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human activity and the destruction of the planet


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Decline in insect numbers threatens food availability

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.

https://www.theguardian.com/environment/2019/feb/10/plummeting-insect-numbers-threaten-collapse-of-nature

insects

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.

https://www.sciencedirect.com/science/article/pii/S0006320718313636#f0005



A new article by Science Direct has been published this month (Feb 2020), entitled,

Scientists’ warning to humanity on insect extinctions

https://www.sciencedirect.com/science/article/pii/S0006320719317823

The following is the Abstract and Highlights:

Abstract

Here we build on the manifesto ‘World Scientists’ Warning to Humanity, issued by the Alliance of World Scientists. As a group of conservation biologists deeply concerned about the decline of insect populations, we here review what we know about the drivers of insect extinctions, their consequences, and how extinctions can negatively impact humanity.

We are causing insect extinctions by driving habitat loss, degradation, and fragmentation, use of polluting and harmful substances, the spread of invasive species, global climate change, direct overexploitation, and co-extinction of species dependent on other species.

With insect extinctions, we lose much more than species. We lose abundance and biomass of insects, diversity across space and time with consequent homogenization, large parts of the tree of life, unique ecological functions and traits, and fundamental parts of extensive networks of biotic interactions. Such losses lead to the decline of key ecosystem services on which humanity depends. From pollination and decomposition, to being resources for new medicines, habitat quality indication and many others, insects provide essential and irreplaceable services. We appeal for urgent action to close key knowledge gaps and curb insect extinctions. An investment in research programs that generate local, regional and global strategies that counter this trend is essential. Solutions are available and implementable, but urgent action is needed now to match our intentions.

Highlights

We are pushing many ecosystems beyond recovery, resulting in insect extinctions.

Causes are habitat loss, pollution, invasives, climate change, and overexploitation.

We lose biomass, diversity, unique histories, functions, and interaction networks.

Insect declines lead to loss of essential, irreplaceable services to humanity.

Action to save insect species is urgent, for both ecosystems and human survival.