Busy time for bees

25 September 2012

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Spring is in full swing in the Boland, which means that it’s time for the bees to do their job in the food chain: pollinate. In fact, in the fruit industry the contribution of these tiny beasts is indispensable.

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There is one important fact you need to understand about pollination to appreciate the crucial role of bees in our business. A fruit variety is considered “self-fertile” when its own pollen can successfully pollinate the flowers of the same fruit variety. Most stone fruit varieties fall into this category (apricot, peach, nectarine and some plum cultivars). However, all pome fruit (apples and pears) and many plum cultivars are “self-sterile” which means that their flowers need to be pollinated by the pollen from another cultivar in order for the ovules to be fertilised to form seed. If there is no seed, the flower will not evolve into fruit and we will not have a crop. And the more fertilised seeds a fruit contains, the bigger that fruit will grow. We therefore, in our apple and pear orchards, plant every 10th tree with another variety that flower at the same time as the main cultivar in that orchard.

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But to carry the cross-pollinating pollen from the anthers of the flowers of one tree to the stigmas of the flowers of the other trees, we need the services of the honeybee. These little insects are by far the best pollinators we know of (other insects, birds and even bats also play their part) so at this time of year we place large numbers of beehives out into our orchards to increase our chances of achieving an optimal crop. We have a number of our own hives, but we also contract in the services of professional beekeepers to provide us with additional colonies during this critical period.

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Moving beehives is a tricky business as these little friends of ours do have a foul temper at times! So, we seal the hives with a rag at night when the bees are inactive and then move the hives from one orchard to another early morning before the bees get active. The handlers do however wear protective clothing as well because some of these little buggers manage to get out and can be a menace.

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Bees can venture up to 3km away from their hives, but the rule of thumb is to put out four colonies per hectare for pear orchards and two for apples to achieve optimal pollinator pressure. We place the hive on an old tyre to raise it from the ground in order to protect it’s sweet contents from ants – for some reason ants don’t like to walk over rubber. Once all of that is done, the colony can get to work collecting the nectar they need for producing honey as well as pollen which is their source of protein for the “brood” (the term used to refer to the early life cycle of a bee i.e. egg, larva and pupa stages) back home. In the process they do the fruit trees a favour by carrying pollen from flower to flower through the entire orchard.

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Weather conditions also need to be ideal. Bees do not go out to forage if there is more than 70% cloud cover, ostensibly because they use the sun to navigate their way back to the hive. They are also immobile at temperatures below 13 degrees Celsius. During those times all the worker bees cluster around their queen and the brood in the centre of the hive to keep it warm with their own body heat. Ideal foraging temperatures are 22-25 degrees Celsius, so the mild sunny days that we have mostly experienced over the last few weeks in the Cape were perfect.

It should be clear by now that the honey bee is critical to the commercial fruit industry and it is not a surprise that the global beekeeping industry is worth billions. In 2009 an outbreak of American Foulbrood Disease (“AFB”) was first reported in South Africa. It is a spore-forming bacterium that infects and kills the larvae and young pupa in a colony and inevitably leads to the death of the entire colony. The only way to effectively combat the disease, is to incinerate infected hives. Because the disease can be latent in a colony for 2-3 years, it was not clear at the time of the outbreak how extensively it has already spread throughout the Western Cape. Fortunately fruit industry and professional beekeepers’ bodies and the Department of Agriculture worked together to quickly identify and destroy infected colonies and disaster was averted.

One can carry on forever about the fascinating science of honeybees and pollination (a Nobel Prize was even awarded to Karl von Frisch in 1973 for his research into how bees communicate with one another by dancing!) or get philosophical about their exemplary work ethic. I’ll rather just leave you with one last bit of trivia: no fewer than 17 American states have the honey bee as its official “designated state insect”.  Hope that creates a buzz at your next dinner party conversation.

– Handri