“The unobserved insect apocalypse” should be sounding alarm bells, according to nature conservation advocates who claim that if it is not stopped, it will leave significant consequences for humans and all life on Earth.
theguardian.com, 13 November
Nothing in this world is eternal, not even the Earth or the Sun itself, let alone species. 99% of the species that have ever lived on Earth are extinct. The average lifespan of a species is considered to be around one million years, and the usual rate of evolutionary turnover, if mass extinction is not occurring, fluctuates between 0.1 and 2 species extinctions per million species-years. Assuming there are about 5 million species living on Earth, one has to come to terms with the loss of some 10 species a year. Over the last 500 years, mostly due to man's insatiable economic activity, 322 land-dwelling vertebrate species have disappeared, which is an average of 1.6 species per year. About 158 fish species are also considered recently extinct. When measured against the total number of all possible species, this seems like a mere trifle; however, compared to the number of mammalian (currently 5,416) and bird (currently about 10,000) species, this is an extinction rate at least 20 times faster than would be expected in the course of civilisation-free evolution.
On 13 November 2019, the British newspaper The Guardian once again sounded the alarm regarding threats to biodiversity, this time drawing attention to the death of insects. The publication was prompted by a report prepared at the request of a nature conservation society by Professor Dave Goulson, a Fellow of the Royal Entomological Society: “Insect declines and why they matter”.
Goulson's report, as is usual for works intended for the general public, describes the situation more subjectively than would be permissible in a scientific publication, not sparing the colours to portray the drama of the situation and calling on the public to take immediate action to save what can still be saved. The report does not use results obtained by the author himself, but rather recounts purposefully selected publications that summarise data collected over several decades in several countries on the number and occurrence of insect species.
Recently, insects have become as popular in articles dedicated to nature conservation as birds or plants. Goulson reports, for instance, that in Germany the biomass of flying insects has decreased by 75% since 1989, that the number of butterflies in the British countryside has decreased by 46% since 1976, that the distribution range of 13 (out of 23) bumblebee species has halved, and that in Europe and North America 41% of insect species are threatened with extinction. It is thus concluded that “we are experiencing the largest mass extinction since the late Permian period” 250 million years ago. The drama of the perception of the situation is exacerbated by the terms “insect armageddon” which have been in circulation for several years, and “insectageddon”, coined after the model of “Brexit”.
Insects are a significant part of the ecosystem. Having arrived in the world 400 million years ago, they have managed both to sting plesiosaurs and, as amber formed, to get stuck in the resin of ancient pines like flypaper. Even then, they achieved surprising diversity and distribution. Today, nearly a million insect species have been described – more than half of all known species. It is estimated that at least thirty times more insect species are waiting for their naming ceremony. The total calculated mass of land insects is 3–4 times that of human biomass, despite its tendency towards obesity. The presence of insects is necessary for maintaining balance in nature, for the coordinated functioning of food chains, for the sustenance of insectivorous animals, especially birds, for the pollination of plants and for the formation of soil structure. From the point of view of man's selfish interests, the most economically important task of insects would be to provide the harvest for 75% of crops that cannot do without pollinators. In the spirit of folk songs, one could refer to honey and wax, but let us not forget the brilliant culinary prospects of crickets and insect larvae, silk, chitin, carmine, bee venom and so on and so forth.
If we assume that what is presented in Goulson's report is true and that in the “insect armageddon” of the sixth mass extinction, species are currently disappearing eight times faster than vertebrate species, we can roughly estimate that about 3,900 insect species would have disappeared over 500 years. Given that the possible total number of insect species is 4 million, such an extinction rate still falls within the standard evolutionary turnover: let us remember, up to two extinct species per million species-years.
Apocalyptic visions of the future of insects could perhaps be evaluated not as the extinction of species, but as a demographic crisis and a decline in the biomass of insect species – “nations”. And this, too, is a path to destruction; here, too, civilisation has shown its volcanic power. If the sixth mass extinction is currently gaining momentum, it, like the previous five, is destroying natural habitats, poisoning the environment and causing climate change; only their cause is not natural disaster, but the “eruption” of civilisation. Not volcanic lava, but humans, livestock and crops are taking over natural territories and displacing indigenous species. All elephants, giraffes, lions, bears, hyenas, raccoons and others together make up about one-fifteenth of the total biomass of livestock, primarily cows and pigs.
At the same time, it must be pointed out that insects are characterised by much greater plasticity than mammalian or bird populations; an insect population is capable of both rapidly multiplying in favourable environmental conditions and shrinking in poor ones. One must understand which point in time we choose as the baseline for comparison. Just as in economics: in a given year we can have both GDP growth and a decline, if we take the previous year, 2008, 1989 or 1913 for comparison. Several sources used in Goulson's report can be accused of a tendentious selection of data documenting population decline, and insufficiently long or fragmented observation time series. Thus, a study conducted in Great Britain that showed a gradual decrease in the number of moths after 1982 would be another drop in the mill of armageddon, if it were not known that in the period from 1967 to 1982 the number of these insects increased rapidly and that currently there are more moths in Great Britain than in the time before the great student unrest in Europe and the occupation of Czechoslovakia.
In conclusion, when talking about natural disasters, mass extinctions and crises, we must remember that, in addition to all the destruction, they also possess a creative power. Were it not for the fifth mass extinction 66 million years ago, when a natural disaster caused by an asteroid swept away the hegemony of the dinosaurs, our mammalian ancestors would not have had the opportunity to ride the wave of evolution, and we would most likely still be hiding in caves today, in the form of half-apes, from the teeth of nasty reptiles. Likewise, diversity has its downsides – not even speaking of the contacts on mobile phone chargers. Were it not for the Toba volcanic eruption 75,000 years ago and our cousins in the Homo genus freezing in the volcanic winter, perhaps we would have to fight yetis, bigfoots and snowmen for a seat on the tram.
However, let us not get carried away with revolutionary ideas. So far, mass extinctions of species in Earth's history have ended with the death of the dominant species – whether they be graptolites, trilobites or dinosaurs. At the moment, we are the ones in charge, so let us quote Goethe: “Linger, you are so beautiful!”
Article first published in the January 2020 issue of Rīgas Laiks magazine