How pollution confuses bees and butterflies

By Mark Waghorn via SWNS

Air pollution is confusing bees and butterflies - severely reducing pollination, according to new research.

Fumes from traffic and industry prevent insects from sniffing out crops and wildflowers by changing their scent.

Disturbingly, the phenomenon has been identified in the countryside - as well as towns and cities.

In tests numbers of pollinators and visits to plants plunged by 70 and 90 percent, respectively.

Overall pollination fell by almost a third when diesel exhaust chemicals, ozone and other common pollutants were present.

Project leader Dr. Robbie Girling, of Reading University, said: "We knew from our previous lab studies diesel exhaust can have negative effects on insect pollinators.

"But the impacts we found in the field were much more dramatic than we had expected."

The study in Environmental Pollution is the first to identify the crisis in the natural environment.

It is believed dirty air reacts with flowers, altering the odor - making them harder to find.

First author Dr. James Ryalls, also from Reading University, described the findings as "worrying."

He said: "These pollutants are commonly found in the air many of us breathe every day.

"We know these pollutants are bad for our health, and the significant reductions we saw in pollinator numbers and activity shows there are also clear implications for the natural ecosystems we depend on."

It suggests they are fuelling ongoing declines in pollinating insects by disguising their food - pollen and nectar.

The British team used a purpose-built fumigation facility to regulate levels of nitrogen oxides (NOx) from diesel exhaust and ozone in an open field.

Effects were then observed on the pollination of black mustard plants by free-flying, locally-occurring insects over the course of two summers.

Concentrations were well below maximum average levels - equating to less than half the limits currently defined by US law as safe.

This pales in comparison with far higher levels recorded around the world - including the UK.

For example, outside of London, a 2019 analysis showed illegal levels of NOx across northern England - including Cheshire and Gateshead.

They were also reported in the south - such as Wiltshire, Chichester and rural areas like the New Forest.

There were 62 to 70 percent fewer pollinator visits to plants located in polluted air.

This reduction was seen in seven groups - particularly bees, moths, hoverflies and butterflies.

There were also 83 to 90 percent fewer flower visits by the insects - and ultimately a 14 to 31 percent reduction in pollination based on seed yield and other factors.

Such findings could have wide-ranging implications. Insect pollination delivers hundreds of billions of pounds worth of economic value every year.

It supports around eight percent of the total value of agricultural food production worldwide. Most crops (70%) - including apples, strawberries and cocoa - rely on it.

Co-author Dr. Christian Pfrang, of Birmingham University, said: "This truly cross-disciplinary work demonstrated very clearly how atmospheric pollutants negatively impact on pollination with direct consequences for food production as well as the resilience of our natural environment."

In Britain, a third of wild bees are in decline. If current trends continue, certain species will be lost altogether.

They pollinate flowering crops, such as oilseed rape. Previous research found every square kilometer in the UK lost an average of 11 species of bee and hoverfly between 1980 and 2013.

It has far-reaching consequences. Insects provide a food source for many birds, amphibians, bats and reptiles.

A recent scientific review of insect numbers around the world suggested that 40% of species were undergoing "dramatic rates of decline."

Bees, ants and beetles are disappearing eight times faster than mammals, birds or reptiles.

Earlier studies have found losses of butterflies, moths, beetles, bees and hoverflies across the UK.

According to the World Health Organisation air pollution accounts for an estimated 4.2 million deaths a year from stroke, heart disease, lung cancer and chronic respiratory diseases.