“IF ALL MANKIND WERE TO DISAPPEAR, THE WORLD WOULD REGENERATE BACK TO THE RICH STATE OF EQUILIBRIUM THAT EXISTED TEN THOUSAND YEARS AGO. IF INSECTS WERE TO VANISH, THE ENVIRONMENT WOULD COLLAPSE INTO CHAOS.”
Edward O. Wilson, biologist
Insects are the most diverse group of animals on Earth and are omnipresent in terrestrial food webs. However, insect populations are declining drastically across the globe. This phenomenon has accelerated significantly in recent years, particularly in those countries and areas where agriculture is highly industrialized.
Insects – especially pollinators – play a crucial role for the planet as a whole, for the protection of biodiversity, and for agriculture. They are an integral part of our food systems because they pollinate the cultivated plants that end up as food on our tables.
Many insects transport pollen between flowers of the same plant species, allowing for the fertilization of those plants and the subsequent development of fruits and seeds. The miracle of pollination occurs in a variety of ways, but most often relies on the unceasing work of insects: More than 80% (about 300 thousand species) of all plants and 75% (more than 300 species) of our major crops depend on insect pollinators for reproduction. The value of the service that insects provide is enormous – were insects to be paid for the work that they do to produce our food, the cost to society would amount to an estimated 260 billion euros each year.
In addition to pollination services, bees provide precious products including honey, pollen, royal jelly, wax, and propolis, which humans have used and appreciated for our entire history.
When we hear about the decline of bees, it is important to remember that it’s not just honey bees that are being affected, but all species of Apoidea, of which there are more than 25,000. These bees, which are often called “wild” because they are not farmed like honey bees, are just as important for pollination as their domesticated cousins. Their disappearance may be less talked about, but it is no less catastrophic.
The decline of these insects threatens not only their biodiversity and that of the plants they pollinate, but also the diversity of other animals, many of which (e.g. birds and amphibians) feed on insects. And, of course, it poses serious dangers to humanity, putting our food supply at risk.
What are the causes of this apocalyptic threat?
They are many, complex, and interrelated, and humans are at the center of the problem.
Among the most important causes is the wide use of pesticides in conventional agriculture over the last several decades, and the failure to account for the direct and indirect consequences that these substances have on the environment.
Today we are aware of the harmful effects of pesticides, and some have been banned – for example, the European Union has banned the use of various neonicotinoid insecticides that are clearly toxic to pollinators. However, the EU’s current risk assessment system is based on the mortality of adult bees.
This is insufficient because it does not account for pesticides’ “sublethal” effects: The permitted doses of these chemicals cause bees to become disoriented and compromise their immune and reproductive systems; they effect successive generations of bees because larvae may be fed with contaminated pollen (even long after the chemicals are spread), which leads to incomplete and improper development and, eventually, the failure of the colony; and their effects on other wild pollinators are not measured.
Pesticides, fungicides, and herbicides persist in the soil for a long time and can contaminate water and flowers for years after being used.
The climate crises, driven by rising temperatures and CO2 concentrations in the atmosphere, is altering the life cycles of plants: Droughts, violent weather events, and sudden frosts or heat waves compromise plants’ ability to supply nectar and pollen, and when blossoms appear too early or too late, pollinators cannot perform their services or gather the food they need.
According to an article in Science entitled “The projected effect on insects, vertebrates, and plants of limiting global warming to 1.5°C rather than 2°C” with the current forecast of a 3.2°C increase in average global temperature by the year 2100, it is expected that 49% of insect species, 44% of plant species, and 26% of vertebrate species will see their geographic ranges decrease by over 50%.
A temperature increase of 2°C would lead to a range reduction of at least 50% for 18% of insects, 16% of plants, and 8 % of vertebrates, and for a 1.5°C increase, these numbers would fall to 6% of insects, 8% of plants, and 4% of vertebrates.
Widespread bee death and biodiversity loss are locked together in a vicious cycle: Each is both a cause and a consequence of the other. The growing expanses of agricultural monocultures all over the world are food deserts for pollinators and do not offer the habitats that these insects need for nesting and reproduction, thereby weakening their populations and making it difficult for them to adapt.
Another threat to bees is the degradation of soil, a fundamental natural resource at the basis of the ecosystem services that provide for and regulate life on Earth. It takes 500 years for a 2.5-centimeter layer of fertile soil to form under normal conditions, but today phenomena such as erosion, contamination, salinization, and compaction – all caused or exacerbated, directly or indirectly, by human activity – make soil arid and sterile, damaging the ecosystems of which bees and other insects are a part. And this is without even mentioning the rapidly growing areas of land under cement and other kinds of pavement.
In this context, pollinators are becoming increasingly vulnerable and are unable to adapt to the sudden changes that humans are causing in the environments where they live. Globalization has facilitated the rise and spread of ever more aggressive diseases and parasites, which can weaken and kill entire bee colonies.
Beekeepers are constantly engaged with monitoring, prevention, and containment measures, but wild bees have no protection.
Most insects are not dangerous or harmful, and they should not be exterminated indiscriminately.
Natural habitats must be restored and agriculture redesigned. Agroecological practices favor not only pollinators, but also the natural enemies of parasites, thus allowing the agroecosystem to keep itself in balance. It is important to plant crops in alternating strips, to include hedges and mixed species meadows, and to rotate crops with clover and other legumes.
It is also essential to minimize the use of pesticides, especially insecticides and fungicides, in order to allow insect populations to recover and to continue to carry out their beneficial work in the ecosystems that we share with them.