Persecuted fruit bat may be key to Durian’s survival in Asia

Durian has yet to take off as a major fruit in the West. This might be due to the smell, which as been described as “turpentine and onions, garnished with a gym sock“.

Despite this demand is booming for durian. And this means that management of durian orchards is becoming more pressured. Obviously there’s no fruit without pollination and durian has some unusual pollinators. Chiefly it seems to be pollinated by bats, along with spiderhunters (a bird) and giant honey bees. This is due to a rich nectar, which packs 869 calories per millilitre. To get a whole millilitre you’d need to visit just three flowers. That’s quite a food source and it’s not just attractive to cave bats and birds. It also attracts Pteropus hypomelanus, the flying fox, the biggest fruitbat in the world. What happens when a massive bat hits the durian trees? It’s been thought that it’s damage to the flowers, but a team of scientists have been investigating further.

Using camera traps, researchers collected video evidence showing the island flying fox (Pteropus hypomelanus) pollinating durian flowers, leading to the production of healthy durian fruit. Their study – Pollination by the locally endangered island flying fox (Pteropus hypomelanus) enhances fruit production of the economically important durian (Durio zibethinus) – has been published in the Journal of Ecology and Evolution.

The video footage was captured on Tioman Island by a team led by Dr Sheema Abdul Aziz as part of her PhD. Dr Sheema said: “These are very important findings because they shed more light on the crucial ecosystem services provided by flying foxes. Previously it was known that the smaller, nectar-feeding bats are pollinators for durian – but many people believed that flying foxes were too large and destructive to play such a role. Our study shows the exact opposite: that these giant fruit bats are actually very effective in pollinating durian trees.” The team was able to show this because there was vertical stratification in the feeding niches of flying foxes and nectar bats, with flying foxes feeding at greater heights in the trees.

This is critically important news for durian farmers as the island flying fox is already classified as ‘endangered’ on Malaysia’s National Red List.

Large fruit bats of the genus Pteropus are severely threatened by hunting and deforestation. They are often sold and eaten as exotic meat due to an unsubstantiated belief that consuming them can help cure asthma and other respiratory problems. They are also persecuted and killed as agricultural pests, as some people claim that the bats cause damage and economic loss by feeding on cultivated fruits.

Consequently, these factors have led to a severe decline in flying fox populations worldwide. This could be a problem for tropical plants in fragmented habitats, such as durian plantations isolated by deforestation.

Dr Ahimsa Campos-Arceiz, one of the coauthors of the study, said: “The durian is a fascinating plant that, with its flowers pollinated by bats and its seeds dispersed by large animals like elephants, beautifully exemplifies the importance of plant animal interactions. The durian fruit is particularly famous for its pungent smell and unique taste, adored by most people in Southeast Asia and so often misunderstood – abhorred? – by westerners. We hope this study brings attention to the urgency of conserving flying foxes in Southeast Asia.”

Source: AlphaGalileo