'Insect apocalypse' may not be happening in US
Long-term ecological site study shows no net insect changes

Date:
August 11, 2020
Source:
University of Georgia
Summary:
Scientists have been warning about an 'insect apocalypse' in recent
years, noting sharp declines in specific areas -- particularly
in Europe.

A new study shows these warnings may have been exaggerated and are
not representative of what's happening to insects on a larger scale.



FULL STORY ========================================================================== Scientists have been warning about an "insect apocalypse" in recent years, noting sharp declines in specific areas -- particularly in Europe. A
new study shows these warnings may have been exaggerated and are not representative of what's happening to insects on a larger scale.


========================================================================== University of Georgia professor of agroecology Bill Snyder sought to
find out if the so-called "insect apocalypse" is really going to happen,
and if so, had it already begun. Some scientists say it might be only
30 years before all insects are extinct, so this is a really important
and timely question for agriculture and conservation.

Snyder and a team of researchers from UGA, Hendrix College and the U.S.

Department of Agriculture used more than 5,300 data points for insects
and other arthropods -- collected over four to 36 years at monitoring
sites representing 68 natural and managed areas -- to search for evidence
of declines across the United States.

Some groups and sites showed increases or decreases in abundance and
diversity, but many remained unchanged, yielding net abundance and
biodiversity trends generally indistinguishable from zero. This lack
of overall increase or decline was consistent across arthropod feeding
groups, and was similar for heavily disturbed versus relatively natural
sites. These results were recently published in Nature Ecology and
Evolution.

Local observations The idea for the study started last year with a cross-country road trip for Snyder from Washington state to his new home
in Georgia.



==========================================================================
"I had the same observation a lot of people had. We had our drive across
the country -- you don't see as many insects squished on your car or windshield." When he got to his home in Bishop, Georgia, it seemed like
a different story.

"I noticed the lights outside were full of insects, as many as I remember
as a kid," he said. "People have this notion -- there seems like [there
are] fewer insects -- but what is the evidence?" There is some alarming evidence that European honey bees have problems, but Snyder was curious
if insects everywhere are in decline. "We depend on insects for so many things," he said. "If insects disappear it would be really, really
bad. Maybe the end of human existence." He was discussing the topic
with another biologist and friend, Matthew Moran at Hendrix College,
and they recalled the U.S. National Science Foundation's network of
Long-Term Ecological Research (LTER) sites, which were established in
1980 and encompass a network of 25 monitoring locations across each of
the country's major ecoregions.



========================================================================== Ecological sampling The NSF's LTER data is publicly available, but has not previously been gathered into a single dataset to be examined for evidence
of broad-scale density and biodiversity change through time until now.

Arthropod data sampled by the team included grasshoppers in the Konza
Prairie in Kansas; ground arthropods in the Sevilleta desert/grassland in
New Mexico; mosquito larvae in Baltimore, Maryland; macroinvertebrates
and crayfish in North Temperate Lakes in Wisconsin; aphids in the
Midwestern U.S.; crab burrows in Georgia coastal ecosystems; ticks in
Harvard Forest in Massachusetts; caterpillars in Hubbard Brook in New Hampshire; arthropods in Phoenix, Arizona; and stream insects in the
Arctic in Alaska.

The team compared the samples with human footprint index data, which
includes multiple factors like insecticides, light pollution and built environments to see if there were any overall trends.

"No matter what factor we looked at, nothing could explain the trends in
a satisfactory way," said Michael Crossley, a postdoctoral researcher in
the UGA department of entomology and lead author of the study. "We just
took all the data and, when you look, there are as many things going
up as going down. Even when we broke it out in functional groups there
wasn't really a clear story like predators are decreasing or herbivores
are increasing." "This is an implication for conservation and one for scientists, who have been calling for more data due to under-sampling
in certain areas or certain insects. We took this opportunity to use
this wealth of data that hasn't been used yet," explained Crossley,
an agricultural entomologist who uses molecular and geospatial tools
to understand pest ecology and evolution and to improve management
outcomes. "There's got to be even more data sets that we don't even know
about. We want to continue to canvass to get a better idea about what's
going on." Good and bad news To answer Snyder's broad question of,
"Are there overall declines?" No, according to the study. "But we're
not going to ignore small changes," Snyder said. "It's worthwhile to differentiate between the two issues." Particular insect species that
we rely on for the key ecosystem services of pollination, natural pest
control and decomposition remain unambiguously in decline in North
America, the authors note.

In Europe, where studies have found dramatic insect declines, there may
be a bigger, longer-term impact on insects than the U.S., which has a
lower population density, according to Snyder.

"It's not the worst thing in the world to take a deep breath," suggested Snyder. "There's been a lot of environmental policies and changes. A
lot of the insecticides used in agriculture now are narrow-acting. Some
of those effects look like they may be working." When it comes to conservation, there's always room for everyone to pitch in and do
their part.

"It's hard to tell when you're a single homeowner if you're having an
effect when you plant more flowers in your garden," he said. "Maybe some
of these things we're doing are starting to have a beneficial impact. This could be a bit of a hopeful message that things that people are doing
to protect bees, butterflies and other insects are actually working."

========================================================================== Story Source: Materials provided by University_of_Georgia. Original
written by Joshua Paine.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Michael S. Crossley, Amanda R. Meier, Emily M. Baldwin, Lauren
L. Berry,
Leah C. Crenshaw, Glen L. Hartman, Doris Lagos-Kutz, David
H. Nichols, Krishna Patel, Sofia Varriano, William E. Snyder,
Matthew D. Moran. No net insect abundance and diversity declines
across US Long Term Ecological Research sites. Nature Ecology &
Evolution, 2020; DOI: 10.1038/s41559-020-1269-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200811125040.htm

--- up 3 weeks, 6 days, 1 hour, 55 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)