Are We in an Insect Armageddon?

A recent study found that bug biomass has been steadily decreasing -- in some areas, we may only have 25% of the insects that we had 30 years ago. But what's to blame, and what could this mean for the future?

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Episode Transcript

Speaker 1 (00:02):
Welcome to Brainstuff from How Stuff Works. Hey there, brain Stuff,
Lauren Vogel. Bomb here. When you hear the word armageddon,
you might imagine a battle thought at the end of
the world by humans. But it's possible that battle is
being fought right now. Only all the casualties are bugs.
Insects are vitally important to the functioning of the world's ecosystems.

(00:24):
They do most of the plant pollination, after all, while
providing food for the bulk of the world's birds, amphibians, reptiles,
and mammals. They're also essential in nutrient cycling, breaking down
the world's dead stuff, manure, and what have you to
make more dirt for us to grow our food in.
Every ecosystem on the planet needs insects, which is why
the apparent tanking of bug biomass is so alarming. Study

(00:46):
published in October in the journal Plos one confirms the
insect decline that many scientists and insect enthusiasts previously suspected,
and it turns out their suspicions weren't just validated, but surpassed.
In Germany, insect biomass is declined by roughly seventy percent
over a little less than three decades. We spoke with

(01:07):
co author Casper Hallman of the Institute for Water and
Wetland Research at Radbound University in the Netherlands. In an email,
he said declines in insects as a group have been
suspected for quite some time, indirectly through declines in insectivorious birds,
but around the globe only a few data sets exist
to inform us, and these data are mainly concentrated around bees,

(01:28):
butterflies and moths. Since a group of amateur entomologists in Kerfeld, Germany,
has been collecting all kinds of insects from sixty three
German nature reserves between spring and autumn each year, following
a highly standardized sampling protocol. Over the years, they realized
that the tent like traps specially designed to catch flying

(01:48):
insects were yielding a smaller and smaller catch each year,
even though every aspect of their sampling regime remained constant.
Weighing the total biomass of the yearly hall over time
allowed them to quantify it exactly how big a hit
these flying insects have taken over the decades. They found
an overall three quarters decline in insects when they looked
at the entire collecting season, but in high summer, when

(02:10):
insect numbers are at their highest, the decline was even
more noticeable at These findings are of course specific to
Germany and data are very scarce for nature preserves in
other parts of the world, but the drop in insect
populations is in no way limited to Germany. The study
authors speculate that their study locations are representative of similar
preserves around the world, and study published in the journal

(02:33):
Science detailed the decline in worldwide populations. The reason it's
important to compare these data to those taken from other
protected areas has to do with the fact that agricultural
or urban areas have relatively little to offer insects and
are often outright toxic to them. Therefore, it's tough to
note based on data from these areas whether insects are
doing poorly in other places in the world, in habitats

(02:55):
where they should be thriving. That said, general data sets
on butterflies, moths, and most famously bees around the world
mostly point in the same disabal direction. Additionally, the so
called windshield phenomenon might not be data driven science, but
it seems that all over the world in recent decades,
people have been noticing fewer squashed bugs on their windshields

(03:15):
than ever before. But what could be causing this more
than decimation of Germany's insects. While the research team looked
at whether changes in climatic conditions, the landscape, or the
local habitat may have caused the decline, co author Hallman
says they were unable to explain it based on these analyzes. Quote,
Our best guess at this point are the negative influences
of land use surrounding the nature reserves, particularly agricultural practices

(03:39):
such as extensive use of pesticides and fertilizers, as well
as over decline in habitat sustainability in between the reserves.
But the effects of so many fewer insects can already
be observed in the decline of birds in Germany. During
the same time period, twelve million pairs of breeding birds
have disappeared, and the same trend has been observed in
other parts of Europe. So the next time you see

(04:00):
a bug in your house, reconsider squashing it and maybe
just escorted outside. It's kind of having a tough thirty
years of it. Today's episode was written by Justlyin Shields
and produced by Tristan McNeil. For more on this and
lots of other depressing yet important topics, visit our home planet,

(04:20):
how Stuff Works dot com