Several sources recently have reported that insect numbers are declining rapidly. For a long time, we have been concerned about bees, especially in their roll as pollinators of fruit and vegetable species of plants, but now it would seem that other insects are declining too. According to an exclusive report by Damian Carrington in The Guardian, at the current rate of decline, insects might be lost by the end of this century.
A global analysis of insect populations has found that 40% of insect special are in decline and a third are endangered. And the rate of extinction is eight times faster than that of birds, mammals and reptiles. The number of insects present on the earth is 17 times greater than that of humans but they are essential for the proper functioning of all ecosystems. Not only do they have a function as pollinators but they also serve as food for some species and have a role in recycling nutrients.
The analysis, published in the journal Biological Conservation, says intensive agriculture is the main driver of the declines, particularly the heavy use of pesticides. Urbanisation and climate change are also significant factors. The main author of this report, Francisco Sánchez-Bayo said that, “The 2.5% rate of annual loss over the last 25-30 years is shocking. It is very rapid. In 10 years you will have a quarter less, in 50 years only half left and in 100 years you will have none.” The report was a comprehensive review of 73 historical reports of insect declines from across the globe, and systematically assessed the underlying drivers.
Habitat loss by conversion to intensive agriculture is the main driver of the declines but other factors are present too, such as agro-chemical pollutants, invasive species and climate change. An abstract of the report mentioned that, in terrestrial ecosystems, Lepidoptera, Hymenoptera and dung beetles (Coleoptera) appear to be the taxa most affected, whereas four major aquatic taxa (Odonata, Plecoptera, Tricpotera and Ephemeroptera) have already lost a considerable proportion of species. Affected insect groups not only include specialists that occupy particular ecological niches, but also many common and generalist species.
A rethinking of current agricultural practices, in particular a serious reduction in pesticide usage and its substitution with more sustainable, ecologically-based practices, is urgently needed to slow or reverse current trends, allow the recovery of declining insect populations and safeguard the vital ecosystem services they provide. In addition, effective remediation technologies should be applied to clean polluted waters in both agricultural and urban environments.
A new article by Science Direct has been published this month (Feb 2020), entitled,
Scientists’ warning to humanity on insect extinctions
The following is the Abstract and Highlights: