Insect biologists have long sung the praises of these unrewarded miniature heroes, from JBS Haldane's supposed adage about God being "inordinately fond of stars and beetles" to EO Wilson's 1987 speech that described them as "the little things that run the world." In terms of numbers of species and individuals, invertebrates, especially insects, are the great success story of macroscopic life on our planet. So if they are in serious decline, does that spell trouble for Homo sapiens?
The new research claims that one-third of all insect species are currently endangered, extrapolating to wholesale extinction for the class Insecta over the next century. Although the popular press has started using evocative phrases such as "insect genocide" and even "insectageddon", just how accurate are these dramatic claims?
The United Nation's Red List currently describes three hundred insect species as critically endangered and a further seven hundred as vulnerable, but this is a tiny proportion of the total of...well, at lot more, at any rate. One oft-quoted figure is around one million insect species, although entomologists have estimated anywhere from 750,000 up to 30 million, with many species still lacking formal scientific identification. The hyperbole could therefore easily sound like unnecessary scaremongering, until you consider the details.
The new report states that butterflies and caddis flies are suffering the greatest decline, while cockroaches - as anyone who has faced a household infestation of them will know, they are likely to remain around until the end of world - and flies are the least affected orders. So, to paraphrase Monty Python, what have the insects ever done for us?
Pollination is of course of key importance, to both horticulture and un-managed 'wild' environments. Insects are near the base of many food webs; if numbers were much reduced, never mind removed, the impact on the rest of the ecosystem would be catastrophic. With the human population set to top ten billion in thirty years' time, we require ever larger regions of productive land for agriculture. They may be small at an individual level, but arthropods in general total about seventeen times the mass of all us H. sapiens. Insects replenish the soil, as alongside bacteria they break down dead matter and fecal material. So important is this latter function that New Zealand has been trialling non-native dung beetles to aid cattle farmers.
One key way to save fresh water and lessen the generation of the potent greenhouse gas methane is to reduce meat consumption in favour of insect protein. If insects are no longer around, then that will be an additional challenge in reducing environmental degradation. This of course also ignores the fact that insects are already a component in the diet of many developing nations. Last year I wrote about how scientists have been creating advanced materials derived from animals. Again, we are shooting ourselves in the foot if we allow this ready-made molecular library to be destroyed.
What is responsible for this global decline? Perhaps unsurprisingly, it turns out to be the usual suspects. Agricultural chemicals including pesticides have been associated with honey-bee colony collapse disorder (not incidentally, some tests have found honey samples with neonicotinoids - the mostly widely-used insecticides - exceeding the recommended human dosage) so clearly the same culprit is affecting other insects. Fresh waterways, home to many aquatic insect species, are frequently as polluted as the soil, either due to agricultural run-off or industrial contaminants. Wild landscapes are being converted with great haste into farm land and urban sprawl, with an obviously much-reduced biota.
Climate change is playing its part, with soil acidity increasing just as it is in the oceans. Even areas as remote as central Australia have seen marked decreases in insects as higher temperatures and lower rainfall outpaces the ability to adapt to the new conditions. I've often mentioned the role of invasive species in the decimation of indigenous vertebrates, but insects are equally prone to suffer from the arrival of newcomers. Although New Zealand has very strict biosecurity protocols, the likes of Queensland fruit flies and brown marmorated stink bugs are still occasionally found in or around ports of entry.
Many nations have no such procedures in place, resulting in local species being out-competed or killed by introduced species or pathogens to which they have no resistance. Until fairly recently, even New Zealand had a lax attitude to the issue, resulting in the decline of native species such as carabid beetles. When I conducted a brief survey of my garden in 2017 I found that one-third of the insect species were non-native, most of these being accidental imports since the arrival of European settlers.
If insects are so vital to our survival, why has there been so little interest in their well-being? There are some fairly obvious suggestions here. Firstly, at least in Western cultures, insects have been deemed dirty, ugly things that can be killed without a second thought. Wasps, ants and cockroaches in particular are seen in this light of being unwelcome pests, with typical insect-related phrases including "creepy crawlies" and "don't let the bed bugs bite".
It's fairly well-known that malaria-carrying mosquitoes are the most dangerous animals for us humans in terms of fatalities. The widespread outbreaks of the Zika virus haven't done them any favours either. As Brian Cox's television series Wonders of Life showed, their small size has given them veritable super powers compared to us lumbering mammals, from climbing up sheer surfaces (as a praying mantis was doing a few nights' ago on my window) to having amazing strength-to-weight ratios. All in all, insects are a bit too alien for their own good!
Clearly, scale prejudice is also a key factor. On a recent trip to Auckland Central Library I only found one book on insects versus dozens on birds. Photographic technology has been a double-edged sword when it comes to giving us a clearer picture of insects: close-ups are often greeted with revulsion, yet until Sir David Attenborough's 2005 BBC series Life in the Undergrowth, there was little attempt to film their behaviour with the same level of detail as say, the lions and antelopes of the Serengeti. It should also be mentioned that when Rachel Carson's ground-breaking book about the dangers of pesticides, Silent Spring, was published in 1962, the resulting environmentalism was largely in support of birds rather than insects.
Among all this doom and gloom, are there any ways to prevent it? One thing is for certain, and that is that it won't be easy. The agricultural sector would have to make drastic changes for a start, becoming much smarter in the use of chemicals and be held responsible for the local environment, including waterways. Vertical farming and other novel techniques could reduce the need for new agricultural land and water usage, but developing nations would be hard-pressed to fund these themselves.
Before any major undertaking, there's going to have to be either a fundamental crisis, such as food shortages, in a rich nation or a massive public relations exercise to convince people to consider insects in the same light as giant pandas or dolphins. This is not going to be easy, but as David Attenborough put it: "These small creatures are within a few inches of our feet, wherever we go on land - but often, they're disregarded. We would do very well to remember them."
