By Lambert Strether of Corrente
Recently, Francisco Sánchez-Bayo (The University of Sydney) and Kris A.G. Wyckhuys (University of Queensland) published an enormous review article, “Worldwide decline of the entomofauna: A review of its drivers,” in Biological Conservation. (I’ve uploaded a PDF version of the study in the Appendix. I encourage you to read it, or at least skim it. It’s very lucid, and written to be understandable by lay people like ourselves.) From the abstract:
Here, we present a comprehensive review of 73 historical reports of insect declines from across the globe, and systematically assess the underlying drivers.
Before delving into the Bayo-Wyckhuys (BW) article — and by “delve,” I mean take a brief and superficial view of an enormous topic — I’ll summarize the reactions to it (which are perhaps a bit more highly colored than the study itself, alarming though it is). Then I’ll summarize the reports and drivers, commenting on both. Finally, I’ll look at things that you or I could do to contribute to a solution, prior to (and perhaps, through action, encouraging) intervention by larger entities, like the Federal government).
Reactions to Insect Population Decline
— Scene & Heard (@SaHreports) February 10, 2019
Not sure why British bug splats are on the registation plate instead of the windscreen, but it’s the same phenomenon. And from The Onion, in direct response to BW:
Here are the headlines for more reactions to BW. In no particular order:
Insects are dying at an alarming rate – and this is terrible news for life on Earth World Economic Forum
Why insect populations are plummeting—and why it matters National Geographic
Is the Insect Apocalypse Really Upon Us? The Atlantic
I’m not going to go through these articles one by one, because I don’t think they add much value to the report itself, which, again, is quite readable. (The Atlantic article is a critique, hence more useful.) A few comments on the headlines, however. In general, all of them evoke fear, yet none of them make the fear concrete. As far as inducing action, that seems to be to be about as bad as bad can be. First, we already have a media environment that’s saturated with fear; and when the herd is being simultaneously spooked from so many directions, who knows if it will move it all? For a long time, I’ve been skipping any articles on the Trump administration with words like “terrifying” in the headline. Second, if you want to induce fear successfully, be concrete! For good or ill, you can’t mobilize people with purely abstract terms like “mankind,” “life on Earth,” “ecosystems,” “huge risk,” or even “apocalypse” (the Christians already know what the real Apocalypse is, and for the rest of us, it’s just a metaphor). The environmental movement has been doing this for forty years, it hasn’t worked, and it still isn’t working. I argue again that the most serious moral commitment most people make, in the aggregate, is to their families and especially to their children. And yet the collapse of the biosphere, though it will very obviously harm those who are children today, and even more their children, is never framed in those terms. These headlines certainly don’t. It’s very odd. Now let’s turn to the report.
Reports and Drivers of Insect Population Decline
First, the methodology. From the BW PDF (p 9):
We aimed at compiling all long-term insect surveys conducted over the past 40 years that are available through global peer-reviewed lit- erature databases. To that effect we performed a search on the online Web of Science database using the keywords [insect*] AND [declin*] AND [survey], which resulted in a total of 653 publications.
(We will return to this in a moment.) Now from the discussion of insect population decline (pp 15-17):
Biodiversity loss has become a major global issue, and the current rates of species decline – which could progress into extinction – are unprecedented (Barnosky et al., 2011; Pimm and Raven, 2000). Yet, until recently, most scientific and public attention has focused on charismatic vertebrates, particularly on mammals and birds (Ceballos and Ehrlich, 2002; Manne et al., 1999), whereas insects were routinely underrepresented in biodiversity and conservation studies in spite of their paramount importance to the overall functioning and stability of ecosystems worldwide (Fox, 2013; McKinney, 1999; Thomas et al., 2004).
This review brings to the fore the demise of major insect taxa (albeit no studies are available for most Diptera, Orthoptera and Hemiptera), which started at the dawn of the 20th century, accelerated during the 1950s–1960s, and attained alarming proportions globally over the last two decades…..
(Dirzo et al., 2014). At present, about a third of all insect species are threatened with extinction in the countries studied (Table 1). Moreover, every year about 1% of all insect species are added to the list, with such biodiversity declines resulting in an annual 2.5% loss of biomass worldwide (Fig. 2).
The pace of modern insect extinctions surpasses that of vertebrates by a large margin, although the extent of losses cannot be accurately quantified…. Since the declines affect the majority of species in all taxa, it is evident that we are witnessing the largest extinction event on Earth since the late Permian and Cretaceous periods (Ceballos et al., 2017; Raup and Sepkoski Jr, 1986). (May, 2010).
Most worrying is the fact that the declining terrestrial insect fauna comprise not only specialists with narrow ecological requirements, such as dependence on particular host plants (e.g., Coenonympha oedippus in bogs), ecological niches (e.g., roller dung-beetles) or restricted habitats (e.g., Bombus terricola in the USA), but also generalist species that were once common in many countries (e.g., Aglais io in the Netherlands or Macaria wauaria in the U.K.). This suggests that the causes of insect declines are not tied to particular habitats, but instead affect common traits shared among all insects.
(The part about “generalist species” is interesting; assuming, perhaps wrongly, that the cockroach is one such, “Do you want your children to grow up in a world where the only insects are cockroaches? If so, proceed along your present course.)
And now to the drivers. From the BW PDF (p 12), in rank order:
A large proportion of studies (49.7%) point to as the main driver of insect declines, a factor equally implicated in global bird and mammal declines (Chamberlain and Fuller, 2000; Diamond, 1989). Next on the list is
pollution(25.8%) followed by a variety of (17.6%), whereas few studies (6.9%) indicate as triggering the losses
(Note that “climate change” is not a primary driver; the issue really is with the biosphere as such, with climate a subsystem thereof).
And from the Conclusion (p 22):
Habitat change and pollution are the main drivers of such declines. In particular, the intensification of agriculture over the past six decades stands as the root cause of the problem, and within it the widespread, relentless use of synthetic pesticides is a major driver of insect losses in recent times (Dudley and Alexander, 2017). Given that these factors apply to all countries in the world, insects are not expected to fare differently in tropical and developing countries. The conclusion is clear: unless we change our ways of producing food, insects as a whole will go down the path of extinction in a few decades (Dudley et al., 2017; Fischer et al., 2008; Gomiero et al., 2011). The repercussions this will have for the planet’s ecosystems are catastrophic to say the least, as insects are at the structural and functional base of many of the world’s ecosystems since their rise at the end of the Devonian period, almost 400 million years ago.
With a conclusion like that, some relief might be welcome; The Atlantic provides it, in two ways. First, reputable scientists disagree. From “Is the Insect Apocalypse Really Upon Us?“:
First, some good news: The claim that insects will all be annihilated within the century is absurd. Almost everyone I spoke with says that it’s not even plausible, let alone probable. “Not going to happen,” says Elsa Youngsteadt from North Carolina State University. “They’re the most diverse group of organisms on the planet. Some of them will make it.” Indeed, insects of some sort are likely to be the last ones standing. Any event sufficiently catastrophic to scour the world of insects would also render it inhospitable to other animal life. “If it happened, humans would no longer be on the planet,” says Corrie Moreau from Cornell University.
(Note that BW write “go down the path of extinction in a few decades,” not “be annihilated within the century,” although their popularizers are far less measured.) Although “Any event sufficiently catastrophic to scour the world of insects would also render it inhospitable to other animal life”…. That’s a bit of a self-own, isn’t it? If you assume that the bourgeiosposcence (hat tip, Interfluidity) is, precisely, that event sufficiently catastrophic.
Second, the methodology:
n their review, Sánchez-Bayo and Wyckhuys found 73 studies showing insect declines. But that’s what they went looking for! They searched a database using the keywords insect and decline, and so wouldn’t have considered research showing stability or increases. The studies they found aren’t representative either: Most were done in Europe and North America, and the majority of insects live in the tropics. This spotty geographical spread makes it hard to know if insects are disappearing from some areas but recovering or surging in others.
Well, yes. I suppose there could be “insect” + “increase” studies (and no doubt the biosphere’s equivalent of the American Tobacco Institute is aggregating them right now). But that’s a bit of a debater’s point (not that there’s anything wrong with that. I go back to the disappearance of bug splats. When you think about it, that’s an enormous event. And everybody knows about it! Poke holes in the studies as you will, clearly something is very, very wrong.
Things We Can Do to Ameliorate Insect Population Decline
For the number one driver,
Big Ag the “intensification of agriculture,” BW offer suggestions:
Habitat restoration, coupled with a drastic reduction in agro-che- mical inputs and agricultural ‘redesign’, is probably the most effective way to stop further declines, particularly in areas under intensive agriculture. For example, flower and grassland strips established at the field edge enhance the abundance of wild pollinators (Blaauw and Isaacs, 2014; Hopwood, 2008), and rotation of crops with clover boosts the abundance and diversity of bumblebees (Ekroos et al., 2014; Haaland and Bersier, 2011), which in turn boost crop yield and farm profitability. These ‘ecological engineering’ tactics not only favour pollinators but also conserve insect natural enemies that are essential for keeping at bay the herbivorous pest species of many crops (Dover et al., 2011; Gurr et al., 2012; Lu et al., 2015). However, for these measures to be effective, it is imperative that current pesticide usage patterns, mainly insecticides and fungicides, are reduced to a minimum as to permit a recovery of insect numbers and their associated ‘biolo- gical control’ services (Heong et al., 2015; Way and Heong, 1994). There is no danger in reducing synthetic insecticides drastically, as they do not contribute significantly to crop yields, but trigger pest resistance, negatively affect food safety and sometimes lower farm revenue (Bredeson and Lundgren, 2018; Lechenet et al., 2017)…. For aquatic insects, rehabilitation of marshlands and improved water quality are a must for the recovery of biodiversity (van Strien et al., 2016). This may require the implementation of effective re- mediation technologies to clean the existing polluted waters (Arzate et al., 2017; Pascal-Lorber and Laurent, 2011). However, priority should be given to reducing the contamination by runoff and leaching of toxic chemicals, particularly pesticides.
It’s worth noting that HR 109 includes the following project:
(G) working collaboratively with farmers and ranchers in the United States to remove pollution and greenhouse gas emissions from the agricultural sector as much as is technologically feasible, including—
(i) by supporting family farming;
(ii) by investing in sustainable farming and land use practices that increase soil health; and
(iii) by building a more sustainable food system that ensures universal access to healthy food;
I think all of BW’s recommendations for habitat restoration would fit or could be made to fit under this rubric. (I remember being taught in grade school about the New Deal, which also included changes in agricultural practice to reduce topsoil loss, which had, IIRC, led to “The Dust Bowl.”) Readers will also recall a recent link to regenerative agriculture.
And so to things you or I might do in our sphere of influence, below the Federal level, to end or mitigate insect population decline. Off the top of my head:
(1) Get involved in local zoning and permitting. The zoning and permitting process should be a powerful process to eliminate or mitigate both habitat loss and the use of pesticides. Make an issue of your town’s program to spray insecticides! Make an issue of your town’s program to cut back habitat along the roadside and along median strips!
(2) Get involved or create efforts in citizen science. BW write:
The above literature records use accurate scientific data on species distribution from museum specimens (56%), which are compared with long-term survey data obtained decades later (72%), and sometimes rely upon citizen science data (8%)
Surely 8% is much too low? Let’s increase it! Once more from HR 109:
(K) restoring and protecting threatened, endangered, and fragile ecosystems through that enhance biodiversity and support climate resiliency;
I would imagine public libraries would be a very good place to publicize such events and hold meetings.
(3) Abolish your lawn (if you have one). You have the power to create a pollinator- and insect-friendly habitat, so do so! (You will be amazed.)
(4) Check that your local extension agent is up on the issue and has appropriate solutions to recommend.
(5) Make insect population decline a political issue through the usual channels: Calling your legislators, getting letters to the editor printed, and so on. (Just remember that if you use fear as a tool, make the fear concrete and not abstract!)
Readers, other ideas?
Bug splats alone show the problem of insect population decline is real and serious. BW have created a masterful aggregation and serious that shows how serious at the species level, and gives the drivers. Readers will be aware, at this point, that I’m a meliorist. So let’s go ameliorate! The science is there — enough.
 I mean, I lived through the Bush administration; Bush got us into an actual shooting war with a disinformation campaign, slaughtered a few hundred thousand people, and destroyed the Fourth Amendment — all with Democrat help, mind you. Now that was a terrifying administration! (OK, OK, “you were lucky.”)
 The studies aggregated by BW are from the global north, so I would like very much to hear from any NC travelers or expatriates about equally powerful studies in other parts of the world.
Here is a PDF of the study:1-s2.0-S0006320718313636-main