Large cardamom blooms

If you are finding it difficult to replenish your cardamom stock, you may blame the honeybee for it. For while the insects are supposed to aid pollination, researchers have now found that they lead to low cardamom yields in the eastern Himalayan region.

Scientists from Bangalore’s Ashoka Trust of Research in Ecology and the Environment (Atree) have found that maintaining colonies of Apis cerena F, a local honeybee species, is actually working against the interests of farmers as the insect is a pollen robber.

As a result, crops of large cardamom (Amomum subulatum) — extensively cultivated as a cash crop in Sikkim, Nepal and Bhutan — are in dire straits with nearly 70 per cent of the flowers remaining un-pollinated.

According to K.R. Shivanna, who led the study, another reason for the poor yield is the dwindling population of bumblebees, a wild bee variety and the sole pollinator for the large cardamom.

The scientists observed that large cardamom flowers were visited by only two insects — honeybees and bumblebees. “The bumblebee is the effective pollinator while the other is a pollen robber,” Shivanna told KnowHow. The findings were reported recently in Current Science.

Although pollination may appear to happen by accident, plants and pollinators have been ensuring for millions of years that this “accident” takes place. Often a plant and its pollinator co-evolve — each adapting to the changes in the other — to improve their own chances of survival.

Cardamom flowers have their petals and labellum (yellowish lip of the bloom) fused to form a nectar tube, which lies at the base of the ovary. This is accessible to only those insects with a large proboscis (sucking organ). The bumblebee, being larger than the honeybee, is able to push the anther-stigma column to enter the nectar tube. This makes a few pollen grains adhere to its body, so that when it enters another flower, pollination occurs. Honeybees, being smaller and with a small proboscis, fail to reach the nectar. As a result, they keep visiting the same flowers again and again, reducing the pollen availability, explains Shivanna.

“The farmers failed to realise that it’s the wild species that brings about pollination. There is, however, no appropriate technology to rear bumblebees. The only way to maintain their population is to keep the wilderness intact,” he says.

With reduced pollination efficiency and fungal infestation plaguing plantations, the going seems tough for large cardamom planters in the eastern Himalayas.