scientists Max Planck Institute for Chemical Ecology in Jena (Germany) have settled a fraud case pending for 40 million years. Arum plant palaestinum , also known as 'Black Creek', attracts fruit fly infestation (fruit flies) to act as pollinators and emit odorous molecules that resemble those produced during alcoholic fermentation of rotting fruit.
"The plant gets to imitate the yeast producing six compounds chemicals that, united in a specific mix, create the impression of fermentation in the fly brain, "say the researchers from the Max Planck Institute for Chemical Ecology. Among the volatiles produced two compounds are very rare in plants but which are characteristic of the wine and vinegar (in fact, products of yeast activity).
Scientists have shown that the smell of the creek has its target in a highly conserved neuronal path tailored specifically to the smell of yeast. Thus, Black Creek operates a drive of millions of years of flies in their own benefit.
Flytrap Plants
Gender Drosophila (fruit flies) consists of many species that feed on various substances ranging from fruit to the layers of bacteria of certain species of tropical land crabs. For most of the Drosophila, yeast are their main food. Their antennae and antennal lobes, the first region of the brain that receives information from olfactory sensory neurons are specialized to perceive therefore that typically emit odorous molecules in yeast growth. The smallest concentrations are sufficient to drive the fruit flies to their food source.
Many flowering plants depend on insect pollinators, they ensure the formation of seeds and ensure genetic variability. Using colorful flower petals and smells to attract them. Although often the pollination service is rewarded with a sweet nectar, Arum palaestinum tricks their pollinators. The plant, also known as Black Creek, emits an odor in their dark violet flowers, to the human nose is very similar to a fruity wine.
clear that the plant was attracted to the smell of pollinators, fruit flies. But unlike most flowers, Arum palaestinum not offer a reward in the form of nectar, in fact, flies are trapped in the flower at night and can not escape until the next day.
Drosophila melanogaster also falls on deception
Stoklos and Marcus Johannes Stensmyr have analyzed this odor and have also examined and identified the species of Drosophila trapped in the plant. Together with Markus Knaden ethologist, studied the reactions of insects to different odorant molecules. In addition, their partners Silke Sachse and Antonia Strutz neurophysiological measurements have been made in flies.
The study has provided interesting results: Arum palaestinum attracts an average of 140 flies per plant, especially individuals from eight different species of Drosophila , including the famous Drosophila melanogaster, model experiments in the laboratories and nuisance in kitchens. The plant produced 14 chemical compounds that made the antennas of the flies respond.
To test these reactions, Johannes Stoklos measured and recorded action potentials of the antennae of insects. The chemical analysis of odorous compounds released by plants showed that most were esters.
"The most notable of all odors were acetate 2.3-butanediol and acetyl methyl carbinol acetate, "says Marcus Stensmyr, director of the study. Interestingly, these molecules are not part of the scent of flowering plants, but which are characteristic of vinegar, aceto balsamico especially , and wine (or, in other words: products of yeast fermentation).
These two compounds, as well as four others that also appear during the fermentation of yeast, generated the strongest signals in the electroantennogram stable.
Two receivers, a fraud
In experiments Neurophysiological, the team exposed the flies to various natural flavors such as peaches and smells of rotten bananas and the Lambrusco (red wine) and aceto balsamico (vinegar). The corresponding electroantennogram bore a striking resemblance to the records of flies that had been exposed to the odor of the plant, indicating that these aromas have an odor "strikingly similar" to a fly.
"The flies are unable to distinguish the rotten fruit Creek, the creek cheated because it mimics the smell of yeast but not yeast as food offered," says Johannes Stoklos. The inadvertent pollination service insects is not even rewarded, in fact, the opposite happens: the flies are trapped in the flower until it is reopened after 24 hours, and still hungry.
Using transgenic flies expressing an indicator of calcium-sensitive activity, Silke Sachse, director of the Functional Imaging Group, and his PhD student Antonia Strutz were able to monitor the activity of the stimulating smell of yeast in brains of flies.
This functional imaging technology helped to demonstrate that activated 11 different olfactory receptors. Since the Black Creek deceived different species of Drosophila, it seemed likely that olfactory receptors ancient conserved during evolution were among those that were activated, and it turned out it was.
"The sequence of two olfactory receptor, namely the Or42b and Or92a is highly conserved. It is likely that these genes have a crucial role as 'yeast detectors' in most of the fruit fly Drosophila, or even at all, "says Bill Hansson, director of the institute.
Asked if the black Creek is the ultimate solution to get rid of flies in the kitchen, Stensmyr Marcus says: "Given that only bloom once a year, and only for a few hours a cup of vinegar is still the best option. However, during the hours when it blooms, I can assure you that there is not a fly in your kitchen. "
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