We can think of some insects as pests, but we cannot ignore that they play a very important role in maintaining the natural order of the planet. They provide food for many other species, pollinate plants, recycle nutrients …
However, we are faced with a worrying situation. A review of 73 studies published in the journal Biological Conservation reveals that more than 40% of insect species are in danger of extinction. In some of the cases, the extinction rate of local species is eight times faster than what we are seeing in vertebrates, such as mammals, birds, and reptiles.
The report warns that the dramatic drop in the number of insects around the world faces us with a “catastrophic” collapse of natural ecosystems.
Insects are rapidly declining
” The trends confirm that the sixth major extinction event is profoundly affecting life forms on our planet, ” the researchers wrote in their conclusion.
As early as October 2018, a team of German researchers announced that the country’s insect population had decreased by 77% between 1989 and 2016. An expert from Puerto Rico also reported similar decreases in insect biomass after comparing data from the 70s with those of the present times.
However, local can often be global, and the review just published points in this direction.
In addition to the 40% decline in insects, a third of insect species are in danger of extinction. If we add to the finding that the biomass of insects, the mass of organisms that live in an area, is decreasing by 2.5% per year, we obtain a clear conclusion: there could be widespread extinctions of insects by the end of the century. In 100 years there will be none left.
“Because insects constitute the most abundant and (species-diverse) animal group in the world and provide critical services within ecosystems, such events cannot be ignored and must provoke decisive action to prevent a catastrophic collapse of the ecosystems of nature “, explains Francisco Sánchez-Bayo from the University of Sydney (Australia) and co-author of the work.
To judge the decline of insects, the scientists collected 73 of the best studies ever of insect population declines. Most focused on European and American insect populations, but they also included studies from Australia, China, Brazil, and all of South America.
The most affected species
According to the work, butterflies and moths are among the most affected, with bees and beetles closely following. As an example, butterfly populations have decreased by 58% on cultivated land in England between 2000 and 2009. California’s monarch butterfly population declined by 86% between 2017 and 2018.
Other species, such as ants, flies, and crickets are difficult to measure, but there is little reason to believe that they are much better than butterflies.
The reason
As for the reasons behind this decline, the authors point out that our current agricultural practices are to blame. Removing the trees and shrubs that usually surround fields is fatal to insects. Also, insecticides that harm insects and the soil around crops don’t help either.
Experts recommend drastic changes to our farming methods, seriously reducing the use of pesticides “and replacing them with more sustainable and ecologically based practices.”
If we do not change this rhythm, all insects will follow the path of extinction in a few decades.
Reference: Worldwide decline of the entomofauna: A review of its drivers. Francisco Sánchez-Bayoa, Kris AG Wyckhuys. Biological Conservation 2019 DOI: https://doi.org/10.1016/j.biocon.2019.01.020
