Seed-Eating Fly Threatening Endangered Japanese Orchids

This photo shows the Golden Orchid blooms (left) and J. tokunagai fly on the flower. (Takuto Shitara)

(CN) – Japan’s already-endangered orchid populations faces a new threat from a type of seed-eating fly, according to a new study.

There are thousands of varieties of the highly coveted and colorful orchids, some of the most diverse flowers on the planet.

In Japan, more than 70 percent of native orchids are endangered due to a number of factors like overharvesting and development.

While the endangered plants can be reproduced through cloning, scientists say reproduction through seeds is better for genetic diversity.

If the plants can’t reproduce with their seeds they face even bigger threats, scientists believe.

A new study by a team of Japanese researchers identified a type of fly that feeds on orchid seeds in five varieties of the flower. Their findings were published in the journal Ecology.

The fly, Japanagromyza tokunagai, lays its eggs inside the young fruit of blooming orchids. When they hatch, the flies make a hole in the fruit.

At a glance this fruit looks healthy, but it has been infested by the seed-eating fly J. tokunagai. The brown area indicated by the arrow is fly pupae. When the fruit is dissected, we can see that there are no seeds left. (Kobe University)

Because the orchid fruit grows to the same size as fruit without the flies, scientists may have underestimated the damage those flies have on seed production.

The team looked at five species of orchids they artificially pollinated, covering some with bags and leaving others uncovered.

They found that the fly’s damage to the orchids reduced seed production by more than 95 percent.

But further study is needed, they say.

“Going forward, we want to shed more light on the damage caused by J. tokunagai,” said Kenji Suetsugu from Kobe University Graduate School of Science.

“We plan to do this by quantifying the damage in other areas of Japan, and by testing the theory that J. tokunagai is a non-native species through genetic analysis.”

The non-native species theory is part of the reason the team believes the damage caused by the flies has worsened over the years. If the fly is indeed non-native, it may not have natural predators.

Fragmentation of orchid populations could also be a factor, the scientists concluded.

Team members also included Shigeki Fukushima from the Chiba Prefectural Agriculture and Forestry Research Center and Masahiro Sueyoshi of the Forestry and Forest Products Research Institute.

In 19th century England, wealthy orchid enthusiasts sent explorers all over the world looking for new varieties of the flower, in a sort of madness that was dubbed “orchidelirium.”

Collecting wild orchards has been banned since 1973 by the Convention of International Trade in Endangered Species of Wild Fauna and Flora.

“Generally speaking, orchids seem to drive people crazy,” wrote Susan Orlean in her 1995 piece for The New Yorker titled “Orchid Fever.”

“The people who love orchids love them madly, but the passion for orchids is not necessarily a passion for beauty. Something about the form of an orchid makes it seem almost more like a creature than a flower.”


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