Insects and other arthropods do us countless services, often without our knowledge. If they disappeared overnight, our daily life would be turned upside down! Without them, the whole chain of life would be profoundly changed and the effects on the environment and humanity would be disastrous. Examples? The pollination of many plants would no longer be assured. A host of animals (fish, birds, mammals) would be deprived of food. The recycling of nutrients in soils would be greatly impaired.
In 2006, American researchers assessed the monetary value of services rendered by insects including pest control, pollination, feeding of wildlife and decomposition of excreta. According to them, in the United States alone, these services are equivalent to more than 57 billion US dollars.
It is therefore in our well-being to save insects. To do this, we must first take a fresh look at these little animals. Then, we have to get to know them better and become aware of their ecological role and the benefits we derive from them.
What do insects such as bees, wasps, bumblebees, butterflies, hoverflies, bombyliids, some birds and some mammals have in common? They are pollinators! This role is of paramount importance, since the fruits and seeds generated by the pollination of flowers are used to nourish humans as well as several animal populations. Without pollination, many of the foods and medicines we need to live and survive would not be available.
What is pollination?
When an insect visits a flower, a few grains of pollen (male) attach themselves to its body and have the chance to end up on the pistil (female organ) of a flower of the same species. The meeting between the pollen and the pistil will allow the latter to transform into a fruit filled with seeds. By transporting the pollen from one flower to another, the pollinator therefore allows the fertilization of the flowers. This is pollination!
Some insects are indefatigable pollinators that roam from flower to flower. Without them, you would have to say goodbye to many fruits, vegetables, condiments and spices! It is estimated that one in three mouthfuls of what we eat comes from pollination and that nearly 80% of flowering plants need pollinators to produce fruit and seeds.
Environmental quality indicators
Insects react strongly to environmental disturbances resulting, among other things, from pollution or natural phenomena such as frost, floods or drought. This is why certain insect species are used as biological indicators. Bioindicator species provide valuable information on the quality of the environment, because a more or less abrupt change in the environment often leads to the proliferation or decline of their populations.
Recent studies on the decline of biodiversity around the world point to the destruction of habitats and the extinction of many species. This process is normal and is part of evolution. On the other hand, it increases 100 to 1000 times faster than the normal rate. The balance that exists between living beings and their natural environment is therefore upset to a point that had never been achieved before.
A source of food
Decomposers and plowmen
Certain insects play a fundamental role in the formation of soils and the maintenance of their fertility. By digging tunnels in the earth, insects aerate and loosen the soil, which promotes plant growth. Without the scavenging-decomposing insects, the ground would be littered with rubbish, corpses and feces, which would lead to the growth of potentially dangerous bacteria.
Decomposers are recycling experts. Thanks to their action, the nutrients contained in excreta, dead plants and animals become available again for plants and the entire ecosystem.
Biological control agents
Rather little known, some insects participate in the natural control of insect pest populations. They are divided into three categories: predators, parasites and parasitoids.
Predators attack, kill and consume many preys.
Parasites attack only a small number of preys and their short-term action is rarely lethal to their host.
The parasitoids are very numerous and often very small. In them, the attack leads to the death of the victim in the more or less short term. At first, the victim does not seem bothered by the presence of its occupant, and it develops normally, although it is gradually eaten from the inside. Then, the death of the host is followed by the emergence of one or more adult parasitoids ready to mate and repeat the process.