Massive yet grossly underestimated global costs of invasive insects

4 10 2016
Portrait of a red imported fire ant, Solenopsis invicta. This species arrived to the southeastern United States from South America in the 1930s. Specimen from Brackenridge Field Laboratory, Austin, Texas, USA. Public domain image by Alex Wild, produced by the University of Texas "Insects Unlocked" program.

Portrait of a red imported fire ant Solenopsis invicta. This species arrived to the southeastern USA from South America in the 1930s. Specimen from Brackenridge Field Laboratory, Austin, Texas, USA. Public domain image by Alex Wild, produced by the University of Texas “Insects Unlocked” program.

As many of you already know, I spent a good deal of time in France last year basking in the hospitality of Franck Courchamp and his vibrant Systematic Ecology & Evolution lab at Université Paris-Sud. Of course, I had a wonderful time and was sad to leave in the end, but now I have some hard evidence that I wasn’t just eating cheese and visiting castles. I was actually doing some pretty cool science too.

Financed by BNP-Paribas and Agence Nationale de Recherche, the project InvaCost was designed to look at the global impact of invasive insects, including projections of range dynamics under climate change and shifting trade patterns. The first of hopefully many papers is now out.

Just published in Nature Communications, I am proud that many months of hard work by a brilliant team of ecologists, epidemiologists and economists has culminated in this article entitled Massive yet grossly underestimated costs of invasive insects, which in my opinion is  the first robust analysis of its kind. Despite some previous attempts at estimating the global costs of invasive species1-4 (which have been largely exposed as guesswork and fantasy5-10), our paper rigorously treats the economic cost estimates and categorises them into ‘reproducible’ and ‘irreproducible’ categories.


Gypsy moth (Lymantria dispar) adult. Dimitri Geystor (France)

What we found was sobering. If we look at just ‘goods and services’ affected by invasive insects, the annual global costs run at about US$70 billion. These include agricultural, forestry and infrastructure damages, as well as many of the direct costs of clean-up and eradication, and the indirect costs of prevention. When you examine that number a little more closely and only include the ‘reproducible’ studies, the total annual costs dip to about US$25 billion, meaning that almost 65% of the costs recorded are without any real empirical support. Scary, especially considering how much credence people put on previously published global ‘estimates’ (for example, see some citation statistics here).


Formosan subterranean termite Coptotermes formosanus by Scott Bauer, US Department of Agriculture, Agricultural Research Service

There’s a great example to illustrate this. If you take it at face value, the most expensive invasive insect in the world is the Formosan subterranean termite Coptotermes formosanus estimated at US$30.2 billion/yr globally. However, that irreproducible estimate is based on a single non-sourced value of US$2.2 billion per year for the USA, a personal communication supporting a ratio of 1:4 of control:repair costs in a single US city (New Orleans), and an unvalidated assumption that the US costs represent 50% of the global total.

Read the rest of this entry »

Cartoon guide to biodiversity loss XXXVIII

25 08 2016

Another six biodiversity cartoons for your midday chuckle & groan. There’s even one in there that takes the mickey out of some of my own research (see if you can figure out which one). See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

Read the rest of this entry »

One-two carbon punch of defaunation

30 04 2016

1-2 punchI’ve just read a well-planned and lateral-thinking paper in Nature Communications that I think readers of ought to appreciate. The study is a simulation of a complex ecosystem service that would be nigh impossible to examine experimentally. Being a self-diagnosed fanatic of simulation studies for just such purposes, I took particular delight in the results.

In many ways, the results of the paper by Osuri and colleagues are intuitive, but that should never be a reason to avoid empirical demonstration of a suspected phenomenon because intuition rarely equals fact. The idea itself is straightforward, but takes more than a few logical steps to describe: Read the rest of this entry »

Higher biodiversity imparts greater disease resistance

12 03 2016

fungal infection

Is biodiversity good for us? In many ways, this is a stupid question because at some point, losing species that we use directly will obviously impact us negatively — think of food crops, pollination and carbon uptake.

But how much can we afford to lose before we notice anything bad is happening? Is the sort of biodiversity erosion we’re seeing today really such a big deal?

One area of research experiencing a surge in popularity is examining how variation in biodiversity (biowealth1) affects the severity of infectious diseases, and it is particularly controversial with respect to the evidence for a direct effect on human pathogens (e.g., see a recent paper here, a critique of it, and a reply).

Controversy surrounding the biodiversity-disease relationship among non-human species is less intense, but there are still arguments about the main mechanisms involved. The amplification hypothesis asserts that a community with more species has a greater pool of potential hosts for pathogens, so pathogens increase as biodiversity increases. On the contrary, the dilution hypothesis asserts that disease prevalence decreases with increasing host species diversity via several possible mechanisms, such as more host species reducing the chance that a given pathogen will ‘encounter’ a suitable host, and that in highly biodiverse communities, an infected individual is less likely to be surrounded by the same species, so the pathogen cannot easily be transmitted to a new host (the so-called transmission interference hypothesis).

So I’ve joined the ecological bandwagon and teamed up yet again with some very clever Chinese collaborators to test these hypotheses in — if I can be so bold to claim — a rather novel and exciting way.

Our new paper was just published online in EcologyWarming and fertilization alter the dilution effect of host diversity on disease severity2. Read the rest of this entry »


24 02 2016

frogWhile I’ve blogged about this before in general terms (here and here), I thought it wise to reproduce the (open-access) chapter of the same name published in late 2013 in the unfortunately rather obscure book The Curious Country produced by the Office of the Chief Scientist of Australia. I think it deserves a little more limelight.

As I stepped off the helicopter’s pontoon and into the swamp’s chest-deep, tepid and opaque water, I experienced for the first time what it must feel like to be some other life form’s dinner. As the helicopter flittered away, the last vestiges of that protective blanket of human technological innovation flew away with it.

Two other similarly susceptible, hairless, clawless and fangless Homo sapiens and I were now in the middle of one of the Northern Territory’s largest swamps at the height of the crocodile-nesting season. We were there to collect crocodile eggs for a local crocodile farm that, ironically, has assisted the amazing recovery of the species since its near-extinction in the 1960s. Removing the commercial incentive to hunt wild crocodiles by flooding the international market with scar-free, farmed skins gave the dwindling population a chance to recover.

redwoodConservation scientists like me rejoice at these rare recoveries, while many of our fellow humans ponder why we want to encourage the proliferation of animals that can easily kill and eat us. The problem is, once people put a value on a species, it is usually consigned to one of two states. It either flourishes as do domestic crops, dogs, cats and livestock, or dwindles towards or to extinction. Consider bison, passenger pigeons, crocodiles and caviar sturgeon.

As a conservation scientist, it’s my job not only to document these declines, but to find ways to prevent them. Through careful measurement and experiments, we provide evidence to support smart policy decisions on land and in the sea. We advise on the best way to protect species in reserves, inform hunters and fishers on how to avoid over-harvesting, and demonstrate the ways in which humans benefit from maintaining healthy ecosystems. Read the rest of this entry »

Bee informed: Quick pollination facts about our most important pollinators

27 11 2015

if we die

If bees were to disappear, humans will disappear within a few years.

Albert Einstein

I find it interesting that so much is said about bees (including here on this blog), yet many of the ‘facts’ that one hears mentioned in any variety of news sources, public presentations and even scientific articles aren’t very well sourced and at times highly suspect.

For your fact-finding benefit then, I present to you some of the established facts about bees: Read the rest of this entry »

How things have (not) changed

13 04 2015

The other night I had the pleasure of dining with the former Australian Democrats leader and senator, Dr John Coulter, at the home of Dr Paul Willis (Director of the Royal Institution of Australia). It was an enlightening evening.

While we discussed many things, the 84 year-old Dr Coulter showed me a rather amazing advert that he and several hundred other scientists, technologists and economists constructed to alert the leaders of Australia that it was heading down the wrong path. It was amazing for three reasons: (i) it was written in 1971, (ii) it was published in The Australian, and (iii) it could have, with a few modifications, been written for today’s Australia.

If you’re an Australian and have even a modicum of environmental understanding, you’ll know that The Australian is a Murdochian rag infamous for its war on science and reason. Even I have had a run-in with its outdated, consumerist and blinkered editorial board. You certainly wouldn’t find an article like Dr Coulter’s in today’s Australian.

More importantly, this 44 year-old article has a lot today that is still relevant. While the language is a little outdated (and sexist), the grammar could use a few updates, and there are some predictions that clearly never came true, it’s telling that scientists and others have been worrying about the same things for quite some time.

In reading the article (reproduced below), one could challenge the authors for being naïve about how society can survive and even prosper despite a declining ecological life-support system. As I once queried Paul Ehrlich about some of his particularly doomerist predictions from over 50 years ago, he politely pointed out that much of what he predicted did, in fact, come true. There are over 1 billion people today that are starving, and another billion or so that are malnourished; combined, this is greater than the entire world population when Paul was born.

So while we might have delayed the crises, we certainly haven’t averted them. Technology does potentially play a positive role, but it can also increase our short-term carrying capacity and buffer the system against shocks. We then tend to ignore the indirect causes of failures like wars, famines and political instability because we do not recognise the real drivers: resource scarcity and ecosystem malfunction.

Australia has yet to learn its lesson.

To Those Who Shape Australia’s Destiny

We believe that western technological society has ignored two vital facts: Read the rest of this entry »

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