Conservationists on Wednesday called for immediate action by governments, industries, and the public to address a decades-long, human-caused insect "apocalypse" detailed in a new report and warned of the sweeping, serious consequences of inaction.

"If we don't stop the decline of our insects, there will be profound consequences for all life on Earth."

—Dave Goulson, ecologist

Insect Declines and Why They Matter (pdf) was commissioned by an alliance of The Wildlife Trusts in the United Kingdom and authored by University of Sussex biology professor Dave Goulson, described by The Guardian as "one of the U.K.'s leading ecologists."

"Insects make up the bulk of known species on Earth and are integral to the functioning of terrestrial and freshwater ecosystems, performing vital roles such as pollination, seed dispersal, and nutrient cycling. They are also food for numerous larger animals, including birds, bats, fish, amphibians, and lizards," Goulson said in a statement Wednesday. "If we don't stop the decline of our insects, there will be profound consequences for all life on Earth."

The report's executive summary says that over that past 50 years, "we have reduced the abundance of wildlife on Earth dramatically." Although "much attention focuses on declines of large, charismatic animals," the report continues, "recent evidence suggests that abundance of insects may have fallen by 50% or more since 1970."

Prof @DaveGoulson's new report reveals that if insect declines are not halted, ecosystems will collapse with ‘profound consequences for human wellbeing’: https://t.co/xyHD1thBoh See the full report here: https://t.co/aI1iR7A4h3#WednesdayWisdom pic.twitter.com/QEqZDMVKpm — Research Development - Sussex Uni (@SussexUniRE) November 13, 2019

Recent findings on insect declines driven by habitat loss and pesticide use are "troubling" because "if insect declines are not halted, terrestrial and freshwater ecosystems will collapse," the report explains. Underscoring the need for action, the report warns that 41% of the planet's five million insect species are "threatened with extinction."

"The good news is that it is not too late," the report emphasizes. "We urgently need to stop all routine and unnecessary use of pesticides and start to build a Nature Recovery Network by creating more and better connected, insect friendly habitat in our gardens, towns, cities, and countryside."

We are sawing off the very branch on which we are standing. This has to stop. Biodiversity loss and carbon emissions must be halted as soon as possible. https://t.co/KOxLHjGtwB — Extinction Rebellion Godalming (@XR_Godalming) November 13, 2019

Insect Declines and Why They Matter outlines the emerging evidence of what it calls "the unnoticed apocalypse," highlighting key takeaways from various studies:

23 bee and flower-visiting wasp species have gone extinct in the U.K. since 1850;

Approximately two-thirds of the crop types grown by humans require pollination by insects;

U.K. "wider countryside" butterflies declined 46% and habitat specialists by 77% between 1976 and 2017;

[The] number of pesticide applications has approximately doubled over the last 25 years;

A survey of honey samples from around the world reveals that 75% contain neonicotinoid insecticides;

U.K. populations of the spotted flycatcher fell by 93% between 1967 and 2016;

Other once-common insectivorous birds have suffered similarly, including the grey partridge (92%), nightingale (93%), [and] cuckoo (77%); and

The red-backed shrike, a specialist predator of large insects, went extinct in the U.K. in the 1990s.

"This unnoticed apocalypse should set alarms ringing," Wiltshire Wildlife Trust chief executive Gary Mantle declared in response to the report.

"We have put at risk some of the fundamental building blocks of life," Mantle said. "But as this report highlights, the main causes of insect declines are known and we can address them; insects and other invertebrates can recover quickly if we stop killing them and restore the habitats they require to thrive. But we all need to take action now in our gardens, parks, farms, and places of work."

The report details various actions that garderners and allotment holders, local authorities, governments, regulators, industry, farmers, growers, land managers, policymakers, consumers, parents, and doctors can take "to help invertebrate populations to recover."

Very worrying new report from @SomersetWT shows the risk to food production if insect declines continue. We can reverse this if we move to nature-friendly farming methods, with farmers rewarded for providing public benefits such as habitats for wildlifehttps://t.co/KRQEYROFPH — CPRE The countryside charity (@CPRE) November 13, 2019

Steve Garland, entomologist and chair of The Wildlife Trusts' policy body for England, said Wednesday that "I really believe that the catastrophic decline of insects can be reversed by drastically reducing the use of chemicals in the environment and by creating a strong Nature Recovery Network to give them space to live and thrive in safety."

Josie Cohen, head of policy and campaigns for Pesticide Action Network U.K., concurred.

"Reducing pesticide use is a challenge that society can no longer ignore," said Cohen. "We applaud the Wildlife Trusts and others for highlighting that routine overuse of pesticides is harming wildlife and the ecosystems that underpin our health and prosperity."

Urging the U.K. government to adopt measures to drive down pesticide use, she added that "we need an ambitious pesticide reduction target accompanied by a package of support for farmers to help them transition to non-chemical alternatives."

We *can* reverse this worrying trend. Author @DaveGoulson supports farming reform; if you agree, please sign our petition calling for gov't action on #pesticide reduction, and help for farmers to shift to nature friendly methods.https://t.co/1RjLpDIAQ4 #NatureFriendlyFarming — Friends of the Earth (@friends_earth) November 13, 2019

While Insect Declines and Why They Matter points to habitat loss and pesticide use as key causes of insect declines, it also acknowledges other pollutants and stressors, from "heavy metals such as mercury released by mining and industrial processes" to invasive species and the human-caused climate crisis.

The Wildlife Trusts' new report followed global scientists' demand last month for a "paradigm shift" in land-use policy in response to a decade-long biodiversity study that showed "frightening" declines of insects and spiders in German grasslands and forests.

Other recent research on insect decline includes a May report by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services that found human activity threatens one million plant and animal species with extinction as well as a study published last year about climate crisis-driven 'bugpocalypse' in Puerto Rico's Luquillo rainforest.