Flowers' fragrance diminished by air pollution, study indicates

Air pollution from power plants and automobiles is destroying the fragrance of flowers and thereby inhibiting the ability of pollinating insects to follow scent trails to their source, a new University of Virginia study indicates. This could partially explain why wild populations of some pollinators, particularly bees – which need nectar for food – are declining in several areas of the world, including California and the Netherlands.

The study appears online in the journal Atmospheric Environment.

"The scent molecules produced by flowers in a less polluted environment, such as in the 1800s, could travel for roughly 1,000 to 1,200 meters; but in today's polluted environment downwind of major cites, they may travel only 200 to 300 meters," said Jose D. Fuentes, a professor of environmental sciences at the University of Virginia and a co-author of the study. "This makes it increasingly difficult for pollinators to locate the flowers."

The result, potentially, is a vicious cycle where pollinators struggle to find enough food to sustain their populations, and populations of flowering plants, in turn, do not get pollinated sufficiently to proliferate and diversify.

Other studies, as well as the actual experience of farmers, have shown that populations of bees, particularly bumblebees, and butterflies have declined greatly in recent years. Fuentes and his team of U.Va. researchers, including Quinn McFrederick and James Kathilankal, believe that air pollution, especially during the peak period of summer, may be a factor.

To investigate this, they created a mathematical model of how the scents of flowers travel with the wind. The scent molecules produced by flowers are very volatile and they quickly bond with pollutants such as ozone, hydroxyl and nitrate radicals, which destroy the aromas they produce. This means that instead of traveling intact for long distances with the wind, the scents are chemically altered and the flowers, in a sense, no longer smell like flowers. This forces pollinators to search farther and longer and possibly to rely more on sight and less on smell.

The scientists calculated scent levels and distances that scents can travel under different conditions, from relatively unpolluted pre-industrial revolution levels, to the conditions now existing in rural areas downwind from large cities.

"It quickly became apparent that air pollution destroys the aroma of flowers, by as much as 90 percent from periods before automobiles and heavy industry," Fuentes said. "And the more air pollution there is in a region, the greater the destruction of the flower scents."

Source: University of Virginia

Related stories:

Memory in honeybees: What the right and left antenna tell the left and right brain
It is widely known that the right and left hemispheres of the brain perform different tasks. Lesions to the left hemisphere typically bring impairments in language production and comprehension, while lesions to the right hemisphere give rise to deficits in the visual-spatial perception, such as the inability to recognize familiar faces.
Sky's the limit for bee brain power
Families flocked to see the latest animated hit Bee Movie, but scientists from UQ's Queensland Brain Institute (QBI) have long embraced the bee for very different reasons.
Cold conspirators: Ice crystals implicated in Arctic pollution
Frost flowers. Diamond dust. Hoarfrost. These poetically named ice crystal forms are part of the stark beauty of the Arctic. But they also play a role in its pollution, a new study by scientists at the University of Michigan, the Cold Regions Research & Engineering Laboratory and the University of Alaska has found.
Probing Question: Why are flowers beautiful?
In the 1930s, American artist Georgia O'Keefe wrote: "What is my experience of the flower if it is not color?" O'Keefe is best known for her vibrantly colorful close-ups of petals and stamens on large canvases.
Fast learning bumblebees reap greater nectar rewards
The speed with which bees learn affects their ability to collect food from flowers, according to a new study from Queen Mary, University of London.
Neuronal circuits able to rewire on the fly to sharpen senses
Researchers from the Center for the Neural Basis of Cognition (CNBC), a joint project of Carnegie Mellon University and the University of Pittsburgh, have for the first time described a mechanism called “dynamic connectivity,” in which neuronal circuits are rewired “on the fly” allowing stimuli to be more keenly sensed. The process is described in a paper in the January 2008 issue of Nature Neuroscience.
Size and positioning of floral anthers facilitates
Unlike moths and butterflies that are often brilliantly colored to warn potential predators that they carry toxins, flowers and the fruits they produce have brilliant colors and unusual shapes because they want to attract the attention of pollinators and frugivores who will disperse their pollen and seed, thus guaranteeing the next generation.
Researchers demonstrate way to control tree height
Forest scientists at Oregon State University have used genetic modification to successfully manipulate the growth in height of trees, showing that it’s possible to create miniature trees that look similar to normal trees – but after several years of growth may range anywhere from 50 feet tall to a few inches.

News discussion:

Space & Earth science news