(Down to Earth: Pollution)
Jan 25: Is air pollution contributing to the ‘insect apocalypse’? – https://www.downtoearth.org.in/news/pollution/is-air-pollution-contributing-to-the-insect-apocalypse-yes-experts-tell-dte-81268
- GS-3: Biodiversity and Conservation
- GS-3: Pollution, Climate change
Is air pollution contributing to the ‘insect apocalypse’?
Context: There is an ‘insect apocalypse’ underway across the world. The threats to insects include habitat loss, climate change, land-use change and insecticides. But there appears to be another insidious contributor: polluted air.
Insects in the ecosystem
- Vital for India’s food security: Insects have an essential role to play in our ecosystem. They pollinate many of our fruits, flowers and vegetables, contributing significantly to the productivity of at least 75 per cent of global crop species. Their services are.
- Insects keep pests in check: For example, ladybird preys on aphids, that damage crops. Insects are also food sources for amphibians, reptiles, birds and mammals.
- If we were to lose all pollinating insects tomorrow, we would no longer be able to produce cocoa beans, brazil nuts and some fruits (like melon and pumpkin)
Blame it on Air Pollution
Air pollution is likely an important, but currently overlooked, factor contributing to insect pollinator declines. A study in Bengaluru found a drastic reduction in honeybee health at levels which were target levels by the World Health Organization for cities
A. Impact of respirable suspended particulate matter (RSPM) on health of Giant Asian honey bees:
- Giant Asian honey bees produce more than 80 per cent of the honey in India and pollinate more than 687 plant species.
- Over 80 per cent of bees survived for 24 hours at moderately polluted sites. Research in this area is relevant for India as nine of its cities rank in the top 10 most polluted cities globally. Most polluted Tier-2 cities are much more embedded in agricultural lands.
- RSPM is a complex mixture of particles measuring less than 10 or 2.5 micrometres in diameter. They are commonly called Particulate Matter.
B. How could pollution hurt insects?
- In the study, the health impacts of pollutants on bees were quite severe, Honey bees’ heart rates, stress, blood cells counts were affected.
- Air pollutants can do a lot more. They can mess with the insects’ ability to sniff flowers, lowering pollination services.
- Flowers release odour as chemicals called volatile organic compounds, which help insects locate flowers. Pollutants could react with and change the scents of flowers, making them harder to find.
- One study found that honey bees exposed to low medium and high air pollutant concentrations had an impaired ability to recollect odour.
- Pollutants might also mess with social bonds. Insects use odours for a huge variety of interactions with each other and their environment. For example, insects use airborne odours to attract a mate. If pheromone communication is disrupted similarly, it could result in insects struggling to find mates, which could have ramifications for insect biodiversity.
- Some insects like Beetles and parasitic wasps appeared resilient to pollutants. The researchers suspect that this could be because the above insects relied on visual cues rather than odour to reach flowers. Future experiments will need to explain why some species or groups of insects are more affected than others.
The Way Forward
- There is a need to relook and ascertain our regulations across the world
- Future studies should quantify the levels of pollutants safe for insects’ health