Insects are essential for the proper functioning of ecosystems, and their extinction could threaten the survival of humanity. This is the alarming finding of a report published by the scientific journal Biological Conservation, which indicates that 40% of the insect species could disappear in the next decades. Within a century, there may well be no more insects at all, even claimed researchers interviewed by the Guardian.
Francisco Sánchez-Bayo, from the University of Sydney, is one of two researchers behind the publication. With Kris Wyckhuys, from the Academy of Agricultural Sciences in Beijing, he has selected 73 studies to document the decline of insects in order to measure and highlight the causes of this phenomenon.
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How is this report on insects unpublished?
Studies at the national level have already revealed a significant decline in insect populations in Germany (-75% in 30 years) and in Puerto Rico (-98% in 35 years), but this is the first to be carried out on a scale. World. It is because long-term studies were available, as is the case for the 73 studies from around the world that we compiled, that it is now possible to identify global trends in species decline for the world. 'to come up. Thus, our study found that the total mass of insects on the planet has decreased by 2.5% each year for thirty years. Butterflies and Trichoptera are the most affected.
What method (s) were used to produce your report?
We collected data on the extinction and decline of each species provided by each study. Then we calculated the average number of declining and endangered species for each group of insects and for each region of the globe. Similarly, we have calculated percentages of declining or endangered species. These entomological studies [qui étudient les insectes, ndlr] use very similar methods to estimate the number of species in a given region.
How to explain the decline in the number of insects?
The causes are multiple, and some are simultaneous. In order of importance: the disappearance of the living environment of insects due to agricultural expansion and urbanization – deforestation also playing a decisive role; pollution caused by industrial and agricultural chemicals, especially fertilizers and pesticides; biological agents (such as invasive species and pathogens) and finally climate change. This latter factor is important in the tropics and in the mountains, where insects do not withstand rising temperatures. On the contrary, in Europe and America, insects live better in a hot climate.
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What could be the solutions to slow down or stop the decline of insects?
We need to change the way we produce food. Our modern agriculture has become intolerable to insects, which has never happened in the millennium. Today, the difference is that instead of using pesticides only when necessary (for example to stop an invasion of pests), we cover most insecticide crops. These remain in the ground, then water, and contaminate the entire environment. This preventive use of insecticides kills all insects in the fields, land and water, regardless of whether or not they are pests. This irrational system does not even lead to better returns, as evidenced by recent studies. It is urgent to restructure our agricultural system, otherwise all the insects will disappear during our life, and with them all the other animals (birds, lizards, frogs …) that feed on them.