Pollution in cities damaging insects and ecosystems

High levels of pollution in many of the world's major cities are having negative effects on the plants and insects, according to a new UK-based research.

The research titled 'Plant defences mediate interactions between herbivory and the direct foliar uptake of atmospheric reactive nitrogen' done at the University of Sheffield in the UK was published in the journal 'Nature Communications'.

It revealed that plants exposed to high levels of nitrogen dioxide (NO2) - similar to levels recorded in major urban centres - are able to better defend themselves against herbivorous insects.

According to the research, NO2 significantly impacts plants and insects. Insects are crucial for food production and also ensure long-term survival of wild flowers, shrubs and trees.

Plants exposed to increased levels of pollution produce more defensive chemicals in their leaves, said the research led by Dr Stuart Campbell from the University's Department of Animal and Plant Sciences.

"Results from the study show that insects feeding on these leaves grew poorly, which suggests high levels of air pollution may be having cascading negative effects on communities of herbivorous creatures," the study said.

Insects are crucial for food production and also ensure long-term survival of wild flowers, shrubs and trees, according to the research.

"Insects that feed on plants (herbivorous insects) help return plant nutrients to the soil, and are themselves food for wild birds, reptiles, mammals, and yet more insects. Insects are also immensely important for decomposing decaying organic matter and maintaining healthy soils," said Campbell, who is also part of the P3 Centre - a centre of excellence for translational plant science at the university.

Scientists are warning about massive decline in insect numbers, which should be incredibly alarming to anyone who values the natural world and our sources of food, he said.

The research suggest that the urban vegetation plays a modest role in taking up NO2.

More work is needed, because many factors may influence the effect of urban plants on air quality, including herbivory. Plant feeding insects, however, face a number of different human threats, potentially including air pollution," according to the research.