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Fires may have affected up to 85 percent of threatened Amazon species

ScienceNews

Since 2001, an area up to the size of Washington state has burned

flames and smoke billow from trees in the Amazon
A fire burns trees in the Amazon basin in Brazil’s Maranhão state in 2014. Fires like these are searing the geographic ranges of thousands of Amazonian species, an analysis of nearly 15,000 plant and vertebrate species finds.MARIO TAMA/GETTY IMAGES

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By Jake Buehler

SEPTEMBER 1, 2021 AT 11:38 AM

Much of the Amazon’s biodiversity is under fire — literally.

In the last two decades, deforestation and forest fires have encroached on the ranges of thousands of plant and animal species in the Amazon rainforest, including up to 85 percent of threatened species in the region, researchers report September 1 in Nature.

The extent of the damage is closely tied to the enforcement, or lack thereof, of regulations in Brazil aimed at protecting the forest from widespread logging as well as the fires often used to clear open space in the forest and other encroachments. The findings illustrate the key role that forest use regulations have in the fate of the Amazon rainforest, the researchers argue.

Threats to the survival of this biodiversity could have long-term effects. Biodiversity boosts a forest’s resilience to drought, says Arie Staal, an ecologist at Utrecht University in the Netherlands who was not involved with this research. A deep bench of tree species allows the plants to replace those that may not survive drought conditions, he says. “If fire-impacted area continues to rise, not only does the Amazon lose forest cover, but also some of its capacity to cope with the changing climate.”

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And as fires advance deeper into the rainforest, more species will experience fire for the first time, Staal says. “These species, including many threatened ones, have not evolved under circumstances with regular fires, so the consequences for those species can be severe.” Such consequences may include increased risk of population declines or extinction, similar to the fears following the major outbreak of fires in Australia in 2019 and 2020 (SN: 3/9/21).

In recent decades, ongoing deforestation and periodic drought in the Amazon basin have been associated with intensifying fires there (SN: 11/20/15). In 2019, a particularly severe series of fires scorched the region (SN: 8/23/19). 

“But we do not know how fires are impacting the biodiversity across the Amazon basin,” says Xiao Feng, a biogeographer at Florida State University in Tallahassee. The Amazon “is a huge area, and it is generally impossible for people to go there and count the number of species before the fire and after the fire,” he says. “That’s an incredible amount of work.”

So Feng and a team of collaborators from Brazil, China, the Netherlands and the United States instead investigated how Amazonian plant and animal species’ geographic ranges have been exposed to recent fires. The team compiled range maps of 11,514 plant and 3,079 vertebrate species, creating what may be the most comprehensive dataset of range maps for the Amazon. The team compared these maps with satellite images of Amazon forest cover from 2001 to 2019. Those images let the team track how logging and fires have led to the degradation of rainforest habitat.

Fire impacted up to about 190,000 square kilometers — an area roughly the size of Washington state, the team found. Up to about 95 percent of the species featured in the study had ranges that overlapped with fires during this period, though for many species, burned areas made up less than 15 percent of their overall range.

Affected species include up to 85 percent of the 610 considered threatened — so vulnerable to extinction or already endangered or critically endangered — by the International Union for Conservation of Nature. This category includes as many as 264 kinds of plants, 107 amphibians and 55 mammals. In 2019 alone, over 12,000 species experienced fire somewhere in their geographic range. 

two white-cheeked spider monkeys swing from trees
From 2001 to 2019, the endangered white-cheeked spider monkey (Ateles marginatus) has had up to about 6 percent of its Amazon forest range affected by fire, researchers say.IGNACIO PALACIOS/GETTY IMAGES PLUS

Starting in 2009, when a series of regulations aimed at reducing deforestation started being enforced, the extent of fires generally decreased, except in drought years, the team found. Then in 2019, fires ticked back up again, coinciding with a relaxation of regulations. Much of the fire-driven forest loss was congregated along the more intensely logged southern reaches of the rainforest.

The shift suggests that effective forest preservation policies can slow this trend of destruction, and may be crucial for preventing the region from reaching a tipping point. That point would occur when the cycle of deforestation, drying and fire triggers widespread transformation of the Amazon basin into a savanna-like habitat.

While this study couldn’t track the fate of specific plants or animals, Feng now plans to look at fire’s impact on certain groups of species that may have very different vulnerabilities to an increasingly flammable Amazon. “We know some trees may be more resistant to burns, but some may not. So it may also be really important to distinguish differences,” he says.

Questions or comments on this article? E-mail us at feedback@sciencenews.org

CITATIONS

X. Feng et alHow deregulation, drought and increasing fire impact Amazonian biodiversityNature. Published online September 1, 2021. doi: 10.1038/s41586-021-03876-7.

About Jake Buehler

Jake Buehler is a freelance science writer, covering natural history, wildlife conservation and Earth’s splendid biodiversity, from salamanders to sequoias. He has a master’s degree in zoology from the University of Hawaii at Manoa.

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NATURE

Deforestation Can Cause Rapid Evolutionary Changes in Insects, New Zealand Case Shows

CARLY CASSELLA15 AUGUST 2021

People in New Zealand have cut down so many trees, some native insects are losing their wings.

In the space of 750 years, humans have changed the natural landscape of the country’s South Island so much, scientists say it’s causing rapid evolutionary changes among certain species.

With no more alpine forest to break the strong mountaintop winds, at least one type of insect is already transitioning out of the flight industry.

Zelandoperla fenestrata is a stonefly with two distinct phenotypes: one with wings, capable of flight; and one with stunted wings or even none, described as flightless.

The flightless type of stonefly is usually found at higher altitudes, where trees are scarce and strong winds can therefore easily blow a flying insect out into the abyss. Meanwhile, the flight-capable flies are typically sheltered in alpine forests, where insects need to explore the full extent of the habitat.

However, in regions where alpine forests have been cut down, researchers have noticed something intriguing. The insects at this elevation, which should usually be able to fly, can’t do so.

It appears that human-caused deforestation has indirectly deprived these insects of their ability to fly, and we did so in a very short space of time, evolutionarily speaking.

Widespread burning of native forest commenced shortly after Māori arrival sometime after 1200 CE, and by now, more than 40 percent of the forests that once covered New Zealand’s South Island have been transformed into grassland and fern-shrubland. Even though this was the last major landmass to be developed by humans, we are already seeing the evolutionary impact on local wildlife.

The now-flightless stonefly is likely just the tip of the iceberg.

“In addition to the local shifts inferred here, it is likely that widespread deforestation has increased the proportion of flightless lineages across large areas of southern New Zealand,” the authors write.

The team worries that without wings, stoneflies won’t be able to search for mates in a larger territorial range, thus increasing genetic diversity. This could possibly impact the species’ health in the long run, as well as the insects’ risk of extinction.

In a rapidly changing world where so many other insects are dying out, that fear isn’t unfounded. By removing the forests that once sheltered stoneflies, we are changing the very way the wind blows.

The authors admit there are probably factors other than wind that make insect flight unappealing on an open mountaintop – such as habitat stability and temperature – but they argue these powerful gusts are the most prominent feature of New Zealand’s mountaintops.

Charles Darwin would probably agree with that conclusion. More than a century and a half ago, Darwin and the botanist Joseph Hooker got into a fiery debate over why so many insects can lose their wings, when they are clearly such useful appendages.

On the islands between Antarctica and Australia, the two scientists had noticed almost all the insects had lost their wings. Even the flies didn’t fly anymore.

Despite skepticism from his colleague, Darwin contended that the wind was to blame. If an insect tries to fly on an open landscape like this, it will simply get swept out to sea. In this situation, the flightless phenotype will always win. 

In recent years, his simple hypothesis has gained more support. In 2020, for example, researchers indeed found wind plays a major role – albeit not an exclusive one – in the loss of insect flight on remote islands of the Southern Ocean. 

In the case of the New Zealand stonefly, researchers suspect the presence of water, the amount of light or the productivity of the population, can all dictate whether an insect population will fly or not.

In all likelihood though, wind, as Darwin once predicted, blows all those factors away.

The study was published in Biology Letters.

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Video: Confronting the ‘insect apocalypse’

by University of Connecticut

insect
Credit: Unsplash/CC0 Public Domain

It’s not just bees and butterflies that are under threat: UConn entomologist and Professor David Wagner says all kinds of insects are at risk for “a death by a thousand cuts.” This is alarming, since insects play vital roles in earth’s ecosystems, including pollination of plants, driving food webs around the planet, and cycling nutrients.

The insect decline is attributed to multiple factors, including the climate crisis, agricultural intensification, development, deforestation, and the introduction of exotic and invasive species into new environments. Wagner cautions that many of these creatures will not be with us for much longer, and says people must act swiftly to help prevent these tremendous losses before it is too late.

Wagner remains hopeful, and says there are many actions that can be taken now—from encouraging political leaders to enact policy changes, to simply letting part of the front lawn grow freely to provide a food-rich environment for insects.

“This planet isn’t here for us to exploit,” Wagner says.https://www.youtube.com/embed/Osg-8HRN8l0?color=whiteCredit: University of Connecticut


Explore furtherScientists decry death by 1,000 cuts for world’s insects

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The impact of field margins on nature and biodiversity 
Field margins are important habitats and networks for nature and they provide corridors for the movement of wildlife and a place for native flora to flourish, without impacting on productivity. File Picture. 

SUN, 20 JUN, 2021 – 17:00AOIFE WALSH 

Thinking about the world outside of the field by managing its margins can have a very positive impact on nature and contribute to the improvement of biodiversity on Irish farms. 

Field margins are important habitats and networks for nature and they provide corridors for the movement of wildlife and a place for native flora to flourish, without impacting on productivity.

Aoife Walsh, Teagasc, and UCD MAIS student highlights some of the key actions that farmers can take to ensure that field margins are retained, maintained, and enhanced for farmland biodiversity.

“Field margins are easy to manage strips of naturally growing vegetation that are found along the edge of fields beside linear features like hedgerows. 

“Field margins are extremely valuable biodiversity habitats that are structurally different from what you might find in the centre of a ryegrass field.

“They are comprised of a variety of plants, including naturally growing wildflowers and grasses that produce flowers and seeds which benefit seed-eating birds like the House Sparrow, the Linnet and the Yellowhammer and pollinators like Bumblebees and solitary bees who avail of pollen and nectar from the margin’s flowering plants.

“Field margins facilitate the movement of wildlife throughout the farming landscape, acting as a highway for nature and providing cover for small mammals like shrews and voles, in turn providing owls with an ideal hunting ground.” 

Field margins require some management in order to optimise them as habitats for biodiversity, Aoife adds. 

Grazing

In grazing situations, field margins should be fenced off to exclude livestock. The area that is fenced can range in width with wider margins providing more room for biodiversity. 

This action will further enhance the structural diversity of the margin by allowing vegetation to flower and go-to-seed.

“Margins should be cut in autumn after plants have flowered, at least once every three years, and this will prevent the vegetation within the margin becoming too rank or turning into scrub.” 

Space

In addition, a minimum space of 1.5m between the main field crop and the base of the surrounding boundary should be maintained when spraying, cultivating, and applying fertiliser, urges Aoife.

“Increasing the width of field margins reduces the need for sprays as the space created will allow for a hedge cutter to mechanically control any encroachment. 

“Blanket spraying under the wire should be avoided as this will lead to the removal of plant diversity. If chemically controlling noxious weeds (ragwort, thistle, docks, male wild hop, common barberry, and wild oats, as listed under the noxious weed act) targeted spot spraying should be practised.

“As is the case with spraying, cultivation also leads to the removal of field margin habitats. 

“Maintaining a minimum distance of 1.5m out from the base of boundaries when cultivating will ensure that an area of margin remains undisturbed allowing the existing diversity to continue to flourish.

  • Aoife Walsh, Teagasc

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Soil Biodiversity Under Grave Threat from Pesticides – Most Comprehensive Review Ever

Posted on May 7 2021 – 3:00pm by Sustainable Pulse« PREVIOUSNEXT »Categorized as

new study published Tuesday by the academic journal Frontiers in Environmental Science finds that pesticides widely used in American agriculture pose a grave threat to organisms that are critical to healthy soil, biodiversity and soil carbon sequestration to fight climate change. Yet those harms are not considered by U.S. regulators.

The study, by researchers at the Center for Biological Diversity, Friends of the Earth U.S. and the University of Maryland, is the largest, most comprehensive review of the impacts of agricultural pesticides on soil organisms ever conducted.

The researchers compiled data from nearly 400 studies, finding that pesticides harmed beneficial, soil-dwelling invertebrates including earthworms, ants, beetles and ground nesting bees in 71% of cases reviewed.

“It’s extremely concerning that 71% of cases show pesticides significantly harm soil invertebrates,” said Dr. Tara Cornelisse, an entomologist at the Center and co-author of the study. “Our results add to the evidence that pesticides are contributing to widespread declines of insects, like beneficial predaceous beetles and pollinating solitary bees. These troubling findings add to the urgency of reining in pesticide use.”

The findings come on the heels of a recent study published in the journal Science showing pesticide toxicity has more than doubled for many invertebrates since 2005. Despite reduced overall use of insecticides, the chemicals most commonly used today, including neonicotinoids, are increasingly toxic to beneficial insects and other invertebrates. Pesticides can linger in the soil for years or decades after they are applied, continuing to harm soil health.

The reviewed studies showed impacts on soil organisms that ranged from increased mortality to reduced reproduction, growth, cellular functions and even reduced overall species diversity. Despite these known harms, the Environmental Protection Agency does not require soil organisms to be considered in any risk analysis of pesticides. What’s more, the EPA gravely underestimates the risk of pesticides to soil health by using a species that spends its entire life aboveground — the European honeybee — to estimate harm to all soil invertebrates.

“Below the surface of fields covered with monoculture crops of corn and soybeans, pesticides are destroying the very foundations of the web of life,” said Dr. Nathan Donley, another co-author and scientist at the Center. “Study after study indicates the unchecked use of pesticides across hundreds of millions of acres each year is poisoning the organisms critical to maintaining healthy soils. But our regulators have been ignoring the harm to these important ecosystems for decades.”

Soil invertebrates provide a variety of essential ecosystem benefits such as cycling nutrients that plants need to grow, decomposing dead plants and animals so that they can nourish new life, and regulating pests and diseases. They’re also critical for the process of carbon conversion. As the idea of “regenerative agriculture” and using soil as a carbon sponge to help fight climate change gains momentum around the world, the findings of this study confirm that reducing pesticide use is a key factor in protecting the invertebrate ecosystem engineers that play a critical role in carbon sequestration in the soil.

“Pesticide companies are continually trying to greenwash their products, arguing for the use of pesticides in ‘regenerative’ or ‘climate-smart’ agriculture,” said Dr. Kendra Klein, a co-author who’s also a senior scientist at Friends of the Earth. “This research shatters that notion and demonstrates that pesticide reduction must be a key part of combatting climate change in agriculture.”

“We know that farming practices such as cover cropping and composting build healthy soil ecosystems and reduce the need for pesticides in the first place,” said co-author Dr. Aditi Dubey of the University of Maryland. “However, our farm policies continue to prop up a pesticide-intensive food system. Our results highlight the need for policies that support farmers to adopt ecological farming methods that help biodiversity flourish both in the soil and above ground.”

Background

The review paper looked at 394 published papers on the effects of pesticides on non-target invertebrates that have egg, larval or immature development in the soil. That review encompassed 275 unique species or groups of soil organisms and 284 different pesticide active ingredients or unique mixtures of pesticides.

The assessment analyzed how pesticides affected the following endpoints: mortality, abundance, richness and diversity, behavior, biochemical markers, impairment of reproduction and growth, and structural changes to the organism. This resulted in an analysis of more than 2,800 separate “cases” for analysis, measured as a change in a specific endpoint following exposure of a specific organism to a specific pesticide. It found that 71% of cases showed negative effects.

Negative effects were evident in both lab and field studies, across all studied pesticide classes, and in a wide variety of soil organisms and endpoints. Organophosphate, neonicotinoid, pyrethroid and carbamate insecticides, amide/anilide herbicides and benzimidazole and inorganic fungicides harmed soil organisms in more than 70% of cases reviewed.

Insecticides caused the most harm to nontarget invertebrates, with studies showing around 80% of tested endpoints negatively affected in ground beetles, ground nesting solitary bees, parasitic wasps, millipedes, centipedes, earthworms and springtails.

Herbicides and fungicides were especially detrimental to earthworms, nematodes and springtails.

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OPINION EXCHANGE 600042914

Minnesota is poised to lead an environmental breakthrough

Minnesota StarTribune

Pending bills would give communities local control over pesticides, safeguard protected wildlife areas and more. By Karin Winegar APRIL 6, 2021 — 5:29PM

NICOLE NERI • NICOLE.NERI@STARTRIBUNE.COMBees are one of the many pollinators harmed by pesticides.TEXT SIZEEMAILPRINTMORE

When I was a child in a southern Minnesota farm town, summers were filled with bird music, bee hum, firefly light and frog song. Then the city sprayed with what I presume was DDT. A great silence followed that fogger.

In 1962, marine biologist Rachel Carson’s bestseller “Silent Spring,” an indictment of DDT, appeared and led to a ban on the pesticide by the U.S. Environmental Protection Agency in 1972.

As an adult, I watched a growing range of chemicals being linked to rises in cancer, nerve damage, obesity, endocrine disruption, death and deformities (frogs, alligators) and die-offs (birds, pollinators, fish) in the natural world. As a journalist, I sometimes wrote about the effects of man-made chemicals and, in particular, the consequences of pesticide and herbicide use.

Now Minnesota stands on the cusp of passing some of the most enlightened legislation in the nation to protect human and ecosystem health. With a handful of bills slated to be heard in the Legislature, we may have reached a critical mass of scientific documentation, legislative smarts and public understanding that could result in a state that is cleaner, safer and healthier for people, pets and vital pollinators.

The pending bills give communities local control over pesticides (HF 718), set rules for pesticide-coated corn and soy seed to avoid contamination (HF 766), prohibit neonicotinoid systemic pesticides (aka “neonics”) and chlorpyrifos (insecticide) in protected wildlife areas (HF 1210), impose a statewide ban on chlorpyrifos (HF 670) and increase pollinator-lethal insecticide fees with revenue allocated to pollinator research (HF 408).

Decades of study by institutions including Cornell University, Harvard University’s School of Public Health, Rutgers University and consumer protection groups show correlations between pesticides and the current insect apocalypse, rises in cancer and pet illness and deaths, and damage to child development.

DDT may have gone, but neonics are far more powerful. Results of a study by the University Koblenz and Landau in Germany, published in Science magazine on April 1, finds “that the toxicity of applied insecticides to aquatic invertebrates and pollinators has increased considerably.”

“These are extremely challenging and complex issues, and Minnesota is offering a number of innovative ways to respond to much-needed protections,” says Aimée Code, pesticide program director of the nonprofit Xerces Society based in Portland, Ore. “Across the country people are seeking answers, and states are looking at what is happening in Minnesota. Minnesota has been creative in seeking solutions through such actions as the Lawns to Legumes program and efforts to label pesticides, to ratchet down pesticide use, to create more bio-sensitive and sustainable agriculture and to give farmers incentives to not use treated seed.

“Currently, [people] think pest control and pesticide are synonymous, and that pesticides should be a first line of defense, ” Code explained. “The vast majority of our invertebrates are foundational species that offer ecological services — everything from pest management, to help filtering our water, to pollination. Chemical pesticides have become ingrained in our agriculture and homeowner practices. We have to think of smarter solutions.”

As farmers, consumers and legislative bodies continue to get smarter about solutions, neonics were banned for outdoor use in the European Union in 2018. Legislation pending in New York, California, Alaska and Massachusetts would do likewise.

Mac Ehrhardt is co-owner of the Albert Lea Seed House, a third generation family firm that put certified organic seed on its menu in 1998. The latter is a small but increasing percentage of Seed House business, he says. And while a majority of farmers purchase seed there based on costs, others recognize the concerns around chemicals.

What is also new on the issue, Ehrhardt says, is “we are getting legislators brave enough to stand up and do what is right even though they know a percentage of constituents will be angry with them.”

The Minnesota bills reflect an understanding that what affects insects, plants and animals affects humans as well.

“The evidence is very clear that neonics can be found throughout the environment now in places they are not expected to be,” says Jonathan Lundgren, an agroecologist, director of ECDYSIS Foundation, CEO of Blue Dasher Farm in Estilline, S.D., and former U.S. Department of Agriculture award-winning entomologist. Lundgren’s recent study of white tail deer spleens demonstrates that the world’s most widely used pesticide class today has negative effects on mammals.

“This has implications for our ecosystem that farmers and legislators alike can appreciate. The response from the ag chem industry is to say their products are safe and helping farmers, but the data really doesn’t support that. Neonics and other chemicals simply aren’t necessary. Farmers are developing systems that make the pesticide question kind of moot. Regenerative farming is proving to be more resilient and more profitable. The scientists got it, and farmers are getting it.”

Karin Winegar, of St. Paul, is a freelance journalist and former Star Tribune staff writer.

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‘No shortage of dangers’ and no easy answers for the monarch butterfly

Justin Cremer | Cornell Alliance for Science | March 25, 2021

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Credit: Edgard Garrido/Reuters
Credit: Edgard Garrido/Reuters

This article or excerpt is included in the GLP’s daily curated selection of ideologically diverse news, opinion and analysis of biotechnology innovation.North America’s monarch butterfly population is in trouble. That much has been clear for decades but scientists have found that affixing blame to the problem is not so simple. Habitat loss, weather changes and pesticides have all at one time or another been fingered as the primary cause, but the truth is messier and somewhat unsatisfying: there is no easy or single answer. Because of that, just what can be done to stop the monarchs’ decline also remains unclear.

Anurag Agrawal, one of the world’s leading authorities on the subject, wishes he could provide a simple solution to the plight of the monarchs, but he can’t.

“When you look at the 25-year trend, it seems quite dire,” Agrawal, a Cornell University professor of ecology and evolutionary biology and the author of Monarchs and Milkweed, says. “There has been a steep, persistent decline in the number of monarchs that overwinter in Mexico every year. But no one is arguing that the monarch butterflies are threatened or endangered as a species. What we are arguing is that the eastern North American migration, in which hundreds of millions of monarchs travel several thousand kilometers every year, is in serious trouble and may be lost.”

“That’s complicated for people to understand,” he says.

Adding to that complication is the fact that monarchs are also found in large numbers in California, Hawaii, Spain, Australia and New Zealand. While Agrawal specializes in the butterflies that live in the Midwest and Northeastern US and Canada, he says that studies also show a 45-year negative trend for California monarchs.

‘No doubt’ humans are to blame

Agrawal, who recently published an analysis of the monarchs’ migration woes in Science, says “there is no shortage of dangers” facing the monarch population, including extreme weather, disease and the loss of milkweed to industrial agriculture. Though he’s hesitant to quantify those dangers, it’s not hard to see the underlying source: mankind.

“There is no doubt that the decline in monarch butterflies over the last 25 years is caused by humans,” he says.

While a host of human factors are contributing to the stark decline in the number of monarchs overwintering in Mexico each year – some 20 million are thought to be killed by vehicles alone – the conventional wisdom for years has been that widespread herbicide use throughout great swaths of the United States has decimated milkweed, which is the only source of food for monarch caterpillars.

But simply pointing to herbicide use as the butterfly-killing bogeyman is oversimplifying a complex issue, Agrawal warns.

“There is no question that in the core agricultural Midwest there is a lot less milkweed than there used to be. But there are two important questions to ask about that. One is what fraction of the monarchs that go to Mexico come from that core area? It could be as low as ten percent or as high as 60 percent, we really don’t know. The second question is that, while it is clear that there is much less milkweed, is there still enough of it? That is another source of debate and it is very complicated,” he says.

According to a 2017 study from the US Geological Survey, over 860 million milkweed stems were lost in the northern US over the past decade and nearly two billion additional sets of milkweed would be needed for the Eastern migratory population of the monarch butterfly to rebound to a sustainable level.

Anurag Agrawal. Credit: Frank DiMeo

‘Constantly changing narrative’

Although monarchs have been embraced by anti-GMO activists (the Non-GMO Project uses a monarch butterfly in its logo), pesticides are hardly the first culprit to be blamed for the long decline of the species. Agrawal says he’s been digging into media coverage of monarchs over the past several decades and “the narrative is constantly changing.”

After scientists discovered in 1975 that hundreds of millions of butterflies from all across the US east of the Rockies were going to what he calls “12 very tiny mountaintops in central Mexico” each winter, the initial thought was that logging in their winter home was the problem. In the 1980s, after a series of ice storms killed as many as half of the butterfly populations in Mexico, extreme weather was blamed. But the debate was changed irrevocably with the 1999 publication of an initial study by Cornell entomology professor John Losey in the journal Nature that said pollen from genetically-engineered Bt corn increased butterfly mortality.Related article:  Honeybees and monarch butterflies on decline but GMOs are not to blame

“The massive amount of attention drawn to this one single-page study was just crazy,” Agrawal says. “It had an incredibly profound effect on the field of agricultural biotechnology. It changed laws in Europe and caused major discussions in the US that really drove the media narrative for more than a decade.”

But Agrawal thinks that the narrative is once again starting to change as scientists and non-scientists alike come to realize the true complexity of the problem. When a species has a life cycle as complicated as that of the monarch butterfly, which has four generations every year and faces a long and treacherous migration, it’s very difficult to put a relative importance to the various dangers it faces.

While Agrawal argues that in the unlikely event that all pesticides were suddenly banned, it would “not necessarily” make monarchs bounce back, he thinks part of the reason the pesticide angle has been so widely embraced is because “it is understandable and it presents a solution: plant milkweed.”


Monarch caterpillar. Credit: Joshua Mayer/Flickr

‘Icon of nature’

The plight of the monarch butterfly also became somewhat conflated with that of the honeybee, which has also experienced puzzling dips in its population. Unlike bees, however, monarch butterflies are not pollinators and Agrawal acknowledges they are “not particularly special from an ecological perspective”.

“If the monarch disappeared it’s unlikely that there would be considerable impact on the rest of the natural world,” he concedes.

Why then, in a world filled with depressing news, should we care about a species that doesn’t really impact us and whose troubles are multi-faceted and hard to understand?

“The monarch is an icon of nature in part because it is such a spectacular looking insect. In the US in particular, you can go out in your backyard and frequently find them, so unlike the polar bear, many Americans feel a personal connection to monarch butterflies,” Agrawal says.

The monarch’s troubles should also serve as a giant red flag, Agrawal adds.

“Some organisms are sort of like the canary in the coal mine and are indicators of the health of a particular location. One of the things that is so cool about monarch butterflies is that they travel from Canada to central Mexico, drinking nectar all along the way. That makes them a potential indicator species for the health of our entire continent. With their numbers declining like they have been over the past 25 years, that should really set off a light bulb,” he says.

Agrawal, who was animated and talkative throughout our nearly 90-minute chat, was at a temporary loss of words when asked how to save the butterflies.

“We have to take a step back and ask ourselves the harder questions that none of us what to deal with. We want to plant milkweed or give $10 to the Nature Conservancy or have an enviro-friendly garden, and I encourage all of those things. But the truth of the matter is monarchs are health indicators for our continent and they are exhibiting multi-decadal declines that point to very big systemic problems. We shouldn’t fool ourselves.”

Justin Cremer is a professional communicator who has spent nearly two decades alternating between journalism and marketing/communications. Find Justin on Twitter @MrJustinCremer

A version of this article was originally posted at the Cornell Alliance for Science and has been reposted here with permission. The Cornell Alliance for Science can be found on Twitter @ScienceAlly

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Sustainable Pulse

US EPA Evaluation Finds Glyphosate Likely to Injure or Kill 93% of Endangered Species

Posted on Nov 28 2020 – 3:21pm by Sustainable Pulse« PREVIOUS| Categorized as

The Environmental Protection Agency released a draft biological evaluation on Wednesday finding that glyphosate is likely to injure or kill 93% of the plants and animals protected under the Endangered Species Act.

Endangered Species

The long-anticipated draft biological evaluation released by the agency’s pesticide office found that 1,676 endangered species are likely to be harmed by glyphosate, the active ingredient in Roundup and the world’s most-used pesticide.

The draft biological opinion also found that glyphosate adversely modifies critical habitat for 759 endangered species, or 96% of all species for which critical habitat has been designated.

“The hideous impacts of glyphosate on the nation’s most endangered species are impossible to ignore now,” said Lori Ann Burd, environmental health director at the Center for Biological Diversity. “Glyphosate use is so widespread that even the EPA’s notoriously industry-friendly pesticide office had to conclude that there are hardly any endangered species that can manage to evade its toxic impacts.”

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Hundreds of millions of pounds of glyphosate are used each year in the United States, mostly in agriculture but also on lawns, gardens, landscaping, roadsides, schoolyards, national forests, rangelands, power lines and more.

According to the EPA, 280 million pounds of glyphosate are used just in agriculture, and glyphosate is sprayed on 298 million acres of crop land each year. Eighty-four percent of glyphosate pounds applied in agriculture are applied to soy, corn and cotton, commodity crops that are genetically engineered to tolerate being drenched with quantities of glyphosate that would normally kill a plant.

Glyphosate is also widely used in oats, wheat, pulses, fruit and vegetable production.

“If we want to stop the extinction of amazing creatures like monarch butterflies, we need the EPA to take action to stop the out-of-control spraying of deadly poisons,” Burd continued.

The EPA has, for decades, steadfastly refused to comply with its obligation under the Endangered Species Act to assess the harms of pesticides to protected plants and animals. But it was finally forced to do this evaluation under the terms of a 2016 legal agreement with the Center for Biological Diversity.

Emails obtained in litigation brought against Monsanto/Bayer by cancer victims and their families have uncovered a disturbingly cozy relationship between the agency and the company on matters involving the glyphosate risk assessment.

In one example, when the U.S. Department of Health and Human Services announced it would be reviewing glyphosate’s safety, an EPA official assured Monsanto he would work to thwart the review, saying, “If I can kill this, I should get a medal.” The Health and Human Services review was delayed for three years.on.”

Earlier this year, relying on confidential industry research, the EPA reapproved glyphosate. The EPA’s assessment contradicts a 2015 World Health Organization analysis of published research that determined glyphosate is a probable carcinogen.

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Science

Toward a world that values insects

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Science  28 Jun 2019:
Vol. 364, Issue 6447, pp. 1230-1231
DOI: 10.1126/science.aaw7071

Insects make up the bulk of terrestrial diversity (1). Reports of insect declines, best documented in Europe and North America, suggest that 40% of insect species in temperate countries may face extinction over the next few decades (2), although this figure is probably inflated (3). Other studies have highlighted falling insect biomass in Germany and Puerto Rico (4, 5), as well as threats to many insect taxa in Europe (5) and insect pollinators worldwide (6) that support food production (7). To protect insects, it is crucial that they are considered as separate species with distinct responses to threats, with particular attention to tropical insects and their habitats. Bees and butterflies may serve as an initial focus, but conservation efforts must go far beyond these iconic species. Halting habitat loss and fragmentation, reducing pesticide use, and limiting climate change are all required if insect populations are to be preserved.

The Main Threats

Trends in biodiversity decline are more severe for invertebrates than for vertebrates (4), because the former are highly specialized in terms of food resources and microhabitats. About half of insect species are herbivores and have intimate relationships with their host plants; the slightest alteration to plant abundance or phenology may therefore have severe consequences for insect populations. Multiple interacting threats affect insects, often with negative consequences not just for the insect species themselves but also for other species that rely on them and for overall ecosystem functioning. However, little is known about the identity, genomics, or ecological role of most insect species.

Habitat loss and fragmentation are probably the most serious threats to temperate and tropical insects, particularly to rare, endemic, and specialized species, resulting in reduced and homogeneous assemblages of generalist species across space (8). Habitat loss is fueled by agricultural expansion and intensification, which involves substantial use of chemical pesticides (insecticides and herbicides). The latter are another substantial threat to insect species; insecticides have been linked to insect decline in temperate countries (2, 4) and to global pollinator decline (6). The increasing introduction of large-scale agriculture in the tropics may similarly cause substantial harm to insect populations through the impacts of pesticides beyond agricultural systems (9). The use of fertilizers and herbicides may also shift plant composition, altering the population dynamics of host plants and dependent insects (3).

Climate change, and especially the frequency of extreme climatic anomalies, may be especially detrimental to tropical insects, which tend to have narrow geographic ranges and low tolerance to changes in temperature and rainfall (5, 10). Invasive species and pathogens may also threaten local populations, as can light pollution (2, 3).

Improving Knowledge

Insects are the central component of the living world, and their protection is crucial to maintaining functioning ecosystems and ensuring food security (4, 7). However, scientific knowledge is limited because of insufficient funding for entomological science and the resulting scarcity of adequate field studies. Many past studies have relied on overall insect biomass measurements, which are relatively easy to conduct (2, 5). However, insect biomass greatly varies in space and time and provides little information about the population dynamics of specific species. Instead, population trends can be summarized by combining insect species into different functional groups (10), which may help to identify which species are coping better or worse with anthropogenic changes (3).

Furthermore, many studies are resurveys—that is, snapshots taken at specific time intervals rather than continuous monitoring. The latter is crucial for evaluating how insects respond to individual threats. Comparison of snapshots is further complicated by habitat changes, does not accurately capture which species are present or absent, and may yield misleading trends (3).

Assemblages monitored in the long term must be representative of local insect populations and reasonably diverse. Findings of low insect densities and rates of local extinction must be corroborated with independent studies, particularly in the tropics, where many species subsist at low densities (10). Further, contrasting insect responses to threats must be acknowledged and scrutinized (3, 10). For example, many native species may be declining in temperate forests, but several pest species are expanding their geographical range in response to climate change (7). Efficient monitoring programs can benefit from recently developed technologies involving molecular methods (11) or bioacoustics, as well as from citizen participation (6).

Conservation efforts cannot succeed without sound ecological knowledge of the role of insects in ecosystem maintenance and functioning and of the complex processes, such as adaptive strategies, food behavior, or cascading trophic interactions, that may be disrupted by threats (5). Because even small ecosystem fragments have conservation value for insect biodiversity and ecosystem services, studies should focus on how to preserve forest heterogeneity, enhance the values of fragments by increasing forest connectivity, and promote habitat restoration favorable to insects. Experiments should investigate the consequences of extreme temperatures, which may reduce the fitness of predatory and parasitoid species. A better understanding and delineation of the species that need to be protected is also important. Taxonomic knowledge can be advanced by training more taxonomists and by developing DNA barcode libraries, which provide tractable and testable taxonomic frameworks (11).

Protection Measures

Insects are of crucial importance for ecosystem functioning (including pollination and forest regeneration), for mitigation of pests, and as a source of protein for animals and humans (7). Effective protection measures can be implemented now to mitigate insect decline by examining the evidence available for temperate insects. If decision-makers fulfill their commitments toward the implementation of the 2015 Paris Agreement to mitigate global warming, threats to insect populations resulting directly from global climate change will be alleviated. In urban areas, policies that favor organic agriculture and insect-friendly gardens can greatly support insect species (12). Planting native species in urban environments such as parks, roofs, and backyards can also help to protect insect populations and deliver pollination services.

In rural areas, insect species would benefit from support for organic agriculture and permaculture, the reduction and more efficient use of pesticides, use of integrated pest management (7), and local-scale farming practices that nurture insect populations. Boosting the abundance, diversity, and continuity of floral resources and providing nesting sites are efficient ways to mitigate pollinator decline (6).

Efficient, appropriate, and permanent conservation measures for natural habitats (such as old-growth forests) and human-influenced areas of even very small sizes can support high insect diversity (3). National coordination, informed by scientific results, can lead to better conservation management, such as supporting effective landscape-scale ecological networks (13). Funding of long-term research activities on habitat conservation in general, and specifically on insect science and taxonomy, is especially important to evaluate and mitigate future changes in insect communities, obtain reliable insect time series, and discover species before they go extinct (1).

Engaging the Public

In general, the public tends to appreciate aesthetic insects such as butterflies and the beneficial role of pollinators (6). These perceptions can be used to strengthen the conservation value of insects. However, bee and butterfly species represent only <4% of the insect species described worldwide (1). Many people have negative perceptions of insects in general and do not perceive them as separate species (14). Further, the roles of insects in ecosystem services can be difficult to comprehend (except for pollinators), as are the consequences of insect species loss and overall attrition of biodiversity.

Although public interest in insects varies from one country to another, biological education about the conservation of insects and their natural habitats is urgently needed at all levels of society, starting with field education programs (14). The extraordinary natural history of insects offers many opportunities in biological education and citizen science (14). Field surveys and experiments help the public to appreciate the importance of insects in terrestrial biodiversity (14). Such activities may promote greater empathy and curiosity toward insects and their habitats. Finally, promoting science through traditional and social media can spread enthusiasm and respect for insects and those who study them.

Embedded Image

A male weevil (Rhinostomus barbirostris) protects an egg-laying female in Panama.

PHOTO: YVES BASSET

Tropical Data Gaps

In the tropics, where most insect species live, circumstantial data exist, but long-term records are too sparse to support the conclusion of a global insect decline. Most tropical datasets (see supplementary materials) were collected in locations buffered from the effects of agricultural practices and habitat disturbance. Most of these studies do not unequivocally suggest a decline in insect abundance or species richness; rather, they point to contrasting patterns in population dynamics and to the possible impact of climate change. This may reflect an initial positive effect of rising temperatures or merely the dynamics of common species (see fig. S1 in supplementary materials). For example, the species richness of a community of leaf litter ants in Ecuador remained constant for a study period of 11 years, with little or no evidence of directional change toward a new community (15).

Longer time series including diverse taxa are urgently required to understand what is going on. However, tropical regions mostly composed of developing countries can only devote limited funds to research on nature conservation. Successful examples of conservation planning and public outreach in temperate regions could be shared with tropical regions and could help to guide insect conservation in those locations. International collaborations involving scientists from both developed and developing nations will be key to expertise sharing, as will be the development of global databases with open access.

Outlook

No matter whether the insect apocalypse is global or not, immediate actions are necessary to mitigate insect decline. Here, more insect-friendly agricultural practices are key. Scientific research into the cost effectiveness of pesticide use will help to reduce unnecessary pesticide applications (9). Redistribution of eco-friendly subsidies to favor insect protection (5) can target integrated pest management, the use of pesticide and fertilizers only when necessary for food security and the protection of remaining natural habitats from land-use conversion. Changes of laws can be implemented quickly using bees or butterflies as the focus of attention, as recently demonstrated in Bavaria, Germany, where a grassroots citizen campaign and a state referendum led to a law necessitating drastic changes in agricultural practice to protect biodiversity.

Efforts to mitigate the effects of climate change, such as the boycott of harmful chemical products by both the public and governments, will also help insect populations to recover. To allow insect populations to prosper in both temperate and tropical areas, scientists and policy-makers need to rethink scientific and public priorities to reach out to the public and develop effective protection measures. We need a bioliterate society that protects insects to ensure humanity’s own survival.

References and Notes

Acknowledgments: Supported by ForestGEO and SENACYT (FID2016-070) (Y.B.) and by GAČ R (19-15645Y) and ERC (669609) (G.P.A.L.).

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Phys Org

Light pollution a reason for insect decline

June 20, 2018, Forschungsverbund Berlin e.V. (FVB)
Counting insects is part of the job. Credit: Gabriel Singer/IGB

Climate change, pesticides and land use changes alone cannot fully explain the decline in insect populations in Germany. Scientists from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) have now discovered that regions that have experienced a sharp decline in flying insects also have high levels of light pollution. Many studies have suggested that artificial light at night has negative impacts on insects, and scientists should pay greater attention to this factor when exploring the causes of insect population declines in the future.

The biomass of flying has decreased by more than 75 per cent—this alarming figure made front page news in autumn 2017. The study, published in 2017, analysed trends in biomass of flying insects in selected protected areas within agricultural landscapes over the last 27 years, and concluded that changes of climate and habitat are to blame for the decline in insect populations. At the same time, they pointed out that these impacts alone are unable to explain this drastic decline.

Light at the wrong time disturbs the balance of ecosystems

Clearly an assignment for scientists from the Light Pollution and Ecophysiology research group at IGB. After all, they know from previous studies that at night strongly affects the number of insects and insect communities. Therefore, the team led by IGB researcher Dr. Maja Grubisic looked at the locations of the areas involved in the 2017 study: areas in conurbations that have a higher than average level of pollution. “Half of all insect species are nocturnal. As such, they depend on darkness and natural light from the moon and stars for orientation and movement or to escape from predators, and to go about their nightly tasks of seeking food and reproducing. An artificially lit night disturbs this natural behaviour—and has a negative impact on their chances of survival,” explains Maja Grubisic the starting point of their investigation.

Experimental field site in Westhavelland Nature Park. Credit: Maja Grubisic / IGB

The scientists analysed all recent studies on the effects of artificial light at night on insects, and found that there is strong evidence to suggest a credible link between light pollution and declines in insect populations. For example, flying insects are attracted by artificial lights—and, at the same time, are removed from other ecosystems—and die from exhaustion or as easy prey. Additionally, rows of light prevent flying insects from spreading; causing a lack of genetic exchange within fragmented insect populations that could reduce their resistance to other negative environmental influences, which are especially pronounced in agrarian areas.

A decline in in agricultural areas—which make up no less than eleven per cent of land use worldwide—does not only mean a decline in species diversity, but also jeopardises important ecosystem services: for example, there are then fewer moths, beetles and flies to pollinate plants. Also, changes in the occurrence and behaviour of pests such as aphids or their enemies such as beetles and spiders can disturb the balance of this well-tuned system. Furthermore, artificial light at night may also have a direct impact on the growth and flowering time of plants, and therefore on yield.

“Our overview study shows that artificial light at night is widely present and can have complex impacts in agricultural areas, with unknown consequences for biodiversity and crop production. Thus, should be generally considered as a potential ecosystem disturbance in future studies to identify ways in which practical steps can be taken to reduce environmental concerns,” says Dr. Franz Hoelker, head of the Light Pollution and Ecophysiology research group at IGB.

Explore further: More than 75 percent decrease in total flying insect biomass over 27 years

More information: M. Grubisic et al, Insect declines and agroecosystems: does light pollution matter?, Annals of Applied Biology (2018). DOI: 10.1111/aab.12440

Read more at: https://phys.org/news/2018-06-pollution-insect-decline.html#jCp

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The Guardian

beetle

Where have all our insects gone?

There is a crisis in the countryside – and a massive decline in insect numbers could have significant consequences for the environmentby , Observer science editor

When Simon Leather was a student in the 1970s, he took a summer job as a postman and delivered mail to the villages of Kirk Hammerton and Green Hammerton in North Yorkshire. He recalls his early morning walks through its lanes, past the porches of houses on his round. At virtually every home, he saw the same picture: windows plastered with tiger moths that had been attracted by lights the previous night and were still clinging to the glass. “It was quite a sight,” says Leather, who is now a professor of entomology at Harper Adams University in Shropshire.

But it is not a vision that he has experienced in recent years. Those tiger moths have almost disappeared. “You hardly see any, although there used to be thousands in summer and that was just a couple of villages.”

It is an intriguing story and it is likely to be repeated over the next few weeks. The start of summer is the time of year when the nation’s insects should make their presence known by coating countryside windows with their fluttering presence, and splattering themselves on car windscreens. But they are spectacularly failing to do so. Instead they are making themselves newsworthy through their absence. Britain’s insects, it seems, are disappearing.

This point was underlined last week when tweets from the naturalist and TV presenter Chris Packham went viral after he commented on the absence of insects during a weekend at his home in the New Forest. Packham said he had not seen a single butterfly in his garden, and added that he sleeps with his windows open but rarely finds craneflies or moths in his room in the morning. By contrast, they were commonplace when he was a boy. “Our generation is presiding over an ecological apocalypse and we’ve somehow or other normalised it,” he later said.

Certainly, the statistics are grim. Native ladybird populations are crashing; three quarters of butterfly species – such as the painted lady and the Glanville fritillary – have dropped significantly in numbers; while bees, of which there are more than 250 species in the UK, are also suffering major plunges in populations, with great yellow bumblebees, solitary potter flower bees and other species declining steeply in recent years. Other threatened insects include the New Forest cicada, the tansy beetle and the oil beetle.

As for moths, some of the most beautiful visitors to our homes and gardens, the picture is particularly alarming. Apart from the tiger moth, which was once widespread in the UK, the V-moth (Marcaria wauaria) recorded a 99% fall in numbers between 1968 and 2007 and is now threatened with extinction, a fate that has already befallen the orange upperwing, the bordered gothic and the Brighton wainscot in recent years.

A great yellow bumblebee. Its numbers have declined steeply in recent years.
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A great yellow bumblebee. Its numbers have declined steeply in recent years. Photograph: Alamy

An insect Armageddon is under way, say many entomologists, the result of a multiple whammy of environmental impacts: pollution, habitat changes, overuse of pesticides, and global warming. And it is a decline that could have crucial consequences. Our creepy crawlies may have unsettling looks but they lie at the foot of a wildlife food chain that makes them vitally important to the makeup and nature of the countryside. They are “the little things that run the world” according to the distinguished Harvard biologist Edward O Wilson, who once observed: “If all humankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed 10,000 years ago. If insects were to vanish, the environment would collapse into chaos.”

The best illustration of the ecological importance of insects is provided by our birdlife. Without insects, hundred of species face starvation and some ornithologists believe this lack of food is already causing serious declines in bird numbers, a point stressed by the naturalist and wildlife author Michael McCarthy. “Britain’s farmland birds have more than halved in number since 1970,” he points out. “Some declines have been catastrophic: the spotted flycatcher, a specialist predator of aerial insects, has both declined by more than 95%, while the red-backed shrike, which feeds on big beetles, became extinct in Britain in the 1990s.”

Further confirmation of the link between insect and bird numbers was provided last week with the publication of a study by Aberdeen University researchers which showed that the plunge in numbers of cuckoos in some areas of England was closely linked to declines in tiger moth caterpillars on which cuckoos feed.

“There is now a lot of correlational evidence to show that when certain insects do badly, very often the birds that feed on them get into trouble as well,” said David Gibbon, of the RSPB.

However, insects also play invaluable roles in other parts of the environment – for example as pollinators of our orchards and fruit fields. And again, scientists are worried. “People think that it is just bees that pollinate orchards, but there are huge numbers of flies that also pollinate – and they are all also threatened,” said Leather.

In addition, flies, beetles and wasps are predators and decomposers who control pests and who generally clean up the countryside. “Just think of the work of the dung beetle,” added Leather. “If they go, the land would be covered with the excrement of cows, sheep and other animals.

The tansy beetle, which is ‘nationally rare’, is the subject of a major conservation programme in Yorkshire.
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The tansy beetle, which is ‘nationally rare’, is the subject of a major conservation programme in Yorkshire. Photograph: Alamy

But perhaps the most alarming indication of the ecological apocalypse we face was provided a few months ago by researchers who published a startling paper in the journal Plos One. Their work was based on the efforts of dozens of amateur entomologists in Germany who began employing strictly standardised ways of collecting insects in 1989. They used special tents called malaise traps to capture thousands of samples of insects in flight over dozens of different nature reserves.

Then the weight of the insects caught in each sample was measured and analysed – revealing a remarkable pattern. The annual average weight of insects found in the traps fell by 76% over the 27-year period of their research. Most alarming, however, was the discovery that the decrease was even higher – 82% – in summer, a time when insect numbers should reach their peak.

Such figures give strong numerical support to the veracity of anecdotes about splattered car windscreens and moth-plastered patio windows becoming a thing of the past. Equally stark is the fact that although meteorological patterns fluctuated to some degree during the years of the study, it was clear that weather was not the cause of the declines.

But perhaps the most alarming aspect of the research was the realisation that these grim drops in insect numbers were occurring in nature reserves – in other words, in areas where the landscape was highly protected and should be the most friendly of habitats for insects. Conditions elsewhere were likely to be a lot worse, the scientists warned.

“Insects make up about two-thirds of all life on Earth [but] there has been some kind of horrific decline,” Professor Dave Goulson of Sussex University, said at the time. “We appear to be making vast tracts of land inhospitable to most forms of life, and are currently on course for ecological armageddon. If we lose the insects, then everything is going to collapse.”

The fact that insect biomass has been declining at a steady rate for almost three decades strongly suggests some profound influences must be at work. Most entomologists believe habitat change lies at the heart of the problem. “There have been massive alterations to the way we use the land and it is hard not to believe these are closely involved in what we are seeing,” said Leather.

As he points out, intensively farmed wheat and cornfields support virtually no insect life, and this means that as intensive agriculture spreads there are fewer and fewer islands of natural habitat left to support them.

A garden tiger moth caterpillar. Changes in habitat caused by intensive farming have been blamed for the decline of insect populations.
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A garden tiger moth caterpillar. Changes in habitat caused by intensive farming have been blamed for the decline of insect populations. Photograph: H Lansdown/Alamy

And then there is the issue of urban spread. Housing schemes continue to encroach on our woods and heaths so that streets and buildings generate light pollution that leads nocturnal insects astray and interrupts their mating. “That is the reason we see most changes to insect life in south-east England, for that is where we see the greatest spread of cities and towns,” said Leather.

In addition to habitat changes, there are the dangers posed by pesticides, in particular neonicotinoid pesticides, which have already been blamed for recent crashes in bee populations. These chemicals are water soluble and so leach out of fields after they are applied to crops.

According to research quoted in the journal Science last year, these pesticides have since been found in high concentrations in nectar and pollen in wildflowers near treated fields. Though still not at levels sufficiently high to kill insects directly, they do affect their abilities to navigate and communicate.

In the face of this mixture of ecological woes, it is perhaps not surprising that insects in Britain are faring so badly. Whether or not they face an ecological apocalypse is a different matter, for not every expert shares a sense of doom. Professor Helen Roy of the Centre for Ecology and Hydrology, for example, sees cause for hope. She told the Observer that there were too many success stories – tales of insects that were recovering in numbers and thriving – to feel a sense of despair. “Obviously, many species are suffering, but I am an optimist and I just don’t think it is right to call this an apocalypse,” she said.

Roy pointed to explosions in the number of ladybirds and painted lady butterflies that have occurred in the past as evidence. “There are huge variations in numbers of a particular insect species in a year and huge variation in the places you see them.” She also pointed to one study of pollinators that showed while 32% became less widespread between 1980 and 2014, 16% became more widespread. “It is not all doom and gloom,” Roy added.

This view was supported by David Gibbons of the RSPB who agreed that not every investigation about insect numbers revealed a tale of irrevocable decline – though he added that he still believed the overall picture was worrying. “It is hard not to see a link between some of the bird number declines and drops in insect populations we are experiencing. There are very close correlations in many cases. But proving there is a causative link – in establishing the one effect is leading to the other – is much more difficult.”

An illustration of the problem is provided by one of the few cases where a causative link between insect loss and bird-number declines has been established: the grey partridge, Gibbons said. “During the 70s and 80s, pesticides were killing off plants on which sawflies and other insects fed. Grey partridge chicks feed on these insects and so this process led to a decline in their numbers – and that has since become dramatic.” In fact, the grey partridge’s drop in numbers has brought its population to less than 5% of its figure last century.

The crucial point is that researchers were able to show that these twin declines were connnected by manipulating herbicide levels in places where chicks were being reared. When herbicide levels went up, insect levels went down and so did bird numbers. “That manipulation provided the causative link,” said Gibbons. “It was possible to change insect numbers and so see the impact. However, such research is difficult to carry out and is very rare.”

And of course, threats to our birdlife are only one aspect of the dangers posed by losses of insects in the UK. As entomologists point out, they also keep our soil fertile, degrade waste, pollinate our orchards and control pests such as the aphid.

“We cannot afford to lose them and that’s what makes this issue so urgent and so important,” Leather concluded. “That’s worth keeping in mind as the summer evenings begin – and we see hardly any insects.”

Ladybirds

Many of Britain’s native species of ladybirds are suffering serious declines in numbers, thanks to the arrival of the harlequin ladybird. It has been declared the UK’s fastest invading species, after reaching almost every corner of the country in just a decade. It preys on native ladybirds and is believed to have caused the decline of at least seven species, including the popular two-spot ladybird, which – when last assessed in 2012 – had slumped by 44% in numbers.

Moths

More than 2,500 moth species have been recorded in Great Britain, of which around 900 are called larger moths. In the report The State of Britain’s Larger Moths 2013, it was revealed that larger moths had declined by 28% between 1968 and 2007. This was most noticeable in southern Britain where there was a 40% decline. By contrast, numbers showed no significant change in northern Britain, where disappearing species are balanced by moths spreading north because of climate change.

Bees

Seventy of the 100 crop species that provide 90% of food worldwide are pollinated by bees. In the UK, there are more than 250 species of bee: 25 species of bumble bee, 224 species of solitary bee and one honey bee species. According to a government report in 2014, figures there has been an overall decline in wild and honey bees over the past 50 years. The figures also revealed evidence that there has been parallel declines in the plants that rely on them for pollination.

Butterflies

The State of the UK’s Butterflies report – produced in 2015 by Butterfly Conservation – provided further evidence of “the serious, long-term and ongoing decline of UK butterflies”. Overall, 76% of the UK’s resident and regular migrant butterfly species had declined in either abundance or occurrence (or both) over the past four decades, it was found. “This is of great concern not just for butterflies but for other wildlife species and the overall state of the environment,” the report noted.

Beetles

These insects eat large volumes of slugs and aphids and large numbers of weed seeds, thus helping to stop fields being overrun by unwanted plants and pests. However, a study, published in the Journal of Applied Ecology in 2012 – which looked at 68 beetle species at 11 locations around the British Isles over 15 years – found that three-quarters of those examined had declined in number over the periodOf these, half had fallen at rate equivalent to 30% per decade.

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