When was the last time you saw a firefly? It turns out that the luminous insect of our childhood days is disappearing due to man's continuous damage to the ecosystems
Yali Katz, Angle - news agency for science and the environment
"Where have the fireflies disappeared/ Where is the magical light that flickered in the secret language/ Lanterns of lust signal with a green-yellow light/ that the time has come./ We stopped by them when we returned from the action in the youth movement/ We looked at each other with sweaty faces/ and continued on our way,/ I put my arm/ on her shoulder "(Where have the fireflies gone" - Amos Navon. Stand release)
It is likely that the poet Amos Navon did not direct his poem to ecological issues, but to more personal matters, but the question that gave his book of poems its name, could certainly also be the title of a study in environmental sciences.
In recent years, the sightings of fireflies in Israel have indeed decreased, especially in areas that have undergone accelerated development and in urban areas. Israel is not alone in this field, and in the world in recent years there has been an increase in research that examines where the fireflies have disappeared and also how it is possible to return Oran to the darkness of our night.
lighting up the night
So for the benefit of the generation that only saw fireflies on TV - a firefly is a small beetle no more than 2.5 centimeters long. It has an elongated body structure, and is mostly yellowish-brown in color. All this is true in broad daylight; At night the story is completely different.
At the end of the firefly's belly are special lighting organs, where a chemical reaction takes place in which a substance called luciferin is oxidized in contact with the air, with the help of an enzyme called luciferase. This process is called bioluminescence (biological light), and is very common among marine animals but very rare on land.
Using the light signals, the fireflies communicate with each other and manage to find potential partners for reproduction. The firefly family has about 2,000 species (of which only eight live in Israel), and each species has its own unique signal, that is, each species uses a different signal in the sequence and frequency of the flashes. In addition, the start time of signaling may also vary between different firefly species: some species start signaling 15 minutes after sunset, while others 30 minutes after sunset.
Apart from the prominent feature of producing light, fireflies have other features that make them important in the ecological fabric. Fireflies have a very diverse menu and prey on insects and molluscs, which may serve as a biological pest control measure. There are even species of fireflies that feed on nectar and dust in their adulthood.
Last light?
If we've made you want to go out and find a firefly, you'll surely be happy to hear that, in principle, fireflies can be found almost anywhere on land - from forest areas to urban areas - with the exception of Antarctica. So if fireflies can be found in so many areas, why are they so hard to find these days?
This question has occupied researchers around the world in recent years, and their studies indicate that the main reason for harming fireflies is the same reason that causes harm to other wild animals: the destruction of open areas and the fragmentation of habitats. The same severance causes isolation of the populations, and damage to their ability to reproduce. The female fireflies are particularly sensitive to amputation, because they lack the ability to fly, and are therefore limited in their movement. Other factors, such as the use of fertilizers and pesticides, also harm the firefly population. Another significant cause of damage to fireflies - an animal that uses light to reproduce - is the unusual use of artificial light by humans, which is known as "light pollution".
A recent study conducted in Maryland in the United States examined how the introduction of artificial lighting into natural, dark areas affects the behavior of fireflies. In the study, six sites were examined, where a test was conducted on the number of fireflies every night. At each site it was found that when exposed to artificial lighting, there was a significant decrease (almost 50 percent) in the number of signals per minute. This result supported the researchers' hypothesis that artificial lighting has a negative effect on the firefly population and harms their ability to communicate.
The researchers also note that it is likely that this effect of artificial light is especially strong in urban areas, where the lighting intensities are much higher compared to the lighting intensities to which the fireflies in the study were exposed. As confirmation of this, in a study conducted in the city of Turin in Italy, which was based on information obtained from observations of citizens, it was found that fireflies tend to avoid areas with high lighting intensities.
Search the winter puddles
And what's going on in our backyard? A study conducted in 2009 at the Hebrew University, under the direction of Prof. Salait Karak and in collaboration with the Society for the Protection of Nature, revealed that over the past 20 years the number of sightings of fireflies has been decreasing, with an emphasis on areas that have undergone accelerated development. The students who participated in the research (Michal Hershkowitz, Yael Barna and Tal Shapira) concluded that changes in land use and artificial light interference, as well as the disappearance of moist habitats and even changes in the population of snails that are a food source for firefly larvae, are possible explanations for this trend.
Dr. Neta Dorchin, from the Department of Zoology at Tel Aviv University, points out that fireflies are not the only ones affected by the destruction and loss of habitats. However, "because they are more noticeable for identification, we notice the deterioration of their population". In this sense, the disappearance of the fireflies is a warning light or a marker for damage to thousands of species of insects and the ecosystem as a whole.
There is no doubt that the firefly population is affected by human activity and there is a need to increase research in the field. But in the meantime, the existing studies indicate a series of steps that can be taken today: the preservation of the inner-city green areas, and in particular the preservation of the humid habitats, alongside reducing the impact of artificial lighting.
Although we cannot turn off the light in urban spaces completely, we can make use of friendlier lighting techniques, prevent the leakage of light into natural areas, as well as establish policy rules regarding lighting near natural areas. If we work towards achieving these goals, the next time you go for a night walk, you may encounter a firefly.
Until then, where can we still find fireflies anyway? Dorchin suggests going outside the city, to open areas with preference for moist habitats such as winter puddles. In these habitats it is likely that there will be molluscs, and therefore fireflies may also be found there. But even in the city, in green and humid areas like Yarkon Park, for example, you may be able to witness an insect that lights up the night in secret.
