Researchers from the Department of Biology at the University of Oregon, Eugene, have come up with an innovative use of 3D printing to study the biology of flower mimicry.
One of their models was the “Dracula Orchid” (Dracula effleurii). Despite its vampiric name, the flower is not carnivorous. They attract flies as pollinators, not food. Dracula here means “little dragon,” referring to their appearance.
Bitty Roy, the principle investigator on the study, described the pollination process: "What the orchid wants the fly to do when it arrives is to crawl into the column, whereupon the orchid sticks a pollinium (mass of pollen) onto the fly so that the fly can't possibly get it off. The fly then goes to another orchid, which then pulls it off."
The researchers travelled to Ecuador, South America, to study the orchids and their fly pollinators in the wild.
Roy also put the study into a larger evolutionary and ecological context: "Mimicry is one of the best examples of natural selection that we have," she said. "How mimicry evolves is a big question in evolutionary biology. In this case, there are about 150 species of these orchids. How are they pollinated? What sorts of connections are there? It's a case where these orchids plug into an entire endangered system. This work was done in the last unlogged watershed in western Ecuador, where cloud forests are disappearing at an alarming rate."
Roy and her research team wanted to know whether the different visual parts of the flower, its scent, or a combination of both, were responsible for attracting the flies. They presented their results in a paper published last month in The New Phytologist.
"Dracula orchids look and smell like mushrooms. We wanted to understand what it is about the flowers that is attractive to these mushroom-visiting flies," said Tobias Policha, the lead author of the paper.
The researchers designed their study to separate out the different parts of the flower: the triangular outer part (the calyx) and the inner pouch-shaped part (the labellum).
From upper left, counter-clockwise: completely artificial flower, completely real flower; real calyx, artificial labellum; artificial calyx, real labellum. Photo credit: Aleah Davis
To manufacture the artificial flowers, the team collaborated with Melinda Barnadas, co-owner of Magpie Studios, an arts studio expert in creating scientific art and models for museums.
The process to make the artificial flowers had several steps: casting the real flowers in impression molds, making a positive plaster cast of the molds, digitally scanning the cast, then 3D printing the files using a Zcorp Spectrum 510 printer. Finally the 3D-printed molds served to cast the flowers from medical grade, scentless silicon. The color was done using dye encapsulated in silicon, so the flies couldn’t smell it.
Real flower, on left, and a series of artificial flowers, created from 3D printed molds, in decreasing order of fly attractiveness. Image from research paper.
As a result of this study the researchers found that the flies were most attracted to the scented labellum. They hope their idea will be used in other studies where genetically modifiable models are not available.
Quotes from researchers pulled from the press release at EurekaAlert!