In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span

Posted By: Haggart

In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 02:11 PM

The study was conducted by Researchers from Radboud University in the Netherlands and the Entomological Society Krefeld in Germany.

"Co-author Caspar Hallman said he and his colleagues were "very, very surprised" by the results"

"Here, we investigate total aerial insect biomass between 1989 and 2016 across 96 unique location-year combinations in Germany, representative of Western European low-altitude nature protection areas embedded in a human-dominated landscape (S1 Fig). In all years we sampled insects throughout the season (March through October), based on a standardized sampling scheme using Malaise traps. We investigated rate of decline in insect biomass, and examined how factors such as weather, habitat and land use variables influenced the declines. Knowledge on the state of insect biomass, and it’s direction over time, are of broad importance to ecology and conservation, but historical data on insect biomass have been lacking. Our study makes a first step into filling this gap, and provides information that is vital for the assessment of biodiversity conservation and ecosystem health in agricultural landscapes"

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809

I wonder what a comparative study would look like across different continents. Growing up in Corpus Christi we had lots of butterflies throughout our neighborhood but i don't see that in our current neighborhood in the Houston area despite the fact that we live in a area with abundant trees and natural areas. It could be the mosquito spraying we receive frequently. In another post someone mentioned the dramatic decline in bee populations so this makes this study even more troubling.

Posted By: MarkG

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 02:36 PM

I remember growing up, playing outside with the neighborhood kids until the streetlights came on, waiting for our parents to start hollering for us to come in. At a certain time of year at dusk you'd hear locusts, lots of them, really loud. They'd eventually leave a shell that you could stick on your clothes, they were everywhere.

Posted By: Veteran66

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 02:44 PM

it have many changet fom my childhood to now (50+ Years)
In my region of south Germany we lost many nature for agriculture and house building.
Yes to many people live here

Posted By: Haggart

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 02:49 PM

I assume you mean the Cicadas (not locusts which are swarms of hungry grasshoppers) and yea you can hear them here in Houston neighborhoods even in the afternoon and i believe there are at least 4 or 5 different species if not more. I still work today with insects - it was also my favorite hobby growing up in Corpus Christi.

Posted By: MarkG

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 03:17 PM

Haggart, I'd never heard of an "entomologist " until you posted you were one on my "...I'm old" thread. That sounds pretty cool.

Looked up "Cicadas". Yeah, that's it, thanks for clearing that up.

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Posted By: PanzerMeyer

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 04:11 PM

Originally Posted by NSU

Yes to many people live here

Well, the population of Germany has been steadily declining since about 2000 so that's a good trend!

Posted By: DaBBQ

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 06:49 PM

Lets see....what happened 30 years ago that could affect the insect population and changed the european lands forever. (Possible PWEC material)

Posted By: finlander

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 08:32 PM

I read that article last nite, disturbing. I live in Wisconsin, insects seem very healthy here. Especially mosquitos and deer flies...
But our butterflies still seem normal. My area is low population density tho, farms and woods.

Posted By: RedToo

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/19/17 09:06 PM

I find this very disturbing. Insects are at the bottom of many food chains/ webs. Lots of bigger critters depend on them. Not good at all. Made me think - my car windscreen gets far fewer squashed insects on it than in the past - far far fewer. This is more worrying than global warming.

Posted By: Aiobhill

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/20/17 06:14 AM

"...Have Decreased 75% Over a 27 Year Time Span"

...and I can tell you why. They now live in the kitchen of my 86 year old mother's house.

The backside of her place - right at the French border, in one of the warmest regions of the country - is facing SW, protected from strong wind, overlooking a small pond as the ideal breeding ground; and she just loves to keep the kitchen door open while cooking or having jam, sausages or fruits in the open. I'm willing to sell all those wonderful little critters by the handful so other parts of the country can be repopulated.

Posted By: Raw Kryptonite

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/20/17 12:59 PM

Originally Posted by MarkG

Haggart, I'd never heard of an "entomologist " until you posted you were one on my "...I'm old" thread. That sounds pretty cool.

Looked up "Cicadas". Yeah, that's it, thanks for clearing that up.

As kids we all called these locust shells, not sure why. No one does now.
I have one pine tree in particular these guys LOVE to shed their skin on. Must've been 20 on there, all on one side too for some reason. Very few on the other pines.

I've noticed that we don't have the numbers of black birds we did. 30-40 years ago when they migrate. They used to be in massive flocks and would cover the yard looking for something to eat and totally cover trees they landed in. Extremely loud. Practically blot out the sun in flight there were so many. Much smaller groups now.

Posted By: BD-123

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/20/17 01:52 PM

Originally Posted by RedToo

my car windscreen gets far fewer squashed insects on it than in the past - far far fewer.

Indeed. drivers noticing this triggered research into falling insect population here; makes quite disturbing reading concerning the impact on pollination etc.

Here, in one of the most sheltered areas of England, largely a fruit growing area (Vale of Evesham) I haven't seen a wasp hardly for a number of years. Probably no more than 5-6 years ago I was compelled to put up traps due to the risk of children being stung by pissed-up wasps drunk on the damsons from the remains of an orchard in our garden.
Our old Labrador used to munch them too and pass out snoring on the lawn, producing poos that looked like nut brittle toffee. Fortunately the big bugger wasn't an aggressive drunk!
Perhaps my traps contributed to the wasp's demise! Same with butterflies, solitary bees and even ants. Haven't even seen much in the way of the annual flight of crane-flies or ants; which used to be a persistent annoyance. Come to think of it, wife's crops haven't been munched by aphids either.

Plenty of house spiders though!

Posted By: Chucky

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/20/17 02:21 PM

I don't think I've seen many Crane flies this year BD-123,did you trap all those as well?

My mum's house has a south-east facing wall that used to get covered in them. Had a job keeping them out of the house tbh. She hasn't seen many this year either.

Posted By: Haggart

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/20/17 10:33 PM

There are a few crane flies that take nectar from flowers or take moisture from a drop of water but most don't feed and only live a few days. None are predatory and none bite or sting humans or anything else. They spend most of their lives in larval form in ponds and other wet places.

Posted By: Blade_RJ

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/20/17 11:38 PM

i stilll live in the same neighboorhood i grew up, when i was a kid we had those huge butteflies the size of an adult hands, wood moths that were also big,cicadas,and LOTS of fireflies at night, dragon flies and lady bugs were everywhere in my neighborhood, after they started gassing against aedis egypt mosquito, you can not find a lady bug anywhere anymore ZERO,you see the odd butterfly here and there all the others DEAD,and the mosquitoe are still here....not a good trade. Also i find funny,and revolting how people complain they dont see butterflies anymore but step on cattepillars because they are disgusting or could burn them,or remove the caccon from their garden.......WHERE DO YOU THINK THEY COME FROM ?

Posted By: jroc

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 10/21/17 12:05 AM

Originally Posted by Blade_RJ

.......WHERE DO YOU THINK THEY COME FROM ?

You mean adult butterflies don't lay tiny baby butterflies?

Next you are going to tell me that chocolate milk doesn't come from a milk factory, but from brown cows.

Or that some lady bugs are male.

Sheesh.

Posted By: Li'lJugs

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 11/04/17 12:27 PM

The disappearance of lightning bugs, or fireflies, has been very noticeable to me in the last 20-30 years. (Wisconsin/ Minnesota) Used to be everywhere, can't remember when I last saw one. Also frogs and toads are much rarer than in past years-related to less food in the form of flying insects?

Posted By: Haggart

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 11/05/17 02:49 PM

I've noticed that too in some state parks in Texas and yea it's like a bad omen

Posted By: ADorante

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 11/27/17 10:47 AM

One addition to the topic - every good and complicated story takes its time:

I stumbled over the discussion of the merits of this study on behalf of its statistical weight. What I was looking for a step before was the illiteracy of German people on all things mathematical and statistical.

First the source and then my short summary:

Un-Statistics of the month awards by Max-Planck-Institute Berlin

Quote

Insektensterben die zweite
Presseinformation vom 27.10.2017

Die Unstatistik des Monats Oktober dreht sich erneut um Meldungen zur stark abnehmenden Zahl von Insekten in Deutschland.

Die Unstatistik des Monats Oktober ist eine Fortsetzung der Unstatistik aus dem August 2017. Damals hatten verschiedene Medien gemeldet, dass 80 Prozent der Insekten in Deutschland verschwunden seien: In zwei Fallen in einem Naturschutzgebiet nahe Krefeld hatte man 1989 etwas mehr als ein Kilo Flug-Insekten gefangen, 2013, also 24 Jahre später, 80 Prozent weniger. Natürlich darf man aus einer lokalen Stichprobe vom Umfang zwei keine Schlüsse auf ganz Deutschland ziehen (siehe die Unstatistik August 2017).

Im Oktober ging dieses Thema aufgrund einer größeren Stichprobe nochmals durch die Medien (unter anderem im Tagesspiegel, im Deutschlandfunk, in der Weltund in der Frankfurter Allgemeinen Zeitung). Dort wird über eine Studie berichtet, die auf Daten von 63 Insektenfallen zurückgreift, die der Krefelder Verein zwischen 1989 bis 2016 aufgestellt hatte. Nach diesen 27 Jahren hatte man 76 Prozent weniger Insekten-Biomasse in den Fallen. Jedoch war keine einzige dieser 63 Fallen über den gesamten Zeitraum an einem Ort aufgestellt. Stattdessen – wie die Autoren der Studie selbstkritisch anmerken – wechselten viele Standorte von Jahr zu Jahr. An den meisten Standorten wurde keine einzige Wiederholungsmessung durchgeführt.

Genauso wichtig für die Bewertung der „76 Prozent“ ist aber auch ein allgemeines Prinzip des kritischen Denkens: Jede berichtete Abnahme zwischen zwei Zeitpunkten hängt davon ab, welchen Anfangszeitpunkt man wählt. Dies gilt besonders bei drastisch schwankenden Werten, wie bei Börsenkursen und Biomassen von Insekten. Hätte man das Jahr 1991 statt 1989 als Anfangspunkt gewählt, dann wären es statt 76 Prozent weniger Insekten nur etwa 30 Prozent weniger gewesen. Das ist immer noch ein Anlass zum Nachdenken über die Ursachen – eine Frage, worauf die Studie keine Antwort findet. Es ist aber auch ein Anlass darüber nachzudenken, warum man immer wieder versucht, uns mit möglichst erschreckenden Zahlen Panik zu machen.

My short translation of the text:
Regarding the press release about a 80% decrease of insect population in Germany. In two cases bio mass of trapped insects were measured for 1989 and 2013 at Krefeld. In no way this is representative for all of Germany.
A bigger sample of 63 traps was used in a second study with a 76% decrease in insect biomass, but none of those traps were used during the whole time. As the authors of the study admitted, even the locations of the traps changed during the stuy. No repeated experiments were conducted.
Considering the meaning of a found result against the application of overall critical thinking on a hypothesis: Be it stock market or biomass - every reported decrease is depending on the starting point. A stating point of 1991 instead of 1989 would change the decrease from 76% to 30% less insects. This is still a reason to ponder the causes. But it is also a reason to reflect on why somenone uses numbers to inflict panic.
End translation.

Posted By: Ssnake

Re: In Nature Reserves of Germany - Flying Insect Populations Have Decreased 75% Over a 27 Year Time Span - 11/28/17 10:00 AM

Well, like they wrote, even a 30% loss in total insect biomass would be a reason for concern. Also, it's not as if those insect trap measurements are the only indicators. I remember the travels on the autobahn where you needed multiple attempts with the hard insect sponge and plenty of water to get rid of the insect crust building up on the windshield, the number plate, the front lights. I remember plenty of mosquito swatting on summer evenings. These days, I drive four hours on the autobahn with just a handful of bug stains, and I've had entire summers without mosquito blisters. Bird counts are dropping, particularly outside of the cities. Hardly the kind of indicators that will satisfy a statistician, but they all fit the scenario of a general decline in insect population.

Note that the Max Planck guys are following the same principle of attention economics by criticizing the one study that received most public attention recently. By picking that, and no other statistic, they are latching on the "success" of the "attention grabbing headline" and generate another headline of their own that it's "fake news" when they actually can't prove that it's "fake", just not meeting their rigid standards for measurement that are fine in theory but hard to meet in practice when you just don't have enough money - and above all, people - to perform a long-term, nation-wide survey. They truly are mathematicians - absolutely right in their mathematical critique, yet missing the point by a mile. It would be a lot more helpful if their message would be "we need more samples, and for that we need more entomologists" rather than thrusting at "the whole study is useless, because 'lack of stochastic rigidity' ".