Where Are All The Flying Insects Going? Researchers Observe A 75% Decrease In The Amount Of Flying Insects Over The Past 27 YearssteemCreated with Sketch.

in #steemstem4 years ago (edited)

Today lets talk about bugs.

Icky, icky, give me the shivers, bugs.

But rather than a cute post about a bug I found outside, lets talk instead about a recent publication from the journal PLoS One titled "More than 75 percent decline over 27 years in total flying insect biomass in protected areas."

In this publication, the researchers spent an very long time studying flying insect population biomass (the studies were done from the years 1989 to 2016) at a large number (96) of different locations all across Germany. The point of these studies were to get a better handle on how insect populations change, depending on where they are located relative to human habitation.

A humming bird hawk moth, Image Source [1]

There have been a variety of studies performed in the past which have indicated that insect populations have been on the decline. With extensive studies having been done on insects that are important for plant pollination like bees ([2], [3]) and the hawk moth, all showing that the populations of these insects are in decline. [4]

These decreases pose a problems for both we humans as well as the ecosystems of our planet as a whole, as pollination is absolutely essential for plant growth and maintenance of the habitats in which the many organisms that inhabit the planet live. It's also essential for food production, and I don't know about all of your opinions on eating, but I really like doing that and would like to continue to!

A Malaise trap, reproduced from Figure 1 in source [1]

Onto The Research

The scientists conducting this study were monitoring flying insect populations and to do this they used Malaise traps, which to my untrained eye just looks like a tent made of mesh. These traps catch the flying insects, the amounts and identities of which can then be painstakingly calculated and determined (likely by some graduate student or unpaid intern).

Most of the 92 locations where the data was generated from were only sampled one time, one year and were not returned to in subsequent years. The sampling was done about every 11 days after the trap was set up (in the spring) and over the course of the whole study the researchers collected over 1500 samples. It is from these bug samples that the data is generated.

Reproduced from Figure 2 in [1]

What Did They Observe?

They saw a significantly negative relationship between the overall biomass of insects relative to time. The authors state that there was a 6.1% decrease in biomass on average, PER YEAR, over the duration of their study. This is reflected in the figure to the left. Here what we are looking at is the average number of grams of insects caught in the traps, per day relative to the years that the study went on. Looking at these box plots we can first state that the error is huge, but that seems reasonable as collecting insects likely has a lot of sample to sample variation. However we can also see a VERY clear trend with regards to the average value and this trend goes down by quite a lot over the years.

Reproduced from Figure 3 in [1]

The researchers further quantified this data and looked at when this decrease was happening. They saw that the observed loss of biomass disproportionately occurred in the summer months when the insect population should have been at its highest, and was less pronounced in the spring and fall. We can see this in the plot to the right where most of the change occurs in July and August.

The researchers explored their data looking for discrepancies between the various sampling locations, but found the trends held for the general regions in which the samples were obtained. The authors discuss that depending on the area that the samples were taken there were always more or less insects (marshy wetlands had more then say a sandy area with fewer nutrients. However the general decline in the insect populations were consistent in both areas, relative to the total amount of insects that these areas supported. Meaning, the decrease wasn't just because of one type of ecosystem, it was everywhere.

They also searched for explanations like weather conditions and found that parameters like temperature or amount of moisture were unable to account for the decreases they observed.

The authors summarize stating that over the 27 years in which the flying insects were studied, a decrease in total population of around 76% was observed. Their results here mirroring that of previous studies on bees, and moths that I mentioned before, but expanding upon that data indicating that the issue is not limited to just these pollinators but to ALL flying insects.

What Does This Mean?

They don't know!

One of the prevailing theories put forth to explain why bee and moth populations were declining was climate change. [5]. They make it clear that their data does NOT support climate change as the cause for this phenomenon, nor does it support that changes to the landscape itself are affecting the insect populations.

They state in their discussion that the rate of decline in the insect population they observe here is "alarming," and stress the urgency in quickly figuring out what the true cause is, as well as better understanding just how quickly this will be affecting ecosystems as a whole.

Flying insects appear to be dying, and their populations are dwindling quite quickly. Additional research is needed to figure out the why, all we know now is what is happening. Hopefully data like this stokes the fires for researchers and we can identify the culprit. Allowing for a solution to be put in place, before it is too late and ecosystems are irreparably damaged.


Text Sources

  1. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185809
  2. https://www.ncbi.nlm.nih.gov/pubmed/17803456
  3. https://www.ncbi.nlm.nih.gov/pubmed/26699460
  4. https://www.ncbi.nlm.nih.gov/pubmed/28982152
  5. http://www.sciencedirect.com/science/article/pii/S0006320701002580

Image Sources


All Non Cited Images Are From Pixabay.com, Flickr.com, Pexels.com, or Wikipedia.com And Are Available For Reuse Under Creative Commons Licenses

Any Gifs Are From Giphy.com and Are Also Available for Use Under Creative Commons Licences

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Most German beekeepers think that insecticides and other chemicals in combination with a decreasing food supply are the most serious threat for the survival of the bees and bumblebees.

The monocultures of our industrial agriculture must appear the honey bees like 'green deserts' without any usable food sources (= flowers). In addition many garden owners prefer trimmed grass together with some conifers and cherry laurel plants instead to give rich flowering plants any chances and let some corners in their gardens grow wild with stones and deadwood as useful hiding spots for many insects.

For the ones who want to help our insects:

Most conservationist organizations like for example the NABU don't consider other factors like the climate change or bee diseases as main causes: "Den Klimawandel oder besonders kalte oder warme Winter können wir ausschließen. Vieles deutet darauf hin, dass wir es mit einer weit reichenden Vergiftung der Insekten in unserer Umwelt zu tun haben." Means they exclude the climate change respectively especially warm or cold winters as most important factor and instead of that focus on the pollution of the environment.
One reason why I tend to agree are regions in China where bees are already completely extincted because of the extensive use of chemicals (which happened long time ago when the climate change was still not as advanced as nowadays). In these regions humans have to polinate the fruit trees manually.

I think it is because we spray fertilizers, herbicides, pesticides and other chemical sh.it on our fields. It is either toxic for insects or interferes with their growth mechanism.

Could be, but I'd wait for data to support that before getting out the pitchforks.

Part of Me Wonders

if the insect population is just getting progressively smarter and avoiding the traps? lol

I thought this too! haha


Doubt it lol.

...........a decrease in total population of around 76% was observed
that is really a huge amount which definitely threat our ecosystem.

Well articulated, @justtryme! Great job and a good read. Definitely following you now!

Thank you! I'm glad you enjoyed it.

This report is really alarming my friend! 75% decrease is a huge decrease amount of insects.
I have read quite a lot about the importance of insects in our eco system. I even read if all bees happen to disappear, life in general on earth will be in danger in couple of years!
This is really scary and hope there's some solution for this.

I hope so too.

Definitely worth an upvote and a resteem :]

Well my friends Israeli our concern for our environment and also for us as if it continue very soon all the land will get unfertilized. and then its create a very huge problem for everyone

Sir thanks for your response over my comment

Nice survey data send by you we all have to think about it because they are also one of the important species in the world

Indeed, not taking these observations seriously could have some pretty bad effects in the long run.

Yes u are right my friend but we have to face it in future you are nice person followed you

We human just only think About ourself and but as it well continue , people will pay for this .

The new banner looks fantastic, @zord189 does great work!

Amelia Earhart : The most difficult thing is the decision to act, the rest is merely tenacity.

Too bad they couldn't figure out why this was happening. At least the refutation of climate change is interesting (though I'd like to know how they came to that conclusion). Also, nice banner!

Good questions man. Perhaps they only could conclusively state that there was nothing in their data to support climate change as a driver. I don't know how much of what they are saying is trying to overstate the impact of their data. This is only a PLoS One paper, the chip on their shoulders could be a contributing factor.

Thanks for the shoutout @justtryme90 :) Let me know if u ever need anything else.

That indeed sounds alarming, just thinking about all the risk on pollination at least.
Also comes to mind this statement usually attributed to Einstein
"If the bee disappeared off the face of the Earth, man would only have four years left to live."
On a more positive note, I gotta say again, i love your new profile picture :P
Just looks so happy and positive !

Thanks, yeah it's a nice image. Perhaps more representative of me as a person then the DNA. We need the extra positivity with all of the bad news circulating in the world these days. Everything is always so negative.

However we can also see a VERY clear trend with regards to the average value and this trend goes down by quite a lot over the years.

As a disclaimer, I accept this conclusions. However, being the devil's advocate, the results seem to be as compatible as being constant over time, when accounting for the error bars.

Note that I am also very amazed by the conclusions of the study that are very scientific and objective!

PS: why Germany?!

In this data the error reported is the standard deviation, perhaps reporting confidence in the mean would be a more appropriate error determinant for this sort of data? (I don't think the authors are (should be?) as concerned with ease of replication study as they are in the trust-ability of their measurements )

Beyond this, the y-axis scale of the plot is non linear, which masks the magnitude of the change, it would appear more obvious with a different scale.

All of that said, the data is really noisy but what can one expect from catching bugs in nets? ;)

I think they did a poor job of presenting this data. You definitely want to use standard error over standard deviation in this case, and the log scale minimizes the appearance of the effect.

I agree. You can check my answer above (sorry, I only noted your comment after having answered to @justtryme90) :)

That is right. In noticed the log scale which is really not a good choice (since the range covers two orders of magnitude, I guess presenting the results under both forms (log and linear ) could have been better.

But even, I think a flat curve would work as well. Having compared both options and given the outcome as the confidence level of the trend would have been better...

Anyways, I am always biased by my physics background where anything can be properly (well, most of the time) quantified. As you said elsewhere, I should learn thinking as a biologist (or at least stop commenting biology works as a physicist :p ).

Nah, you should keep your high expectations that physics holds. Wanting more proof from data or to be better convinced is never a bad thing.

I should pass the message in some way. Jut to let you know, at each interview of a biophysicist, this is always the same question I ask: error bars, confidence level, etc... (yes, biophysics is part of theoretical physics so that I may interview those guys :p )

Biophysics is not technically a part of theoretical physics by terminology. Much of the work I do falls under that term for pharma as I define molecular interaction strength. Biophysics in that context falls under biochemistry ironically.

Honestly a good understanding of error propagation and when to apply a particular analysis is a must in any scientific discipline. It is also something that a lot of people don't understand. You would be surprised (well YOU personally probably wouldn't be surprised) how few people understand the difference between simple concepts like standard deviation and standard error for instance.

It depends how you define theoretical physics. In France, it really includes the theory side of particle physics, astrophysics and cosmology, formal stuff like string theories or mathematical physics, condensed matter, statistical physics and finally areas like turbulence and biophysics. At the end of the day, it turns out that theoretical physics is kind of multidisciplinary.

Honestly a good understanding of error propagation and when to apply a particular analysis is a must in any scientific discipline. It is also something that a lot of people don't understand. You would be surprised (well YOU personally probably wouldn't be surprised) how few people understand the difference between simple concepts like standard deviation and standard error for instance.

it is very rare to have good statistics courses in standard curriculums. This is where one should start to hope for a change. Even in my field, sometimes... (remember the Madala story I wrote about some time ago... we can chat about it on the steemit chat if you want and I will give you more details about the statistics procedure and its weak spots; which does not prevent to recognize that the Madala exercise is interesting per se).

Thanks you for posting such a important message to steemit society

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You are really a great persionality no thinks about this small thinks and also do not share these type of servery

I found an article on my glyphosate research that looked specifically at the bee population decline in response to the increases usage of neonicotinoid insecticides and was wondering if you think the potential might be a main cause here as well? I know in the post that you pointed out one of the prevailing theories is climate change but, asking for a personal opinion here, do you think that it may be more likely a combination of the increased rate of climate change combined with the increased use of non-selective insecticides? Or do you, from your own research, believe that the insecticides are too selective to have any kind of impact like the one we see here?

Past those questions I must say that I enjoyed the post and must thank you for the sharing of it! Sorry for such a long comment.

Brodie (Kryzsec)