We often think of ozone as a stratosphere pollutant, where it does a useful job blocking out harmful ultraviolet radiation, but it is harmful to breathe, damages our crops, and is now thought to be behind the collapse in the insect population. In a typical May, UK air pollution can reach between four and six on the government’s 10-point scale for a week or so. This May if you remember was hot – the hottest since records began in 1919. This brought air pollution problems to the whole of England and Wales. Air pollution reached level 4 or above on 30 days during the month and ozone was one of the main culprits. In Europe we can lose up to 12% of wheat yields to ozone each year, but the impact is worst in the poorest parts of the world.
With no global agreement to control the pollutants that form ozone at ground level, – mainly from vehicle exhausts releasing nitrogen oxides into the atmosphere which react with sunlight – this problem will only get worse. The race is on to find crop varieties that are better able to resist this air pollutant.
The insect custodian at the Berlin Natural History Museum, says he is worried that “the decline in insect populations is gradual and that there’s a risk we will only really take notice once it is too late.”
It seems that there is an air of complacency pervading the planet
Canadian biologists in 2010, suggested that bird species that depend on aerial insects for feeding themselves and their offspring have suffered much more pronounced declines in recent years than other perching birds that largely feed on seeds. British birds like spotted flycatcher, tree pipit, wagtails or wren fall into this category.
So far, only the decline of honeybee populations has received widespread public attention, in large measure because of their vital role in pollinating food crops. The rest of the insect world has been widely ignored. Often insects are perceived as a nuisance or merely as potential pests but scientists emphasize the ecological importance of diverse and abundant insect populations for the food chain.
Until recently pesticides have been considered as the prime suspect for insect losses. However hill farmers in Wales who have no need for chemicals report a decline in butterfly and insect numbers despite a favourable floral habitat so there must be an invasion of pollutants – waves of ozone created in the urban and industrial areas. To understand the problem better, scientists are now urging increased monitoring efforts. A recent increase of monitoring efforts stems from the rise of “citizen science” projects, where lay people with an interest in the outdoors are trained to collect data. Closer to home volunteers could monitor the insect population in the Ashridge woods.
Currently if you took a quick look into the leaf litter beneath oak or beech you would be hard-pressed to find any insects – no spiders to speak of, the occasional snail or worm, a single woodlouse or millipede. Not much to show despite years of conservation with decaying piles of brushwood everywhere! Beware of any fungi and look out for the ozone!