Katharina Buczek
These insights enabled the researchers to concoct a synthetic version of the primrose scent and then taint it with chemicals to mimic a flower affected by typical air pollutants.
The addition of just ozone reduced the concentration of monoterpenes in the fragrance by roughly 30%. However, when they introduced nitrate radicals, which are predominantly active at night when hawk moths are active, the levels of these sweet-smelling monoterpenes plummeted by a whopping 84%.
The diminishing strength of the fragrance resulted in two species of hawk moths showing less interest in the artificial primrose.
In a controlled wind tunnel experiment, the researchers placed a faux flower infused with the synthetically polluted primrose scent. They observed that, compared to a natural primrose in the same wind tunnel, the tobacco hawk moths reduced their visits by 50%, while the white-lined sphinx moths completely ceased visiting the altered flower, showing a 100% decrease in visitation.
In response to these findings, Ilaria Negri, a zoologist who did not participate in the study, claimed that “Pollinators are literally starving.”
“That pollinators are unable to find already scarce food due to pollution is challenging for many species,” Negri said.
The scientists found that when they introduced their artificial flower, mimicking a pollution-affected primrose, into a field of healthy primroses, hawk moths were 70% less likely to visit the imitation over the course of one night compared to the natural flowers.
This decline in visits, they note, would result in the primroses producing 28% fewer seeds.
Furthermore, the researchers developed computer simulations to examine how fragrances would have interacted with the atmosphere before industrialization.
Their findings indicated that, due to the current levels of air pollution in most urban areas globally, the distance at which pollinators such as hawk moths can detect scents has been reduced by as much as 75% since preindustrial times.
These results highlight the effects of “sensory pollution,” which refers to human-created disturbances that disrupt animals’ sensory perception.
