Insect decline: 40 percent of species decline

In a long article of the New York Times the title says it all: «A world without insects». The story begins with a bicycle ride in the woods north of Copenhagen, by the professor Sune Boye Riis, a high school science and math teacher: he was driving fast with his youngest son, but during the whole hot morning, not a single insect had ended up in his mouth. Is it possible? Riis remembered well the car trips with his parents, when the windshield and the headlights were covered in insects to the point that you couldn't see anything anymore.

DECREASE IN INSECTS

From that day on, Riis, along with some colleagues, never stopped trying to study in the field the phenomenon of insect decline, and drove around Denmark's back roads with nets on his cars. With one worry in mind: insect species are numerous, often inconspicuous and therefore difficult to monitor. This is why species extinction can be detected, but not population declines. It's like taking note of a death that has occurred, without any possibility of intervening with a therapy to try to avoid it in good time.

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THE WINDSHIELD PHENOMENON

Riis' discovery has long been at the centre of attention of entomologists who, not by chance, have named it the «windshield phenomenon". That is, a progressive disappearance of insects recorded through the marked decrease, especially in the summer months, of insects that stick to car windshields. This extermination is proceeding at an annual rate., according to studies published on Biological Conservation, 2,5 percent, but this is an absolutely approximate number. 40 percent of the species of known insects is in constant decline, a third of the species are in serious danger. And it is no coincidence that inUN 2030 Agenda for Sustainable Development, as goal number 15 appears the objective of «Protect, restore and promote sustainable use of terrestrial ecosystems».

A WORLD WITHOUT INSECTS

In 2014 the magazine Science he tried to quantify the decline by calculating a synthesis of the results of several scientific studies already concluded: the result, for some monitored species, it was a 45 percent dropMore specific and limited research has yielded even more alarming numbers. For example, the quantity of flying insects in German nature reserves has decreased by 75 percent in the last quarter of a century. In the last twenty years the population of butterflies Monarch butterflies in the United States have declined by 90 percent, with a loss of approximately 900 million individuals. In England, 58 percent of butterflies in cultivated fields disappeared in less than ten years, from 2.000 to 2009.

THE INSECT ECOSYSTEM

So far they have been catalogued and described about one million species of insectsBut entomologists believe there are another four million "submerged" species, that is, not yet certified by man. Completely ignored by science. Meanwhile, we have 12 types of ants, 20 thousand varieties of bees, almost 400 thousand species of cockroaches. Such impressive numbers are tangible proof of the biodiversity of nature, there is the risk that, in the case of insects, serious problems for everyone will come not with the disappearance of a species, but even just with the decrease that experts call "functional extinction"When the decline of an insect species is such that it threatens its function within an ecosystem. There are various birds and fish that feed on insects, and if these become too few, food and general nutrition problems arise. Similarly, in the case of insects, a loss of even just 30 percent of the population of a species can be so destabilizing that it causes the total extinction of other species. And in 80 percent of cases, these are precisely the ones that have suffered this loss. side effect to disappear first.

CAUSES OF THE DECREASE OF INSECTS

What are the causes most important ones that are leading to a world without insects, a prelude, according to the most catastrophic scientists in their predictions, to the sixth mass extinction? Three in particularThe first concerns the destruction of natural habitatsIn urban areas, with the reduction of green and open spaces, in the countryside due to agricultural expansion that alters the balance of vegetation. Secondly, Insects are threatened by herbicides and insecticides: extremely powerful in their action, capable of spreading deadly poisons that then linger for a long time. Finally, the most current cause and also the one that is growing most intensely: global warmingEven insects, at every latitude on the planet, are accustomed to living and reproducing at certain temperatures. If these temperatures rise too high, they can no longer lay eggs, and reproduction slows down. And that's what's happening.

THE IMPORTANCE OF INSECTS IN OUR LIVES

We are a accustomed to associating insects with a series of annoyances In our lives. Ants while we're picnicking or when, in the summer, we leave something in the kitchen that attracts them. Ticks attached to our pets. Cockroaches, which usually make us scream, are signs of dirt. Spiders in some areas of the house, like in the shower, where mold has formed. It's all true. But... we are completely ignorant, and even at school we talk about it too little, of some vital functions that insects performVital for ecosystems and, first and foremost, for humans. Insects are essential pollinators and recyclers of ecosystems. And they are at the base of the food chain. Trillions of insects, moving from flower to flower, pollinate approximately three-quarters of the crops we eat, an activity worth 500 billion dollars a year. By eating and being eaten by birds and fish, insects transform plants into protein and promote the growth of all the countless species that feed on them. We have also discussed this on our website regarding catastrophic decline of bees and butterflies. Then there's a completely invisible, yet no less essential, role of insects: decomposition, which allows for the recycling of nutrients, keeps the soil healthy, promotes plant growth, and the efficient functioning of ecosystems.

HOW TO SAVE INSECTS

THEalarm on the catastrophic decline of insects is now shared by the entire scientific community International. But what can be done that is useful and coordinated? This is where politics and supranational bodies come into play, starting with the European Union. The old continent has always been at the forefront in this field and the time has come to launch monitoring projects of insects on a transnational, European scale. The local dimension is no longer needed, and has already provided the numbers we have partially seen. More studies will also lead to greater understanding of the phenomenon and a new awareness among citizens of the importance of insects. We must move forward with bans and reductions, across the board, of pesticides, instead trying to encourage alternatives that don't jeopardize the results of the agricultural sector. And we need to invent new spaces for insects: some researchers talk about places like roads, power lines, and railways. And private individuals themselves can do a lot: think of the trend ofurban beekeeping. Finally, it goes without saying that all policies against global warming will also, indirectly, lead to a reduction in insect decline.

We cannot slip into cosmic pessimism and catastrophism, but we cannot even imagine that resilience is eternal. Insects have the advantage of enjoying great fertility: but how long will they be able to save themselves thanks to this gift from Mother Nature?

HOW TO PROTECT THE ENVIRONMENT AND ANIMALS:

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• From bus gardens to shelters for bees and other insects, combining sustainable mobility and love for the environment.
• Let's clean up the air and reduce plastic pollution. And with more recycling: this is how we celebrate the environment.
• The life raft sails toward Australia. The size of a pumice island, it rescues coral and marine life.