in the honeybee Apis mellifera L. Journal of Chemical Ecology 8(10): 1283-1288.

Swarming Bees and Pseudoscorpions

By Karin Sternberg and Jenny Cullinan

The chelifer found in South Africa is mostly Ellingsenius fulleri and is believed to be a predator of small mites, wax moth larvae and other arthropods found in the nest debris. They often cling onto the legs of bees and are believed to be spread in this way to other colonies (Geoff Tribe).

When bees swarm, thousands of bees pour out of a nest only to collect a short distance away in a cluster, often on a branch, but otherwise on any other structure. In September 2017 we were watching bees on the move, temporarily clustered under a concrete table, with scout bees heading out to look for possible new nesting sites and, on their return, performing dances on the surface of the cluster (on other bees) as to the location of the nesting sites found. We watched and waited over a couple of days as slowly the number of possibilities and therefore dances diminished, as the colony came closer to a consensus as to the location of their new nesting site. On the third day of watching this intriguing behaviour and to our utter amazement, we noticed that we were not alone in our waiting.

Pseudoscorpions emerging

From the edge of the first layer of bees in direct contact with the table, we spotted a number of pseudoscorpions emerging. They appeared to be restless and hungry as they moved out and away from the hanging colony, using their pincers which had fine and relatively long hairs to sensitively feel for food in the cracks and gaps of the table undersurface.

They did not get very far as certain (dedicated?) bees seemed concerned and actively encouraged them back. There was a very clear communication between these two species and they were continually touching each other; the pseudoscorpions using their pincers either in a waving motion or by clasping at the bee, and the bees using their antennae and legs to touch and usher the pseudoscorpions back into the cluster.

From all of the fussing, one could tell that the pseudoscorpions were crucial to the bees. With colony activity and communication between the bees increasing as the colony prepared to leave for their final nesting site, the bees kept a close eye on their fellow-travellers. As more and more surface bees stopped dancing and started almost buzz-running and whirling like dervishes on the surface before pushing their way into the middle of the colony as paths clearly opened up for them, the vibrations and sounds of the bees increased and activity peaked. No doubt this was also a cue completely understood by the pseudoscorpions. For when the colony finally departed for their new nesting site, remarkably not a single pseudoscorpion was left behind. 

Holes opening in the cluster

 

These observations showed us an extraordinary interdependence between bees and pseudoscorpions, and highlighted how vital each are to the other that these wild bees on the move should take the pseudoscorpions along with them. The pseudoscorpions are absolutely necessary to the health and well-being of a colony and are very much part of the bees’ hygiene. We would be very interested to hear if this has ever been documented before?

A pseudoscorpion attaching itself to the leg of a bee

Swarming bees departing for their new nesting site

(All photos are copyrighted and are thus the property of the authors. If you wish to use any, please contact us at ujubeeconservation@gmail.com)

The authors at work:

Honeybees and The Great Fire of 1869 extending from Swellendam to Uitenhage

By Geoff Tribe

The devastating fires of 7 June 2017 extending over a distance of 125 kilometres from George to beyond Plettenberg Bay resulted in the loss of life of seven people, thousands of animals, and of much property.  On 6 June the speed of the hot Berg wind blowing from the north-west was recorded between 90km/h and 100km/h with gusts exceeding 110km/h which were responsible for fanning the fire which can superheat it in excess of 2000°C (Preston 2017). The first fire was reported near Knysna following in the wake of a fierce hot wind with over 50 fires following this and resulting in more than 10 000ha reduced to ash.  It will take many years for this region to recover, a region which relies heavily on tourism of its scenic attractions. But this is not the first time this region has experienced a devastating fire, and then over a much larger area. As we know from back then, the wild bees will survive after a fire, even if they are forced to abscond.

The Great Fire of 1869

Between the years 1862-1869 large parts of South Africa were experiencing a severe drought in which hundreds of thousands of sheep and other stock died (Du Preez). In early February 1869, following several weeks of exceptionally hot weather, a fierce hot bergwind blowing from the north fanned bushfires which had started all over the area from Swellendam in the west to Uitenhage in the east. The fires swept through the mountains, gorges and lower coastal plateau, one branch swept down a gorge and raced through the hills towards Knysna but by a miracle the wind changed and the town was saved from certain destruction (Van der Merwe 1998). During this fire 27 people died in the Humansdorp district alone and many elegant homes were razed to the ground while their occupants took refuge in dams and rivers, covering themselves with blankets against the falling cinders.

The belt of dense forests along the upper coastal plateau was hardly touched by the Great Fire, for fire seldom penetrates deep into moist forest (Van der Merwe 1998). Dry coastal forest, wooded valleys and isolated mountain forests were however totally destroyed.

  The Eastern Province Herald reported this disaster of unimaginable proportions:

In February 1869 the Herald reported that: “A correspondent in Knysna mentioned that the sun had just risen … when we had the sense that something unusual was going to happen. Between 9 and 10 o’clock a strange wind, unknown in these parts, started blowing. It was such a hot wind that a person could hardly go outdoors. A few hours later it appeared that our feeling had come true, because between 12 and 1 o’clock Plettenberg Bay was covered in thick smoke, soon we could see a tremendous fire; it looked as if the whole of Plettenberg Bay stood in ligte laaie [basically, as smoky as anything].

“The fire came from all sides so that in a moment Wittedrif, Ramdorings River and the whole area was one huge inferno, At Wittedrif the houses were fortunately saved but everything else was burnt. It was the same story everywhere, and people were only too relieved to have escaped with their lives. It was moving to hear the weeping and wailing of the women and to see the great confusion which reigned. The valleys, forests and caves were covered in such thick smoke that one didn’t know where to flee. Particularly pathetic was the sight of pigs, dogs, geese and chickens and even doves which had died in the flames. The intense heat forced birds to tumble out of the sky like leaves of a tree. Sheep died by the hundred as did buck in great numbers.

Some people who fled towards the sea were rescued by the wind changing direction. Jan Groenewald ran to the river with his wife and children where their lives were saved by sitting in a boat. The next day the whole world wore a huge black cloak. It was painful to see how earthly possessions were destroyed in just one day. It was fortunate that the fire did not break out at night because then it would almost certainly have occasioned loss of human life. For this reason many of cried out as did Job, ‘The lord giveth and the Lord hath taken away. Blessed be the name of the Lord’. Knysna was in great peril, at one stage all the forests around the town were burning fiercely. Then, suddenly, the wind changed and the town was saved”.

The huge loss of life and the destruction of property and the aftermath of the fire is vividly portrayed in other newspaper reports at that time where the fire was reported to have originated at Bedford where a farmer named Dixic was injudiciously burning rank grass during a high wind, which carried the flames along with fearful rapidity (see Papers Past).

Outeniqualand before the Great Fire

When the 1869 Great Fire swept through Outeniqualand there were no pine and eucalyptus plantations and no ploughed land except around certain homesteads, the forests being surrounded by great swathes of fynbos vegetation. The density of the forest and the many deep gorges across the coastal plateau with the rockbound sea coast caused early travellers in the area to instead use a more inland course through Pampoenkraal (Saarsveld) and into the Langkloof. Elephant trails were initially used to penetrate the forest but the Great Fire served to facilitate greater access to the region because it cleared the way for the completion of the coastal road system which created the Garden Route.

An indigenous forest

Historical records recount hundreds of elephants and buffalo which grazed on the grass in the coastal valleys and used the forest as shelter (Skead 2011; Van der Merwe 1998). Local memory recounts that elephants sought refuge in the sea during the fire, yet this could not be substantiated from records. The large animals were decimated over two centuries of hunting and farm expansion, with the last buffalo shot in 1883 (Van der Merwe 1998). No information appears regarding the presence or nesting localities of bats, of which the Egyptian fruit-bat is essential for the regeneration of forests by eating only fleshy fruit such as that of yellowwood where the fleshy part is removed and the pip is dropped, thus dispersing the seed.

South Africa is poorly endowed with natural forests with only 0.3% of the land afforested. These forests represent a relic of large coastal forests which dominated the Cape about five-million years ago under a tropical climate. The Mediterranean climate became established and has persisted for the last two million years when the tropical forests slowly gave way to sub-tropical thicket, grasslands and fynbos species (Newton 2009). Fires driven by hot, desiccating winds are the major agents that keep forests in check; forests shelter on the lee side of steep ridges or in narrow gorges where eddies branching from the main wind prevent the fires from burning down the lee slopes (Van der Merwe 1998). Such eddies do not develop on the gradual slopes of rounded hills which are consequently covered with fire-adapted fynbos. Dr John Phillips maintained that the extensive areas of Kuistervaring or Ystervaring (Gleichenia polypodioides) found in the Deepwalls forests are to be attributed to honey-hunters [burning out nests] and also to incendiaries aiming at burning portions that they might report the damage done, and thereafter buy the burned trees at a tariff less than normal (Skead 2011). The biomass of these Kuistervarings within the Pinus plantations, where they form a dense mat several meters deep, requires that each tree needs to be excavated to its base before it can be felled.

Preston (2017) explains the phenomenon of the ‘thermal wave’ as a sine wave flow of super-heated air associated with fires such as these. As heat from the fire rises it is blown horizontally by the wind over distances of 300m to 1000m before it touches down and ignites a new fire and then again bounces off downwind. As the superheated air descends, it heats everything before it which then erupts into flame spontaneously before any flame reaches the area. The immense pressure and heat of the descending air forces down the roof of a house and melts the glass and disintegrates the bricks, leaving a pile of rubble. Because the wave is able to jump over valleys and rivers, the effect appears random as single houses explode into flames while others remain unscathed.

The forests were under constant attack long before the early explorers arrived there with fire having played a major role in reducing their area, resulting in patches of isolated forest surrounded by grasslands or dense fynbos (Skead 2011). Dias, Da Gama and others have recorded that in the fifteenth century great smoke banks were seen from their vessels, the sun appearing as if veiled in a grey cloud; undoubtedly the Outeniquas were to some extent responsible for the first burning of some of the larger ‘eilands’ now existing – a work in which they were later assisted by elephant, buffalo and honey hunters (Skead 2011).

Origin of the name Outeniqua

The earliest records show that this region was inhabited by the semi-nomadic Outeniqua clan. According to Raper (2004), Outeniqua means ‘men who carry honey’ from ‘tou, t’hou, ou, recorded in 1752 for ‘honey’; teni, ‘carry’; qua, ‘men’. Tsitsikamma means ‘waters begin’ from tsoa-tsoa, ‘begin’, kamma, ‘water’ due to the high rainfall and the occurrence of many rivers and streams. The name Knysna is of Khoi origin and probably means ‘ferns’ or ‘fern leaves’. There are a number of other Quena names of places associated with honeybees which have survived (Tribe 1982; 1997).

However, Hromnik (2009) in a series of articles in the George Herald further elucidates on the origin of the name Outeniqua. In 1766 Jan Willem Cloppenburg recorded that “… the name Houteniquas, means houtini – to carry a bag, quas – men or people; because the people that live there carry in bags honey from the forests”. François le Vaillant in 1780-85 reported that the name “Auteniquoi” meant ‘men loaded with honey’ and confirmed that the local forests were full of honeybees. Hromnik’s interpretation is that the word Outeniqua consists of three component words: Ou-teni-qua (i.e., ‘/Hao-teni-qua’) meaning ’People Living United or in Harmony with Honeybees’. These Honeybee People, the Outeniquas, associated themselves with the honeybee as a symbolism of Mother Earth as found in other civilizations from India to Egypt.

Importation of English honeybees

The early settlers in Outeniqualand regarded the indigenous Cape bee as ‘… indolent, [and] thus good, muscular, wise and hardworking bees were sent for from England” (Du Preez). Replacing the indigenous honeybees of Southern Africa with docile European races (mainly the Italian bee) had been advocated and attempted from 1925 to 1942 as a government program which was finally abandoned only in 1965. This bee breeding station with Italian bees (Apis mellifera ligustica) was situated just below the Union Buildings in Pretoria. However in the 1970s on the removal of wild nests in Pretoria and the taking of cell measurements, no influence of these Italian bees could be discerned in the wild suburban population.  The presence of their genes in a milieu of Apis mellifera scutellata swarms was completely smothered. The rationale behind this was to breed a less aggressive and more productive race of bees. Yet all these attempts failed to establish European honeybee races in South Africa because they were outcompeted by the indigenous bees. It is now accepted that the indigenous races are adapted to the conditions of Africa. For example, the smaller size of the African bee which is linked to a shorter development period from egg to adult is an adaptation to meagre and erratic rainfall (resulting in short and erratic nectar flows) which may be taken advantage of by the local race having a faster developmental period in synchrony with the flow.

Henry Barrington of Knysna is first documented as importing bees, the Black English bee (Apis mellifera mellifera), in 1871 to his farm Portland.  This was not a success because “The English bees imported at the Knysna with Nutt’s hives, at great expense, finding the climate so genial – no winter, the flowers all the year round – refused to make honey, preferring a life of enjoyment to work” (Du Preez). It was probably more a case of insufficient forage needed for a much larger bee than laziness of behalf of the bees! This also indicates that he must have hived and kept the Cape bee as well. Presumably his bees also died in the inferno of the Great Fire which consumed his house and farm which he described as ‘complete’. Barrington imported two more hives of bees from London in March 1869 after the fire and continued multiplying his black bees until his death in 1882 (Du Preez). Because of the difficulty in transporting hives of bees by ship from England to Cape Town (a journey of at least 64 days) and on to Mossel Bay, then by cart to George and finally carried the 50 kilometres to Portland through dense undergrowth by two men (Du Preez), meant that only a limited number of hives must have been imported during this period.

Disappearance of forest ecotype of the Cape bee?

Thunberg in November 1772 passed through the Southern Cape and recorded that it was rich in honeybees and honey. In much later years, the presence of numerous wild honeybee colonies and their potential for commercial beekeeping was used in a prospectus to lure British settlers to the Outeniqua region. Yet today this region is not renowned as an exceptional area for honeybees even despite the many exotic eucalypts grown there. An intriguing theory for this discrepancy was recounted to me by Hennie Steyl, a forester and beekeeper from George. He suggests that after the Great Fire that the locally adapted ecotype of the indigenous Cape bee (Apis mellifera capensis) within the forest was destroyed and later replaced by the ecotype from the surrounding fynbos which moved into the area as the forest slowly regrew. Hence the noticeable incompatibility of the honeybees seen today within this region.

People living in harmony with Honeybees

The 2017 fire destroyed many hives of honeybees which will be replaced mainly by the time honoured South African way of placing out trap boxes for migrating swarms. Should these swarms originate mainly from the fynbos on the periphery of the forest, will this reinforce this incompatibility? More so, over time will the bee finally adapt to the forest biome even though today it is largely disjointed and does no longer cover the same area when the Outeniqua people collected honey to trade in times gone bye.

 

The intricacies of a forest system:

The author at work:

Geoff Tribe

References

Du Preez, F.M. (no date) A History of Beekeeping in South Africa. Office 444 Govan Mbeki Avenue, Port Elizabeth. pp201.

Hromník, C.A. (1997) Quena and the Kung: aka the Hottentots and Bushmen. Cape Times 29 September, pp8.

Hromník, C. A. (1999) The ethnonym Quena: The true name of the Hottentots. In: Actas del XX Congreso Internacional de Ciencias Onomásticas, Ed: Ana Isabel Boullón A Coruna, Galicia: Biblioteca Filolóxicca Galega, 202, pp1463-1480.

Hromník, C.A. (2007) Free the Ottentotu from the ideologues. Sunday Times 15 April 2007.

Hromnik, C.A. (2009) Outeniqua Quena & Mountains in the realm of Dik!areb. George Herald 18 June pp37; 23 July pp24; 27 August pp52; 24 September pp48; 29 October pp43; 28 January pp28; 4 February pp30.

Newton, I (2009) The future of Fynbos. Full Circle 6(11): 70.

Papers Past (internet) The Great Fire at the Cape of Good Hope. – Loss of Life and Destruction of Properties. Daily Southern Cross, Vol. XXV, Issue 3718, 18 June 1869.

Preston, G. (2017) Knysna Fires: Five factors that produced the perfect inferno.

Raper, P.E. (2004) New Dictionary of South African Place Names. Jonathan Ball Publishers, Johannesburg & Cape Town. 421pages.

Skead, C.J. (2011) Historical Incidence of the larger Land Mammals in the broader Western and Northern Cape. (second edition). Centre for African Conservation Ecology, Nelson Mandela Metropolitan University, Port Elizabeth, South Africa. 519pages.

Tribe, G.D. (1982) Bees of the Outeniqua in 1781. South African Bee Journal 54(4): 91.

Tribe, G.D. (1997) Hottentot (Khoekhoen) place names associated with honeybees in southern Africa. South African Bee Journal 69(1): 3-6.

Van der Merwe, I. (1998) The Knysna and Tsitsikamma forests. Chief Directorate: Forestry, Department of Water Affairs and Forestry. 152 pages

Pollination by deception

By Jenny Cullinan and Karin Sternberg

Disperis capensis (Cape witch orchid) which has no nectar or other reward for bees, uses deception to attract the male carpenter bee to its flowers for pollination.

Mild winter days of late July, bring the first flowerings of Disperis capensis. The witch orchid times its display in this section of Cape Point Nature Reserve with the similarly coloured Muraltia (purplegorse). Overcast days make the purple of both Muraltia and the orchid stand out in an otherwise flower-barren patch. The orchid has a gentle, but beautiful sweet scent, reminiscent of both a component of Serruria villosa’s fragrance as well as Wurmbea hiemalis. Muraltia has little to no fragrance perceivable to the human nose.

Xylocopa rufitarsis visits Muraltia for nectar and sometimes mistakenly visits the delicately-scented orchid. Realising that there is no nectar to be had, he immediately flies off, the sticky viscidium adhering to the visiting bee and a pollinarium is withdrawn; it becomes immediately coiled so that the pollen massulae (individual pollen grains) become outwardly orientated so as to be correctly positioned to break off onto the stigmatic surface of the next Disperis visited by the bee. These are visible as individual grains on the sticky orchid stigma (Bill Liltved). The carpenter bee seems quite irritated with the pollinaria stuck under his thorax, but continues collecting nectar from Muraltia in a methodical way, only to make the same mistake with another orchid depositing the pollen in this way. 

Once D. capensis is fertilised it fades from its purple-pinks to a burnt orange and her bonnet folds in on itself.

It was previously thought that Disperis capensis only mimicked the nectar-secreting shrublet Polygala bracteolata, (Johnson 1994; Pauw & Johnson 1999), but these observations show how fascinating the unknown is and how much there still is to discover.

In a completely different biome in Cape Point Nature Reserve, we have found pockets of D. capensis resembling none of the other flowers surrounding them, neither in colour, shape nor fragrance. The only flowers in close proximity are Metalasia compacta, Diastella divaricata and Lobelias. However, the orchids in this location still have to be visited by a bee.

Disperis capensis and Muraltia. Both displaying similar colour combinations.

X. rufitarsis, realising that there is no nectar to be had, quickly flies off from the orchid carrying the pollinaria under his thorax

The pollen grains are outwardly orientated as he flies from flower to flower sipping nectar

An unpollinated orchid

A pollinated orchid

After fertilisation the orchid’s bonnet folds in on itself and turns a burnt orange

As a small exercise to show how a pollinarium is released, we mimicked a bee’s arrival by touching the sticky viscidium with a sterile tool, as a carpenter bee would make contact with the orchid with its thorax, and slowly withdrew the spring-loaded pollinarium from the anther sac while photographing it. Once released it immediately coiled.

We then took the pollinarium to a separate orchid, touching it on the sticky stigmatic surface as the carpenter bee would come into contact with it. Immediately the pollen grains broke off from the caudicle, the stalk to which the pollen masses are attached, leaving individual grains of pollen on the stigma.

Further reading:

The Cape Orchids (Liltved & Johnson 2012)

 

The authors at work:

When smoke gets in your eyes!

The perception that honeybees can escape an approaching wild fire by absconding in advance of the fire is so well entrenched that no thought appears to have been given to see that it is an utter fallacy. Entire apiaries in the Western Cape have been utterly consumed by fire on a fairly regular basis over the years with not a single swarm issuing from them as the fire bears down on the apiary.

The reason for such thinking is as a result of the well-known behaviour of bees to imbibe honey when a reproductive swarm departs the hive or the colony absconds. This honey stored in the bodies of workers tides the bees over the period in which they found a new colony by creating combs in which to rear brood.  Thus the reasoning that follows is that in responding to smoke by imbibing honey the honeybees are preparing to abscond.

However, a gravid queen is too heavy to fly and honeybees rarely abscond if brood is present. Thus for a swarm to issue from a hive takes preparation in advance – which is impossible with the sudden arrival of a fire. Pheromones are crucial in co-ordinating such a swarm and smoke disrupts and smothers such chemical communication – which in the case of a beekeeper using a smoker, disrupts the alarm pheromone which targets concentrated attack on the perpetrator who is disrupting the hive.

Reaction of wild colonies of honeybees to fire

Such questions regarding the behaviour of honeybees to fire were raised after the devastating wild fire in the Cape Point section of Table Mountain National Park on 4 March 2015 which incinerated 988 ha of fynbos before it was brought under control. How many of the wild honeybee swarms in this burnt area had survived the fire? We realized then that the swiftness of the fire alone would have ensured that no colony could have escaped in advance of the fire. The question then arose as to why the bees always respond to fire by imbibing honey when there is no intention to abscond? An analysis of the 17 nests within the fire zone supplied an explanation.

The fynbos vegetation is adapted to fire which is essential for its maintenance and which occurs at intervals of 15 to 25 years. Analysis of the wild honeybee nests throughout Cape Point revealed that 78% were located under rock outcrops, within clefts in rocks or in cliff faces; 11% were directly in the ground; 8% in cavities in trees and 3%within the intertwined branches of bushes. Of these nests, 68% had their openings entirely enclosed in propolis with small openings within this propolis wall serving as entrances to the nest.

Honeybee colonies within the burnt area

Within the burnt area were 17 wild nests of which 13 were situated under the bases of boulders and 4 in clefts within boulders. Propolis walls enclosed all these nests, of which two walls and adjacent combs had been totally destroyed by the fire and two walls partially destroyed. However, all these colonies survived the fire. The response of the bees to fire was to imbibe honey and retreat to the deepest recess of the cavity.

Fynbos fires are not exceptionally intense but flames tend to be high (2 to 5m) and of short duration where temperatures may reach 550 °C for only 10 seconds. Experimental fires in the fynbos spread at a rate of 0.04 t0 0.89msˉ¹. Once the fire has passed, the landscape is filled with powdery grey sand and the blackened skeletons of the larger shrubs. It is this devastation of their environment which the bees encounter after the fire has passed where neither nectar nor pollen is available to them. This is when the imbibed honey is essential to tide them over this dearth period which is about 2 to 3 weeks long before the fire-loving ephemerals sprout from underground bulbs or rhizomes and flower in profusion, having been relieved of competition from other plants. However, the surviving swarms were considerably weakened because of the suspension of foraging which was possibly followed by the eating of existing eggs and larvae which could not be reared further due to such a lack of food.

Firmly established, innate behaviour

The response of honeybees to smoke by imbibing honey which tends to make them less inclined to sting, coupled with the masking of their alarm pheromone is a godsend to beekeepers in their manipulation of hives in extensive apiaries. This behaviour is innate and firmly established. That all honeybees of the genus Apis respond in a similar way by imbibing honey in the presence of smoke indicates an evolution in a fire-prone ecology.

Original publication

Tribe, G., Tautz, J., Sternberg, K. and Cullinan, J. 2017. Firewalls in bee nests – survival value of propolis walls of wild Cape honeybee (Apis mellifera capensis). Sci. Nat. 104:29.

DOI 10.1007/s00114-017-1449-5

http://rdcu.be/p2u4

HOBOS

Acknowledgment: The permission granted by SANParks to locate and analyse the nesting sites of honeybees in the Table Mountain National Park is gratefully acknowledged.

The authors at work…

Carpenter bees indicate pheromone is released by drones in Drone Congregation Areas

By Geoff Tribe, Karin Sternberg and Jenny Cullinan

Fig. 1 Male Xylocopa caffra carpenter bee at his patch of Pelargonium cucullatum busy challenging the photographer.

Fig. 1. Male Xylocopa caffra carpenter bee at his patch of Pelargonium cucullatum busy challenging the photographer.

Patrolling his patch!

Ever wonder about the antics of the yellow-haired carpenter bee hovering around a flowering shrub (Fig. 1), then darting off, only to return seconds later to hover briefly again? This is the male Xylocopa caffra which is distributed throughout South Africa. The females are unlike the males in that they are black and hairy with two bands of yellow hair (Fig. 2).

Fig. 2. The female Xylocopa caffra carpenter bee does not resemble the male.

Fig. 2. The female Xylocopa caffra carpenter bee does not resemble the male.

What the males are doing is to patrol a patch of flowers to which females are attracted out of necessity whilst foraging in order to mate with them. A patrolling male will aggressively chase away intruding males and will even attempt to discourage you from coming too close by mock diving at you. Stretch out your arm and point your finger at the carpenter bee and it will often approach the finger directly and will follow the finger as it is moved slowly up and down – as if it is an intruder.

Xylocopa caffra males make quick circuits of an area of several square meters and females that are receptive allow themselves to be seized in flight (Watmough, 1974). The receptive female will vibrate her wings and help the male carry her in flight, a successful mating flight ending 50 meters or so up in the air about a kilometre away.

Exposing interstitial membranes

What is most fascinating is that the normally completely yellow male, when hovering around its patch of flowers, lowers its abdomen and exposes two of its interstitial membranes which appear as two black bands on the abdomen (Fig. 3). The most likely explanation for this behaviour is that the male is releasing a sex pheromone, both as a species specific chemical signal and female sexual attraction. When the male momentarily darts away, the membranes are less exposed when compared to when it hovers.

Fig. 3. Male Xylocopa caffra with his interstitial membranes exposed while patrolling his patch of Pelargonium.

Fig. 3. Male Xylocopa caffra with his interstitial membranes exposed while patrolling his patch of Pelargonium.

For semi-social carpenter bees which nest in tunnels they construct within dead branches of trees or dried Aloe inflorescences, this method of patrolling patches of flowers that females must visit for the collection of pollen and nectar, is obviously suffice for the sexes to meet. The success of these encounters is enhanced by the permeation of a sex pheromone released by the male while patrolling his patch of flowers. Males of the carpenter bee Xylocopa hirsutissima have a different strategy and fly to the top of the mountain where they spread mandibular gland secretion over the ventral surface of their abdomen while hovering in the air awaiting the female (Velthuis and Camargo, 1975).

Drone Congregation Areas

For highly specialized social insects like honeybees, a more intricate and highly efficient behaviour has evolved to bring virgin queens and drones together. Mating in honeybees takes place in the air at considerable distance from the hive. These are called drone congregation areas (DCA) where thousands of drones congregate in certain locations in the air where they await the arrival of a virgin queen. Drones from as many as 240 colonies have been recorded in a DCA at one time. The phenomenon of DCAs is still little understood but certain characteristics pertaining to them are known.  Both drones and queens independently find these locations, some of whose locations have been known for hundreds of years and are therefore persistent from year to year (Zmarlicki and Morse 1963). Drones and queens from hives brought in from outside the region are immediately able to find these DCAs.

Thousands of drones milling about in a DCA greatly reduce the chance of a queen being eaten by alpine swifts (Fig. 4a), bee-eaters, redwinged starlings (Fig. 4b) or other avian predators.

Swallows in Perth, Western Australia were found to have up to 19 drones in their stomachs (Tribe 1989). Even spider’s webs may prove a hazard, even within a DCA (Fig. 5). A virgin queen always leaves on her mating flight during a worker orientation flight which persists until the queen returns – thus further reducing the chance of predation.

Fig. 5. Drones caught in a spider’s web between two tall trees in a pine plantation at Grabouw, Western Cape. The web was eventually shredded by comets of drones attracted to those caught in the web.

Fig. 5. Drones within a DCA caught in a spider’s web between two tall trees in a pine plantation at Grabouw, Western Cape. The web was eventually shredded by comets of drones attracted to those caught in the web.

Advantages of a Drone Congregation Area

Obviously the DCA must serve an important function, especially if one considers the resources entailed in rearing hundreds of drones in each honeybee colony each year. The amount of drone comb and the number of adult drones present is positively correlated with the number of workers in the hive and represent a maximum of 14% of the total brood at any time. The number of drones kept in an active colony is restricted to about 1000. Because it takes 24 days from egg to emergence (compared with 19 days for an African worker) the larger drones consume abundant pollen. The cessation of the rearing of drone brood is in response to pollen shortage, while the killing or expulsion of drones by workers is mostly the result of a shortage of nectar and may occur at periods throughout the year (Currie 1987).  Because the mating flights of drones and virgin queens are not random but concentrated into distinct areas, mating takes place in the shortest possible time. In times of very low drone population density, queens have a reasonable chance of being mated in a DCA. The lifespan of a drone is between 13-59 days.

The main advantage of a DCA appears to be to lessen the chance of a virgin queen mating with a related drone which is detrimental to the colony. With the sometimes thousands of drones drawn from diverse colonies in the area, the possibility of mating with a related drone is much reduced. In addition, queens of European races mate with an average of 8 drones and up to 17 (Woyke, 1962) which further reduces the level of inbreeding if she inadvertently mates with a related drone. By using DNA fingerprinting techniques, Moritz et al. (1996) determined that Apis mellifera capensis queens of the same population will have mated between 24 and 44 times.

Although the spermatozoa from one drone (12.7million) is suffice to fill the spermatheca of the queen, as the spermatozoa move from the oviduct past the spermatheca, fractions of the sperm of each drone is absorbed into it.  Only about 370 000 spermatozoa (3%) are retained in the spermatheca.  On the eversion of the aedeagus of the drone (like a glove blown inside out) (Fig. 6), the clump of sperm is followed by mucus and following the dissection of a recently mated queen the number of drones with which a queen has mated can thus be calculated.

The mated queen determines whether she must lay a fertilized or un-fertilized egg by measuring the cell width with her forelegs before commencing oviposition. At the height of summer a huge number of drones are present in a DCA, the majority of which will never mate – an estimate that only 4% of drones mate naturally. This huge investment in the transfer of genes indicates the importance of DCAs.

Characteristics of Drone Congregation Areas

DCAs vary greatly but most appear to have some form of relief in the form of trees or mountains near which they are established. Usually they occur high above the ground and are discerned from the noise the drones make whilst flying which sounds like a huge swarm of bees about to settle. Years back in Pretoria an irate grounds manager of a rugby club phoned to ask if we could remove a huge swarm of bees that interfered with their rugby matches on Saturday afternoons. It was quickly ascertained that no one had ever been stung, nor had any bees been observed but that the swarm ‘hovered high above the ground’. The rugby field was below a DCA and was flanked by high Eucalyptus trees. A DCA may expand or contract in size throughout the year but there is always a ‘core’ area which persists from year to year.

DCAs in Europe are recorded located at heights of 15-25m above ground (range of 8-40+m) over open ground or on summits, often in areas demarcated by buildings or rows of trees. They were 50m to 5km from the apiary and their individual sizes fluctuated from 30 to 200m in diameter but there was always a ‘steady centre’. Researchers found that drones of European races did not follow queens out of DCAs but always remained within its limits and could not be attracted to ground level with queen pheromone lures. Certain DCAs were more attractive than others and the number of drones visiting a DCA varied between sites and on different days. The sun was not used to orientate to DCAs. And of course there were no dances among the drones to indicate the location of a DCA! Successful matings from 10 to 16km distant have been recorded but the usual distance is from 5-7km. By placing drone-less colonies on islands or in desert areas, it was shown that to prevent mating an isolation of at least 15km from the nearest hive was required.

Drone Flight

Drone flight in Pretoria during the summer months began at about 12h00 and ended after 17h00 with peak flight times between 14h30-15h45. The average number of flights undertaken by flight mature A. m. scutellata drones in Pretoria was 3.7 flights/day (n=23) with a range of 3-5 flights. Individual marked drones made multiple flights in an afternoon with a mean duration of 21min 30sec (range 12min 15sec to 33min 53sec).  Using 8m/s as the flight speed, an A. m. scutellata drone is able to travel a distance of 10.3km in 21.5min with a maximum of 16.4km. When visiting a DCA no further than 1 to 1.5km distant (in ±3min), a drone could be cruising within the DCA for 45min on each flight. Between flights, drones would spend an average of 4 minutes feeding on uncapped honey.   With three flights in an afternoon, including feeding intervals between flights, drones on average would spend 72min/day on mating.

From limited data it appeared that the older the drone, the longer the duration of the mating flight. The African bee produces and maintains larger numbers of drones even in resource-scarce conditions than do European races, which accounts for the huge numbers found in DCAs.

Queen Flight

The first orientation flight of an Apis mellifera scutellata queen would take place on the third day after emergence. Usually there were orientation flights on two successive days before the virgin queen departed on a mating flight. The queen would only leave the hive during a worker orientation flight and such orientation flights would persist until the queen returned to the hive. The queen would fly once or several times in the same afternoon or on successive days until she was fully mated.

Gary (1971) recorded queen flight at 340m/min (5.6m/s), enabling a queen to take 2min 56sec to fly 1 000m. On Sylt Island (Germany) where the wind hardly ever stops blowing, matings took place at windspeeds of up to 5m/s (Tiesler 1972). The mean duration of a queen flight in Pretoria was 13 minutes 17 seconds (range 6min 11s – 21min 58s) (Fletcher and Tribe, 1977). Thus the A.m. scutellata queen could fly 4 515m in 13.28min or a return journey of 2 257m. Two further queen flights in November 1979 gave a duration of 19min 49sec and 26min 34sec which gives a maximum range of 9km.  Drones evert within 1-6 seconds on mounting the queen. Upon eversion, the drone falls backwards and the resulting pressure within the aedeagus causes the non-chitinized section to rupture, the drone falling to the ground while the queen flies off with the ‘mating sign’.

Flight experienced workers appear to determine if and when the queen departs on her mating flight. They orientate in front of the hive in ever widening circles, possibly gauging if weather conditions are suitable for flight. In an observation hive, a virgin queen primed for a flight can be seen preening herself on the comb. Ever more workers vacate the hive on their orientation flight, and the cue for the queen to leave happens after several of the orientating workers return to the hive and run ‘randomly’ around on the comb. The queen, while trying to find the exit (because the cover is off the observation hive), invariably ‘jumps’ onto the glass window and then quickly follows the bees out of the entrance.

Behaviour within the Drone Congregation Area

Fig. 7. Honeybee drones attracted to a strip of cloth attached to fishing gut and a helium filled balloon which had been lowered to near ground level within a drone congregation area in Pretoria.

Fig. 7. Honeybee drones attracted to a strip of cloth attached to fishing gut and a helium filled balloon which had been lowered to near ground level within a drone congregation area in Pretoria.

Drones form comets within the DCA of several hundred individuals which can dissipate as fast as they may be formed (Fig.7). Comets may be formed even in the absence of a queen when they orientate to any object that may enter the space such as butterflies, or even to another drone. Despite the literature recording that drones of European races of honeybees never descend near the ground (Gary 1962), in October 1986 in Floreat Park, Perth, Western Australia drone comets were observed flying at head height in an open park surrounded by trees (Tribe 1989b). Within the DCA of about 100m x 50m, individual drones were flying at knee height.

The queen is approached from below where she is silhouetted – hence the function of the abnormally large eyes of the drones. Because of its small visual acuity, a drone must fly within 1m of an object the size of a queen in order to see it (Butler and Fairey 1964). Queens may return fully mated on their first flight or may undertake subsequent mating flights on the same day or subsequent days.

Types of DCAs

How do drones and queens independently locate DCAs? Olfaction, especially pheromones, plays a crucial role in the life of the honeybee and no doubt this extends also to the formation and function of DCAs. Pioneering research into DCAs in Pretoria showed what appeared to be three types of DCAs which were used interchangeably in response to varying weather conditions: ‘barrier’, ‘sheltered’ and ‘convectional’. The most regularly visited DCA was situated downwind from a ridge which formed a barrier (e.g.  A in figure 9, the most consistent DCA). After consulting weather bureau personnel, it was determined that a breeze passing over the ridge on an otherwise relatively still day would cause an eddy downwind. The height of the ridge and the velocity of the wind would determine the strength of the eddy and its distance from the ridge. Drones fly in the afternoons on hot days and ground that bakes in the sun during the day results in late afternoon breezes as cooler air is drawn in as the hotter air rises which often results in showers of rain.

Fig. 8. Map of the situation of drone congregation Areas around the apiary on the University of Pretoria Experiment Farm.

Fig. 8. Map of the situation of drone congregation Areas around the apiary on the University of Pretoria Experiment Farm.

Eight DCAs were located around the apiary situated on the University of Pretoria Experimental Farm in 1975 with an average distance from the apiary of one kilometre (Fig. 8). By monitoring the wind speed at the entrance to the hive, it was determined that queens would not fly if the wind speed ≥5m/s, and drones at ≥7m/s. On extremely windy and usually overcast days, a DCA which normally attracted a smaller number of drones would supplant the barrier DCA in numbers. It occurred in the sheltered lee of a kopje where the air within was relatively calm compared to the gusts of wind all around it (D in figure 9). On Lion’s Rump in Cape Town there is such a DCA which can be looked down upon where the drones can be observed flying. Here again there is relatively calm air while all about the easterly rages.

At the height of summer in Pretoria with its oppressive heat with nary a breeze, the air is filled with the sound of drones. Huge convection currents were initiated by the air above the hot soil attracting in cooler air with the DCAs expanding considerably in size in response to this.

When comparing DCAs in Europe with those in Africa, it must be remembered that in Europe most honeybee colonies are hived and relatively few are feral, whereas in Africa the opposite is true and drones within a DCA are mostly from wild swarms in natural nesting sites. The late Beowulf Cooper when visiting the Pretoria DCAs related that DCAs in the United Kingdom were perceptibly warmer within them than without and regarded this as a distinctive feature for their formation in Britain. Cooper (1977) proposed a thermal vortex of warmer air within the DCA contributing to its formation.

Pheromone plume

This is what appears to be happening. The drones exiting their hives on mating flights appear to fly mostly upwind or alternately downwind until they reach an area of mild turbulence where they congregate.  Here they fly around randomly within the limits of the eddy. Drones from comets caught in nets in DCAs (Fig. 9) were transferred to plastic bottles where they were marked by dabbing them with ‘tippex’ of different colours according to their DCA location. As they emerged between the fingers of the hand placed over the mouth of the bottle, a distinct musty smell could be detected (which incidentally attracted the occasional worker bee which would not leave). This odour could be a pheromone which not only assists the queen in finding the DCA but helps create the comets. Guard bees have been recorded in prolonged lapping over much of the dead body of a drone, especially near its thorax, apparently to salvage some highly desirable substance (Australian Beekeeper 1979, 80(8): 174). Crushed drones are highly attractive to worker bees and may produce a substance which is attractive to workers in summer, enabling a drone to drift to other colonies with immunity (Holmes and Henniker 1972). Another indication of a substance produced by drones is when drones and workers were returned to their queenless colony they were accepted, but the workers when confined to a cage with their queen and drones and returned to their colony are killed – but not the queen or drones (Orὅssi-Pál 1959). Drones could be attracted in DCAs with drone extracts as efficiently as with queen extracts – head extracts being the most successful (Ruttner H. 1972). In the presence of queen pheromone the drones will form comets as one drone follows the other. They will attempt to mate with any object silhouetted above them, a butterfly or stone thrown into the air.

A queen flying into a DCA releases queen pheromone (9-oxodecenoic acid) which results in the immediate formation of comets which zigzag after her, following her pheromone plume from at least 420m downwind of her. Drones are attracted by 9-oxodecenoic acid from distances of 50m and more while the queen tergite gland’s pheromone is effective only within short distances (less than 30cm) and increases copulation activity (Renner & Vierling 1977). A pheromone is also produced from the abdominal tergites in virgin queens 8 days or older and in mated queens, probably in the glands described by Renner and Baumann (1964) which are most active at the time of mating (Butler 1971). Production of a chemical from the abdominal sternites shows that it is restricted to nubile virgin queens because ‘wipes’ of newly emerged and very young laying queens had none of the perfume (Boch, Shearer and Young 1975).  Several comets may be seen simultaneously within the DCA, dissipating as they lose the scent and reforming at will.  They approach from below the queen and mate in the air, each drone in turn removing the previous ‘mating sign’ before inturn mating with her. Thus the reason why DCAs form in certain areas appears to be to facilitate through pheromones, the fast and efficient mating of the queen by following the pheromone plume.

Of interest is the question of why the multitudes of drones within a hive do not attempt to mate with their own mated or virgin queen who is continually secreting queen pheromone? Presumably the pheromone ‘bouquet’ released by a virgin as opposed to that of a mated queen is perceptibly different. Yet if mating within the hive were to occur, it would negate the major function of a DCA to prevent in-breeding. The difference between an inactive drone within the hive and that of a drone in a DCA is one of flight. Thus presumably flight changes the physiology of a drone and makes it responsive to queen pheromone. This could be a result of the accumulation of carbon dioxide in their tissues caused by exercise.

Sound

Could sound play an integral part in the formation of a DCA? Quietly sitting in a meadow, one of the most harmonious sounds is that of honeybees going about their business. Yet we are all familiar with the raised, high-pitched sound of an angry bee. Sound plays almost as important a role within the hive as that of pheromones. The piping of queens, the moaning of bees besieged by banded bee pirates (Palarus latifrons), the distress calls of worker bees in a queenless A. m. capensis colony, and many more sounds are familiar to the beekeeper. In addition, the male semi-social carpenter bee Xylocopa hirsutissima is known to raise its flight tone when it perceives the female approaching the top of the mountain that it is patrolling (Velthuis and Camargo, 1975).

Sounds have frequencies which are distinct, and in some instances the frequency or vibration may be more important than the sound that we hear. For example, following the departure of the old queen in a reproductive swarm, several virgin queens cut their way out of their queen cells. They soon detect the presence of the other queens and are further agitated by the workers which goad them on by harassing them. To shake off the harassing workers, the queen pipes with her wings. This high pitched sound causes the workers around her to freeze, and she scoots away temporarily before they again catch up with her. In an observation hive it is possible to follow the path of the queen as she pipes on the opposite side of the comb by observing the bees ‘freezing’ in the absence of the queen on this side. The sounds/ vibrations are carried through the comb.

The sound of drones returning to their hive after a mating flight is distinctive and cannot be confused with that of a worker bee. The screeching sound of a Stuka fighter aircraft in a bombing dive was deliberately built into the plane to terrify the enemy on the ground. Surely then, the loud and distinctive sound of a drone in flight also has an important purpose? The sound (and vibrations in the air?) of several thousand drones in a DCA could serve to make the locating of the DCA easier for both drones and virgin queens. Sound could also assist, besides sight and pheromones, in the creation of a DCA and the formation of drone comets and also to help distinguish a drone from a queen within the DCA. While marking drones in a DCA several would accidentally have ‘tippex’ splattered on their wings. This would result in a different sound being produced as it flew off which immediately attracted other drones to it. A major function of a DCA is to facilitate the complete mating of a virgin queen in the shortest possible time and a combination of sound, sight and pheromones may serve to accomplish this.

Evolution of male bee pheromone glands for mating?

While monitoring the number of times marked drones flew each afternoon and the duration of their flights, it was observed on many occasions that returning drones had the two interstitial abdominal membranes exposed – in exactly the same position as that of Xylocopa caffra males. Although dissections of drones were made to discover any underlying pheromone glands, they were so small that the equipment used could not detect them. If this is the source of a mating pheromone, it appears that it may be present in many bee species from solitary, sub-social and social species. Besides different flight times, the comparison of the composition of this pheromone could possibly help explain the sexual isolation of the different species of Apis and their phylogenetic linkages.

The authors at work:

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