The Scent of the Fly

Area of Science:

• Chemical Ecology
• Animal Behavior
• Sensory Science

Background:

• The vinegar fly, Drosophila melanogaster, uses the volatile pheromone (Z)-4-undecenal (Z4-11Al) for species-specific communication and mate-finding.
• Only female D. melanogaster produce Z4-11Al, making scent a reliable indicator of sex.

Purpose of the Study:

• To investigate the human perception of synthetic (Z)-4-undecenal.
• To determine the concentration threshold for human detection of Z4-11Al.
• To explain the spoilage of wine by D. melanogaster through Z4-11Al.

Main Methods:

• A sensory panel evaluated the odor and flavor of synthetic Z4-11Al.
• Detection thresholds for Z4-11Al in a wine matrix were determined.
• The contribution of Z4-11Al to wine spoilage by D. melanogaster was assessed.

Main Results:

• Synthetic Z4-11Al possesses a distinct flavor detectable by humans at low concentrations (1 ng in a glass of wine).
• A tenfold increase in concentration resulted in a strong off-flavor.
• The presence of a single D. melanogaster fly in wine significantly alters its flavor due to Z4-11Al release.

Conclusions:

• Human olfactory perception readily detects the D. melanogaster pheromone Z4-11Al.
• Z4-11Al is responsible for the off-flavor associated with D. melanogaster contamination in beverages like wine.
• The biological significance of Z4-11Al and similar aldehydes in human olfaction remains an open question.