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BATS
AND THE VANILLA ORCHID |
Like bats, orchids live all over the world with the exception of Antarctica and some islands. Like bats, the majority of orchids are found in the tropics.
The Britannica Concise Encyclopedia states that there are 400 to 800 Orchidaceae genera and 15,000 to 35,000 species of orchids.(3)P.F. Hunt in Plants of the World writes that: "Bees, wasps, flies, ants, beetles, hummingbirds, bats and frogs have all been observed as the pollinating agents of orchids . . " (7)
The Vanilla genus consists of 110 species, according to Wikipedia.(9) Hamilton says there are about 60 Vanilla species and four species are cultivated commercially for vanilla beans. Vanilla planifolia is the most important commercial species.(5)
The known pollinator of V. planifolia in its native Mexico and Central America is a melipone bee.
The New York Botanic Gardens Bat-Plant Database lists Dobat and Peikert-Holle as citing evidence that the Jamaican fruit eating bat (Artibeus jamaicensis) and the long-tongued nectar bat (Glossophaga soricina) pollinate the flowers of Vanilla chamissonis, variety longifolia.(8)
V. chamissonis is not identified by Hamilton as a cultivated vanilla species.
Arenas received information that in Costa Rica an unidentified bat was observed eating the vanilla bean of a cultivated plant, Vanilla pompona. (1)
V. pompona is grown in plantations and is utilized as a source of commercial vanilla.
Jamaican fruit bat (Artibeus jamaicensis)
Photograph by Pam Thomas, Lubee Bat Conservancy
Vanilla planifolia, the species of choice for commercial vanilla, originally grew in Mexico and Central America. Now it is cultivated in plantations in Madagascar, Indonesia, Papua New Guinea, Uganda, Costa Rica, Columbia, the Comoro and Reunion Islands.
Away from Mexico, Central America and melipone bees, hand pollination of vanilla orchid flowers is required. The fruit ripens unevenly, has to be inspected daily and picked as it ripens. Those tasks along with other processing steps combine to make vanilla one of the world's most labour-intensive and expensive crops. It is therefore a source of jobs for many human beings and wealth for some human beings.
Arenas considers V. planifolia as an endangered species. He believes that there may only be 30 plants growing in the wild. The wild plant is the victim of habitat destruction. It is attempting to survive in disconnected, patchy habitat remnants. It may have been over-collected. (1)
Divakaran et al. state that the wild plant may be threated by loss of habitat and that other species of wild vanilla are considered rare and endangered thus necessitating the need to conserve them by sophisticated scientific procedures. (10)
The complexity of the plant's growth pattern and its commercial existence in vast monocultures where there is little or no genetic diversity make it subject to all the perils that attend monocultures. Should there be a vast die off of plantation plants, the existence of a healthy wild plant population, serviced in part by bats, could be a gene bank for commercial plantation rehabilitation.
Growing habit of the Vanilla orchid
Hamilton says that the Totonac Indians of east-central Mexico are devoted to the cultivation of V. planifolia around their homes. Perhaps the Totonac Indians will help to save V. planifolia from extinction. Perhaps an unidentified bat species in Costa Rica will help to preserve V. pompona plants in the wild. Perhaps there are unidentified species of bats that are providing the same life-saving pollination and seed-planting services for wild V. planifolia and other vanilla orchids.
See: Pain, Stephanie, In a chocolate garden, NewScientist, 29 November 2008, page 48. This article describes the efforts that have been made to determine the origin of V. tahitensis which is cultivated in French Polynesia. DNA studies have revealed that it is a hybrid of V. planifolia and V. odorata. It may have hybridised in the chocolate-vanilla gardens of Guatemala and then travelled to the Philippines and to French Polynesia.
(See: "Blight Hits World's Vanilla, NewScientist, 20/27 December 2008, page 6. An unidentified fungal disease is affecting the majority of vanilla plantations in Madagascar, source of most of the world's vanilla and source of income for poor farmers. Lack of genetic diversity, (as with bananas) makes the plant very vulnerable to disease.
