Common air pollutants may be reducing insect-provided pollination services by preventing bees and butterflies from sniffing out crops and flowers, new research suggests. The study is the first to observe a negative impact of common air pollutants on pollination in the natural environment.
Scientists from the University of Reading, the UK Centre for Ecology & Hydrology (UKCEH) and the University of Birmingham investigated common ground-level air pollutants, including diesel exhaust pollutants and ozone, from both urban and rural environments.
They found there were up to 70% fewer pollinators, up to 90% fewer flower visits and an overall pollination reduction of up to 31% in test plants when the pollutants were present, but still at levels below current air quality standards.
Previous lab studies had shown that diesel exhaust can have negative effects on insect pollinators, but the impacts found in the field were much more dramatic than expected, the researchers say. The results suggest that floral odours are altered by the pollutants or their reactions with the atmosphere, making the flowers harder to find.
The impact this phenomenon has in nature, where insects provide pollination of important food crops and native wildflowers, was less well understood, so the new study aimed to gather evidence on how air pollution affects different pollinating insect species, some of which rely on scent more than others.
The study, funded by the UKRI Natural Environment Research Council, used a purpose-built fumigation facility to regulate levels of nitrogen oxides – present in diesel exhaust fumes – and ozone in an open field environment.
Dr Ben Langford and Dr Neil Mullinger, atmospheric scientists at UKCEH, designed the novel facility that allowed the team to release regulated quantities of the pollutants being studied. The team used pollution concentrations well below maximum average levels - equating to 40-50% of the limits currently defined as safe for the environment.