Air pollution cutting short life span of wild honey bees2 min read . Updated: 11 Aug 2020, 08:54 AM IST
- A four year long study by NCBS researchers, published in an international journal recently, provides quantitative data on the impact air pollution is having on Giant Asian bees, the major pollinators of crops and food and flowering plants
The health of wild honey bees and, in turn the future of our food security, is in peril. While there have been many anecdotal evidence of the honey bee population decreasing in urban area, a recently published study lead by National Centre for Biological Sciences (NCBS) researchers have shown evidence of air pollution’s adverse effect on Apis dorsata, the Gian Asian honey bee, which are also found in the cities. These bees are major contributors of pollinating our crops, fruits and flowering plants.
Irregular heart rate, fewer blood cells, and alternations in gene expressions linked to stress, metabolism and immunity, were some of the key findings that came up after studying 1800 wild bees in and around Bengaluru, over a span of four years. One of the striking differences that could be clearly seen on bees’ bodies was the toxic metal debris found on the wings of these bees like lead, arsenic, tungsten, aluminum, chromium and cobalt. What’s alarming, however, is that over 80% bees collected from moderate and highly polluted locations die within 24 hours.
The study titled ‘A field-based quantitative analysis of sub lethal effects of air pollution on pollinators’ lead by Prof Shannon Olsson , Postdoctoral scholar Dr Geetha Thimmegowda along with eight member team, was published in Proceedings of the National Academy of Sciences, USA, this week.
According to Prof Olsson, four sites were chosen for the collection and observation sites were chosen as representative of varying pollution levels, pesticide use, floral abundance, traffic, shade, man-made structures and presence of Giant Asian honey bee colonies. Each site – Hessarghatta (rural), NCBS Campus (low), Lalbagh Botanical Garden (moderate), and Peenya park (high) – was roughly eight kilometer from each other. To confirm the harmful effects they noticed in these bees was due indeed due to air pollution, the researchers repeated the experiments by exposing 2100 lab-reared Drosophila Melanogaster (common fruit fly) to similar environmental conditions. “We got similar results, suggesting that air pollution is the most likely factor, and that the effects are not specific to a single species, since the flies were also impacted," says Dr Olsson.
While there have been assumed connection between the decrease in insect and bee population with poor air quality in the past, this study shows definitive, quantitative numbers, Prof Olsson says. “With this study, we know the overall effects of air pollution on the honey bees. We are now proceeding to do controlled experiments to see which specific air pollutants will affect the bees physiologically," says Dr Thimmegowda.
So, why does this study matter? Besides, being the source of 80% of the country’s honey, our food generating crops, fruit and flowering plants are highly dependent on wild bees. Consider this, 53% of mangoes will be lost, in addition to yearly export worth ₹65000 lakh of the fruit getting wiped out without insect pollinators like honey bees. In fact, 75% of our crop species rely mostly on insects for production.
Dr Olsson hopes that this would help other researchers to conduct similar studies on other species. “The Air Quality Index is used for human health. However, there are plants and animals too which are exposed to the same air. We hope that our study will be a jumping off point for other researchers to study all sorts of animal and plant systems and impact of air quality parameters on them. After all, human health too will be ultimately affected if there is an impact on food production," she says.