BATS AND DURIANS

BATS, DURIANS, ICE CREAM and UNWASHED SOCKS

I am having difficulty writing a description of the durian tree and its fruit.

START WITH SOMETHING EASY. WHERE DOES THE DURIAN TREE GROW?

Mainly in southeast Asia. It may have first grown in Borneo and Sumatra. Now it grows from southeast India and Ceylon to New Guinea. The big commercial producers in southeast Asia are in Thailand, Malaysia and south Vietnam.(1)

IS THE DURIAN FRUIT AN IMPORTANT PRODUCT IN THOSE COUNTRIES?

Immensely important. It is the most important local fruit in the countries where it grows. The durian has royal ranking. It is known as "The King of Fruits."

IF THE DURIAN IS A REGAL FRUIT, IT MUST BE VERY DELICIOUS. CORRECT?

That is one of the durian fruit puzzles. Yes, it is said to be very delicious. But take a look at the words used to describe its taste and smell. It is a mixture of:

MY GOODNESS! SO FAR, THE PROSPECT OF DIGGING INTO A DURIAN FRUIT IS NOT ENTICING.

HERE'S ANOTHER EASY QUESTION: WHAT IS THE BAT CONNECTION WITH THIS PECULIAR FRUIT?

The nectar-filled flowers of the durian tree bloom at night and are open for only one night. The flowers have a very strong fragrance which attracts the dawn bat and other species of fruit bats including the Malaysian flying fox.(2,3,4) Although a few species of durian can pollinate themselves,cross-pollination of durian flowers is generally considered to be essential for a good harvest of durian fruit.(1)

WHO CARES ABOUT A GOOD CROP OF FRUIT THAT SMELLS LIKE UNWASHED SOCKS, EVEN IF IT DOES TASTE LIKE ICE CREAM?

Millions of people who live in southeast Asia and many travellers to those countries. Some people make southeast Asia their destination just to have the durian fruit eating experience.

One non-human animal that has a passion for durian fruit is the orang-utan. Mainly a vegetarian, the orang-utan is said to eat various parts of some 400 kinds of plants. When the durians are ripe, orang-utans establish one of their base camps in the vicinity of the fruiting tree to take advantage of its succulent offerings. (5)

REALLY. HMMM, THEN IT MUST BE A BIT LIKE THE FRUIT OF THE STINKING TOE TREE IN SOUTH AMERICA.

Yes, apparently the taste is so good you can block out the complaining messages from your nose.

IN THAT CASE, THE DURIAN FRUIT MUST BE A BIG MONEY MAKER AND SOURCE OF JOBS FOR LOCAL PEOPLE.

Some durian trees are owned by individuals. If the trees are one of the top durian species in demand and are old enough to produce one or two hundred fruits, the owner of those trees possesses a major financial asset.

A French traveller in l687 described the cultivation of durian trees. Even then the great value of the trees and their fruit was recognized. A person who had the good fortune to own a durian tree or trees had to pay a tax on them to the government. If a tree died, the owner was obligated to plant another tree so the government would not be deprived of income.(6)

The majority of producing trees grow on plantations. The harvesting is done by local employees who construct grass huts near the trees and live there for six to eight weeks so they can collect each fruit when it drops.(1)

This work has hazards. The workers have to use caution. A durian fruit can be 12 inches long and weigh up to 18 pounds (over a stone or about 8 kilograms).(1) Besides being heavy it has a thick rind armed with very sharp thorns. The Indonesian word for thorn is "duro". The word "durian" means thorny. A falling durian can inflict a grievious wound on human skin and flesh.

I GET IT: BIG HEAVY FRUIT AND SHARP THORNS. IN OTHER WORDS, DO NOT SIT UNDER A DURIAN TREE.

Not when the fruits are ripening. To protect the fruit from damage some plantations have workers tie the ripening durians to the trees with cords in a pulley system. When the durian drops, it stops short of hitting the ground. Nets are placed under durian trees for the same reason. (7)

Workers on durian fruit plantations face another hazard, the greatly increased use of pesticides. Consumers who pay quite a bit for a durian fruit want an unblemished fruit. The workers who apply the pesticides are at risk during the application, and so is the land and people living nearby. Only 4 percent of the insecticide applied reaches the insect culprits, according to WHO statistics. The rest goes into the soil and is dispersed elsewhere by the wind.(8)

It varies between locations and among different kinds of durians. In Ceylon the flowers bloom in March and April and the harvest is in July and August. There are two durian harvests in Malaysia; March and April, September and October.(1)

SO THE DURIAN DEPENDS ON BATS FOR POLLINATION BUT THE BATS CAN'T DEPEND ON THE DURIAN FOR A YEAR-ROUND SOURCE OF NECTAR.

That's right. In fact, one of the best known of the commercial durian-pollinators, the dawn bat or cave bat (Eonycteris spelaea), makes seasonal treks between the flowering mangroves on the southeast Asian coasts to the inland stands of durian trees. One of the bats' major sources of nectar and pollen is a genus of mangrove, Sonneratia, which blooms most of the year. When the durian blooms inland, then dawn bats add durian nectar to their diet.(9)

It seems that the Sonneratia mangroves and the commercial durians of Penninsular Malaysia are both reliant for cross-fertilization in large part on the long distance journeys of the dawn bat. The dawn bat can make a journey of up to 100 kilometres(about 60 miles)between the food sources.

Although one species of durian, Durio zibethinus, and its varieties, are the source of commercial durians, Julia Morton says that there are 28 species of durians in Malaysia, but of those only five bear fruit known to be edible. One species which bears edible fruit is Durio kutejensis. Another edible species is D. grandiflorus. (1)

Takakazu Yumoto studied the pollination of three species of wild durians, including Durio kutejensis and D. grandiflorus. Yumoto discovered that two of the three durian species, including D. grandiflorus, were pollinated by the spiderhunter bird. The third species, D. kutejensis, was pollinated by bees, birds and the dawn bat.(10) It would appear from that study that bats have much needed assistance from birds and insects in assuring the existence of edible wild durians, the highly valued reservoirs of genetic diversity.

MANY BAT-TREES HAVE MEDICAL, RELIGIOUS, SPIRITUAL AND HISTORICAL SIGNIFICANCE. WHAT ABOUT THE DURIAN?

The general lack of other uses is one reason why I find the durian an unusual member of the bat-plant family.

Durian wood is considered inferior, good only for cheap furniture. It rots quickly and is readily attacked by termites and beetles.(11)

Leaves and roots of the durian tree have been used to treat fevers, jaundice and swellings, but the tree is an inferior physician compared to other bat-trees such as the neem, sausage and shea trees.(1)

The durian tree apparently has no recorded spiritual or religious significance. It is not known to be part of ceremonies attached to birth, marriage and death as are the mango and neem trees. Unlike the sausage tree, the durian tree is not recorded as controlling whirlwinds or evil spirits or being used to diagnose diseases. Compared to the fig and carob trees, it does not have a well-known ancient history.

SO THE GREAT VALUE OF THIS TREE SEEMS TO REST ALMOST ENTIRELY ON THE GUSTATORY ATTRACTION OF ITS STRANGE FRUIT AND ITS SEASONAL ECONOMIC VALUE.

Attempts are also being made to satisfy demands for the fruit in other parts of the world. If you are the eager customer, have substantial cash in yout hand. In April 2004 a fresh durian in a San Francisco market cost $4.99 a pound (about £2.50), about $30 (about £15)for a 6 pound fruit.(12) Durians can be very expensive as well closer to where they grow in southeast Asia. And yet, for all that money, the edible fruit pulp only accounts for 15 to 25 percent of the durian's total weight. You are paying a lot for big seeds and a very thick rind.

The durian flesh is canned in syrup or made into blocks of paste or frozen for export. However, any durian addict will tell you that those products will not provide you with the supremely unique experience of eating a fresh durian.

I SIMPLY HAVE TO TRY THIS FRUIT, FRESH. YOU KNOW SOMETHING? WHEN I GO ON MY MANGROVE SWAMP EXPLORATION I'M GOING TO MALAYSIA AND TIME IT FOR THE RIPE DURIAN SEASON.

Like the pollinating dawn bats, you will have a bit of a journey from the mangroves to the durians. Durians have no tolerance for salt and do not live close to the sea. But as long as you're in the vicinity you might as well follow the oft-quoted advice of the great explorer-scientist, Alfred Wallace Russell, who explored the Malaysian Archipelago between 1854 and 1862. He said, " . . . to eat durians is a new sensation worth a voyage to the East to experience." (13)

(2)Fujita, M.S. 1991. Flying Fox (Chiroptera:Pteropodidae) Pollination, Seed Dispersal, and Economic Importance: A Tabular Summary of Current Knowledge, Resource Publication No. 2, Bat Conservation International

(3)Heinrichs, Scott, Besieged Bats of Mentawai, BATS Magazine, Bat Conservation International, Volume 23, Number 3, Fall 2005, page 14

(5)van Oosterzee, Penny, Where Worlds Collide, The Wallace Line,Cornell University Press, 1997

(9)Hogarth, Peter J., The Biology of Mangroves, Oxford University Press, 1999

(10)Yumoto, Takakazu, Bird-pollination of three Durio species (Bombacaceae) in a tropical rainforest in Sarawak, Malaysia, American Journal of Botany, 87:1181-1188, 2000 http://www.amjbot.org/cgi/content/abstract/87/8/1181

(13 )Wallace, Alfred Russell, The Malay Archipelago:The Land of the Orang-utan and the bird of paradise, Macmillan, London, 1869.