"Some taxa and sites showed decreases in abundance and diversity while others increased or were unchanged, yielding net abundance and biodiversity trends generally indistinguishable from zero. "
That's very interesting, and REALLY surprising. Even the citations listed there has this one:
"More than 75 percent decline over 27 years in total flying insect biomass in protected areas."
Ecology is incredibly difficult because everything is horrendously under-sampled. Essentially all ecology reduces to counting species over time and somehow extrapolating to huge areas. So-called total count surveys are extremely expensive.
I can only speak from a megafauna perspective (eg not insects), but there were recently some results that suggested that animal decline in Africa was overestimated. Caused quite a stir. And it makes sense when you learn how people count animals in aerial surveys - photographic interpretation is novel because most ecologists are not used to dealing with that level of data, nor the complexity in designing the camera systems, and it was impractical to do with film in the past. The gold standard is someone with a voice recorder in a plane. When you actually go through aerial photographic surveys, you spot all sorts of things that the observers missed, because they're not superhuman. That's not to say there is no decline - poaching has still decimated populations - but for some species it might not be as bad as you think. In theory the methods (things like JOLLY2) are supposed to correct for you missing a certain percentage, and distance to the animals etc, but that relies on you knowing what those uncertainties are.
I don't know how insect surveys are performed, but you have to understand that you're always trying to make sweeping assumption about "the whole of the US" based on very sparse sampling. Not to mention controlling for different environments. For example in the paper you cited, they try and control for a ton of stuff like habitat. I'm not an entomologist so I won't comment on the paper beyond that, but do be aware that "standard techniques" may well be something that we've done since the 60s and nobody questions it.
> but that relies on you knowing what those uncertainties are.
And it also relies on those uncertainties not changing. "Elephants start spending more time in the forests and not open areas to avoid poachers" would reduce counts from airplanes without changing the number of elephants, for example.
As I understand the sampling, you pretty much just put the traps out and count up how many insects you get of each type.
Purely anecdotally, I feel like the number of butterflies is way down from the level you'd see during, say, the 90s. It seems like I just don't see as many different types any more and even the more common types feel vastly reduced in number. I used to see monarchs and sulfers and painted ladies and red admirals and cabbage butterflies all the time, now I barely see a few cabbage butterflies or sulfers and occasionally a painted lady or two. I never get to see the less common things like buckeyes any more, which is a pity given that they're my favorite.
This is anecdotal, but during Singapore's lockdown, one of the many services cut for about two months was curb maintenance. Being deep in the tropics, all green spaces immediately turned into jungles of flowers and weeds, and the butterfly population consequently exploded:
On the other hand, mosquito populations also increased and there were lots of people stuck at home as bait for them, contributing to Singapore's worst dengue outbreak in years:
Singapore is also going through a particularly bad Dengue fever season, so there is a ton being done for mosquito control including spraying of insecticides.
I have no idea how selective those insecticides are, but one could imagine an impact on other insects.
In the UK there have been fairly successful movements to stop councils trimming verges, since it promotes wildflowers and insects. This was pre-covid, but probably it's helped. You should check out Wilding by the serendipitously named Isabella Tree, if you've not already.
I don't know anything about entomology or ecology, etc.
But I noticed a stark decline in dead insects on the windshield of the car after a road trip in Europe over the last 20 years. Not so in the US. Meaning: 20 years ago I saw lots of dead insects on the windshield in Europe, very few in the US. Now it's very few in both places.
So, I can corroborate: noticeable insect decline in Europe, no noticeable decline in the US, but unfortunately from a low level to begin with.
Funny you mention this. Having driven in the US, Mexico, and Italy (in recent years) I had never experienced a thing I had seen in movies, a windshield full of bugs.
This was until I went to a remoter part of northern Quebec and found that without intervention the windshield would become opaque and driving with the window open created a horrifying mess near the rear window.
I've worked with Richard and the folks at STE on a different digital imaging survey, they're doing some fantastic work and are really pioneers, despite a lot of push back from the community.
This discussion thread has me wondering if there's a good opportunity between the ubiquity of modern cameras (drones/satellites/phones) + computer vision to reduce the cost of those "total count" surveys you mentioned.
Not that I was prepping for an interview but a couple questions I asked myself...
* How could you use social media to establish the size of the pidgeon population in NYC?
* Design a system for tracking Bluefin Tuna populations with an unlimited satellite imagery budget.
* How many drones would it take to count the total number of wolves in Yellowstone in 1 week?
* In safari destinations in Africa like the Maasai Mara, what % of megafauna are photographed annually?
Makes you wonder if all of our facial recognition tech could find a better use in ecology.
This is basically what I've spent the last two years working on - my postdoc has been building an open-source drone payload that does real-time animal detection in visible/thermal images.
Drones aren't practical for total counts. These tend to be e.g. an entire safari park. You need multiple planes flying for several hours each day. Huge expense - hundreds of thousands easily. What's more common is to do transect counts where you fly in a sort of raster pattern and then do your statistics to estimate the population that you didn't see. Drones are still massively limited by flight time, typically an hour at most. Maybe a bit more if you have a really good fixed wing. See https://www.nationalgeographic.com/news/2016/01/160104-great...
On the other hand drones can be used as an effective anti-poaching deterrent - for example if you have a rough location. They can also be used for small scale surveys in locations where you can't really afford a plane and/or it's awkward or dangerous to send people. Some applications like flying very close to cliff faces to monitor birds are only possible to do safely with drones.
Ecology has a whole host of problems that make object detection difficult. You have extreme class imbalance when you capture data - 90%+ of images are empty. Animals are frequently camouflaged. Many animals (like the various gazelles in Africa) look almost identical, especially in low resolution aerial imagery. A lot of animals of interest are small. Even for camera traps, where you have very controlled conditions, the standard approach these days is to have a generic "animal detector" and then have humans do the long tail classification.
On the Africa question though - not a large percentage at all. By the way megafauna covers a lot more than it suggests (40kg+, so that includes deer). Most smaller conservancies have a good idea of how many "rare" species they have, because they're extremely conscious of poaching. But water buffalo? Thompsons gazelle? Who knows exactly. And once you go out of controlled areas into the bush proper, it's anyone's guess. There are charities which organise surveys, but it costs so much to do that it's not feasible to do it annually. See that Nat Geo link - that was the first time anyone had surveyed elephants in Angola. In 2016.
But computer vision is absolutely the future. People are coming round to the idea that we need to start capturing full survey imagery during counts. And while those images are still labelled by people today, once we have that data stored we can always run new models over it in the future.
This all gets really complicated really fast. Which is not to say we shouldn't discuss it or even take preliminary actions, but it does mean the answers will evolve.
One of the profound moments for me reading 1491 is the assertion that the collapse of buffalo and passenger pigeon populations was at once tragic and overblown - the absence of anthropomorphic pressure on the environment caused these populations to explode, draw more attention, and ultimately collapse through predation.
Meanwhile, many of the chemicals we banned post-Silent Spring affected insects and birds. Insect numbers are affected by many ecological stressors, from range, to pollution, to predation by birds.
If you kill or drive away all of the barn swallows and purple martins, you get more mosquitoes. If the barn swallows come back, you get fewer mosquitoes. If you set up martin houses, fewer mosquitoes. Fewer mosquitoes? Fewer dragonflies. All along the food chain things shift.
> Hoping to see the details on how they did things.
Me, too. You can get some inferences based on what others in the field are saying about the paper, although I have no idea how well-representative these folks are, either.
The strongest criticism centers around how well the data sets cover the US biosphere. For example, "Crossley’s datasets include aphids on farmland in the Midwest (40% of all the time series), and samples in urban habitats in Phoenix, Arizona (24% of all time series)." So it seems that which the abstract giveth, the article body taketh away.
When I was a teenager, I caught a bunch of beetles and put a dot of white out on some of them. Then I went back a week later, caught a bunch of beetles again, and counted how many had white out on them. Used that to estimate the beetle population.
Yes, number of aphids goes up, number of butterflies goes down. Conclusion: no net change.
The study has been criticised by German scientists for this reason. With rather drastic words, e.g. "I don't understand how a paper with such obvious weaknesses can pass through the peer reviewing process" and "This paper is not a good example for scientific best practices".
A few careers ago, some agribusiness dude asked me why I opposed the introduction of nonnative species, given that I was concerned about biodiversity loss.
To expand, it comes originally from a poem from Trilussa[0], a poet which wrote satirical poems in the Roman dialect. I'm afraid they lose a lot in translation.
I'm guessing stats where the basic question doesn't reflect reality. "If a chicken and a half lays an egg and a half in a day and a half, how many eggs will three chickens lay in thirty days".
This sounds pretty surprising to me since I thought I kept hearing that insects were in decline globally. This made me curious.
One thing I often check is who the author(s) are and what their links to industry might be. For example if the paper claims that "Smoking is good for you in moderation" and then after googling the author I find they have ties to Marlboro I start to doubt the authenticity of the research.
In this case the authors are mostly organizations that from what I can tell do not have any affiliation with for example an insecticide company or even a company. The only non organization author I see listed is Michael S. Crossley. I googled him and did not find anything suspicious. He does not appear to have a background in entomology or ecology. I am not really sure if that is reason to be suspicious but just thought I would share.
You've linked Michael W. Crossley, the lead author is Michael S. Crossley. The google scholar profile for the latter matches the contact email in the paper and shows a history of related work.
The research that says insects are in decline seems highly questionable to me. They don’t differentiate per species and measure per kilogram. If some heavier species like moths have a successful couple of years, they heavily skew the statistics. There also is not a lot of data on insect populace and the data that is there doesn’t go back for a very long period. I think most articles cite one local German research project on the topic.
This type of measurement using quantitative data should be interpreted with care. At least here in Brazil most of places where some impact occur have an increase in net diversity and abundance. Many new sp. invade the niche left open by the former community and what you see is a shift of the entire community.
Which, while terrible to see the loss, gives me some hope that we have less power over nature than we think. A housing suburb is undeniably a less wonderful place than the forest it replaced. But life will inevitably find a way to colonise that suburb. Black birds and Camel crickets bring me hope. But I wish we would stop burning down rainforests and building boring suburbs.
Fun sentence about the breadth of the data: "Types of arthropod data include grasshoppers per sweep in Konza Prairie (Kansas), ground arthropods per pitfall trap in Sevilleta desert/grassland (New Mexico), mosquito larvae per ovi-trap in Baltimore (Maryland), pelagic macroinvertebrates per tow and crayfish per fyke net in North Temperate Lakes (Wisconsin), aphids per suction trap sample in the Midwestern United States, crab burrows per quadrat in Georgia Coastal Ecosystems, ticks per person/hour in Harvard Forest (Massachusetts), caterpillars per plot in Hubbard Brook (New Hampshire), arthropods per pitfall trap and sweep net in Phoenix metro area (Arizona) and stream insects per rock scrub in the Arctic (Alaska) (Table 1)."
The crayfish and crabs surprised me, considering the title mentions only insect abundance.
> The US National Science Foundation initiated the establishment of a network of Long-Term Ecological Research (LTER) sites in 1980, and these now encompass a web of 25 monitoring locations across each of the country’s major ecoregions (Fig. 1).
The paper includes both source data and source code (R data analysis) [1].
Well, in science you actually usually get bonus points for "surprising" results, so while I'm glad they published it I think the same incentives that encourage scientists to publish some findings and trash others are still at play here.
I think the title of this paper does a real disservice to the much more carefully written abstract. The abstract is very careful to point out the limitations of this study and flesh out why the main conclusion should be considered cautiously.
In biology, if you don't have validation you aren't getting published in Nature. Maybe other fields play faster and looser, but this field demands evidence for claims and support from other sources validating these findings before they are seriously accepted by the community.
If you discover a brand new biological phenomenon, are you saying you can get it published unless someone else does the same experiment and gets the same result?
I know anecdote is not data, but I’ve been driving through rural California for decades. I definitely noticed that in the last few years I have significantly less insects caking my windshield after a long drive than I did ten years ago. This could be explained by changes to windshield design, changes to car lights, and changes to the land adjacent to highways.
Denser bits of the air, like insects, will have a much harder time abruptly changing direction so vehicles with worse aerodynamics tend to pick up insects for the same reasons that water trap style air filters work.
While windshield angles haven't changed much over the years car front ends tend to get much more aerodynamic treatment than even 20yr ago.
I’m not sure about windscreens, but research disagrees overall with your point: “The research included vintage cars up to 70 years old to see if their less aerodynamic shape meant they killed more bugs, but it found that modern cars actually hit slightly more insects.” From https://www.theguardian.com/environment/2020/feb/12/car-spla...
This makes sense to me. A flat box design will push a thicker pillow of air in front of it than an angled surface. I wouldn't expect it to matter for a bumblebee for example, but would think the small mosquitoes get pushed away more easily with airflow.
Indeed, this has been my experience in the 1990s, in the UK I would be regularly cleaning dead squished bugs off the front of my car at the time. I very rarely see any of that nowadays. Maybe they have evolved ...
It's important to look at total diversity and changes within that total. They don't need to happen together.
Noting differences between the US and other places like EU is useful. Might there be something happening in one place that's not happening in another? Identifying differences can provide insight.
Is there a way to check local insect levels without harming their populations?
A lot of comments in here have been anecdotal observations of pretty big population swings and I too (in the northeast of the USA) have noticed the insect populations have increased over the past two years after a nadir in prior years, but I have no real way of determining what's going on scientifically.
It's a fairly common concern, however in the view of entomologists, the number of individual arthropods killed is generally a drop in the bucket. Moreover, many species cannot be identified without detailed examination. As one entomologist explains:
> In addition, a lot of important insect parts need to be extracted for species-level identification. Often the methods required for this aren’t possible to perform on live insects, and when they are they often injure the insects anyways.
> https://askentomologists.com/2015/01/01/why-do-entomologists...
Personally, I've tried to identify certain fly species using several high quality photographs taken from multiple angles, however at best one might get the genus; figuring out which species it is often requires direct access to the insect and may even require dissection in some cases. This was the case when trying to figure out exactly what species of horse fly was attacking me while out hiking. Even with a decent key, provided by the Canadian Journal of Arthropod Identification, I couldn't get a definitive answer on the specific species. (cf http://cjai.biologicalsurvey.ca/t_13/t_1321.htm )
And on iNaturalist.org, a citizen science project based on automated visual recognition (using user-supplied, geotagged photos) and often the participation of expert identifiers, many insect species have never been ID'd even once. And that's a combination of the issues of rarity (and perhaps species loss) and the challenge of visual identification. In one family in Order Diptera (flies) that I examined, less than 1/3 of the Genuses had any observations, and in one of the genuses that did have a decent number of observations, those were assigned to only 12% of the species in that genus.
So there are strong limitations to what we can do without harming individual insects. Nonetheless, these sampling and identification methods don't substantially harm insect populations.
“We have constructed two optical sensing systems for insects based on light attenuation and light backscattering, respectively. The systems, which were tested with the potentially dangerous Aedes albopictus and Culex pipiens, were able to extract the wing-beat frequency, when they passed impinging light, derived from light-emitting diodes. We could achieve distinction between the sexes of A. albopictus and C. pipiens based on the wing-beat frequency”
“We present a novel bimodal optoelectronic sensor based on Fresnel lenses and the associated stereo-recording device that records the wingbeat event of an insect in flight as backscattered and extinction light. We investigate the complementary information of these two sources of biometric evidence and we finally embed part of this technology in an electronic e-trap for fruit flies. The e-trap examines the spectral content of the wingbeat of the insect flying in and reports wirelessly counts and species identity“
I also would think the number of insect deaths by scientist-placed insect traps would be dwarfed by both that of traps placed just to kill insects and ‘traps’ formed by the area of car wind shields being swiped through the world.
I got downvoted to oblivion a few months back for suggesting that maybe cars were just getting more aerodynamic. I still wonder if anybody has really considered that. I assume so, it seems like a plausible first guess.
I have a car that's not very aerodynamic (Jeep Wrangler) and when I'm driving through rural areas the insect mess at dusk or dawn is bad enough that I have to run the windshield wipers. Conversely, I never have to worry about it around my house, which is in the middle of large urban area (SF Bay Area).
Now, consider that there has been massive human migration into urban areas over the last century, plus cars getting far more aerodynamic in the last 40 years, and I think you can make a case for observation bias. However, I think you can also say very firmly that urban areas = less insect populations, so as our urban footprint grows, it is likely costing us. I think suburban sprawl may be even worse, because of the habitat destruction your typical housing development causes without the benefits of density that a truly urban environment offers.
So honestly I think you could be right and wrong at the same time. It is definitely worth correcting for.
Interestingly, this article [0] states that the opposite is true: "The research included vintage cars up to 70 years old to see if their less aerodynamic shape meant they killed more bugs, but it found that modern cars actually hit slightly more insects."
That seems plausible. Perhaps an car with poor aerodynamics pushes a wall of air in front of it that deflects bugs up over the car, where a slippery car may allow the bugs to smash right into the glass.
Now that I've made my comment, I'll go read that article. Thanks for sharing ;-)
With a decent (perhaps high speed?) camera and a trained computer vision model, couldn't a contactless study be performed of flying insects? It should be possible to count the common species in an area with reasonable accuracy and flag photographs of unknown species for human review. Definitely not as cheap as a trap, but perhaps with solar power could be just as easy to place. Unless someone with experience with these studies can make the case that the number of insects killed by these traps is negligible and all this effort isn't worth it of course.
The problem is you simply cannot identify most insect species from photographs of them flying. Depending on which taxon you're working on, you have to do things like count the number of tarsi (foot segments) on each leg, look at the vein pattern on their wings, count the hairs on their thorax, or other minutiae. Also remember that most insects are only a few millimeters in size.
Some taxa can readily be identified in the field (butterflies, most grasshoppers, some beetles and true bugs). Others (dipterans and hymenopterans and pretty much anything smaller than 5mm) need to be done in the lab, with a good stereoscope and big identification books. It helps to have a steady hand and lots of experience...
(In fact, several taxa are so difficult to identify down to the species level that there might only be one or two experts in the whole country that can reliably do so.)
Gotta love the way that good environmental news is greeted with caution and skepticism, while bad news is greeted with immediate acceptance and acclamation.
This is good news! Let's hear it for the bugs! woohoo!
The majority of data we've gathered so far (though mostly in Europe) points in another direction. Therefore this study is unexpected and we're trying to figure out what's going on - is America doing so much better than Europe seems to be, or is the data in this study too patchy?
Actually, even before this study, there's been a lot of discussion among ecologists about just how serious the insect decline actually is. My impression of the recent literature is that while there's definitely a worrisomely strong decline (certainly in Europe), talk of an "apocalypse" is rather overdone. But of course, the wider media usually only pick up on the dramatic results and leave out a lot of nuance.
Yeah, the media reporting is always sensationalised. But they need the clicks, so it's kinda understandable. Annoying, but understandable.
I'm more fascinated by the set of people who refuse to accept that there can be any good environmental news. There was a story a while back about the fact that there are more trees in the world now that in the 70's, and that got greeted with the same skepticism and argument.
I guess some people have a worldview that's locked into environmental catastrophe and are unwilling to accept any evidence that contradicts that.
It entirely obliterates the insect collapse myth in the US. It's not skepticism and caution it's being met with, it's in denial mourning and willful head-in-the-sand'ing at the destruction of a critical piece of propaganda. Accordingly the remarkable, honest, rational, brave and scientifically sound study must be attacked and stopped no matter the cost.
I have noticed a sharp upswing in insect life in the UK this year - but perhaps because I was really thrown by the talk of decline last year so have been looking hard since.
I've noticed a sharp downturn in invasive species in my portion of the US this year (Japanese Beetles and Asian "Lady" Beetles especially) with an upturn in native species.
I attributed it to the really late frost. Maybe there's something else to this? I don't know anymore, everything is upside down anyways.
Anecdotal, but I've seen so many insects this year in the US, more than other years. It could be a factor of being home more and also a resurgence. I'm not sure.
Another aspect, beyond potential differences in pesticides or pesticide application methods might be Air pollution.
Europe has very small footprint compared to the US but proportionally a very high PM2.5 particle concentration and NO2 concentrations (specially Northern Europe) in particular around major port trading hubs and petro-chemical facilities, the market share of Diesel engines in Europe is also a major NO2 contributor.
The US is heavily industrialized but sites are actually much more spread out and most of the pollution above recommended levels is concentrated on the East coast of the US.
If the air pollution aspect is a factor in insect population than it would follow that we would see huge insect population losses in large parts of China and Southeast Asia but I don't have data that supports or denies this?
I believe they also like clover lawns, and gardens... really anything besides the sterile grass and concrete structures that have been marketed to be idolized.
Lavendar is great, but umbels hit a broad variety of insects, especially predatory species.
Yarrow, fennel, Queen Anne's Lace, hemlock (do not grow this please), and many others.
If you are on the west coast, Ceanothus is even more popular among bees of all kinds than is lavender (also bigger, and with better life expectancy). Just don't plant it along a walkway, or people will be brushing past the 'bee bush'.
Our (non-native) fennel plants seem to be a significant attractor of bees and other pollinators. They also serves as a host plant for Anise Swallowtail butterflies. The bees also really like the citrus (oranges, lemons, citron, grapefruit), cuphea, milkweed, buddleia, lavender, and lantana.
On the fennel, or any umbel flower for that matter, you should also be seeing adult ladybugs and lacewings (both eat aphids during part of their lifecycle) as well as hoverflies and predatory wasps.
Nah, I was actively soliciting people to follow it, doubly so given that it is an internal HN link and not an abstract article. It was just a subtle little chuckle of a post.
.. did not read, serious BS radar alarms.. lifelong California resident and this absolutely does not match my observed experience.. Particularly since the Malathion spray event, which showed massive elimination of larger spiders and colorful insects, by direct observation with my own eyes
Is it not consistent with your personal observations that the relative concentrations of diversity have maybe moved? I'm not sure how that possibility would contradict you, given your honestly limited geographical experience.
clarification - I read actual science and large, sourced reports routinely. I also read the history of science obfuscation paid for by companies facing new, legal liability, btw. I don't mean to suggest "ignore science" .. I mean to say "I think I will announce prima facia suspicion and get on with other tasks now"
Certainly true for mosquitoes in the Northeast. Despite me improving drainage on the property, there seems to be at least a dozen of them hovering near my legs as soon as I go outside.
>Recent reports of dramatic declines in insect abundance suggest grave consequences for global ecosystems and human society. Most evidence comes from Europe, however, leaving uncertainty about insect population trends worldwide.
This makes me wonder how much of the decline in Europe is due to the ecological side effects of two highly destructive world wars. Mechanized, combined arms combat moves a lot of dirt around, via explosions, and tracked vehicles ripping up the soil, which would kill or disrupt a lot of insect's breeding/eggs. Large swaths of mainland Europe were carpet bombed, or subject to intense artillery fire. Additionally, after the war, reconstruction efforts would have disturbed even more soil and insect habit, coupled with the Green Revolution's increase in fertilizers, pesticides, etc.
If the insect population in Europe was previously devastated, or diminished by physical upheaval, then it wouldn't surprise me that the population as a whole hasn't recovered from, and is still losing ground to, the more pervasive insecticide and manufactured pollutants (ie all the plastic derivatives, BPAs, etc) that have become part of our environment.
While the world wars certainly would have had some impact, most of the current studies are comparing current populations to what was around in the 80's/90's. This one for example covers 1989-2017: https://journals.plos.org/plosone/article?id=10.1371/journal...
I don’t think tilling of the soil type disruption has any lasting effect. Bugs and such things breed in massive and exponential quantities till they reach equilibrium. But food would be a limiting factor as well as chemicals could be a factor. Ripping up soil would be a temporary setback (of a few years).
That's very interesting, and REALLY surprising. Even the citations listed there has this one: "More than 75 percent decline over 27 years in total flying insect biomass in protected areas."
Hoping to see the details on how they did things.