Praying for time: the rise and fall of the New Zealand mantis

While the decline of the giant panda, great apes and various cetacean species have long garnered headlines, our scale prejudice has meant invertebrates have fared rather less well. Only with the worrying spread of colony collapse disorder (CCD) in bee hives have insect-themed stories gained public attention; yet most of the millions of other small critters remain on the sidelines. I've often mentioned that overlooking these small marvels could backfire on us, considering we don't know the knock-on effect their rapid decline - and possible near-future extinction - would have on the environment we rely on.

One such example here in New Zealand is our native praying mantis Orthodera novaezealandiae, which for all we know could be a key player in the pest control of our farms and gardens. Mantid species are often near the apex of invertebrate food webs, consuming the likes of mosquitoes, moth caterpillars and cockroaches. I admit that they are not exactly discriminating and will also eat useful species such as ladybirds or decorative ones like monarch butterflies. However, they are definitely preferable to pesticides, a known cause of CCD today and an acknowledged factor of insect decline since Rachel Carson's pioneering 1962 book Silent Spring.

Of course, we shouldn't just support species due to their usefulness: giant pandas aren't being conserved for any particular practical benefit. From a moral perspective it's much easier to convince the public that we should prevent their extinction than that of the rather uncuddly mantis. We still know so little about many insect species it's difficult to work out which need to be saved in order to preserve our agribusiness (versus all the others that of course should be preserved regardless). I’m not averse to careful extermination of plagues of locusts or mosquitoes, but indiscriminate destruction due to greed or stupidity is well, stupid, really.

Down but not out: the New Zealand praying mantis Orthodera novaezealandiae

Back to O. novaezealandiae. I've only seen New Zealand's sole native mantis species three times in the 'wild': twice in my garden in the past two years and once in my local reserve before that. What is particularly interesting is that since initial descriptions in the 1870's, hypotheses regarding its origin appear to have evolved due to patriotic trends as much as to factual evidence. Late Nineteenth Century accounts of its spread suggest an accidental importation from Australia by European sailing ship, since it is a clumsy, short-range flier and seabirds are unlikely to carry the insects - and certainly not their cemented oothecae (egg sacks) - on their feet.

However, some Victorian naturalists thought the insect was incorporated into Maori tradition, implying a precolonial existence. In contrast, A.W.B.Powell's 1947 book Native Animals of New Zealand refers to the native mantis as Orthodera ministralis (which today is only used to describe the Australian green mantis) and the author states it may well be a recent arrival from across the Tasman Sea. So the native species may not be particularly native after all! I find this fascinating, insomuch as it shows how little we understand about our local, smaller scale, wildlife when compared to New Zealand's birds, bats and even reptiles.

The specimens in my garden have lived up to their reputation for being feisty: they seem to size you up before launching themselves directly towards you, only for their wings to rapidly falter and force the insect into an emergency landing. After the most recent observation, I looked around the outside of the house and found three oothecae, two of which were under a window sill built in 2016. These finds are cheering, as it means that at least in my neighbourhood they must be holding their own.

Perhaps their chief enemy these days is the invasive Miomantis caffra. This inadvertently-introduced South African mantis was first seen in 1978 and is rapidly spreading throughout New Zealand's North Island. The intruder - frequently spotted in my garden - has several advantages over O. novaezealandiae: firstly, it is able to survive through winter. Second, it produces rather more nymphs per ootheca; combined with hatching over a longer period this presumably leads to a larger numbers of survivors per year. In addition, and most unfortunately, the native male appears to find the (cannibalistic) South African female more attractive than the female of its own species, frequently resulting in its own demise during mating.

Humans too have further aided the decline of the native mantis with the accidental introduction of parasitic wasps and widespread use of pesticides. After less than a century and a half of concerted effort, European settlers have managed to convert a large proportion of the best land in this corner of the Pacific into a facsimile of the English countryside - but at what cost to the local fauna and flora?

Working to the old adage that we won't save what we don't love and cannot love what we don't know, perhaps what is really required is an education piece disguised as entertainment. Promoting mammals in anthropomorphic form has long been a near-monopoly of children's literature (think Wind in the Willows) but perhaps it is about time that invertebrates had greater public exposure too. Gerald Durrell's 1956 semi-autobiographical best-seller My Family and Other Animals includes an hilarious battle in the author's childhood bedroom between Cicely the praying mantis and the slightly smaller Geronimo the gecko, with the lizard only winning after dropping its tail and receiving other injuries. Perhaps a contemporary writer telling tales in a similar vein might inspire more love for these overlooked critters before it is too late. Any takers?

Setting low standards: bovine TB, badger culls and political pressure on science

If there's a single type of news story that's almost guaranteed to generate widespread sympathy across the British Isles it is one concerning the mistreatment of animals. Over the past five years, badger culls aimed at preventing the spread of bovine tuberculosis have generated much public debate, with opinions varying from those who think badgers are completely innocent victims to some who want to see the species eradicated anywhere domestic cattle are kept. Since the number of farmed cattle in the British Isles is close to ten million, this presumably means the no-badger zone is rather on the large size!

When debates concerning agriculture start to get overheated it usually reduces to a battleground between farmers and so-called townies, with mudslinging and emotive slogans taking precedence over the facts. In this particular case the badgers have an unusual ally in the form of rock musician and amateur astronomer Brian May, who has received much of the criticism usually reserved for tree huggers, animal rights' campaigners and environmentalist types in general.

As I've mentioned before, a species often receives support based more on its cuteness factor than anything else (I consider the irascible and curmudgeonly Mr Badger in Wind in the Willows as a fairly accurate representation of the true critter) so the farming community has seen fit to complain that ignorant, urban-based activists are unaware of the challenges Mother Nature throws at the agricultural sector.

Such stereotyping and reductionism does nothing to alleviate the issue, which other nations face in similar circumstances. New Zealand, for example, has a rapidly escalating battle over the use of 1080 to poison introduced predators. Even though many environmental organisations such as Forest and Bird proclaim it the most effective method the debate is far from settled, with the anti-1080 movement using emotive pleas in their campaign that at times combines hysteria and aggression in equal measure.

The UK's Department for Environment, Food and Rural Affairs (Defra) has funded an independent scientific review from Oxford University as to the efficacy of the cull, resulting in popular press reports that the evidence does not support it. Indeed, the high ratio of dead badgers in return for a 'modest' reduction in the disease has been given as a key reason to stop the culls. This might appear to be a nod towards animal welfare, until you read that other issues include their cost and complexity and a desire for the Government to gain in the opinion polls. A key scientific argument against the effectiveness of the culls come from rural vets, who support data suggesting even at maximum success, the reduction in new cases of cattle TB would only be 12-16% - in exchange for a culling of over 70% of local badger populations.

So what does this example say about humanity's attitude towards the environment and the use of science to reinforce that attitude? In terms of numbers of individuals, humans and our domesticated species (both livestock and household pets) vastly outnumber the inhabitants of the wilderness. The once diverse ecosystem has been vastly reduced, predominantly in the temperate regions suitable for intensive farming. But in return for this largely irreversible loss we have gained all-year round access to an incredible variety of inexpensive foodstuffs; clearly, our gastronomic gains take precedence over the wider ecosystem.

In the case of wild badgers as disease vectors, it isn't just the livelihood of individual farmers that are at stake. The European Union's threat to impose trade sanctions on the UK, such as a ban on the export of live cattle, must be considered as a potential loss at the national level. Little wonder then that the British Government implemented the cull after what has been termed 'a randomised trial period' or more impressively, 'over fifteen years of intensive research.' Even so, was the result of all this enough to justify the finality of the chosen method - or was the scientific data manipulated in the name of political expediency?

One telling example of how the culling might have been ordered due to political pressure rather than any scientific smarts was the use of evidence from other nations that are successfully controlling bovine TB. Australia and New Zealand have been held up as examples of how control of the disease vectors can vastly reduce or indeed remove the problem altogether. Except of course that those two nations don't have any badgers; it is the possum, a semi-arboreal marsupial, that is responsible for the spread of tuberculosis there. It seems to me that two creatures from such vastly different lineages should never have been seen as workable comparisons; the natural world just doesn't fall into the neat categories we would like it to. As a matter of fact, the UK Government has partly blamed the lack of success on the badgers themselves for failing to follow predicted behaviour. In 2013 the then Environment Secretary Owen Paterson stated that the animals had cheated by 'moving the goal posts'!

The Oxford University research reports that far more cases of bovine TB result from transmission between cattle rather than directly from badgers, explaining that farmers are not following Defra guidelines to minimise the spread. Even Defra itself states that there has been not nearly enough implementation of badger-proof feed storage and fencing, while its chief scientific adviser, Ian Boyd, has been quoted as admitting that badgers may only be responsible for as little as 6% of bovine TB! This incidentally comes from the man who in 2013 wanted complete control over what scientific results were reported to Government ministers, presumably so as to maintain a clear-cut, pro-STEM political lobby. Hmm, methinks I smell something fishy...

What can we conclude from these shenanigans? If scientific research doesn't provide reliable support for a method, shouldn't the mistake be admitted and a new approach implemented? Science is the sole invention of humanity with built-in error correction but when it gets embroiled in politics, unabashed use of political tools such as spin can prove fatal. In this particular case, the fatalities in the short term were the badgers. In the long run, an unbalanced ecosystem would have resulted. And we all know which species likes to think of itself as the pinnacle of creation. There's enough denial of scientific results as it is, without distortion for the sake of political convenience. Let's hope Defra has the courage to own up and try other tactics against the wily badger.