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January 25, 2013

The pollinators of the Southeast Asian wild orchids are largely unknown. Knowing what they are is essential for successful re-introduction into secondary forests. Without the pollinator, the orchid is genetically dead, incapable of reproduction.

Yesterday when I frequently ran in and out of the orchid nursery to plant our latest orchid donation by Orchid Garden Khaolak, I suddenly saw a fly on a flower labeled Bulbophyllum lasiochilum (Orchidaceae). We had seen the fly before when a member of the Barcelona Orchid Society was here. A second encounter strengthens the hypothesis this is in fact a pollinator, although I have not seen any fruits.

Bulbophyllum lasiochilum.pollinator.Jan24.2013.72The purpose of any flower is reproduction, to make a fruit with seeds. Less conspicuous flowers such as those of pine trees or grasses are pollinated by the wind. White and fragrant flowers often offer nectar to moths, and colourful flowers often attract insects or birds flying around in daytime. In the case of orchids, they lure insects, not necessarily with nectar, but shapes and fragrances resembling females, food or enemy insects. When the insect flies between orchid flowers to have sex, feed or kill the flowers, it transfers the male pollinia to female stigmata without knowing what is going on.

Bulbophyllum lasiochilum pollinator 2.72

This picture shows the insect in more detail. It is a fly (Diptera) in the fruitfly family Tephritidae. The genus is Bactrocera sp. (500 species). In my nose the flower emits a sweet fragrance containing cloves or cinnamon oil, Ketsanee describes the fragrance as ‘banana and butter’, visiting Australian guests described it as sweet and fruity, a visiting American guest described the fragrance as ‘strawberry jam’. In conclusion the fragrance is indeed fruity so it is not surprising fruitflies are attracted. However, it is hard to connect the shape of the flower with fruitflies, and I am open to clarifying suggestions.

A quick search on internet reveals the same fly genus has been observed on the same orchid species in India, and Malaysian orchidologist Ong Poh Teck has also reported Bactrocera from Bulbophyllum lasiochilum. You can read more about his research on orchid pollination in Southeast Asian orchids:

If this is the pollinator, why is there no fruit? The orchid was labelled Bulbophyllum lasiochilum when it was donated to the Orchid Ark. When I took the picture of the fly, I also had a closer look at the magnified flower. This specimen has striped side petals and a striped dorsal sepal, not spotted as in the wild form. According to Ong Poh Teck hybrid bulbophyllums are common garden ornamentals in Thailand, and so we conclude the lack of fruits and peculiar morphology hints that this might be a sterile hybrid, and so unsuitable for restoration work. However, we believe it serves a pedagogic function, showing the difficulties in using nursery clones for restoration projects. They can be wrongly labeled and even sterile hybrids. Passing a law on a salvation picking permit, enabling devoted orchid conservationists to use wild orchids which have fallen down from trees, would be much more beneficial. Today, saving epiphytic orchids from certain death on the ground is illegal.

Text & Photo: Eric Danell

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