Coffee yields

animated_gif_bees_06  When describing ‘The Value of Bees for Crop Pollination’ (1), the Food and Agriculture Organisation when referring to coffee yields state …
A single coffee flower is only open for three to four days when blooming. If a bee or another insect does not pollinate the flower during these days, it will wither, and no coffee bean will be produced. Clever coffee farmers take care that there are plenty of honeybees or stingless bees for pollination in the farm.

ETH-Zurich researchers from the group headed by Jaboury Ghazoul, professor of ecosystem management, set about investigating this argument by studying the influence of pollinator insects on coffee harvests in an agroforestry system at coffee plantations in the province of Kodagu in southern India in 2013 (2). Coffee is grown in a traditional agroforestry system in the region. As coffee plants must not be grown in direct sunlight, they are planted in the forest’s undergrowth or the shade of large, isolated trees. The coffee plants all bloom at the same time after heavy rains between February and March and three species of bee pollinate the flowers: the giant honeybee Apis dorsata, Apis cerana and the solitary wild bee Tetragonula iridipennis. The giant honeybee is the largest and most important pollinator, forming large colonies and needing the thick branches of tall trees to bear the weight of their nest.

Apis dorsata on coffee flowers

The ‘Putyokan’ honeybee or Giant honeybee (Apis dorsata) is the principle coffee pollinator. (Photo: S. Krishnan / ETH Zurich)OLYMPUS DIGITAL CAMERA

‘Ligwan’ bees of the Apis cerana (Asian honeybee) species pollinate coffee flowers. Farmers can increase the services of pollinating insects with particular cultivation methods. (Photo: J. Ghazoul / ETH Zurich)

The study in India (2) found that instead of relying on rainfall, it is worth the farmers’ while to induce flowering with artificial irrigation. “It is particularly in a farmer’s interests to irrigate his plantations at a different time to other farmers in the vicinity,” says Ghazoul. After all, this will turn his plantations into bee magnets. This concentrated pollination increases the yield from the plantation enormously, the ETH-Zurich researchers reveal in their publication. It is a different story if the rain makes all the coffee plants in the region flower at the same time, however: the bees spread out over a wide area, the pollination is less effective and the harvest is poorer.  Coffee plants benefit from the shade of “holy” trees, which go untouched, and which also provide nesting sites for the Giant honeybee, which is a very important pollinator for the coffee crops.

An Indonesian study (7) states: The study ‘results constitute experimental evidence that cross pollination by bees causes a significant increase in fruit set of not only the self-sterile, but also the self-fertile coffee species. The practical implication is that coffee yield may be improved by managing fields for increased flower visitation by bees.’

Even ‘self-fertile’ coffee varieties are shown in studies to have much improved fruit set due to bee pollination.  Research by David Roubik at the Smithsonian Tropical Research Institute in Panama (3) shows bee pollination is much more important than farmers thought.  Roubik studied plantations of the shrub Coffea arabica, which produces 70 per cent of the world’s coffee, in western Panama. (Non-native African honeybees were introduced in the area in 1985.)  Roubik covered some coffee plant branches with netting, and compared the yield of these plants to those regularly visited by the bees. He found that bees consistently increased coffee yields by around 36 percent. In some cases they boosted production by more than 50 percent.

Roubik (3) believes bees improve coffee yield by increasing the amount of pollen placed on the stigma of each plant and increasing the genetic diversity of coffee crops.  UN data on coffee yields worldwide, and on the introduction or elimination of honeybees from different regions, backs his conclusions, Roubik says.

Coffee ripens on a bush. NRCS photo.

Taylor Ricketts of Stanford University’s Center for Conservation Biology says …

To me perhaps the best approach is to understand what roles native bees play in local agriculture and try to conserve a diversity of them in the landscape, so that agriculture is not dependent on a single species of introduced bee, or on a managed pollinator industry.”

In the Philippines there is such a small beekeeping industry that it does not affect significantly the national pollination environment for crops like coffee.  In addition ongoing uncontrolled destructive honey hunting is removing the key Putyokan and Ligwan pollinators, and coffee yields are also suffering.  There are other factors to be considered in assessing yields, but coffee could be considered one of the ‘indicator crops’ for insufficient bee pollination. Philippine coffee production has been declining and there is an 80% gap with Vietnam for coffee yields. (Vietnam also notably has a good pollinator environment and produces 300 times more honey than the Philippines.)

Coffee yields in Philippines

Repeatedly there is also clear evidence from separate studies in other coffee growing countries (5) that considering the ‘pollination environment’ is necessary if good coffee yields are wanted, yet the Philippine Department of Agriculture has no mention of this in their websites.  Since it will take time to build a significant beekeeping sector, it will be important to consider the status of the native pollinators.  Thinking now and acting as soon as possible to improve awareness of the issues and to bring about ‘honey gathering’ rather than ‘honey hunting’ in rural communities could then have widespread benefits for the 500,000 coffee farmers (as well as millions of other farmers dependant on the many other crops associated with bee pollination).

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References …

1) The value of bees for crop pollination
Food and Agriculture Organisation

2) Pollination ‘merely’ one production factor

3) Honeybees boost coffee yields

4) International Coffee Organization

5) Best management practices in Agriculture for sustainable use and conservation of pollinators
Sao Paulo University, Brazil – study on stingless bees

6) Pollination of cultivated plants in the tropics
Edited by David W. Roubik
Food and Agriculture Organization: Bulletin 118 Pub: FAO 1995 194 pages

7) Bee pollination and fruit set of Coffea arabica and C. canephora

One Response to Coffee yields

  1. KASIM ROBAA says:

    thank you very much for this forgotten science by many scientists for important science for the woorld which the back bone for plants m pollination we need to keep bees not only for their products but for their product increament through pollination

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