The Silence of the Bugs

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The Silence of the Bugs

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CURT STAGER - 26 MAY 2018 - THE NEW YORK TIMES

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Credit Enzo Pérès-Labourdette

Fifty-six years after Rachel Carson’s “Silent Spring” warned of bird die-offs from pesticides, a new biocrisis may be emerging. A study published last fall documented a 76 percent decline in the total seasonal biomass of flying insects netted at 63 locations in Germany over the last three decades. Losses in midsummer, when these insects are most numerous, exceeded 80 percent.

This alarming discovery, made by mostly amateur naturalists who make up the volunteer-run Entomological Society Krefeld, raised an obvious question: Was this happening elsewhere? Unfortunately, that question is hard to answer because of another problem: a global decline of field naturalists who study these phenomena.

Most scientists today live in cities and have little direct experience with wild plants and animals, and most biology textbooks now focus more on molecules, cells and internal anatomy than on the diversity and habits of species. It has even become fashionable among some educators to belittle the teaching of natural history and scientific facts that can be “regurgitated” on tests in favor of theoretical concepts.

That attitude may work for armchair physics or mathematics, but it isn’t enough for understanding complex organisms and ecosystems in the real world. Computer models and equations are of little use without details from the field to test them against.

Are we in the midst of a global insect Armageddon that most of us have failed to notice? Here’s another data point: A decades-long decline in plant-pollinating hawk moths has been reported in the Northeast, but its causes and consequences are uncertain because we know so little about the ecology of these insects. In days past, compiling such information would have made a respectable life’s work for a Linnaeus, Humboldt or Darwin. Now such creatures are often ignored because studying them seems unlikely to generate publications, headlines or grants that provide academics with tenure and prestige.

This leaves us with little more than anecdotal evidence to work with. A recent story in The Telegraph noted that automobile windscreens in Britain are no longer heavily caked with splattered insects. It reminded me of the tiny wings, legs and antennas that used to smear the front of my car after midsummer drives during the 1970s. Nowadays, a drive through northern New York, where I live, yields barely a blemish. Is it because cars are more streamlined? Not likely. Last July, I examined parked vehicles in Saranac Lake and found little or no bug debris, even on license plates or the blunt fronts of vans.

What’s behind the decline? Probably not climate change, according to the researchers in the German study who also monitored local weather during the survey. What about collisions with vehicles? Despite my experience and the dashboard observations in Britain, one study published in 2015 estimated that hundreds of billions of insects are being killed in North America by cars and trucks every year. The study’s authors called for additional research to determine whether what they found is “contributing to the substantial declines of pollinating insects occurring on a global scale, thus putting the ecological functioning of natural areas and agricultural productivity in jeopardy.”

Cars were probably not the culprit in the German study, though, because it focused on nature reserves where road carnage is minimal. For some experts, the process of elimination leaves pesticides among the likely suspects.

Why care about this new silence of the bugs? An across-the-board decline in flying insects, if true, means that an entire sector of the animal kingdom is in trouble, representing an immense diversity of life-forms, from butterflies and beetles to hoverflies and damselflies. The eminent biologist Edward O. Wilson, who has spent much of his life studying ants, has warned: “If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos.”

So there it is. Could it be that whatever might be causing these insect deaths could be a threat to us too?

The widely reported decline of honeybees in the United States pales in comparison with the drop-off of bugs in Germany, if not in scale, then in the loss of biodiversity. Insects represent the vast majority of all animal species. Because they are pollinators and a vital part of the food chain, their absence would strike deep at the roots of life on earth.

I’m a lake scientist, and my colleagues and I have been struggling to explain our own mystery: a restructuring of plankton communities in lakes worldwide in recent decades, which we’ve documented by examining sediment cores extracted from lake bottoms. This could signal problems for water quality, fisheries or other aspects of lake ecology. Had we not taken the core samples, the geographic scale of this change might remain undetected, because funding and rigorous field monitoring of plankton composition in lakes has often been lacking.

Some experts have attributed the plankton shift to climate change, others to nitrogen pollution from agricultural runoff, but we need more long-term field studies to confirm the cause and anticipate its effects. The German insect data suggest another possibility. Could agricultural chemicals be poisoning aquatic organisms, including plankton and insects that begin their lives as aquatic larvae? We simply don’t know.

In Britain, the news report about car-insect collisions was based on a study that relied on data from volunteers who monitored gridlike “splat-o-meters” on their license plates. We need more of this sort of scientist-directed crowdsourcing. Citizen scientists and a few field-research-oriented college communities like my own at Paul Smith’s College in the Adirondacks of New York are turning their yards, gardens, lakes and forests into long-term monitoring stations. Online clearinghouses like iNaturalist, Budburst and the North American Breeding Bird Survey compile and archive field data for others to use, and show that many species are changing their ranges and migration habits in response to climate change.

In the United States, research scientists associated with a network of more than two dozen long-term ecological monitoring centers have also been conducting more detailed field research for several decades. But these efforts are still not enough to keep track of a rapidly changing world. We need new crops of professionals trained in field biology and ecology to focus on important but less charismatic or commercially valued creatures than songbirds and honeybees.

In 1996, an editorial in Conservation Biology warned that “naturalists are dying off,” and asked: “Will the next generation of conservation biologists be nothing but a bunch of computer nerds with no firsthand knowledge of natural history?”

Two decades later, we are beginning to realize how lucky we are that dedicated expert and amateur naturalists remain to observe and record the distinctive flash of a firefly or the soft clatter of dragonfly wings. But we need more of them, and soon.

Read original article: https://www.nytimes.com/2018/05/26/opin ... eft-region

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Re: The Silence of the Bugs

Post by Richprins »

Interesting! O-/

Must be climate change, surely!


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Re: The Silence of the Bugs

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Partly, but more likely pesticides -O-


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Re: The Silence of the Bugs

Post by okie »

Hmmm....... I suppose living in a perpetual cloud of pesticides and insecticides must eventually have an effect 0*\


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Re: The Silence of the Bugs

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Insects will struggle to keep pace with global temperature rise – which could be bad news for humans

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Published: October 3, 2022 | Hester Weaving - PhD Candidate in Entomology, University of Bristol

Animals can only endure temperatures within a given range. The upper and lower temperatures of this range are called its critical thermal limits. As these limits are exceeded, an animal must either adjust or migrate to a cooler climate.

However, temperatures are rising across the world at a rapid pace. The record-breaking heatwaves experienced across Europe this summer are indicative of this. Heatwaves such as these can cause temperatures to regularly surpass critical thermal limits, endangering many species.

In a new study, my colleagues and I assessed how well 102 species of insect can adjust their critical thermal limits to survive temperature extremes. We found that insects have a weak capacity to do so, making them particularly vulnerable to climate change.

The impact of climate change on insects could have profound consequences for human life. Many insect species serve important ecological functions while the movement of others can disrupt the balance of ecosystems.

How do animals adjust to temperature extremes?

An animal can extend its critical thermal limits through either acclimation or adaptation.

Acclimation occurs within an animal’s lifetime (often within hours). It’s the process by which previous exposure helps give an animal or insect protection against later environmental stress. Humans acclimate to intense UV exposure through gradual tanning which later protects skin against harmful UV rays.

One way insects acclimate is by producing heat shock proteins in response to heat exposure. This prevents cells dying under temperature extremes.

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A ladybird drinking a speck of water on a narrow leaf. Insects in warmer environments develop fewer spots to reduce heat retention. mehmetkrc/Shutterstock

Some insects can also use colour to acclimate. Ladybirds that develop in warm environments emerge from the pupal stage with less spots than insects that develop in the cold. As darker spots absorb heat, having fewer spots keeps the insect cooler.

Adaptation occurs when useful genes are passed through generations via evolution. There are multiple examples of animals evolving in response to climate change.

Over the past 150 years, some Australian parrot species such as gang-gang cockatoos and red-rumped parrots have evolved larger beaks. As a greater quantity of blood can be diverted to a larger beak, more heat can be lost into the surrounding environment.

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The red-rumped parrot has evolved a larger beak to cope with higher temperatures. Alamin-Khan/Shutterstock

But evolution occurs over a longer period than acclimation and may not allow critical thermal limits to adjust in line with the current pace of global temperature rise. Upper thermal limits are particularly slow to evolve, which may be due to the large genetic changes required for greater heat tolerance.

Research into how acclimation might help animals survive exceptional temperature rise has therefore become an area of growing scientific interest.

A weak ability to adjust to temperature extremes

When exposed to a 1℃ change in temperature, we found that insects could only modify their upper thermal limit by around 10% and their lower limit by around 15% on average. In comparison, a separate study found that fish and crustaceans could modify their limits by around 30%.

But we found that there are windows during development where an insect has a greater tolerance towards heat. As juvenile insects are less mobile than adults, they are less able to use their behaviour to modify their temperature. A caterpillar in its cocoon stage, for example, cannot move into the shade to escape the heat.

Exposed to greater temperature variations, this immobile life stage has faced strong evolutionary pressure to develop mechanisms to withstand temperature stress. Juvenile insects generally had a greater capacity for acclimating to rising temperatures than adult insects. Juveniles were able to modify their upper thermal limit by 11% on average, compared to 7% for adults.

But given that their capacity to acclimate is still relatively weak and may fall as an insect leaves this life stage, the impact is likely to be limited for adjusting to future climate change.

What does this mean for the future?

A weak ability to adjust to higher temperatures will mean many insects will need to migrate to cooler climates in order to survive. The movement of insects into new environments could upset the delicate balance of ecosystems.

Insect pests account for the loss of 40% of global crop production. As their geographical distribution changes, pests could further threaten food security. A UN report from 2021 concluded that fall armyworm populations, which feed on crops such as maize, have already expanded their range due to climate change.

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The fall armyworm is a damaging crop pest which is spreading due to climate change. Alchemist from India/Shutterstock

Insect migration may also carry profound impacts on human health. Many of the major diseases affecting humans, including malaria, are transmitted by insects. The movement of insects over time increases the possibility of introducing infectious diseases to higher latitudes.

There have been over 770 cases of West Nile virus recorded in Europe this year. Italy’s Veneto region, where the majority of the cases originate, has emerged as an ideal habitat for Culex mosquitoes, which can host and transmit the virus. Earlier this year, scientists found that the number of mosquitoes in the region had increased by 27%.

Insect species incapable of migrating may also become extinct. This is of concern because many insects perform important ecological functions. Three quarters of the crops produced globally are fertilised by pollinators. Their loss could cause a sharp reduction in global food production.

The vulnerability of insects to temperature extremes means that we face an uncertain and worrying future if we cannot curb the pace of climate change. A clear way of protecting these species is to slow the pace of climate change by reducing fossil fuel consumption. On a smaller scale, the creation of shady habitats, which contain cooler microclimates, could provide essential respite for insects facing rising temperatures.


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Re: The Silence of the Bugs

Post by Lisbeth »

A second silent spring - The impending insect acopalypse

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Click on the title to read the article.


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Re: The Silence of the Bugs

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We are in big trouble.


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