With insects, there is an annoying paradox: entomologists have warned for a long time that there are more and more disturbing signs about their status (people of a certain age can realize on their own that something has changed in this field), however, since then from the point of view Scientific, the lack of continuous data on the populations of these small organisms makes it extremely difficult to gauge the true scale of the problem. This, in turn, complicates the possible answer. Now a study by researchers from the National Museum of Natural Sciences (MNCN), the University of Murcia and two British institutions, Posted in Preserving biological diversity, Explains that this barrier to knowing what happens with these arthropods does not disappear even with the most complete inventories that exist.

“We wondered what the best insect data in the world were and found it to be that of butterflies in Great Britain,” says Jorge Lobo, an entomologist at MNCN, explaining that there are more than 10 million records of 58 species of Lepidoptera in this region collected for more than 200 General, 1800 to 2014. An exceptional amount of insect information is only available in rare places like this one because of the great British natural fondness and because of the specific affinity for beautiful butterflies.

Although there is already talk about “The end of the world of insects”There are various complications to scientifically prove the collapse of these animals. As Lobo points out, one of them is that strong inter-year differences in their populations are common among these arthropods, with sharp depressions and elevations. It may happen that a simple untimely storm or strong influence of human origin causes specimens of some species to fall into a certain area and their number doubled again at a later time. To determine if a decline is actually occurring, continuous inventories are needed to be able to compare in different places and over long periods, which is very rare for these species on the planet as a whole.

In the case of the butterflies of Great Britain, with many records from the year 1800 of a not very large number of species (there are roughly the same number of Lepidoptera In the city of MadridYou might think that everything is already known about the spread of these insects in this part of the world. According to an MNCN researcher, “The surprise we got was that it wasn’t.” Spanish scientists discovered that the inventory was incomplete in a third of the area analyzed, to be precise, in a few places in northern Great Britain. “We asked why and we realized that this is due to the entry of these northern regions of the species that come from the south. Nature is dynamic and that is why our ability to discover what is happening is limited,” Lobo asserts.

Despite their size, insects can move for miles in search of better conditions, once again making it difficult to tell what’s going on. “Sometimes there is not an extinction as much as there is a change in the distribution,” the researcher notes. “What we have today does not allow us to know the truth, because the moment we get enough information, the truth changes,” he says.

However, this does not remove the mountain of evidence warning that these arthropods are declining. As Lobo warns, there are worrying data: “We are enough scientists to confirm that there is a decrease in the number of insects and a remarkable loss of biodiversity.”

Investigations into Germany, The United kingdom The Puerto Rico They recorded incredible collapses of insect biomass, that is, the weight of these animals in certain areas. And in Spain, an MNCN researcher personally investigated steep falls in dung beetles (those that build and roll fecal balls). In the groups of this family of beetles prior to 1950, the percentage of baseball players was about 30%, but it does not currently reach 5%. “The color is white and in the bottle, the difference is so noticeable that there are no other explanations,” says Lobo.

However, there are other contradictory results. Also in Spain, The 2018 study Researcher Carlos Herrera in the Sierra de Cazorla did not find any decrease in pollinator abundance between 1997 and 2017 despite large changes in temperature or precipitation, suggesting that the decline is not the same everywhere.

For review 73 scientific papers published in 2019 in Biological conservation, By Spanish ecologist Francisco Sanchez Bio, from the University of Sydney (Australia), warned that at current rate 40% of insect species could become extinct in the coming decades. But shortly thereafter, Finnish scientists from the University of Jyväskylä responded to this article with an analysis in Rethinking Ecology They accused the investigation of being troubling and criticized some aspects of the methodology without questioning the insect degradation.

“The pattern that emerges is alarming, but we only have point data. From a scientific point of view, we shouldn’t be worrying if the data aren’t completely reliable, but the signs are alarming and that should be said,” says Lobo.

How do you address the shortage of reliable data even if the best sets of records in the world are not enough? To solve this lack of information, while keeping in mind the dynamic movement of nature, the researchers in this study argue that each country should choose a series of areas to conduct continuous inventories. Just as there are fixed weather stations that record weather changes at every moment, they suggest the existence of stations that measure biodiversity.

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