Doomsday Scenario-Prof Robin Crewe

The threat to honeybee populations in the USA, Europe and Latin America over the past few years has received extensive media attention.Yet, very little is said about African honeybee populations, even though honeybees come from Africa.

We need to understand the impact of African honeybees on global populations to find solutions for the regional crises on the other continents. This is what the University of Pretoria’s bee expert, Prof Robin Crewe, shares with his audience in the first of the UP Expert Lecture Series.

Recent media attention has been focused on the perceived worldwide plight of honeybee populations with predictions about the drastic ecological effects of the loss of honeybees as pollinators. Alison Benjamin and Brian McCallum published a review of this position in their book - A World without Bees: the mysterious decline of the honeybee - and what it means for us. The scientific journal Apidologie has published a special issue on bee health to address:
"... the large-scale loss of honeybee colonies (which) has come into focus under a worldwide spotlight. Colony collapse disorder, winter losses and weak bee colonies are pervasive in many apiaries leading to a serious situation for beekeepers and pollination."

These doomsday scenarios arise from research in the US, Europe and Latin America and suggest that we should be concerned by this apparently global pandemic affecting honeybee populations. However, very little is said about honeybee populations in Africa, and nothing is said about the 'plight' of African populations of honeybees. Furthermore there is very little recognition of the significance of Africa honeybee populations for this story. As with human
populations, the origin of all honeybee populations is the African continent and an exploration of the impact of African and particularly Southern African honeybees on global honeybee populations needs to be understood in order to provide solutions to the regional crises in the US, Europe and Latin America occasioned by honeybee colony losses over the last 3 or 4 years.

The lecture will explore the evolution of honeybees in Africa, their expansion to Europe and the Middle-East followed by their anthropogenic transmission to other continents where they became classic invasion species. The role of Southern African populations of honeybees in this unfolding drama will be explored in depth both to describe one of the most extraordinary invasions of a continent by an organism and to understand the interaction between honeybee populations from the extremes of the species distribution. In addition, the discovery of social parasitism within honeybee colonies has lead to a much better understanding of plasticity of honeybee social organisation.

The insights gained from African honeybees will be used to indicate that the threats to honeybee populations in the northern hemisphere and Latin America may be resolved by recolonisation of these areas using populations of African honeybees.


Questions and Answers

"If the bee disappears from the surface of the earth, man would have no more than four years to live" - Albert Einstein

  1. Name the two bee spesies occurring in RSA?
    Apis mellifera scutellata - also known as "killer bees". These are the most aggressive bees on earth; they get angry very easily, attach in great numbers and also follow their victims over large distances. Apis mellifera capensis - The Cape bee. These bees are less aggressive than the killer bees.
  2. Name the three types of bees in each colony?
    The queen: Lifespan 3, 5 years. She mates once in her lifetime with ± 20 drones and is able to keep the sperms alive for the duration of her life, thus ensuring the genetic diversity of the colony. Her only function is to lay eggs.
    Worker bees (female bees): lifespan ± 6 weeks. A worker bee spends about 2/3 of their lives inside the hive and only 1/3 outside

    Work inside the hive:
    • cleaning and building of new cells, removal of sick/dead bees
    • nurse bees, feeding young larvae
    • production of wax and royal jelly
    • guard bees, protecting the hive

    Work outside the hive:

    • foraging to collect nectar, pollen and water

    Drones (male bees):
    lifespan 2 months. Their only function is to mate with queens.

  3. Which type of bee does not have a father?

  4. How does a queen decide when to lay a fertilised (worker) or unfertilised egg (drones)?
    The queen measures the size of the cell with her antenna and depending on the size decides.

  5. The lifecycle of a bee?
    Egg, larva, pupa and adult bee.

  6. How many eggs does a queen lay per day?
    A maximum of 3 500 eggs per day; 200 000 eggs per year.

  7. How many worker bees are there in an average swarm?
    Between 40 000 and 50 000 bees.

  8. What do bees eat?
    Bees collect pollen, nectar and water. Pollen is the main source of protein while nectar (converted into honey) supplies the energy. Water is used to dilute the concentrated honey as well as to regulate temperature and humidity in the hive.

  9. What is the temperature in a hive?
    Bees regulate the hive temperature between 34ºC and 36ºC, regardless of the ambient temperature. They use heat produced through body movements to regulate temperature and when it gets too warm inside the hive they use evaporating water from the nectar. Air circulation is caused by wing movements.

  10. How do bees produce beeswax?
    Worker bees have a special gland that becomes active when they reach a certain age through which wax cells are produced.

  11. How do bees communicate with each other?
    Worker bees communicate through dance (vision) to transfer information about
    direction and distance to food sources. The queen rules the workers through
    pheromones (smell).

  12. Products of the hive?
    Honey - can be used as food and also as an antibacterial substance to prevent wound infections.
    Wax - used as medicine, skincare products, artistic products, polish as well as candles. Propolis - healthcare products and in wood varnish.
    Pollen - one of the richest and purest foods that contains proteins, sugars, carbohydrates, minerals and vitamins.
    Bee venom - is used as treatment against e.g. arthritis, high blood pressure and high cholesterol.

  13. Where does honey come from?
    Honey is the nectar of flowers of which the water has been removed. A worker bee will produce 1/12 of a teaspoon of honey during her lifetime. In order to produce 500g honey 556 worker bees need to visit ± 2 million flowers; a worker bee visits between 50 to 100 flowers during a single foraging flight.

  14. How far does a bee fly to make ±500g honey?
    A bee can fly as far as 10km at a speed of 24km/h and will thus have to fly 3x around the earth to produce 500g of honey.

  15. Why does honey differ in color and taste?
    The color of honey depends on the nectar source.
    Aloe honey, for example, is white, blue gum honey has an amber color with a strong, distinct aroma while avocado honey is very dark.

  16. How far will a bee fly to collect nectar and pollen?
    A radius of 11/2km to 2km.

  17. How much honey does an average bee swarm produces per year?
    Between 20kg - 30kg.

  18. What is "royal jelly?"
    It is a product that is produced from pollen and nectar and it is mixed with a chemical secretion that is produced by special glands in the head of worker bees. It is used to feed the queen bees and that enables her to lay 3x her bodyweight in eggs.

  19. How many bee visits are required to pollinate an apple blossom in order to produce an export quality apple?
    Between 50 and 60.

  20. Why are bees being used in commercial agriculture?
    Bees are the only pollinators that are available in large numbers and that can be transported to arrive on and be removed from site on a specific date.

  21. What is the difference between beehive and bee swarm?
    A beehive is a container of standardised size that can accommodate bees while a bee swarm is a large number of bees including the queen, workers and drones.

  22. What does a beekeeper use when he works with his bees and why?
    Smoke since it calms down the bees.

  23. What is the color of the protective clothing of beekeepers and why?
    White; dark colors make the bees more aggressive.

  24. What is the value of honeybees?
    Bees are responsible for the pollination of 80% of all insect pollination and one third of the food we eat. The value of bees in the ecosystem is considered to be 20x more than the value of honey production.



Prof Robin Crewe
Vice Principal: Research & Postgraduate Studies
Leader: Social Insects Research Group

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