Air pollution impedes bees' ability to find food

STATE COLLEGE, Pa., July 6 (UPI) -- A new study shows that as air pollution increases, the ability of bees to find food diminishes. The particles interfere with the apian olfactory system, say scientists at Penn State.

Airborne contaminants confuse bees and react with the fragrance molecules put out by flowers, affecting the lifespans of these vital volatile compounds as well as their ability to travel.

Flowers rely on their scent molecules to attract bees. A strong breeze can lead faraway bees to a new source of food, offering the bee sustenance and the flower pollination services.

"Many insects have nests that are up to 3,000 feet away from their food source, which means that scents need to travel long distances before insects can detect them," Jose D. Fuentes, professor of meteorology and atmospheric science at Penn State, explained in a news release. "Each insect has a detection threshold for certain kinds of scents and they find food by moving from areas of low concentrations of scents to areas of high concentrations."

Researchers used complex computer models to simulate how particulate matter and other forms of air pollution interact with the scents being given off by a flower bed. They also modeled the effects of air pollution on air turbulence.

They then combined the model with 90,000 simulations of apian foraging behaviors and movement patterns -- each simulation featuring different scent levels as augmented by air pollution and wind conditions.

The results showed a variety of significant effects on important scent molecules. Alpha-pinene survives for 40 hours in an ozone-free atmosphere. When ozone levels rise to 60 parts per billion, the scent molecule lasts fewer than 10 hours -- and less than an hour when ozone levels hit 120 parts per billion.

In windy, ozone-free conditions, the scent molecule beta-myrcene travels upwards of 3,000 feet. When ozone levels rise to 60 parts per billion, its dispersal was limited to 1,500 feet.

Similar effects were calculated for eight different scent molecules. The model showed bees foraging in polluted air must spend longer searching for food and return less food to the hive. The effects of air pollution affect both generalist and specialist bees, researchers say.

The results of the new study, published in the journal Atmospheric Environment, suggest air pollution can alter important relationships between plants and pollinators, leading to changes in the environment.

"Honeybees and other pollinators are in trouble almost everywhere, and they pay us a lot of services through their pollination," concluded Fuentes. "The more we can understand about what factors are affecting their decline in numbers, the more equipped we will be to intervene if needed."