A syrphid fly (Eristalinus taeniops) pollinating a Common Hawkweed
Pollinators, such as bees, flies and wasps, depend on sensing the minute by steady stream of hydro-carbon molecules emitted by flowering plants to lead them to their target destination. There, the insects gather pollen (as a food source) and inadvertently transfer this genetic packet from the male anther to the female stigma, enabling fertilization (known as syngamy, the joining of germ cells).
This ancient, mutually beneficial arrangement insures each new generation of the flowering plant. It has probably been going since shortly after the first flowering plants (angiosperms) appeared on earth some 250 million years ago. Industrial air pollution is now hampering this ancient relationship.
In a 2008 study (McFrederick, Kathilan-kal, Fuentes, published in Atmospheric Environment) revealed that the molecular signal given off by flowering plants is destroyed (after its initial release) by air polluting chemicals, most notably, low level ozone (O3) which is known to also act as an atmosphere-warming aerosol.
The researchers show that the presence of these pollutants quickly modifies the scent stream released by the flowers, causing it to drop off a certain distance away from the plants. Under perfect conditions, such flower scents can be detected by insect several miles (or kilometers) away. But in areas with significant ozone pollution, for example, the pollinators experience a significant reduction in the distance that they can detect such scents. This has serious implications for such extended ecosystems that depend upon pollinators; bees and flies will have to cover more ground (or air space), and expend more energy, locating the tell-tale, hydrocarbon scent of a flower.
Bees in particular, have been hit hard in the last couple of years. In 2007-2008, I dramatic “collapse” (nearly 40% across the U.S.) of bee colonies occurred. This colony collapse disorder (CCD) has been attributed largely to a virus and has had a huge economic impact on U.S. agriculture, as many commercial crops depend on the pollinating activity of hundreds of thousands of bees. CCD continues to spread.
Other recent studies have shown comparable scent impairment (e.g., in fish) from ambient or water pollutants–even at low concentrations (see my earlier article: Hormone-like Contaminants Block Trout’s Ability to Sense Predators )
Like so many other impacts, the long-term effects on these related ecosystems is unknown, and awaits future study.
photo: Alvesgaspar on wikipedia.org – GNU
About Michael Ricciardi
