Bees and the buzz about higher yields

The answer to higher crop yields, has been within the grasp of famers all along — bees — and what’s more, they are friendly to the environment. PHOTO/FILE

What you need to know:

  • Forget about expensive agricultural equipment, high-tech farming methods and fertilizers to improve food production. The answer to higher crop yields, has been within the grasp of famers all along — bees — and what’s more, they are friendly to the environment.
  • Due to unfavourable human activities such as overgrazing, use of pesticides, clearing and burning of bushes, the number of bee colonies is decreasing every year. There is a need to reverse this trend by using less harmful farm management systems such as weeding and uprooting infected crops to allow bees to survive because they play an invaluable role in crop production.
  • In Africa alone, the value of bee pollination is estimated to be more than 100 times that of honey, tagged on the various cash crops whose yields the insects improve.

African farmers have been struggling to increase crop yields to support a growing population but they are, at the same time, destroying what could be their greatest asset: Bees.

Thanks to their role as pollination agents, bees can be considered fundamental agents in increasing global crop yields and boosting the quality of plant products.

Indeed, according to the Food and Agricultural Organisation (FAO), embracing bee pollination is an efficient agricultural technology that promotes proper land use to ensure sustainable food security.

The agency also says that, of the 100 crop species that contribute 90 per cent of the food produced globally, 71 depend on bee pollination for their growth and development.

Research has also shown that crops previously considered to be independent of bee pollination not only record high yields, but have their quality boosted after exposure to bees.

With the continued decline in land for agricultural use even as the demand for food remains high due to global population growth, the need to find alternative ways of using the available land to gain high yields is paramount.

In Africa alone, the value of bee pollination is estimated to be more than 100 times that of honey, tagged on the various cash crops whose yields the insects improve.

The importance of bees in crop production and conservation of the biodiversity is little appreciated, even though scientific literature says their role has a higher value in monetary returns than honey.

Consequently, farmers destroy many bee colonies across the world. Indeed, many farmers see bees as a danger to their crops and use smoke to keep them away.

It is paradoxical that this happens even as governments, especially in developing countries, continue striving to achieve food sustainability to alleviate hunger.

With better yields and more nutritious crops directly benefiting from the work of bees, many families will have better food and see a decrease in food deficiency-related diseases and improved finances.

SUBSISTENCE FARMING

Most subsistence crops are largely grown by small-scale farmers in rural areas, who contribute more than 85 per cent of the global food production.

Plant species that have become staples for many African communities can yield vastly improved harvests if exposed to bee pollination.

These include pumpkins, cabbage, avocado, carrots, onion seed, squash, pepper, watermelon, passion fruit, legumes, beans, cowpeas, green grams, tomatoes and leafy vegetables.

Meanwhile, those mostly grown large-scale for commercial purposes include apples, apricots, asparagus seed, blackberry, blueberry, canola, oilseed, rape, clover seed, citrus, cotton, cucumber, eggplant, mango, peach and nectarine, pear, strawberry, safflower and sunflower.

Although there are other agents that catalyse fertilisation in plants such as beetles, butterflies, moths, wasps and even wind, bee pollination is more effective and accounts for 85 per cent of the pollination done by animals. And this can be improved even further by using two other species, the solitary and bumble bees.

Hairy bodies

There are several factors that make the honey bee such effective pollinators. For one, they need nectar and pollen to feed their young, so they visit flowers frequently and in large numbers to get these products.

Their hairy bodies also trap pollen, which they then carry from flower to flower. Then their size allows them to pollinate flowers of various shapes and sizes.

In addition, they can remain faithful to a particular plant species and come in large numbers, with a colony consisting of 20,000 to 80,000 bees.

“Beekeeping will certainly increase the yields for many crops dependent on bee pollination such as watermelons, melons, pumpkins, sunflower, macadamia nuts, cashew nuts, mangoes and avocados,” says Dr Muo Kasina, an economic entomologist attached to the Kenya Agricultural Research Institute based in Kabete on the outskirts of Nairobi.

“It will also enhance the protection of other very important bees that do not make honey but are significant in increasing crop yields and quality such as carpenter bees, leafcutter bees and sweat bees,” he adds.

REDUCED YIELDS

In the absence of bee pollination, there are reduced yields, poor seed and fruit development and lower nutritional content in the harvested plant products.

This in turn leads to reduced food supplies and lower earnings for commercial crops.

“If not pollinated by bees, African indigenous crops will record a 40 per cent reduction in yields, with macadamia nuts recording a 46 per cent reduction in kernel weight and 60 per cent loss in yield, while tomatoes will see a 25 per cent loss in yield,” says Dr Lusike  Wasilwa, the assistant director for horticulture and industrial crops at the Kenya Agricultural Research Institute.

Yet, farmers in many parts of the world continue destroying colonies of feral (wild) bees, largely due to ignorance.

For instance, during a study conducted by Dr Kasina on farmland within a 10-kilometre radius of the Kakamega Forest edge, 98 per cent of the farmers interviewed were aware of bee species. However, 50 per cent had no clue with regard to the insects’ significance in crop production.

Dr Kasina’s study, which focused on nine crops – beans, cowpeas, green grams, bambara nuts, tomatoes, capsicum, passion fruit, sunflower and squash ­– showed that bee pollination improves harvests and enhances crop quality.

Following frequent bee visits from the nearby forest, beans, cowpeas, green grams and bambara nuts were found to have a 40 per cent improvement in seed weight.

There was a 25 per cent increase in tomato yield, with a 15 per cent weight gain. Capsicum recorded a 56 per cent weight gain with a 29 per cent increase in yield while the oil content in sunflowers rose by 21 per cent.

“There is a great need to create awareness among farmers regarding the importance of bees to farming so that they can protect their habitats and conserve the forage,” says Mr Stephen Kagio, an apiculture and sericulture lecturer at Egerton University.

The different species of bees thrive in varying conditions, but one thing that is crucial for their survival is sufficient forage.

Honeybees’ tendency of not wasting time on crops not ready for pollination and their ability to remember the time when crops produce most nectar, thus facilitating pollination, makes them a favourite for many farmers in the developed world.

PROTECTING BEES

However, they are greatly affected by extreme climatic conditions. During the dry seasons, the farmer or beekeeper must provide alternative sources of water and food. Sprinkling the hives with water or covering them with a wet hessian sack to keep the bees cool is paramount because if this is not done, they die.

But for the farmers in arid or semi-arid areas who use irrigation, leaf cutter bees – a solitary species – can be reared for pollination.

These bees nest only in straw or other organic horizontal tunnels and do not need water, which makes them suitable for dry areas. Artificial nests made from poles with holes drilled in them can be designed to host them.

One can store their cells at temperatures of between three and five degrees centigrade and when it is blooming season, the larvae can be put in at 30 degrees centigrade for 17 to 26 days to catalyse metamorphosis of the larvae.

In greenhouses, bumble bees are preferable since they can easily be carried in cardboard nest boxes and can withstand room temperature as long as there is enough water.

“All bees are very important, but their effectiveness depends on their environment. Though many people are afraid of keeping bees for fear of getting stung, bees have to be provoked to sting,” says Mr Kagio.

“For instance, a honey bee will rarely sting somebody when moving from one flower to another because it is more concerned about collecting nectar and pollen than in stinging anyone.”

Another notable factor is that the number of bees, as well as the number of visits they make to a plant for effective pollination varies from one crop to another; some plants require more than 25 visits.

For instance beans require three colonies of honey bees per hectare, pumpkin (four), avocado (five), cabbage (five), carrot seed (eight), cotton (eight) and mango (15).

To ensure that bees pollinate a particular crop within a farm, they can either be put closest to the plantation so that they pass through it before heading to another, or be fed with a sugar syrup mixed with the flowers. The bees will then search for the crop with the flower scent.

ENDANGERED SPECIES

Scientists are worried about the dwindling number of bee colonies. Over time, human activities have rapidly destroyed the insects’ natural habitats, resulting in the death of many and reproduction of only a few. For instance, the United Nations Environmental Programme has noted that extensive cutting of trees has denied bees sites for nesting, hiding and mating.

In addition, poor farming methods such as mono-cropping, overgrazing, bush and land clearing have depleted food for bees, directly contributing to their dwindling population.

“It is anticipated that climate change consequences, such as fluctuations in greening, flowering and ageing periods, and an overall shortening of the growing season may hamper the livelihood of pollinators. Changes affecting the distribution of floral resources across space and time also influence the composition of  pollinator communities,” says UNEP’s Division of Early Warning Assessment report titled “Global Honey Bee Colony Disorders and Other Threats to Insect Pollinators.

Ban on insecticides

The use of the synthetic pesticides and insectides on crops has been identified as one of the greatest killers of bees.

Notably, some countries are taking action to help save bees. Some counties in the developed world have imposed a ban on the use of certain insecticides and pesticides. In Denmark, it is illegal to use such pesticides or insecticides and a crop grower who uses them is liable to compensate the beekeeper for the bees lost.

Farmers are encouraged to use biological methods of pest control such as weeding, uprooting the affected crops and destroying them and using non-toxic ashes.

“Documenting all the habitats suitable for bee pollination is extremely necessary. This will be the key to protecting the supporting biodiversity and naturally conserving our environment,” says Mr Kagio.

POLLINATION AND HOW IT WORKS

Pollination is a crucial process in flowering plants, without which neither the seeds nor the fruit will develop.

However, there are crops that can self-pollinate, but even in such cases, bees greatly boosts the pollination, according to Dr Kasina’s report following his research on Bee Pollinators and Economic Importance of Pollination in Crop Production, in Kakamega district in 2007.

Regardless of a crop’s functioning or form and structure, it requires pollination. These are the factors which, apart from the pollinator’s characteristics, determine the eventual success or failure of the pollination.

Plants have different structures, with some having the male and female organs in different plants (dioecious), others having the organs in the same plant but on different flowers, and yet others having male and female organs which mature at different times. But they all depend on bees or other insects for pollination.

The same applies to heterostylous plants, which have different stamen and style lengths; and infertile hermaphrodites, despite their male and female organs maturing at the same time.

The presence of pollinators during the blooming season greatly affects the crop output.

Some require pollination within a limited period and definite time of the day when the temperatures are also favourable for the production of nectar.

They also require a specific number of visits by bees for pollination to be successful. For instance, a single coffee flower can be pollinated for only three to four days during the blooming season. If no bees come to pollinate it within this period, it withers.

Similarly, the white clover seed produces a special smell to attract the bees when the temperatures are above 15 degrees centigrade, if there are no bees around, the whole plantation will fail.

Pollination is the beginning of the process of crop development and determines the final product.