“Descriptions of honey bee social life from early Greek and Roman texts to the late 16th century, were largely fanciful and often proposed bee society as an exemplar for human societies. At the end of the 17th Century, the use of microscopes revealed the internal anatomy of these organisms in all its astonishing detail. The ovaries and associated organs of a queen bee were particularly striking and provided the raw material for reimagining the social life of the honey bee from a biological rather than allegorical perspective.”
“I will present details of the biological discoveries that have provided a richer insight into honey bee societies. The Cape honey bee laying workers have spawned a lineage of workers that act as social parasites in colonies of other honey bee populations. This unique phenomenon allows the effects of social parasitism on bee social organisation and its implications for the survival of colonies to be explored,” said Robin Crewe of the Centre for the Advancement of Scholarship at the University of Pretoria. Crewe was presenting the first STIAS public lecture of 2026.
Crewe studied at the then University of Natal in Pietermaritzburg and at the University of Georgia in the USA. He was the Director of the Communication Biology Research Group at the University of the Witwatersrand; established the Social Insects Research Group at the University of Pretoria; was Vice-Principal at the University of Pretoria from 2003 till 2013; and, is a past President of the Academy of Science of South Africa (ASSAf).
His contributions to the development of academies of science in Africa were pursued through his role as President of the Network of African Science Academies, his election as a Fellow of the African Academy of Science and of the World Academy of Science and as Foreign Associate member of the Hassan II Academy of Science and Technology, Morocco.
He was awarded the Harry Oppenheimer Fellowship for 2012; the ASSAf Gold Medal for meritorious service in 2013; was the 2019 winner of the National Science and Technology Forum-South32 Award for contribution to science over a lifetime; and, was awarded the John F W Herschel Medal of the Royal Society of South Africa for 2026.
Together with Robin Moritz, he published the book, The Dark Side of the Hive. His current projects include a biography of the Cape honey bee and the development of beekeeping practices in South Africa from the 19th century to the present.
Crewe explained that there are 20 000 bee species of which 2000 are found in South Africa. There are 12 species of the honey bee. One of these is the Western honey bee (Apis Mellifera) with 23 sub species, two of which are present in South Africa.
“In Southern Africa we know that honey bees and humans have been interacting for 40 000 years. We also know that bees helped to sustain Khoi pastoralists in the Western Cape. They are also very important from an agricultural point of view. A large part of the Western Cape agriculture economy depends on bees,” he added.
Crewe explained that, much like early humans, bees expanded from Africa to Europe and the Middle East, and were also introduced by humans to the Americas, Far East and Australia. “They were found to be very adaptable to different climates and habitats, probably as a result of their complex social life.
Super organisms
Crewe explained that bee colonies are super organisms in which individuals give up their independent existence for colony survival. “Evolutionary fitness equals a successful colony.
The colony is a complex adaptive system where the males are drones and the females are reproducers and workers. “Successful males mate and die, the unsuccessful don’t mate and die anyway.
At the centre of the colony is the queen. The first detailed drawings of the queen’s ovaries were produced in 1675 by Dutch biologist Jan Swammerdam giving insights into how reproduction and fertilisation occurs with the queen able to store sperm and use it to fertilise or not fertilise the eggs. Because males are produced from unfertilised eggs and females from fertilised eggs, the reproductive female can control the sex ratio of her offspring. Honey bee queens therefore bias the sex ratio in favour of producing large numbers of females (workers) and only producing males when needed. This gives rise to a largely female social group characterised by a single reproductive female and large numbers of non-reproductive female workers.
“Up to 2000 eggs are produced a day,” said Crewe.
“The workers have reduced ovaries and are not capable of significant reproduction, but they do all the other activities including interacting to forage for pollen and making honey. They even regulate the temperature of the colony at 34.5 degrees Celsius. The colony depends on producing large numbers of offspring so it is an incubator. The workers work hard and die young.
The key element is controlling reproduction. “The queen produces pheromones to make docile workers and to attract males for mating. This restricts the workers to doing all of the tasks other than reproduction. But there are sometimes rebels who don’t get the chemical message. These rebels can lay eggs but only produce male offspring. So, the other workers police and harass them, and eat the eggs.
“The queen usually lasts two to four years,” he continued. “When the colony reproduces, the swarm takes the old queen with them and the established nest is left to her daughter. Almost 80% of colonies we studied in Pretoria had an annual turnover of queens. In some instances, a foreign queen may usurp the daughter.”
Thelytoky and social parasites
There are, however, some significant anomalies in this well-run system.
“Work in 1912 by a Cape Town beekeeper, George Onions, introduced a significant anomaly into the seemingly orderly picture of the social life of honey bees,” said Crewe. “He showed that Cape worker honey bees were able to reproduce and clone themselves, producing female offspring rather than males. This resulted from a number of features of these worker bees including mimicry of the queen’s reproductive chemical signal.”
Finding that Cape honey bee workers can produce female offspring – known as thelytoky − until then was not known to occur in bees and Onions’ claims were therefore regarded as incredible for a long time. His discovery was only confirmed by later work by many including Savitri Verma and Friedrich Ruttner in the 1980s who were able to show cell division in the ovaries and the central fusion of meiotic products to produce female offspring.
Crewe explained that a second major anomaly emerged in 1991 when some beekeepers transported Cape honey bees to a location north of Pretoria. There the Cape bees generated a socially parasitic worker that was able to infect local honey bee colonies resulting in the death of the host colonies.
“This was a rare example of intra-specific i social parasitism . Investigations showed the parasites were all from a single lineage. Such social parasites only occur in apiaries because the distance between wild colonies makes it difficult for them to find these colonies.
“One of my students did an analysis of pheromone regulation in social parasites which showed these workers were not only diverse genetically but developmentally diverse. They go from being a docile worker to a false queen with active ovaries and all the queen’s signals – they are therefore fed and received by the host colony. They are basically ambidextrous and can produce both queen and worker compounds when necessary.
“There is strong selection for the parasitic lineage which means it is very virulent and hard to regulate. Intraspecific social parasites are very rare. Parasitism usually occurs between different species. It’s not clear if such parasitism will survive evolution.”
“We still don’t know why it happens in the Cape honey bee and need to understand why the gene exists and survives,” he added. “It’s essentially a super organism with a lurking source of disruption.
Asked about the decline in bee numbers and the fact that European honey bees are now on the endangered red list, Crewe replied: “The population of honey bees globally has never been larger – due to translocation into new habitats and the massive increase in beekeeping. At a local level, we don’t really know what the impact of increased agricultural land use and climate change will be. The size of wild populations of African honey bees needs more exploration, since increased agricultural production generally means increased demands on pollinators. I don’t know if we have enough bee colonies, particularly in Africa which is arid and has sparse bee populations.
