Pollutants change the scent of flowers - this can be fatal for insects
The rampant air pollution makes flowers smell different, sometimes they simply smell weaker - sounds sad, but harmless - but it's not. This can be fatal for insects, as a US research team discovered.
The world is no longer the same as it was 100 years ago - not even 20.
In addition to many other factors, air and light pollution and noise have a massive impact on all living creatures. However, the intensity of the chain reactions triggered here was not clear until now.
Air pollution affects insects and moths so intensively that they "forget" to pollinate flowers.
The team at the University of Washington, Seattle, led by Jeremy Chan, has investigated the phenomenon. The results of the study were presented in the journal "Science".
This means that the animals can apparently no longer find the plants. But why?
The butterfly experiment
The behavior of hawkmoths of a butterfly family(Sphingidae) in relation to pollination of the fragrant pale evening primrose(Oenothera pallida), which generally attracts many pollinating insects, was studied in detail.
The research was carried out both in the laboratory and in a natural environment:
For 200 hours (including 110 hours at night), a field of 300 evening primroses was used to record how many hawkmoths visited the flowers and at what times.
The fragrance mixture of the flowers was also analyzed in detail using gas chromatography.
According to her, the scent of evening primrose flowers contains monoterpenes. These volatile aromas are mainly found in food plants such as citrus plants.
The hawkmoth recognizes the evening primrose by these substances over a distance of several kilometers. In short: if these substances are missing or not pronounced enough, the plant becomes "invisible" to the pollinator.
The research also revealed that the distances at which flowering plants can be seen by insects are becoming ever shorter, especially in urban areas.
Why the loss of fragrance?
Nitrate radicals in the ozone break down various chemical compounds that a flower emits. Unfortunately, these are parts of its aromatic substances.
They do this mainly at dusk or at night. That was known.
If the concentration of nitrate radicals in the air is particularly high, this has an effect on volatile aromas. This means that either the composition of the floral fragrances changes or they are completely broken down very quickly.
