Hawk moths have a second nose for evaluating flowers
Flowers without scent produce fewer seeds, although they are visited as often by pollinators as are flowers that do emit a scent. Scientists from the Max Planck Institute for Chemical Ecology in Jena, Germany, made this surprising observation, when they studied tobacco plants that have been silenced in their ability to produce floral volatiles. The researchers showed that floral scent is crucial for successful pollination: Manduca sexta hawk moths, the most important pollinators of the wild tobacco species Nicotiana attenuata, use their proboscis to smell the floral volatiles when they visit flowers. The olfactory neurons involved in the perception of these volatiles have now been discovered to be located on the Manduca proboscis. Only when flowers produced volatiles did the moths stay long enough to drink nectar, and only when they stayed long enough did they deliver enough pollen on their proboscis to successfully pollinate other scenting flowers. These results...