A bee searches for nectar on a sunflower at the Boggs Tract Community Farm. TNS

Harry Cockburn

The giant Asian honey bee is a vital pollinator, but faces severe declines due to huge increases in air pollution, scientists in India have warned

Breathing toxic fumes due to exposure to heavily polluted air is one of the key contributors to early death all around the world, exacerbating risks posed by lung and heart conditions.

According to the World Health Organisation nine out of 10 people on the planet breathe air containing high levels of pollutants resulting in around seven million premature deaths every year.

But despite growing awareness of the risks toxic air poses to humans, almost no research has been done on the impact on the flora and fauna which are dependent on the same air we breathe.

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In one of the first major efforts to try to understand the physiological impacts of air pollution on wild plants and animals, scientists from India’s National Centre for Biological Sciences in Bangalore show poor air quality could be devastating for organisms we rely on most for our own survival — pollinators such as the honey bee.

After observing declines in the giant Asian honey bee in the urban centres of Bangalore, Geetha Thimmegowda and Shannon Olson set out to understand the causes behind the falling populations of the vital pollinator.

This species of bee produces over 80 per cent of the India’s honey, and pollinates over 687 plants in the state of Karnataka alone.

Thimmegowda collected and examined bees from different parts of the city under a high-powered electron microscope.

First, the scientists examined a bee from the BLiSC campus on the northern and relatively low-polluted edge of the city.

This foraging bee was carrying “copious amounts of pollen on her body”, ready to pollinate new flowers.

 A queen bee, centre, moves around among smaller worker bees. TNS

Then they studied a bee from Peenya, an industrial area of the city, and found it was covered in small particles they later found to contain lead, tungsten, arsenic, and a host of other toxic metals.

The study examined the effects of air pollution on the behaviour, physiology, and molecular aspects of the giant Asian honey bee in Bangalore — one of India’s fastest growing megacities.

In collaboration with other scientists from the NCBS as well as the Institute for Stem Cell Science and Regenerative Medicine (inStem) and the The Knight Cardiovascular Institute, the scientists found that bees from more polluted areas of the city exhibited lower flower visitation rates than in less polluted areas.

Bees from more polluted areas also showed significant differences in heart rhythmicity, blood cell count, and the expression of genes coding for stress, immunity, and metabolism, the scientists said.

Repeating these experiments with lab-reared Drosophila — a species of fruit fly — found similar effects, suggesting the impact of air pollution is not species-specific, nor likely the result of other environmental factors.

Hema Somanathan, who studies bee behaviour and pollination ecology at the Behavioural and Evolutionary Ecology BEE Laboratory, at the Indian Institute of Science Education and Research, in Thiruvananthapuram, the capital of the Indian state of Kerala said the study was “hard evidence” not all was well with wild bee populations around cities in India.

She said: “There are extreme gaps in our knowledge on the status of our wild pollinators in India. This study by Dr Olsson and colleagues is a very important step in addressing this pressing concern.

Arunabha Ghosh, founder and chief executive of Indian thinktank the Council on Energy, Environment and Water, said: “So far, much of the air quality studies in India have either considered sources of pollution or impact on human health, and to an extent on economic productivity.

“This study covers important new ground, by examining the impact of air pollution on pollinators, which would have serious implications for agricultural output in India.”

She called for greater levels of air quality monitoring, more impact studies, and also an effort to communicate the results of the research to communities.

The Independent