Insect populations are crashing.
“We knew that something was amiss in the first couple days,” said Brad Lister. “We were driving into the forest and at the same time both Andres and I said: ‘Where are all the birds?’ There was nothing.”
His return to the Luquillo rainforest in Puerto Rico after 35 years was to reveal an appalling discovery. The insect population that once provided plentiful food for birds throughout the mountainous national park had collapsed. On the ground, 98% had gone. Up in the leafy canopy, 80% had vanished. The most likely culprit by far is global warming.
Look at these numbers.
The Puerto Rico work is one of just a handful of studies assessing this vital issue, but those that do exist are deeply worrying. Flying insect numbers in Germany’s natural reserves have plunged 75% in just 25 years. The virtual disappearance of birds in an Australian eucalyptus forest was blamed on a lack of insects caused by drought and heat. Lister and his colleague Andrés García also found that insect numbers in a dry forest in Mexico had fallen 80% since the 1980s.
Data on other animals that feed on bugs backed up the findings. “The frogs and birds had also declined simultaneously by about 50% to 65%,” Lister said. The population of one dazzling green bird that eats almost nothing but insects, the Puerto Rican tody, dropped by 90%.
Lister calls these impacts a “bottom-up trophic cascade”, in which the knock-on effects of the insect collapse surge up through the food chain.
“I don’t think most people have a systems view of the natural world,” he said. “But it’s all connected and when the invertebrates are declining the entire food web is going to suffer and degrade. It is a system-wide effect.”
Exactly. We are part of a complex web of interdependencies, and it’s also a non-linear dynamical system. There’s a word for when parts of such a system show a pattern of failure: it’s called catastrophe. By the time you notice it, it’s too late to stop it.
I do not dispute insect loss or global warming. But I am skeptical that the latter is the cause of the former. There are too many other candidates.
Global warming as yet has affected temperatures much less than annual temperature swings have in the past. Especially in mountainous areas, migration to a higher elevation of only a few hundred meters should be sufficient to compensate.
The two possibilities that stand out for me are widespread insecticide use and widespread electrical lighting. Both of these are huge here in Ecuador. On the other hand, I don’t see how insecticide contamination would get up mountain slopes, and electrical lighting would only affect species that fly nocturnally.
Can anyone recommend a good resource on this question?
What I’ve noticed is that the insect populations on my farm are changing, surprisingly fast. I used to reliably have black widow spiders in the old feed box in the horse barn. Now, there are pillbugs. I had monarch butterflies in my milkweed (I let it grow for them) – suddenly from hundreds, it is a handful. Instead of my early summer nights being dotted with fireflies, it’s an occasional blink. The toads from the pond are largely gone, too. 15 years ago when I moved up here they were hopping all over the grass in the spring. I haven’t seen one in the last few years. There used to be clouds of bats. For a few years I had massive infestation of ladybug-like beetles which were replaced by stinkbugs which have now been replaced by wasps.
My impression is that a farm’s critter and bug population stayed more or less constant, but mine is like it’s been knocked out of whack. The same has happened with larger critters – but I assumed that was a result of the passing of my dogs, who kept the rabbits down. I had a spike of rabbits but then they dropped off the map and now there’s a family of woodchucks. The in-ground grub population must also be changing – I used to have lots of june bugs but now I have a skunk that comes and spends a week at the grub buffet. I used
I don’t know how dynamic these populations normally are.
The people with the power and money are the only people able to do something about Global warming .
But they won’t because they want to keep hold of their money and power .
Anyway the earth will be just fine after we are gone .
If you want to read a book that might keep you up at night, check out Dust:
https://www.goodreads.com/book/show/376650.Dust
That said, I read it when it came out, so it might have aged poorly. But as for @Marcus’s comments about insect populations changing rapidly, locally we’ve seen three major changes:
We see waaaaaaaaaaaaaaaay more black widow spiders than when I was growing up. Part of that could be that I’m not living by the river now, but still.
Stink bugs are plentiful now in the fall…and I don’t remember every seeing them as a kid.
We did have a major pine beetle epidemic for about 10-15 years which ended about 5-10 years or so ago (which is part of why British Columbia’s wild fires have been horrible the last couple of years as the long-warned burning of the dead trees happens).
Another aspect of the boiling frog characteristic of climate change, Effects like this on ecosystems, invosible to the general public, are the reason I think we are beyond the point where recovery is possible even if CO2 emissions were ended tomorrow.
mikehuben — insecticide use and light pollution are probably not major factors in a 28,000-acre Puerto Rican forest reserve. The paper in question discusses at length the evidence for possible causes, and of course it can’t prove causality but it makes a very, very strong case for climate change.
Chrislawson:
The paper in question DOES NOT discusses at length the evidence for OTHER possible causes. Here is ALL that it says about the possibility of pesticides being responsible:
“Due to the ongoing reduction in agriculture and associated farmland, pesticides use in Puerto Rico also fell up to 80% between 1969 and 2012 (SI Appendix, Fig. S7). Most pesticides have half-lives measured in days, not decades (60), making it improbable that, despite precipitous declines in their use, remaining residues are responsible for waning arthropod abundance.”
While pesticide use may have declined 80% (in what units?), are we to assume that pesticides have remained the same over 43 years? Has their usage perhaps grown nearer the tested forest? They provide no discussion or data.
Further incompetence: the pesticide half-life table they cite does not list ANY agricultural insecticides except pyrethins (as distinct from pyrethroids which have a much longer environmental presence according to Wikipedia.)
This “pigs is pigs” style of analysis is unsatisfactory to me.
That and I find the “N times reduction” expression grotesque and oxymoronic: why can’t they simply say “reduction to 1/Nth”?
Temperature is a massive influence on insect breeding and viability.
Similarly it’s killing fish in the Murray Darling here in OZ. Combined with drought and bad water management, both made worse by a spiral into a hotter climate.
On one hand, I care far less about why insects populations are collapsing than that they are in fact collapsing. But on the other hand, if we’re to do anything about it (big if, as though we actually possess control over anything), then causation needs to be established to know what to do. Most of our collective response to climate change, after studying and determining the broad outlines of what’s occurring (e.g., emission and buildup of greenhouse gases, ocean acidification, ramping up global average temperature, loss of sea and glacial ice, melting permafrost, colony collapse syndrome, chronic wasting disease among dear, moose, elk, and caribou), has been to argue about it to the point of confusion and distraction. For those intent on denying that anything worth worrying about is happening (to preserve profitable activity), it’s a perfect divide-and-conquer strategy, except that it’s also a Pyrrhic victory when cascade collapse catches up with other large mammals, namely, humans.
@8 It’s not just fish that are dying, up to a third of flying fox fruit bats are literally dropping dead due to the extreme heat in some parts of Australia.
In my relatively wild, sparcely populated, mild climate of the southern Canadian Pacific coastal rainforest, I’m hardly seeing any insects at all. Not in my garden. Not on the lawn. Not out in the forest. I found one – one! – spider in the forest last week, in a place where before I carried a stick to swish aside the spider webs before I put my face through them.
There are no pillbugs in my pillbug-heaven wet garden.
The cricket chorus didn’t perform this year.
No western conifer seedbugs came in to wait out the winter.
In my house, where spiders are welcome, only the cellar spiders remain, and few of those. No babies.
Even the ever-present slugs are gone. Even out in the mossy forest. I’ve seen one banana slug all fall and winter. A couple of blacks.
I can’t find any springtails.
What are the birds supposed to feed their chicks this spring?
This is completely anecdotal. Old timers think back to the 80’s, 70’s or earlier. Maybe you were old enough to drive or maybe you took a ride with your parents. How often did you have to hit that windshield washer fluid to clean off the bug splat? How often do you have to now?
It ain’t science, but there’s something to be said about long experience. Something’s changing. Invertebrates are like a canary in a coal mine where the climate is concerned, farmers can read insect populations like they can cloud formations. Populations will explode or deplete depending on variations in the climate from year to year. But something is different now, it’s not just a year to year variance, they’ve been decreasing in number steadily for decades. The signs are easy to miss if you don’t have decades of observation to compare. Again anecdotal, moths on the porch light at night? There was a time when you couldn’t keep a porch light on at night or your house would be flooded with moths every time someone walked in. Nowadays I’d be lucky to see half a dozen moths come by in a night. It’s like that at a dozen locations I visit across the US and Canada every year. Admittedly the populations fluctuate from year to year and location to location. But broadly speaking, something is different. Locally I thought it might have something to do with the gypsy moth treatments they’ve been spraying around here. Some kind of genetically modified fungus that effects the caterpillars. You can smell it at night when they fly over, or drive by with the atomizers in the trucks and it carries on the wind. It’s supposed to only target gypsy moths and not other species. But who knows, I doubt they did any extensive tests to see if it does. Local govt’s were desperate to get something done.. The dragonfly populations wain and gain from year to year too, now it’s hard to find even one near a swampy area. So who knows what the hell’s going on.
I’ve always been fascinated by insects and whatnot, always on the lookout for species that are new to me, populations, behaviors etc. As of last year I’ve been observing them for 90+ seasons. Unless there is some kind of centuries long cycle for insect populations that effects a broad spectrum of species at once, that I’m unaware of, they’re all on the decline for sure. More so the flying species, they’re definitely hardest hit.
I was thinking that maybe they noticed colony collapse in bees earlier because honey bees are somewhat domesticated and obviously a lot more people pay attention to them. But maybe it’s all invertebrates and humans just didn’t notice what was happening with other species as much because, you know, it just didn’t effect someones bottom line like colony collapse does. Okay I’m rambling, signing off.
@1 mikehuben:
While you are asking for evidence at length, where does this come from? Globally the hottest four years on record have been the last four. You can certainly find stories about the results of extremely rare heat – things in the Arctic melting that had not before, nearly a third of a bat species in Australia dying from a summer heat wave. You’re sure Puerto Rico hasn’t yet had such shifts?
I need another drink. Don’t entirely want to live to old age when things really start getting bad.