“Hyperalarming” Study: Insect Populations Crashing – and Climate is Suspect

October 16, 2018

One of climate change’s most terrifying and heart breaking effects is species extinction.

Washington Post:

Insects around the world are in a crisis, according to a small but growing number of long-term studies showing dramatic declines in invertebrate populations. A new report suggests that the problem is more widespread than scientists realized. Huge numbers of bugs have been lost in a pristine national forest in Puerto Rico, the study found, and the forest’s insect-eating animals have gone missing, too.

In 2014, an international team of biologists estimated that, in the past 35 years, the abundance of invertebrates such as beetles and bees had decreased by 45 percent. In places where long-term insect data are available, mainly in Europe, insect numbers are plummeting. A study last year showed a 76 percent decrease in flying insects in the past few decades in German nature preserves.

The latest report, published Monday in the Proceedings of the National Academy of Sciences, shows that this startling loss of insect abundance extends to the Americas. The study’s authors implicate climate change in the loss of tropical invertebrates.

“This study in PNAS is a real wake-up call — a clarion call — that the phenomenon could be much, much bigger, and across many more ecosystems,” said David Wagner, an expert in invertebrate conservation at the University of Connecticut who was not involved with this research. He added: “This is one of the most disturbing articles I have ever read.”

Bradford Lister, a biologist at Rensselaer Polytechnic Institute in New York, has been studying rain forest insects in Puerto Rico since the 1970s. If Puerto Rico is the island of enchantment — “la isla del encanto” — then its rain forest is “the enchanted forest on the enchanted isle,” he said. Birds and coqui frogs trill beneath a 50-foot-tall emerald canopy. The forest, named El Yunque, is well-protected. Spanish King Alfonso XII claimed the jungle as a 19th-century royal preserve. Decades later, Theodore Roosevelt made it a national reserve, and El Yunque remains the only tropical rain forest in the National Forest system.

“We went down in ’76, ’77 expressly to measure the resources: the insects and the insectivores in the rain forest, the birds, the frogs, the lizards,” Lister said.

He came back nearly 40 years later, with his colleague Andrés García, an ecologist at the National Autonomous University of Mexico. What the scientists did not see on their return troubled them. “Boy, it was immediately obvious when we went into that forest,” Lister said. Fewer birds flitted overhead. The butterflies, once abundant, had all but vanished.

García and Lister once again measured the forest’s insects and other invertebrates, a group called arthropods that includes spiders and centipedes. The researchers trapped arthropods on the ground in plates covered in a sticky glue, and raised several more plates about three feet into the canopy. The researchers also swept nets over the brush hundreds of times, collecting the critters that crawled through the vegetation.

Each technique revealed the biomass (the dry weight of all the captured invertebrates) had significantly decreased from 1976 to the present day. The sweep sample biomass decreased to a fourth or an eighth of what it had been. Between January 1977 and January 2013, the catch rate in the sticky ground traps fell 60-fold.

“Everything is dropping,” Lister said. The most common invertebrates in the rain forest — the moths, the butterflies, the grasshoppers, the spiders and others — are all far less abundant.

“Holy crap,” Wagner said of the 60-fold loss.

Louisiana State University entomologist Timothy Schowalter, who is not an author of this recent report, has studied this forest since the 1990s. This research is consistent with his data, as well as the European biomass studies. “It takes these long-term sites, with consistent sampling across a long period of time, to document these trends,” he said. “I find their data pretty compelling.”

The study authors also trapped anole lizards, which eat arthropods, in the rain forest. They compared these numbers with counts from the 1970s. Anole biomass dropped by more than 30 percent. Some anole species have altogether disappeared from the interior forest.

Insect-eating frogs and birds plummeted, too. Another research team used mist nets to capture birds in 1990, and again in 2005. Captures fell by about 50 percent. Garcia and Lister analyzed the data with an eye on the insectivores. The ruddy quail dove, which eats fruits and seeds, had no population change. A brilliant green bird called the Puerto Rican tody, which eats bugs almost exclusively, diminished by 90 percent.

The food web appears to have been obliterated from the bottom. It’s credible that the authors link the cascade to arthropod loss, Schowalter said, because “you have all these different taxa showing the same trends — the insectivorous birds, frogs and lizards — but you don’t see those among seed-feeding birds.”

Lister and Garcia attribute this crash to climate. In the same 40-year period as the arthropod crash, the average high temperature in the rain forest increased by 4 degrees Fahrenheit. The temperatures in the tropics stick to a narrow band. The invertebrates that live there, likewise, are adapted to these temperatures and fare poorly outside them; bugs cannot regulate their internal heat.

9 Responses to ““Hyperalarming” Study: Insect Populations Crashing – and Climate is Suspect”

  1. Bryson Brown Says:

    This may be the most frightening story about climate and environmental change I’ve read in a long while– which is saying something. It sounds like we’re in the process of destroying major ecosystems from the base up– and it’s well, well underway. There will be consequences beyond the absence of fireflies dancing in the fields and mayflies on the windshield in the summer.

    • dumboldguy Says:

      “Most frightening” indeed. The WashPost is my daily paper, and it has been full of frightening and disturbing pieces since the election of 2016 and the arrival of the Dumpster Fire in the White House. But this article this AM ruined what was looking to be a nice day for me—no rain for a change.

      Wagner says it well with “Holy Crap!” I have written before about the decline of honeybees here in NO VA 25 miles west of DC. I have been planting beds of pollinator-attracting wildflowers the past few summers to try to help the bees. It apparently hasn’t helped the bees much, but the number of moths/butterflies visiting is noticeably higher this year—perhaps the reduced competition from the bees has allowed their numbers to climb? Have also had more hummingbirds visit.

  2. It feels ominous to drive through West Texas with a clean windshield. Road trips always used to be accompanied by the incessant splatter of death. We’d pass through clouds of lovebugs, those perpetually copulating critters, which coated the windshield in a greenish sheen; and then the grasshoppers would hit, in blobs of orange-yellow goo. Painted ladies and miller moths and June bugs contributed their own colorful innards. Wipers only made things worse. The whole front of the car would be peppered with insect carcasses, and the Texas sun baked them into a buggy frittata. They were hell to wash off; I remember scrubbing the grill and never getting ti clean enough. Truckers, especially, would protect their radiators with mesh shields. Bugs were simply a part of the Texas air.

    Now when I collide with a bug, I’m surprised. I can only speak for Texas, but the absence of insects seems to be a part of a general diminution of life. The fence lines along our roadsides used to be ornamented with scissor-tailed flycatchers, those elegant acrobats, so rare now that the insects have disappeared. The inventory of life forms is being funneled down to an inventory of hardy pests. We’re living in a world of mosquitos, roaches, fire ants, starlings, rattlesnakes and feral hogs. In fairness to the animals, I suppose I should add humans to the top of the list.

    Lawrence Wright, “God Save Texas” page 311

    • dumboldguy Says:

      Thank you for that eloquent and even touching piece from Wright. I have taken two week-long road trips out west (1966 and 1984), both times driving through nearly a couple of dozen states (including TX both times).

      The bugs were so bad at night in places in several states in 1966 that it was like driving though a snow blizzard—-going faster than 20 mph was dangerous, and you had to stop frequently to clean the windshield and radiator. By 1984, traveling pretty much along the same route, the “splatter of death” was down to perhaps 10% of what it was 20 years before.

      Same thing holds true back here in the Mid-Atlantic east. It might take a week to get a total of three or four bug smears on the windshield, something that happened in a half hour most days 25 years ago. I regularly make a 400+ mile round trip from NO VA to SO NJ to visit family, and seldom have to clean the windshield afterwards. And why have we NOT been talking about this? After a brief flurry of interest a year ago, little has been said.


      • dumboldguy Says:

        ….that’s two MANY WEEKS-long road trips

        I was in a car, not a plane

      • Lawrence Wright’s book is a consistently eloquent, and frequently hilarious, account of our state’s politics and culture. I had not noticed the windshield phenomena until reading it, and then remembering cleaning windshields during road trips with my parents in the 1950’s.

  3. Where Have All The Insects Disappeared To? Insects Highly Sensitive To Heavy Metal Radioactive Poisons; Gigantism; 95% of Silk Worms Die, Survivors Grow 10 times Normal Size On Tokyo Soil Contaminated With Fukushima Heavy Metal Poisons

  4. Fukushima, Chernobyl, TMI Radiation And Man Made Artificial Heavy Metal Poisons Caused Die Offs, Mutations, Deformations; Butterflies, Bees, Pollinators And Other Insects, Birds, Trees, Animals And Humans

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