Scientists' Contributions

Aphids as Indicators of changing air quality

J.N.B. Bell

Imperial College, London, UK

    Aphids are sucking insects which are pests of agricultural crops and other plant species. Research at Imperial College and elsewhere has shown unequivocally that air pollution can change the performance of a wide range of aphid species. In the case of SO₂ and NO₂ in nearly every case stimulation of performance occurs, but O₃ produces more complex responses, with both positive and negative impacts being recorded. All the evidence points towards changes in aphid performance being mediated via pollutant-induced changes in plant chemistry, in particular in amino-acid composition, which alter the host's nutritional value for the insect. Evidence will be presented for changes in aphid performance under ambient levels of common air pollutants, using fumigation, filtration, transect and field survey methods. A new EC-funded project (EXAMINE) is utilising data from aphid traps across Europe to determine the value of using aphids as indicators of environmental change. Imperial College's role in this project is to extend earlier work in which a correlation has been shown between numbers of aphids caught in traps in the UK and prevailing SO₂ levels, to a European scale. This is aimed at identifying correlations in both time and space between catches of different aphid species and ambient SO₂ NO_x and O₃ concentrations.