Loss of Insects

A study published in PLOS ONE finds a massive decline of insect populations.

[U]sing Malaise traps deployed over 27 years in 63 nature protection areas in Germany ..., [o]ur analysis estimates a seasonal decline of 76%, and mid-summer decline of 82% in flying insect biomass.

Explanations are not clear.

Their results align with recently reported declines in vulnerable species such as butterflies, wild bees and moths, but also suggest a severe loss of total flying aerial biomass, suggesting that the entire flying insect community has been decimated over the last few decades. 

The researchers found that this dramatic decline was apparent regardless of habitat type, and changes in weather, land use, and habitat characteristics were not able to explain the overall decline.

The study signals an impending ecosystem collapse.

Loss of insects is certain to have deleterious effects on ecosystem functionality, as insects play a central role in a variety of processes, including pollination, herbivory and detrivory, nutrient cycling, and providing a food source for higher trophic levels such as birds, amphibians, and mammals.

Update (September 26, 2018):  Somehow this seems more depressing that all the political crap we endure day after day.

Monarchs have lost an estimated 165 million acres of breeding habitat in the United States to herbicide spraying and development. The caterpillars only eat milkweed, but the plant has been devastated by increased herbicide spraying in conjunction with corn and soybean crops that have been genetically engineered to tolerate direct spraying with herbicides.

Overall monarchs have declined by more than 80 percent over the past two decades.

Update (October 16, 2018):  A study published in the Proceedings of the National Academy of Sciences finds large declines of insect populations in Puerto Rico. The magnitude of the loss has been described as "alarming".

Update (December 9, 2018):  Robert Hunziker on the loss of insects.

[S]omething is dreadfully horribly wrong. Beyond doubt, it is not normal for 50%-to-90% of a species to drop dead, but that is happening right now from Germany to Australia to Puerto Rico’s tropical rainforest.

Update (December 14, 2018):  Subhankar Banerjee says a biological annihilation is underway.

Update (January 2, 2019):  While there are several troubling studies, Mary Hoff points out that the overall picture on insects is mixed.

Although these results are disturbing, they’re not definitive. In some cases, they could indicate issues facing specific insect species or characteristics of specific locations rather than an overarching trend.

Update (February 11, 2019):  A review of 73 historical reports published in Biological Conservation finds "dramatic rates of decline that may lead to the extinction of 40 percent of the world's insect species over the next few decades". Total insect mass is declining 2.5 percent per year.

[H]abitat loss because of intensive agriculture is the top driver of insect population declines. The heavy use of pesticides, climate change and invasive species were also pinpointed as significant causes.

Update (February 26, 2019):  Evaggelos Vallianatos promotes agroecology.

[W]e have the knowledge and the tools to return to sustainable farming that will take advantage of the "built-in defenses" in the natural world. Insects are part of this equilibrium and strategy.

Now it’s a matter of political choice to work with nature, in which case, we can probably end the decline and extinction of insects and face, with equal determination, our next nemesis of rising global temperatures.

Update (April 10, 2019):  A report from the Universities of Sydney and Queensland and the China Academy of Agricultural Sciences warns that a massive loss of insects could mean a "catastrophic collapse of nature’s ecosystems".

40 percent of insect species are now threatened with extinction, and the world’s insect biomass is declining at 2.5 percent a year.

Update (November 2, 2019):  Robert Burrowes ruminates on the decimation of insects.

Update (February 7, 2020):  A study published in Science finds that bee populations are declining in areas with more frequent instances of extreme heat.

Update (February 18, 2020):  Out of the million species that are at risk for extinction, about half are insects. Pedro Cardoso says many people don't realize their value.

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.

Update (July 30, 2021):  Dave Goulson discusses the value of insects. He notes populations are estimated to have declined by 75 percent or more in the past 50 years.

Few people seem to realise how devastating this is, not only for human wellbeing – we need insects to pollinate our crops, recycle dung, leaves and corpses, keep the soil healthy, control pests, and much more – but for larger animals, such as birds, fish and frogs, which rely on insects for food. Wildflowers rely on them for pollination. As insects become more scarce, our world will slowly grind to a halt, for it cannot function without them.