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Sunday, 15 April 2012





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Protecting and conserving bees :

Honey bee -nature’s pollinators

A close-up of the bee hive

Fruits, vegetables, cereal and grain dominate the food we consume. Any dish, that is sweet, sour, bitter or spicy, is based on these resources that come from plants. Most of the time fruits or vegetables just do not come out of flowers. As we all know behind all these flowery and fruitful plants lies a very magical and technically complicated process called pollination, a brainchild of Mother Nature.

How do plants get pollinated? Well, depending on geographical areas it happens in different ways. Wind, insects and other animals are the main ones. But in most fruiting trees and in certain vegetables the pollen is carried by animals mostly by insects – butterflies, bees as we know.

Pollen is the male part of the flower and it needs to be carried away to the female part of the flower which is called pollination and in most cases in nature, without pollen plants can not produce fruits or seeds. The fruits that we eat, the vegetables we use and even most spices are derived from fruits and seeds of plants would not exist if not for pollination. This is a necessary part of the reproductive biology of plants.

Among the pollinators of nature, bees seem to be doing the largest part of the job. Armed with large number of workers and their ability to fly long distances bees are the best unbeatable pollinating machines and humans have not found a successful alternative machine. In the world of bees living in Sri Lanka, the Bambara (‘Apis dorsata’) is the best pollinator of all, according to researcher Fred Dyre, Professor of Zoology of the Department of Zoology of the Michigan State University, USA. Dyre has been studying bees since his days as a grad student at the Princeton University, USA. What is there to study about bees is a common question scientists like Dyre answer quite often. Currently Dyre is in Sri Lanka to study our ‘Bambara’, the best pollinator among the bees in the world, as part of long standing research.

“This needs further studies to prove the fact,” he added. Yet they have several reasons to believe Bambara is the best pollinator. “ In tropical Asia generally most pollination done by animals and it is mostly bees. Honey bees have long flight ranges, rapid recruitment, precise communication, large colonies and thus we think that honey bees are more efficient as large scale pollinators than other bees of the world,” he explained. Bambara is the biggest bee and has the longest flight range. Bambara spread plant genes over a large distance. “this is important for agricultural plants as well as forest plants,” Dr. Dyre explained.

“There are thousands of bee species. I learned from Sri Lankan zoologists that there are 50 – 60 species of bees in Sri Lanka, possibly more than that. And the group that I study is the true honey bees. And the honey bees are a group of about ten species. There are many common features such as complex societies, large ensemble of workers, a queen, and sterol females. They build wax combs in which they store honey and raise the larva to continue their colony. They heavily depend on nectar and pollen from plants as resources. In the process of that they disperse pollen.

All bees pollinate. But the distance foragers carry pollen and the number of bees get out there in to the crops or to the forests will determine the success of their job, according to Dr. Dyre. “And all of this probably has to do with having a communication system that is very precise and makes a successful forager to recruit a very large number of its nest mates to a feeding patch and successfully compete with the other bees,” Dyre explained. Bees communicating with each other would be a bit difficult to understand yet it’s a remarkable creation in nature.

The Bee Team – from left – right : Dr. Siril Wijesundara (DG, Botanic Gardens Department), Dr. Wasantha Punchihewa, Dr. Fred Dyre and Nayana Wijetilaka

As Dr. Dyre explained this feature of bees can be considered as unique in the animal kingdom. “It is called as the dance language as it involves movements of the body of a successful forager whose gone out and found food at a particular location. It returns to the nest and does these body movements. And by waggling their body in a certain way pointing a particular direction on the nest and doing it with a certain tempo it can certainly tell the other bees they should fly relative to the sun to get to the food and also the distance.

Other bees pay attention to the dancer and after they watched a few cycles of the dance they go out and look for the food. This characteristic of honey bees contribute to the other unique features they display,” he said. According to him this dance language has been identified by scientists nearly 50 years ago. “I studied deeply in to this language and tried to understand how bees use the sun and landmarks as navigational tools.

Trying to find answers to many questions that is with their language,” he added. The dancer bee is giving out a message of a place that may be at 5 to 10 kilometres away from the location where they are communicating. This does not give any signal on the individual bee as in many signals animals do to find a partner for mating. But the bees are actually talking of something far way from where they live. “Even on a cloudy day, where there is no sun to direct the bees, they still communicate and find their way to food.

They have to learn it over time. They have to learn the particular pattern to food location,” Dr. Dyre explained. And he is still curious about it.

Amazingly Bambaras travel in moonlight too. “I did document it in my research that Bambara bees do go out in the moonlight,” Dr. Dyre said. “Such that in the night of the full moon Bambara bees actually make more flights than during the day,” he said.

As he further explained according to research by botanists, flowers do not produce much nectar during the hot climate of the day time it is mostly during the cool early morning hours or late in the evening or night – a typical pattern of tropical flowering plants. “Even the Bambara colonies a pretty much shut down after ten in the morning until about three or four in the afternoon. They are very quiet this time unless they go to collect water to cool themselves,” he explained. “Bees were believed to be diurnal pollinators but this finding makes their behaviour more complex,” he added. None of the other bees belonging to the ‘Apis’ species travel in night only Bambara does. “On full moon days and other days leading to full moon day the bees keep flying,” he said.

In fact the study of Asian Honey bees has taken place at the Peradeniya Royal Botanic Gardens in the early 1950’s by research scientist Prof. Martin Lindauer a student of Karl Von Frisch, who gave the first inspiration to Dr. Dyre to study on ‘Bambara’ during his study at Princeton University.

There is a unique place at the Peradeniya Gardens which was the study centre for Asian Honey bees and it is a tree with lots of Bambara colonies called the bee tree.

This tree which is actually a ‘Hora’ tree (‘Dipterocarpus’ sp.) is still there in the Garden standing nearly a half a century bearing an amazing part of the Sri Lanka bio diversity. The first picture of this tree has appeared in 1951 in the research paper by Prof. Lindauer. “According to our counts we observed nearly 25 colonies,” Dr. Dyre explained. As he further explained during a research in India he has observed 108 colonies in a Banyan tree.

The tree – the bee tree in Peradeniya Royal Botanic Garden. It is a Hora tree (‘Dipterocarpus
sp.’) that has been full with bees and hives for many years

“They aren’t the only bee to make honey. Even the tiny ‘Kona mee’ the small stingless bee commonly found in Sri Lanka also produce honey in tiny amounts.

But honey bees make large amounts of honey and Bambaras can make up to 20 – 30 kg of honey a year in one colony,” Dyre explained revealing an unknown fact about our sweet honey bee the ‘Bambara’. What is the importance in Sri Lanka? Dr. Dyre explained that first of all because tropical Asia is believed to be where the honey bees evolved and got diversified. According to him Sri Lanka shelters about three species of true honey bees.

There are Solitary bees too. They are those who do not reproduce in a community or do not form a stable social group. There is just one female bee, mate with one male bee and raise the young on her own.

She builds a nest on her own, brings pollen and feed the offsprings. It is not a colony. For example in Sri Lanka the bees in the Family of ‘Megachilidae’ are such solitary animals.

In USA sweat bees fall in to this category. Another group of solitary bees found commonly in Sri Lanka falls in to the Family of ‘Anthophoridae’ which includes bees some of which nest in the ground.

A very conspicuous member of this group that lives in Sri Lanka are the so called ‘Carpenter bees’. They build a tunnel in the wood and can be commonly found in old wooden buildings – the big black bees. Deeper in the wooden tunnel the female lays her eggs and deposits the pollen and builds a series of cells and in each cell there is an offspring.

“So far bees do not face severe threat to their existence but unexplainable fear leads to these bees being killed and that is a major threat,” Dr. Dyre explained. “In USA since 2006 bees are facing ‘die back’ syndrome which is believed to be caused by a pesticide. A large number of bee keepers started losing their industry on a mass scale and still research is on going to find the true reason,” he explained.

The identified pesticide makes the bee to lose its direction to return to its hive, according to research. These are possibilities that can happen as we humans develop. To protect the valuable pollinators in Sri Lanka, the Ministry of Environment established a Working Group of Pollinator Conservation that comprises the country’s top botanists and zoologists.

The Working Group is headed by Dr. Wasantha Punchihewa who is a leading researcher on Sri Lankan bees. Dr. Punchihewa is also involved in promoting the bee keeping industry in the villages under the ‘Divi Neguma’ program that is conducted under the Economic Development Ministry. The Working group is working on conserving all pollinators of the animal kingdom and specially the Bambara bee which is facing threats in places like Sigiriya and several other public places where there are a large number of hives.


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