The Holy Trio of Jackfruit, Mango & Banana: What We Owe the Bats
Deeply misunderstood, and often vilified, bats play an important role in preserving our food systems.
During these lockdown evening walks, I have begun to pay more attention to the natural rhythms of time. At dusk, I turn my eyes upwards to a specific patch of sky, and every evening like clockwork, huge colonies of flying fox swarm past, leaving their roosts to go about their batty business. They are huge, like black kites, distinguishable only by the crescent shape of their wings. Closer home, I see butterfly-sized pipistrelles rapidly flying between the same few trees, just over my head, busy chomping close to a 1000 mosquitos per hour.
Bats make up almost 30 percent of all mammals in the world, and with an astounding 1411 known species. They are probably the best known mammalian pollinators. Pollination by bats, known as chiropterophily, is responsible for the pollination over 700 different types of plants. Out of these, an estimated 200 plants are of commercial importance — including the durian, mango, banana, guava, cocoa, avocado, cloves, figs, cashew, coconut, and agave. Several of these crops are economically important to India, which is why it’s alarming that the importance of bat conservation is seldom spoken about.
When I spoke to Rajesh Puttaswamaiah who founded the Bat Conservation Trust of India, he eloquently described bats as “birds of the night”. He explained that bats are important pollinators, and essential for seed dispersal and pest control. “They boost agricultural yield by feeding voraciously on pests.” A USGS study conducted in 2011, arrives at the same conclusion saying that: “Insect-eating bats provide pest-control services that save the U.S. agricultural industry over $3 billion per year.”
Bats help with pollination in many different ways. The banana for example, has co-evolved with bats over 50 millions years. This becomes obvious when you consider the banana’s unique characteristics: nocturnal flowering, a distinctive, strong odour, as well its abundant nectar and pollen. A wild banana fruit is filled with hard-shelled seed, and very little pulp. Bats feed on wild bananas and disperse their seeds. Although these seeds make it difficult for humans to eat the wild fruit, all commercially cultivated bananas in India and South Asia stem from these varieties.
As I studied mango pollination, I realised that bats play an important role here too, despite the tree itself being monoecious (ie, the flowers on any single tree are hermaphroditic). Typically, 75 percent of mango flowers are capable of self-pollinating, and only 25 percent of the flowers are male. However, the yield of a mango orchard significantly increases when trees are cross-pollinated, and this is done by a host of insects including ants, and predominantly, fruit bats. Bat-processed mango seeds have been found to have higher rates of germination. Larger species like flying foxes often travel up to 100 kilometres from their roosts to their feeding sites; they are strong enough to carry larger seeds, like that of the mango, and play an important role in seed dispersal.
Although the mango holds a special place in India, and the banana is the most commonly eaten fruit, there is a third which completes the troika — the jackfruit. In Tamil Nadu, this combination of banana, mango, and jackfruit, known as mukkani, has deep cultural significance. Especially around the celebration of traditional New Year, in the limbo days between a short spring and the onset of summer, the consumption of these fruit gains fervour. Sangam literature describes this in rapturous detail.
Jackfruit, also monoecious and not reliant on external methods of pollination, is commonly found in the forests of the Western Ghats, and is widely grown in Kerala and Tamil Nadu. Here again, bats help the propagation of jackfruit trees by acting as pest control. By feeding voraciously on shoot borers and bark-eating caterpillars, bats protect jackfruit trees and ensure yield is maintained.
In addition to commercially grown crops, bats play a significant role in the regeneration of forest ecosystems, especially rainforests, through seed dispersal. They contribute to pest control, and provide pollination services in forest ecosystems, fertilising the forest floor with their faecal droppings known as guano, rich in beneficial bacteria and fungi, as well as nitrogen, phosphorus, and calcium. Bat guano is also harvested around the world, from caves where bats roost, to be used as bio-fertiliser for agricultural fields.
Great Indian Fruit Bat (Flying Fox), Bhawani Das, circa 1778-82
Part of the reason why bats are so mysterious is that they are nocturnal, which makes it very difficult and very expensive to study them. Sixty-four Indian chiropterologists recently put out an open letter to debunk a lot of the myths and false information surrounding bats, with a solid call for conservation. This was after news that people were petitioning the Bangalore Municipal Corporation (BMC) to cut down trees where bats roost. In Mysuru, two trees were felled for this same reason. In Toothukudi, there were demands to remove all bats after ICMR showed the presence of coronavirus in a bat species in Tamil Nadu, Pondicherry, Kerala, and other states.
This fear and vilification stems solely from ignorance and a lack of understanding of the natural world. Research has repeatedly shown that bats are more active that birds when it comes to pollination, and a decrease in the number of bats can severely affect the propagation of plants. Unfortunately, bat population is already falling, thanks to a combination of factors – the rapid felling of trees, increase of light-pollution, and the use of pesticides in crops.
According to archaeological evidence, the jackfruit has been in cultivation for nearly 5000 years. The mango was domesticated nearly 4000 years ago, with references in both Sanskrit and Sangam literature. The banana was domesticated from its wild phenotype nearly 10,000 years ago. Mukkani is an indirect homage to the bat, which for over 10,000 years, has helped human maintain agricultural systems, despite zero acknowledgement.
I feel an odd fondness for these creatures who do so much to maintain the balance of our natural world, in spite of drawing so much ire. After centuries of misunderstanding, perhaps it is time to acknowledge what evolutionary marvels these amazing little creatures are, and to change that narrative.
Banner image credit: A.M. Ahad for Biographic
Akhila Vijayaraghavan is a trained molecular biologist and environmental consultant.
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