Air pollution damages flies’ sex life
As we spend summer after summer destroying them, it’s not easy to imagine that one day they will disappear forever.
But the flies’ sex lives have been disrupted by air pollution as many species suffer from “dysfunctional” mating signals, the study warns.
A disturbing new study has found that flies struggle to feel attracted to mating partners amidst ozone pollutants that “drastically mess up” their reproductive behavior.
Results come when declining insect populations is a global problemwith flies an integral part of helping to pollinate 80 percent of the world’s crops.
Flies exposed to ozone “unusual courtship behavior” where males are more attracted to their male counterparts and appear to be unable to distinguish between the sexes.
The flies were found to exhibit “unusual courtship behavior” in the face of ozone exposure.
“We knew that elevated ozone levels could affect insect mating systems because breaking down carbon double bonds and therefore pheromones by oxidation is not rocket science in chemistry,” said researchers Nanji Jiang and Markus Knaden from the Max Planck Institute for Chemical Ecology.
“However, we were shocked that even a slight increase in ozone had such a strong effect on the behavior of the flies.”
Ozone gas is harmful to human health and can cause asthma attacks in addition to inflammation of the eyes, nose, airways and throat.
Although it was present in the lower atmosphere in pre-industrial times, its values were only 10 parts per billion (ppb) compared to today’s values of 40 parts per billion, according to experts.
Recently, ozone has also jumped to 210 ppb in Mexico. JGR Atmosphere research, thanks to a combination of climate change and ongoing emissions nitrogen oxides.
As part of the study, flies were placed in an “ozone exposure system” that mimicked urban air pollution levels in the summer.
When exposed to 100 ppb of the pollutant for just two hours, the scientists noticed that the level of chemical attractants in the flies dropped significantly.
Males exposed to ozone have also been observed to form “long courtship chains” that are said to be quite cryptic.
Other fly species that rely on visual cues for mating rather than pheromones have not changed their behavior.
Dr. Jiang and Dr. Knaden added: “We could explain that the males started courting each other after a short exposure to ozone because they obviously couldn’t tell the ozonated males from the females.
A study by the Max Planck Institute placed flies in an “ozone exposure system” that mimicked urban air pollution levels in the summer. Pictured: formation of a courtship chain in male flies at 100 ppb for 20 minutes.
The scientists felt that the flies “couldn’t tell” the females from the males in the experiment.
“However, we did not think about it before.
“We were therefore quite puzzled by the behavior of the ozone-exposed males who lined up in long courtship chains.”
Unfortunately, Bill Hansson, co-founder of the Max Planck Center for the Chemical Ecology of Next Generation Insects, says it is “unlikely” that flies will be able to adapt to rapidly rising air pollution.
He said:Insects and their pheromones have evolved over millions of years. On the contrary, the concentration of air pollutants has only risen sharply since industrialization.
Pictured: another male fly species (D. melanogaster) tested in ozone enriched air.
It is unlikely that the communication systems of insects that have developed in the course of evolution will be able to adapt to new conditions in a short period of time if pheromones suddenly become absent. The only solution to this dilemma is to immediately reduce emissions of pollutants into the atmosphere.”
Now scientists are looking to expand their research by focusing on other insects, including moths, which typically follow pheromone plumes over long distances.
Dr. Knaden added: “We would like to find out if high ozone levels increase the rate of hybridization when closely related fly species share their habitat. Finally, chemical communication in insects is not limited to mating.
“All social insects such as bees, ants and wasps use chemical signals to identify members of their colony. We are also studying whether the social structure in ant colonies is affected when the ants return from their foraging trips, during which they are exposed to elevated levels of pollutants.
“You don’t even want to imagine what would happen if the social structures in ant colonies or hives suddenly collapsed because the pheromone connection no longer works.”
The ozone layer is found in the stratosphere 25 miles above the Earth’s surface and acts as a natural sunscreen.
Ozone is a molecule composed of three oxygen atoms that occurs naturally in small amounts.
In the stratosphere, about seven to 25 miles above the Earth’s surface, the ozone layer acts like a sunscreen, protecting the planet from potentially harmful ultraviolet radiation that can cause skin cancer and cataracts, suppress the immune system, and damage plants.
It is produced in tropical latitudes and distributed throughout the globe.
Closer to the ground, ozone can also form from photochemical reactions between the sun and pollutants from vehicle emissions and other sources, producing harmful smog.
Although warmer than average stratospheric weather conditions have reduced ozone depletion over the past two years, the current area of the ozone hole is still large compared to the 1980s when ozone depletion over Antarctica was first discovered.
In the stratosphere, about seven to 25 miles above the Earth’s surface, the ozone layer acts like a sunscreen, protecting the planet from potentially harmful ultraviolet radiation.
This is because levels of ozone depleting substances such as chlorine and bromine remain high enough to result in a significant loss of ozone.
In the 1970s, it was recognized that chemicals called CFCs, used in refrigeration and aerosols, for example, depleted ozone in the stratosphere.
In 1987, the Montreal Protocol was agreed upon, leading to the phase-out of CFCs and, more recently, the first signs of restoration of the Antarctic ozone layer.
The upper stratosphere at lower latitudes is also showing clear signs of recovery, proving that the Montreal Protocol is working well.
But a new study published in Atmospheric Chemistry and Physics found that it probably doesn’t recover at latitudes between 60°N and 60°S (London is at 51°N).
The cause is unknown, but researchers believe that climate change could change atmospheric circulation patterns, causing more ozone to be transported from the tropics.
They say another possibility is that very short-lived substances (VSLS), which contain chlorine and bromine, could deplete ozone in the lower stratosphere.
VSLS include chemicals used as solvents, paint removers and degreasers.
One is even being used in the production of an ozone-friendly replacement for CFCs.