If these days you happen to go out into the field, and you find a butterfly, a beetle or a grasshopper, take a good look at it, because it might not happen to you again.. The so-called common insects, those that have never caught our attention due to their frequency, and with which we have been living all our lives, are on the path to extinction.
The German Center for Biodiversity Research (iDiv) Halle-Jena-Leipzig has just estimated the speed of disappearance at up to 8% per year, which could wipe them out in just over a decade in habitats in Europe and North America.. On the other hand, less abundant or rarer insect species, although they are also disappearing, do so curiously at a much slower rate, just under 0.3% annually, for a reason that scientists have not yet been able to decipher.
It is estimated that more than 80% of all animal species are insects. It plays crucial roles in almost all ecosystems. They pollinate more than 80% of plants, play a key role in the natural cycle of nutrients and pest control, and are an important food source for thousands of vertebrates.. However, conservation programs have overlooked insects, which only represent 8% of members of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.
Why the world can't afford to lose more insects: “The rate at which they are disappearing is terrifying”
Insects have been reduced by half due to climate change and human pressure in some areas
Although this study did not explicitly investigate the causes of the decline, everything points to human activity and climate change. “Insects seem to be suffering a greater impact than other species as humans conquer the planet,” explains Jonathan Chase, lead author of the study, and professor at iDiv and Martin Luther University (MLU).
The research completes another published in 2020, also by iDiv, which compiled data from 166 studies on insect populations in 1,676 habitats around the world, between 1925 and 2018.. This highlighted the high rate of disappearance of terrestrial insects, such as butterflies, grasshoppers and ants, at a rate of 0.92% per year, which the new study now raises to 1.5%, with peaks of up to 8%.. It is known that these terrestrial species do not do well when it is very hot, such as in the recent waves, and that to survive they need to reduce their physical activity, conserving energy, and seeking refuge in a cooler environment.. The same study also highlighted, at the same time, the increase in the number of insects that live in fresh water, such as mosquitoes and flies, at a rate of 1.08% per year, probably, the study adds, due to protection policies. of the water.
Initially it was thought that the losses of dominant species were being compensated by new species, due to migrations caused by climate change.. Now it turns out that this is not the case. The new ones also suffer, which is having many other implications, since they are a basic food for birds and other animals, and makes them essential to maintain ecosystems.. Other newcomers, however, are doing well, such as the Asian ladybug (Harmonia axyridis), which is now common throughout Europe, America and South Africa.
The iDiv researchers describe their results as “surprising”, although they emphasize that their trends are focused on Europe and North America, and should not be interpreted as a global phenomenon.. Another study, published in 2017, on a nature reserve in western Germany, suggested notable declines in flying insect biomass, as much as 75% over 27 years, sparking a media storm suggesting a worldwide insect apocalypse.. Chase adds: “These declines were seen in long-term data from areas that have remained largely untouched, somewhat like a lifeboat, rather than in areas where there has been a massive conversion from natural area to something like a center.” commercial or a parking lot.
A ground beetle (Poecius versicolor) on a dry leaf. . Vassen
As climate change redistributes terrestrial ecosystems around the world, the world's natural capital is expected to decline, causing a 9% loss of ecosystem services by 2100, according to a study published in Nature.
The disappearance of insects is often referred to as the “windshield phenomenon”: people's perception that there are now fewer insects pressing against their cars compared to a few decades ago.. «Flying insects have indeed decreased on average. However, most are less conspicuous and live out of sight: on the ground, in the treetops or in the water,” explains Chase.
Researcher Ann Swengel has spent more than three decades studying butterfly populations in hundreds of settings in the state of Wisconsin and other nearby states in the United States.. UU: «We have seen a lot of decrease, even in many protected sites. But we have also observed some where the butterflies continue to do well. “It takes many years and many sites to understand the failures and successes, species by species and site by site.”
Regarding the increase in flies and mosquitoes, the positive trend is particularly strong in northern Europe, in the western United States and, since the early 1990s, in Russia. For Jonathan Chase it is a good sign: «Over the last 50 years, measures have been taken to clean polluted rivers and lakes in many places around the world.. “This allowed the recovery of many populations of freshwater insects.”
That's from an environmental point of view, because from a health point of view mosquitoes spread diseases like malaria, yellow fever and the Zika virus, and kill more people than any other creature in the world.. Furthermore, isolated regions are among the most affected areas, so science, at the same time, works for their eradication.. However, their increase, Chase explains: “It shows that we can reverse the negative trends of insects, and it gives us hope.”