Frankly, what do we care about flies, praying mantises and other ants? Not much, if one answers frankly. And yet, we would do well to worry about it… In Silent Land. Preventing the extinction of insects (Rouergue editions), the British biologist Dave Goulson warns of the decline of world populations of insects.
If there are not yet global figures, several local studies attest to the phenomenon. The best known, that of the Krefeld Entomological Society (2017), indicates a 76% decline in the biomass of flying insects between 1986 and 2016 in Germany. Another, from the United Kingdom, observes a 46% decline in the population of butterflies in rural areas between 1976 and 2017. Orders of magnitude that can be found in other industrialized countries such as France or the UNITED STATES.
After a captivating chapter on the history of these small invertebrates, which moreover constitute the majority of known species on our planet, the researcher at the University of Sussex (United Kingdom) describes with pedagogy the “major” role of these critters. In particular, they occupy a fundamental place in the food chain. It’s cruel, but some insects (like caterpillars, grasshoppers, ground beetles, etc.) are “tasty protein” for animals larger than themselves, like birds, bats, reptiles, and small mammals. Without the insects, these would have almost nothing left to eat, breaking the rest of the food chain.
The disappearance of these “babies” would also impact the human diet. Westerners sometimes tend to forget it, but it is absolutely normal to feed on insects elsewhere in the world. “In Japan, canned inago (grasshopper) is widely sold as a delicacy,” recalls Dave Goulson. In South Africa, we also love mopane worms, namely a species of very large juicy caterpillar.
In addition to being nutritious, some insects provide many services to the environment. Raising locusts, for example, produces far less greenhouse gases than raising cattle. “For 1 kg of meat supplied, a cow requires 55 times more water and 14 times more space than a cricket”, adds the professor of biology, aware that there is still a long way to go before convincing Europeans and North Americans to swap their prime rib for a salad of locusts…
Insects also provide wonderful ecosystem services. They are the ones who pollinate the flora and, by extension, govern the world. Nine out of ten plants need animal pollination, carried out largely by insects, to reproduce. “Without pollination, wildflowers would not produce seeds, and most would eventually die out,” writes Dave Goulson.
Without pollinating insects, it would also be impossible to properly feed humanity, whose population is increasing. Certainly wheat, barley, rice and maize, which are satisfied with the pollen carried by the wind, could produce sufficient calories. But we would have to say goodbye to strawberries, apples, cucumbers, beans and other tomatoes… “The world already produces less fruit and vegetables than would be necessary for everyone on the planet to enjoy a healthy diet. healthy,” says the author.
The role of insects is so important that it even has its monetary value – admittedly approximate. It is between $235 and $577 billion globally. It is more or less the GDP of Greece (for its minimum value) or that of Norway (for its maximum value).
After convincing the reader of the close connection between insects and humans, the author tackles the many causes of their “extinction”. The disappearance of their habitat is the first explanation given. The construction of roads, housing estates, the development of intensive agriculture and deforestation are dramatically reducing the place of wild or semi-wild nature. But it is in these places that insects thrive…
The use of insecticides (such as neonicotinoids), whose virtues should be emphasized on the strict aspect of agricultural production, also has the effect of “poisoning” the soil and killing certain insects, such as bees. The spreading of herbicides, in addition to poisoning the insects, drastically reduces the playing field of these little critters. The author also writes that the use of chemical fertilizers in some pastures promotes grass growth at the expense of flowers. So we end up with “green deserts”.
Dave Goulson concludes his book with a valuable suggestion box. He recommends greening urban spaces, installing hives for bees in the city, banning the use of pesticides and reducing light at night as much as possible. All these actions have already been undertaken in a certain number of French cities, such as Paris. The British researcher also suggests increasing the number of shared garden plots in the city, places “favorable to the diversity of pollinators”.
Above all, the author calls for a real revolution in the agricultural model. For example, by reconnecting with bocage hedges, which have shrunk to a trickle with agricultural consolidation and the development of intensive cereal farming. He recommends (unsurprisingly) to develop organic farming, less greedy in pesticides. Finally, Dave Goulson calls for financing the rewilding of the planet. When we let it go, nature regenerates.
Silent land. Prevent the extinction of insects, translated by Ariane Bataille, Rouergue editions, 400 pages, 23.80 euros.
