Light pollution a reason for insect decline
Artificial lighting at night could be a reason for declining insect populations
Climate change, pesticides and land use changes alone cannot fully explain the decline in insect populations in Germany. Scientists from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) have now discovered that regions that have experienced a sharp decline in flying insects also have high levels of light pollution. Many studies already suggest that artificial light at night has negative impacts on insects, and scientists should pay greater attention to this factor when exploring the causes of insect population declines in the future.
The biomass of flying insects has decreased by more than 75 per cent – this alarming figure made front page news in autumn 2017. The study, published in 2017, analysed trends in biomass of flying insects in selected protected areas within agricultural landscapes over the last 27 years, and concluded that changes of climate and habitat are to blame for the decline in insect populations. At the same time, they pointed out that these impacts alone are unable to explain this drastic decline.
Light at the wrong time disturbs the balance of ecosystems
Clearly an assignment for scientists from the Light Pollution and Ecophysiology research group at IGB. After all, they know from previous studies that artificial lighting at night strongly affects the number of insects and insect communities. Therefore, the team led by IGB researcher Dr. Maja Grubisic looked at the locations of the areas involved in the 2017 study: areas in conurbations that have a higher than average level of light pollution. “Half of all insect species are nocturnal. As such, they depend on darkness and natural light from the moon and stars for orientation and movement or to escape from predators, and to go about their nightly tasks of seeking food and reproducing. An artificially lit night disturbs this natural behaviour – and has a negative impact on their chances of survival”, explains Maja Grubisic the starting point of their investigation.
The scientists analysed all recent studies on the effects of artificial light at night on insects, and found that there is strong evidence to suggest a credible link between light pollution and declines in insect populations. For example, flying insects are attracted by artificial lights – and, at the same time, are removed from other ecosystems – and die from exhaustion or as easy prey. Additionally, rows of light prevent flying insects from spreading; causing a lack of genetic exchange within fragmented insect populations that could reduce their resistance to other negative environmental influences, which are especially pronounced in agrarian areas.
A decline in insect populations in agricultural areas – which make up no less than eleven per cent of land use worldwide – does not only mean a decline in species diversity, but also jeopardises important ecosystem services: for example, there are then fewer moths, beetles and flies to pollinate plants. Also, changes in the occurrence and behaviour of pests such as aphids or their enemies such as beetles and spiders can disturb the balance of this well-tuned system. Furthermore, artificial light at night may also have a direct impact on the growth and flowering time of plants, and therefore on yield.
All influencing factors have to be understood and considered – including light pollution
“Our overview study shows that artificial light at night is widely present and can have complex impacts in agricultural areas, with unknown consequences for biodiversity and crop production. Thus, light pollution should be generally considered as a potential ecosystem disturbance in future studies to identify ways in which practical steps can be taken to reduce environmental concerns”, summarises Dr. Franz Hoelker, Head of the Light Pollution and Ecophysiology research group at IGB.
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Is this claim of 75% loss of insect biomass in Germany also found elsewhere in the world? If so, it is a serious problem for the environment, a much bigger problem than CO2. It makes sense that light pollution can be devastating to nocturnal insects, and this can have serious ramifications for the environment as a whole — and it is no joke.
If further study bears this out we should look for a simple solution to removing as much of that pollution as possible.
Yes, but not this dramatic. A much better study from a statistical point of view comes from UK (Rothamsted) and it also sees some decline.
But again, as long as we do not have reliable long term data with a sufficient area coverage this means nothing.
https://farmlandbirds.net/sites/default/files/Decline%20flying%20insects.pdf
Apparently Dr. Franz Hoelker has never gone outside at night where there are street lights. Every light source outside at night is surrounded by clouds of flying insects. If the bats don’t eat them hundreds of them die from exhaustion or contact with the light, littering the ground.
“….changes of climate and habitat are to blame for the decline in insect populations.” Well, ‘duh. You don’t find earthworms climbing trees. Grasshoppers don’t live in trees. Bees don’t touch wind pollinated flowers. But his paper is about Light and insects. Climate and habitat really don’t enter in to it
“….areas in conurbations that have a higher than average level of light pollution.” Large cities are almost by definition highly modified habitats. For some reason many people like to like in large cities with lots of roads, lots of lights at night, small amounts of open ground, and very little dirt farming. I think there is no argument that cities are different than farms, but he immediately goes there, implicity linking lights in cities with lights in farming areas.
We live in a semi-rural area with farms nearby, city streets, street lights and all the accoutrements. I haven’t seen any noticeable change in the number of bugs.
Fortunately it seems the data isn’t good enough to suggest a model for how light affects insect biomass and insect responses to artificial light. I know it’s taken over 60 years to get a good model of how the human retina responds to light of varying frequencies. It may be awhile before we get a good insect model.
I’ve gotta be missing something here….
What is a ‘selected protected agricultural landscape’ Selected on what criteria? Protected from what? Arable or animal agriculture?
What sort of light pollution do you get in rural/agricultural areas?
How is a light-based insect trap gonna attract anything in an urban area with street-lights shining all around?
How are the insects gonna pollinate anything at night – don’t they use reflected/filtered sunlight to find their targets. Don’t many plants close their flowers at night?
Has the agriculture in the selected areas changed? Livestock farms are typically fizzing with flying critters. I know. I used to own, manage and run one.
What was protected – not bats by any chance. Don’t bats eat flying critters. At night.
Are not 20% of all mammals on Planet Earth = bats?
What about insecticides? They have changed drastically over the last few decades from organo-phosphorus compounds to synthetic pyrethroids and neo-niconoids (sp?)
They are gobsmackingly more toxic to insect critters – easily 10,000 times on a weight for weight basis.
By example I used stuff called Spot-On to protect my cows from flies. It cost £90 per litre and comprised 99% baby oil with 1% of stuff called (I think) Deltamethrin
A single 10cc shot of Spot-On, applied on the cow’s back between her shoulder blades would protect her from flies for at least 6 weeks. Out-of-doors in all and any weather.
If any flying biting, stinging or blood sucking critter just so much as landed on the treated cow, that was The Very Last Thing that that critter ever did.
What was the lethal dose rate for that stuff – it had to be a dozen or so molecules.
That stuff is also used on arable crops and often to treat aphids.
And the neo-nics are even more toxic.
As I recall from somewhere, if you had just two sexual able aphids in early spring-time, gave them an unlimited food supply and no predation, 6 or 7 months later at the onset of winter the bio-mass of aphids produced by those 2 would exceed the entire mass of Planet Earth.
And these folks are concerned about flying critters decline of 75%!!!!!
Which is the bigger threat to human civilisation – Paranoia, Ivory Towerism or the Magical Thought Bubble?
And this lot display all three
So, I guess we’ll have to get rid of lights now, too.
Lower CO2 emissions!
Since bugs outnumber us a trillion to one, I am not concerned.
At least they didn’t accuse Mr CO2
“Many studies already suggest that artificial light at night has negative impacts on insects, and scientists should pay greater attention to this factor when exploring the causes of insect population declines in the future.”
So? What about the positive impacts on HUMAN populations? There is more biomass in the form or insects on this rock than all of humanity and our technology put together, they have been on this rock longer than we have, I can confidently say, they will be fine.
Move along, nothing to see here!
Pesticide use is another major reason -ever since we stopped putting them on our lawn, the fireflies have come back strong.
well lights an issue but FAR less than damned chemicals are.
im rural with no streetlights close nearest would be half mile..
living on land thats had not one chem used on it for over 30yrs
I am delighted to see the very rare grasshopper or mantis. at night in summer with no screens doors n windows open I might get 6 moths round the light as i read.
what i am surrounded by is farmland…with the stink of some of the sprays lingering from sunset and all night n day all too often as it drifts miles at ground level in aircurrents.
i’ll use flyspray in the kitchen and a run of surface spray round doorframes to deter entry and thats it.
the external house siding and anywhere else is free to accumulate spiders n webs as and when they take up residence.
majority of folks in town spend 100$ getting entire yards n homes sprayed yearly or more often as well as dousing garden liberally with anything they see advertised.
i have many frogs n worms as well as dung beetles but stuff all normally seen insects.
I have always been opposed to dusk-dawn lights that I can’t control. Now I have a reason!
” Also, changes in the occurrence and behaviour of pests such as aphids or their enemies such as beetles and spiders can disturb the balance of this well-tuned system.”
Goodness ! ANOTHER well-tuned system THAT MANKIND ( or should that be MAN-UN-KIND )
is fouling up. Have you ever driven through the WHEAT FIELDS at night and seen ALL THOSE
STREET-LIGHTS that those careless farmers leave burning all night ??
“Additionally, rows of light prevent flying insects from spreading; causing a lack of genetic exchange within fragmented insect populations that could reduce their resistance to other negative environmental influences, which are especially pronounced in agrarian areas.”
AND
“Furthermore, artificial light at night may also have a direct impact on the growth and flowering time of plants, and therefore on yield.”
DAMN IT MARTHA……….NO WONDER THE POWER BILL IS SO HIGH..
………and the CROP YIELD IS DOWN AGAIN !
Funny though………….the Tomatoes and the Marihuana are doing nicely !!