Bombykol, the sex pheromone emitted by female Bombyx mori silkmoths, travels in an odor plume. When a male encounters such a plume, bombykol molecules waft through his feathery antennae, entering pores in some 17,000 hairlike sex-pheromone sensors on each antenna. That attracts the males and enables them to identify a mating partner by her “scent.” But until now it was not clear at what level in the male nervous system the behavior-triggering recognition of an appropriate mate takes place. A new paper reports that the binding of the pheromone to a specific receptor protein in olfactory neurons is enough to elicit the full sequence of behaviors that culminate in mating.
To demonstrate this, Ryohei Kanzaki of the University of Tokyo and a team of nine scientists created a tansgenic silkmoth: a male B. mori carrying the sex pheromone receptor of another species, the diamond-back moth Plutella xylostella. When the researchers exposed transgenic B. mori males to the pheromone of a diamondback moth, the males responded as if they had found female silkmoths: they eagerly flapped their wings, approached the source of the odor—a piece of paper loaded with the diamondback pheromone—and attempted to copulate with the scent-laden piece of paper.
The results answer a long-standing question and also provide a strong foundation for the development of biosensors. A transgenic silkmoth could be used to detect any odor for which a receptor can be engineered, including volatiles in illicit substances, air pollutants, and contaminants in food and wine.(PLoS Genetics)