Insects

Insects a world without them

The insects they are the most diverse and abundant group of animals and the most unknown.

There are more than a million species of insects described that play crucial roles for the planet. However, and although there are still few studies, all insects, and not just bees, are in clear descent. A first-rate danger to the Earth.

Mosquitoes and their bites; flies, sticky; the wasps and ants that lurk in the picnic baskets; the cockroaches, that appear when you least expect it in any corner. For many, insects are little more than a nuisance. And yet, three out of four mouthfuls we throw into our stomachs are due to them. Also, that the Earth is not a giant dung heap. And the flowers. And helicopters and some of the molecules present in drugs. Antivirals. Antibacteria. Crucial advances in science. Not surprisingly, the famous British entomologist Edward O. Wilson asserts that they are “the little things that make the world work.”

At the current rate of species identification, it would take about a thousand years to complete the inventory; the problem is that every year between 10,000 and 15,000 kinds of insects are decimated or extinguished

At the moment there are 1.4 million documented species, which is 75% of the animals we know. But it is estimated that there are at least seven to eight million more still unidentified. “It is often said that the bottoms of the oceans are less known than Mars. And it is true, but right now if you are going to walk on the mountain, under your feet there are a lot of species that neither have ever seen nor described. Insects are a very abundant and diverse group of animals, but of the most unknown, “says entomologist Ignacio Ribera of the Institute for Evolutionary Biology (IBE), a mixed center of the CSIC and the Universitat Pompeu Fabra.

“About 10,000 species of insects are described per year, a rhythm that is not bad, although if they remain to describe seven or eight million more, we will need 1,000 years to have the complete inventory,” says Xavier Belles, also research professor at the CSIC in the IBE.

The problem is that many of these species, known and to be known, are being extinguished by forced marches, at a rate of no less than 10,000 to 15,000 per year. “They disappear at a much faster rate than it takes for us to describe them. It is absolutely certain that species will have become extinct and extinct without being able to register them, “adds Belles.

Some species fade completely and others are severely depleted. “There are fewer and fewer insects,” laments Ignasi Bartomeus, a researcher at the Biological Station of the CSIC in Doñana. “When we were children,” he continued, “we were going to hunt fireflies in the field with a boat. Now they are not found, very few are left and only in very well preserved forests “.

Fireflies, but also beetles, bees, butterflies, dragonflies, as well as many other lesser known and popular bugs. Just think about our childhood. 20, 30, 40 years ago, spring was very frequent to see parks, gardens, the countryside, full of butterflies fluttering among the flowers. And ladybirds, and oilers, and bumblebees and grasshoppers. And “the windshield test”: before, getting the car and getting on the highway was to see how the windshield was filled with invertebrates that passed to better life. But what about today?
“People come to us and tell us, alarmed, that they have not seen a ladybug all summer, or a moth, or a bee,” the entomologist Briton Imogen Burt reports in a videotape. Where have the insects gone? Where are they? They ask us. “

SIXTH EXTINCTION MASSIVE

A few months ago, a scientific article published in the journal Science sounded the alarm: we are facing a massive extinction of species unparalleled in the history of the Earth and is due to the actions of the human being. According to this study, only in the last five centuries has human action unleashed a wave of extinctions, threat and decline of animal populations comparable in rate and magnitude to the five previous massive extinctions combined.

To put this claim to the truth: among terrestrial vertebrates – according to this work carried out by a team of international scientists and led by Stanford University (United States) – 322 species since 1500, and populations that have survived to today show a decline in abundance of 15% on average. The data are even less flattering for invertebrates. 67% of monitored species have 45% less abundance, and that decline is causing a cascade of side effects on the functioning of ecosystems and, paradoxes, impacting on the human being.

However, and although this research shed some light on the situation of invertebrates, it is very difficult to know for sure the fate of insects. Missing data. Some countries, such as the United Kingdom, with a great naturalistic tradition, or Germany have censuses of many of their native species. And there are some invertebrates, such as honey bees, monarch butterflies or fireflies, which have attracted more attention and their populations are better documented. On the other hand, of others like beetles, moths, flies, hardly know anything.

The Science study noted that long-term monitoring data from a sample of only 452 invertebrate species indicate that there has been a widespread decline since 1970. And focusing only on the lepidoptera genus, daytime and nighttime butterflies, for which there are better data, it has been seen that they have suffered a decline of 35% in the last 40 years.
“There is almost no data to compare how many insects there were 20 or 30 years ago and how many now, so it is difficult to know the magnitude of the change. A century ago no one was going to do insect censuses to see what the typical abundances were, and in fact, even today there is no good data, “Bartomeus laments.

One of the first reasons for the extinction of certain insects is the loss of habitat. The human being is transforming forests and grasslands, gaining ground for cultivation, roads or housing

To a large extent, the lack of accurate censuses is due to the difficulty of sampling. There are global monitoring networks for some species, often the most popular, such as butterflies. For example, in Europe is the Butterfly Monitoring Scheme, which involves more than 20 countries; these networks are made up of scientists, but mainly amateurs who travel the same routes in the same areas year after year to document what populations of butterflies they find. From the data obtained it is possible to extract which species are in decline, disappearing or migrating in response to the changes of climate.

“It requires a lot of work, expert knowledge, dedication and, above all, funding”, says Guillermo Peguero, postdoctoral researcher at the University of Antwerp and associated with the global ecology unit at the Center for Ecological Research and Forest Applications (Creaf). Barcelona. These more traditional identification methods now include CSI-type techniques. Entomologists take samples from the surface, sift through sieves to separate living organisms and then, in the laboratory, employ molecular genome sequencing techniques to classify and begin to describe communities living in different ecosystems.

“We now have a project in French Guiana where we are doing metabarcoding: we use DNA fragments that we extract from leaf litter samples and make a kind of bar code to sort and determine which communities are in those samples. We describe them without knowing the species that inhabit it, “says Peguero.
But the lack of insect censuses is also out of disinterest. “Humans like animals more than others. There is a lot of information about butterflies, beautiful, colorful, and nothing about others that go unnoticed, even though they perform functions crucial to the environment, “complains Bartomeus.

WHY ARE THEY IN DECLINE?

Surely, one of the first reasons is the loss of habitat, “an educated way of saying that we are appropriating their territory,” Peguero points out. The human being is transforming forests and grasslands, gaining land to cultivate, to cities, to roads. And many invertebrate species can not adapt to these new modified scenarios.

“In some European countries, particularly Nordic countries, help is given to farmers and landowners in nature to maintain open spaces, flower meadows, which are key to biodiversity. Few animals live in thick forests, “says Roger Vila, a researcher at the CSIC at the IBE.

A second factor is pesticides. The neonicotinoids, invented and introduced in the eighties, are the most popular and currently used insecticides all over the planet and are directly involved in the decline of bees, as recent scientific studies have shown. As they were applied to the seeds instead of spraying the plants with them, they were initially considered innocuous. However, they have been found to remain in fields where they are used for a long time.

In a study of 2015 it was shown that near the agricultural land where it was used, both the pollen and the nectar of the wild flowers had high concentrations of this insecticide. And while it does not kill bees directly, it does affect their ability to navigate and communicate.

Something similar happens to beetle players. “There is evidence that since cattle are treated with antiparasitic antibiotics, they have declined dramatically,” says Ribera, an IBE researcher.

Pollution is also one of the causes of the disappearance of invertebrates. “We use the rivers, the sea, as dumpsters; the lakes, like places to make disappear a bike or a refrigerator. The waters are contaminated with the large amount of organic matter that is poured, fecal waters, which are a huge deterioration, “says Óscar Soriano, who is dedicated to studying aquatic insects at the National Museum of Natural Sciences (MNCN). And he adds as a warning: “That aggression we do to nature always has its return, in the form of diseases, plagues or whatever.”

Also light pollution affects them. Light with ultraviolet component disorients them, especially to those that have nocturnal activity, like the fireflies.
The increase in global temperatures due to climate change is another of the factors listed to explain insect decline. These animals are cold-blooded, so they can not regulate their body temperature beyond sunbathing when it is cold and shadowing when it is hot. “And all phases of its development are linked to the outside temperature. If grades increase, their cycles are broken, “says Bartomeus

A WORLD WITHOUT INSECTS?

Okay, so what if some species disappear from the 1.4 million documented or 6 or 7 million more than estimated insects have yet been identified?

There are key species that play a very specific role and if they disappear, that could have important repercussions in the environment, like the bee Apis mellifera, which is the main pollinator of the planet. However, most insects perform common functions, so that if one is extinguished, nothing may happen. However, diversity is crucial to the health of ecosystems, and to disappear several species at a time, the ecosystem can collapse.

“That they disappear is much more serious than it seems. In nature everything is related, they are complex networks of species that interact with each other, “says Bartomeus with forcefulness. For example, lowering the mosquito population has repercussions on many birds that feed on these insects as well as small mammals, such as bats. “

“An ecosystem is like a safety net used by acrobats and trapeze artists, in which each of the knots becomes an animal species and all the links that exist are interactions within the system. We can remove knots randomly and the network will continue to fulfill its function. Now, when it is very weak, it will stop holding the fall. And it will be overnight. It is what in biology is called ‘critical transitions’, ecosystems do not respond in a gradual or linear way, “explains Peguero.

And without insects, there is no agriculture. About 80% of the plants we grow depend on pollinators, and nine out of ten are insects, although there are also birds, lizards … Among the insects, the pollinators par excellence are the hymenoptera, such as bees and wasps. In fact, about 70% of the crops are pollinated by honey bee, Apis mellifera.

“In the United States, bees are rented to pollinate fields. There are huge trucks carrying hives from one field to another. It is a business that moves millions of dollars. People often think it’s something that happens naturally, but nothing at all. Especially for fruit, if there are not enough pollinators in the area, you have to rent bees, “explains Ribera.

In U.S.A. they rent bees, transported in trucks, to pollinate fields, especially those of fruit trees. People often believe that it is something that happens naturally, but nothing at all

Without insects, not only would we run out of agriculture, we would also have a planet full of corpses. Invertebrates are essential for decomposing organic matter. The beetles, for example, play a fundamental role in the recirculation of nutrients in the soil. The wasps, predators, eat other insects and take care of much of the food that falls to the ground in cities, in the countryside.

“Without the insects, the planet would be a kind of dunghill,” says Belles, who continues: “I have been to Patagonia, Argentina, and there are places where there are no insects because the climate is very hard and the trees they die stay there. They dry up, but they are not recycled, and they accumulate. ” The recycling of organic matter is key; without it, the fields would end up being barren in a short time. And if the insects were extinguished, behind would go birds, reptiles, amphibians and small mammals that feed on them.

To these valuable functions we must add the economic value of the species. Many molecules that we use to make new drugs, for example, or to make insecticides come from insects. “When a species is extinguished we are losing potential antibiotics, antiseptics, antiviral, antitumor,” says Soriano. And, of course, they also have to take into account their immaterial value: they are part of the Earth’s natural heritage and only for that reason deserve the efforts and resources to conserve them.

CONCERNING SOCIETY
“To a large extent, the reason insects are in danger of extinction and threatened is due to lack of education,” says Imogen Burt. “Okay,” he continues, “there are things like global warming, habitat loss, pesticides. But in the end the most important thing is that people do not realize the crucial role they play and that there is a massive extinction going on. Many people say, ‘You have to save the bees!’, But then they are only able to name two types, honey and bumblebees. If people do not know, they can not help. ” In Spain alone there are over 1,000 different types of bees, twice as many as birds.

Burt is an entomologist and works at Bug Life, one of only two non-profit organizations in the world dedicated to the preservation of invertebrate species. The United Kingdom is an exceptional case, with a long naturalistic tradition. Your society is very much aware of the need to preserve the environment and is involved in its conservation.

Only there could be a campaign like the one carried out by Bug Life, Beelines, in which it urges citizens to plant flowers in their gardens and on their balconies to save the bumblebees. “Most people want to help, get involved, and things like that can do it,” Burt says. It is key that people know, because if they know, they will want to help, get involved. And only then, as a society, together can we fight to preserve the planet’s biodiversity. “

Vanessa cardui,
the most traveling butterfly
La Vane, as the researchers of the Institute of Evolutionary Biology of Barcelona affectionately call it, is undoubtedly the most traveling butterfly. It makes migrations of 4,000 km, from the north of Europe to the African savannah, in just one week. Despite measuring only five centimeters, this lepidopteran reaches heights of 500 meters and almost 50 km / h. It has an internal compass that always tells you where the south is. To help himself in his long journey, he usually expects winds that are favorable to be carried away. The migrations they make are longer than those of the popular monarch butterfly.

The group of IBE researchers led by Roger Vila has studied the stable isotopes of chitin in the wings of these butterflies and has thus been able to document for the first time this migration, which very few insects are capable of doing.

The butterflies we see today were already flying among the dinosaurs. They are about 200 million years old, while the human being is 300,000 years old. They are on all continents except Antarctica, although millions of years ago they also inhabited the now white continent.

Some 200,000 species of butterflies are known. They are the most diverse group of herbivores on Earth and are the food of a large number of birds, reptiles, amphibians, other insects and small mammals, such as bats.

Beetles,
like spaceships
There are a million species of beetles described. Of the majority, only two or three specimens are known, used to describe the species and little else. “If you look under the magnifying glass, some species of beetle are really beautiful, amazing, with structures that look like spaceships, with incredible horns, very beautiful colors,” says IBE researcher Ignacio Ribera.

In this center of Barcelona they use the beetles as a model to study evolution. “There is more evolutionary difference between two species of beetles than between a platypus and an elephant,” says Ribera. As there are so many different species, there are features or traits that have arisen on more than one occasion and in parallel, allowing them to study morphological changes, evolutionary adaptations.

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