‘A Very Scary Thing’: New Study Shows Massive Insect Decline

Written by Dr. Karen Shaw Becker

insect population

Story at-a-glance -

  • One scientist called the rapid disappearance of bugs from a pristine national forest in Puerto Rico over a 35-year period “one of the most disturbing” statistics he’d ever seen
  • Unfortunately, along with the insects, the 191-million-acre National Forest System’s insect-eating animals have gone missing, too
  • Over 35 years, studies indicate that arthropods, including lizards, frogs and birds, rely on insects for food, but insects also serve as the foundation of the food chain for fish, birds and mammals
  • Individuals should do what they can while they can to help protect the environment, by driving fuel-efficient vehicles, turning off electronics when not in use and avoiding pesticides, choosing natural products instead

Insects are both beneficial and necessary because they have the unique ability to pollinate plants, return nutrients to the earth and serve as the foundation of the food chain for fish, birds and mammals, according to National Geographic.1 Experts argue that without insects, the volume of decay from all the garbage, dead animals and decomposing plant life would make the planet a terrible place. In 2006, Cornell University entomologist and applied insect ecologist John Losey, Ph.D. noted:

“A lot of value is added to the economy by insects, but most people just don't realize it … Most insects are tirelessly performing functions that improve our environment and live in ways that scientists are only beginning to understand. We know how to repair roads and other components of our physical infrastructure, but our biological infrastructure is vulnerable to degradation, too … If we do not take care of it, it will break down and could seriously impact the economy.2

Losey stated that in many places worldwide, “cracks in the infrastructure” were becoming more evident as insects are threatened. But that was nearly 15 years ago. In 2014, biologists around the world came together to look at the numbers of invertebrates such as beetles and bees over the previous 35 years and found the number had decreased over that period by around 45 percent.3

Bradford Lister, Ph.D., a biologist at Rensselaer Polytechnic Institute in New York, and a team of scientists measured birds, frogs and lizards in the rainforests of Puerto Rico in 1976 and ’77, then returned 40 years later with a colleague.

Although he was not involved in the featured study, invertebrate conservation expert David Wagner, Ph.D. from the University of Connecticut called the crux of the study research “One of the most disturbing articles I have ever read.”4 The problem seems even worse than scientists had previously thought.

The Devastation in Diminished Biomass Studies

Insects are “in crisis” due to serious declines in invertebrate populations, according to a compilation of research over several decades. Some countries report alarming statistics: In Germany, for instance, flying insects decreased by 76 percent in select nature preserves.5 According to the featured study:

“Arthropods, invertebrates including insects that have external skeletons, are declining at an alarming rate. While the tropics harbor the majority of arthropod species, little is known about trends in their abundance.

We compared arthropod biomass in Puerto Rico’s Luquillo rainforest with data taken during the 1970s and found that biomass had fallen 10 to 60 times. Our analyses revealed synchronous declines in the lizards, frogs and birds that eat arthropods …

El Yunque,6 in Puerto Rico, is the only tropical rain forest in the National Forest System, which, according to Columbia Encyclopedia, encompasses 155 national forests and 191 million acres throughout 41 states and Puerto Rico.7

Once abundant, the butterflies there had become nearly nonexistent, and there were fewer birds. Spiders, centipedes and other arthropods had significantly decreased in number. Using sticky plates at ground level and about 3 feet high in heavy vegetation, the scientists’ insect “catch rate” decreased 60-fold, The Washington Post reports.8

They trapped anole lizards, which eat arthropods, compared the numbers and found a reduction of more than 30 percent, although some species had disappeared altogether. Combined data suggested that the food web had been obliterated from the bottom up.

Another research team9 found that between 1990 and 2005, the numbers of insect-eating frogs and birds declined by about 50 percent. Collective findings were both encouraging and disheartening; numbers of fruit- and seed-eating ruddy quail doves were unchanged, while about 90 percent of the brilliant green Puerto Rican tody bird population was gone from the area.

Who — or What — Is Responsible for the Massive Level of Insect Loss?

The researchers encapsulated their 40-year work by pointing to climate warming as the major factor driving “simultaneous, long-term declines” in arthropod abundance in the pristine rainforests of northeastern Puerto Rico.

But that wasn’t all: Again, “These declines have in turn precipitated decreases in forest insectivores in a classic bottom-up cascade,”10 the authors noted.In short, it’s not just the insects that are disappearing. Insect-eating animals have gone missing from the forests, too. According to the Washington Post:

“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.”11

In another recent study published in Science, the plunge of tropical insect populations was predicted, and with it an increase in insect pests that can handle greater temperature swings, and as a partial result, eat more, especially corn, wheat and rice. But only in the short term. “After a certain thermal threshold, insects will no longer lay eggs, and their internal chemistry breaks down.”12

While the German study in 2017 suggested that habitat loss and pesticides may also be culpable in the lower numbers of flying insects, it’s been a global concern, and not just in the rainforest. Meanwhile, Lister holds that pesticide use in Puerto Rico has dropped more than 80 percent since 1969.

Wagner believes the decline in arthropods numbers may have to do with droughts and lack of rainfall more than temperatures, but he admits it’s bewildering and laments that there’s not just one smoking gun. “I’m scared to death that it’s actually death by a thousand cuts. One of the scariest parts about it is that we don’t have an obvious smoking gun here,” he says.13

The jury’s still out on climate change being the global driver of insect loss, Wagner adds, plus, “The decline of insects in northern Europe precedes that of climate change there. Likewise, in New England, some tangible declines began in the 1950s.” Other researchers think hurricanes are another finger that points at a changing climate.

Whatever’s Causing It, ‘People Should Pay More Attention to the Bugpocalypse’

Far from cavalier, scientists observe the vanishing insects with furrowed brows. Merrill contends it’s a “very scary thing,” especially as the study follows up a “gloomy, gloomy” report14 submitted by the U.N. in October, which warns that the planet has a little more than a decade in which to get a handle on climate change.

His advice is for people to do what they can while they can. Ways to “step up” include driving more fuel-efficient vehicles and turning off electronics when they’re not in use to reduce EMFs. One environmental group recommends planting a garden filled with native plants that will bloom year-round.

If it’s your own backyard you’re looking at, one important step is to eliminate the use of pesticides, including neonicotinoid pesticides, which are basically nerve agents, similar to nicotine. As a result of neonicotinoids, more than half of the flower and vegetable plants and fruit trees sold in garden stores in North America contain substances that are damaging not only to insects, but to you and, ultimately, the environment.