CHAPTER 10

DUNG PROBLEMS – THE END OF WORLD ORDURE AS WE KNOW IT

WHEN CHARLES DARWIN toured Van Diemen’s Land (Tasmania) in early 1836, he showed his true spirit as a coleopterist by finding in cattle droppings two species of Onthophagus, two of Aphodius and another unnamed dung beetle genus (Darwin 1839). He was bemused to note that cattle had only been introduced, with European settlers, some 33 years earlier. He was particularly struck by the fact that native mammals, like kangaroos, had very different dung to cows, and that the transition from marsupial dropping to ungulate pat was highly remarkable. He was right.

The first cows (along with sheep and horses) to arrive in Australia were delivered in January 1788 when the First Fleet arrived to found the British penal colony at Botany Bay, Sydney. Two hundred years later, by the end of the 20th century, there were coming up for 25 million cows, 70 million sheep and 200,000 horses. This is a considerably higher biomass than the estimated 50 million kangaroos, but all would have been well if they had shared a similar digestive metabolism, and produced similar dung. However, as Darwin had noted, the native Australian fauna produced droppings very different indeed from the copious discharge of the colonists’ stock animals.

It all started about 100 million years ago (MYA), when the tectonic plate carrying Australia started drifting away from Gondwana. Dinosaurs were still the dominant land animals at the time, and presumably the major dung producers. We’re not quite sure exactly what happened when they vanished 65 MYA, but marsupials have been the dominant dung deliverers in Australia for the last 25 million years at least. Until the Europeans arrived. Kangaroos (along with wombats, koalas and other herbivore marsupialia) are well adapted to the arid, often drought-locked continent, and their droppings are dry, tough, hard nuggets. Having evolved for so long to this dung format, the sudden arrival of semi-liquid cow pats was about as alien to the native dung beetles as you could get. Darwin was right to be amazed at this transition, a few of the native species found a useful new ecological niche; but only a few.

There are currently thought to be around 600 species of native Australian dung beetle,1 with most found in woodlands and forests. The savannah/grassland habitats are poorly utilized by native herbivores, so few dung beetles occur in this habitat (Doube et al. 1991). But these are exactly the areas ‘improved’ for grazing farm animals. The dung fell, and it was all but ignored by the majority of native dung beetles. It was not ignored by the flies.

A FLY IN THE BUSH IS A PAIN IN THE EYE

As an entomologist I am very tolerant of insects, and refuse to dismiss them as pests… unless they reach pest proportions. Anyone who lived in the Australian outback towards the end of the 19th century could certainly tell you that bush flies had become pests; there were vast black clouds of them, like smoke, and it was not possible to speak without a fly flying into your mouth. They congregated around your eyes, trying to drink the tears, they tried to climb up your nose; they got into your hair, under your shirt, in your ears. They were everywhere. They were horrid. These were pest proportions on a biblical scale.

The bush fly, Musca vetustissima (meaning the ‘inveterate’ fly), is nearly the Australian equivalent of the Eurasian house fly, Musca domestica. It’s of a similar size and shape, but it does not tend to come indoors so much; it’s everywhere else instead. Like the house fly, the bush fly breeds in decaying organic matter, and it just loved the new dung. As a rough estimate, farm animals now drop approximately 2 million tonnes of dung each day onto the grasslands of Australia. With each 2 kg cow pat producing a thousand or more bush flies, populations rose exponentially. The stable fly, Stomoxys calcitrans, and the buffalo fly, Haematobia irritans, were quick to get in on the act too. They bite, and although their blood-sucking habits are not associated with the spread of human diseases, they can raise a painful welt, and they drive farm animals to distraction. The bush fly remains an iconic, if undesirable, Australian animal; it was to combat its attentions that bush hats decorated with corks dangling on string became a staple fashion accessory in the outback, or on TV sitcoms, and its persistent visitations to the eyes and nose gave rise to the Aussie salute, a quick flick of the hand across the scowling face.

Cows, in particular, were the problem. Their wet dung was incomprehensible to most native Australian dung beetles, used to the hard, golfball-sized droppings from kangaroos and the like. And there was just so much of it. Despite the attentions of a few species, like those found by Charles Darwin, native dung beetles just could not cope with the removal; they, and the grasslands now being farmed, were overwhelmed. Instead of being digested, buried, removed, recycled, the pats just sat there, drying to hard pancake crusts in the unrelenting Australian sun. Even during the winter, no noticeable degradation took place and a pat laid one year looked very much the same 12 months later. Two oft-quoted statistics are that the dung of five cows can smother an acre of meadowland in a year, or the dung of ten cows can smother a hectare. These don’t quite marry up mathematically, it ought to be 12.3 cows to cover a hectare in pats, or 4.1 cows for an acre, but that’s in the nature of easily quotable tabloid statistics. But you get the idea. Since the arrival of farm animals with the First Fleet, Australia had been gradually disappearing under excrement. More shocking statistics are offered up: meadowland was being rendered useless at a rate of 200,000 hectares (2,000 km2) per year. Parasitic worms, whose cysts and eggs are spread in the dung, were not being controlled by dung removal, so reinfestation rates soared. By the 1960s, after 200 years, things were getting desperate. It took the arrival of an entomologist with an interest in scatology to get things on the right track.

BEETLES TO THE RESCUE

When Hungarian zoologist Dr György (‘George’) Bornemissza arrived in Australia in late 1950 he immediately noticed that the Australian meadows were disfigured with undecaying cow pats lying about all over the place, completely in contrast to the well-maintained cattle fields he’d grown up with back in Europe. He quickly deduced that what was missing were the hordes of dung beetles that should normally be digging in and burying the stuff. Obviously. So was born the Australian Dung Beetle Project. Its aim was simple: to introduce into Australia some non-native dung beetles, species which had co-evolved with the non-native cattle, and which would be quite at home in the cow pats. This should have the quadruple benefit effect of physically removing cow dung so it did not clog the fields; increasing the nutrient cycle to improve grass quality for better milk and beef production; containing or reducing intestinal worm reinfestation in the cows; and decreasing the breeding grounds of the noisome bush flies and its biting confederates (Ridsdill-Smith and Edwards 2011).

The trouble is, if you introduce an alien organism into a new continent, you never really know whether it will play havoc with the endemic plants and animals that have already evolved through millions of years without it. Australia had already suffered huge environmental damage from the cane toad, Rhinella marina, introduced from South America in 1935 to try and keep down equally exotic insect pests in the sugarcane fields of Queensland. It ate the pests, but also native animals, many of which it has now driven to the point of near extinction. With poison glands behind its head and with no natural predators, the cane toad has itself spread widely and in huge numbers, becoming an invasive pest in need of control. Foxes, cats and rabbits had similarly decimated Australian wildlife. Bornemissza’s aims were true, but great care, and a deal of good public relations, would be needed to try and avoid similar environmental upsets with foreign dung beetles.

It would take some years of careful plotting to select and trial dung beetles for eventual release. Sponsored by the Australian government and funded partly by the beef industry, the project officially began in 1964. As a template, dung beetles were first collected from Hawaii. These were not originally endemic to the Pacific islands, but had themselves been introduced as part of a similar project to try and control buffalo flies and horn flies – insects that had achieved pest status in Hawaii for the same reasons as the bush fly in Australia.

The first beetles to be released (in 1967), namely two clown beetles Hister (Pachylister) chinensis and H. nomas, were not dung-feeders, but fly larva predators. This was almost as an aside, even as they were being let out it was realised that dung removal by true dung beetles would be the only way to try and even out the ecological imbalance caused by Australia’s megatons of cattle dung.

To maintain biosecurity, i.e. to prevent unknown diseases from arriving, no adult beetles were imported; instead surface-sterilised eggs (3% formalin) of 52 dung beetle species were shipped to Australia; 43 species survived captive rearing through several generations in laboratory conditions. Captive breeding is enough to distort population genetics, such that when final release into the wild came round, alterations to the vigour of the species may already have been bred in. To give the chosen colonists a good chance, some were rather pampered – released into crude field cages to prevent predation by birds, and supplied with fresh dung for a week. In the end, though, it was just a case of opening the gates and letting them out into the badlands, hoping they would do alright.

Between 1968 and 1984, 1.73 million dung beetles of the 43 different species were released into thousands of Australian meadowlands. The first of these (1968) was the African Onthophagus gazella, which has now become the dominant cow dung species in the subtropical areas of northern and eastern Australia. Not all of the introductions were successful. Of the 43 release species, 23 have become established. Australia is a far-flung continent, unique in much of its flora and fauna, which has evolved in the last 100 million years, adapted perfectly to its peculiar climate and geography. In sourcing the original target species Bornemissza and his colleagues had to try and work out which world species might be able to slot into the brave new Antipodean dung ecology they were planning. Tropical South African species were tried in tropical northern and eastern Australia, whereas slightly more temperate-adapted species from the Cape Province and Southern Europe were tested in southern and western Australia.

Success was fickle. On the whole, smaller species (<13 mm) did better than larger species (>15 mm), and part of this is no doubt down to the fact that the larger beetles are usually the ones to spend more time caring for low numbers of offspring, so their fecundity remains low, and their increase slow. It was no surprise, really, that Onthophagus gazella should thrive – nearly half a million individuals were released at 421 sites. Other large-scale releases of Euoniticellus intermedius (248,637 specimens, 443 sites), Onitis alexis (186,441 specimens, 251 sites) and Onthophagus binodis (173,018 specimens, 178 sites) were likewise successful.

At the other end of the number scales, only 53 specimens of the elegantly long-legged Sisyphus mirabilis were set free, at one site. It was probably doomed from the off. A neat table produced on the 40th anniversary of the programme’s start (Edwards 2007) would seem to indicate that a minimum release of 8,000 beetles, at six or more sites, with at least one site getting 500 specimens, is the distinction between secure establishment and not. Even so, there are surprises. The large Copris diversus vanished without trace, though 17,775 were sent off in nine localities; however, 294 of its congener Copris hispanus did manage to secure one of its two release sites. These are slow-developing species, with limited numbers of offspring. The African Copris elphenor was released throughout Queensland, but remains confined to one small area around Jambin 35 years after its first liberation.

Success for some species was an understatement. Freed from natural predators and parasites a select few aliens did exceptionally well. In recovery sampling measurements, the biomass (total living weight) of African beetles from dung at Rockhampton, Queensland, was 10–100 times that back in Hluhluwe, South Africa, from where they originally came. There has been some field collection and redistribution of the successful colonists. Between 1989 and 1995 3.5 million beetles were caught using baited traps and shipped off to other sites. By this time funding from the beef producers had run its course, but the dairy industry stepped in to keep things going. Since 1993 private companies have collected, bred and re-released over 6 million beetles, shipping them by the thousand, and charging farmers to supply the meadow clean-up brigade.

Once established at a locality, many of the commoner beetles started to spread of their own accord. Onthophagus gazella was off like a gazelle, extending its range by 50 km/year, and making one leap of 800 km. It was able to colonise offshore islands, flying over 30 km of open sea. This is on its way to becoming one of the most cosmopolitan insects in the world, and has also been deliberately released for dung clearance work in Hawaii (1958), North America (1972), South America (1990) and more recently to Easter Island, New Caledonia, Vanuatu and New Zealand. The southern European Onthophagus taurus spread at 300 km/year, but has now more or less reached its climatic limits in western and southern Australia and Tasmania. A specimen was found in the belly of an Australian herring, Arripis georgianus, caught in the Great Australian Bight (Berry 1993). Most species, though, increased their ranges at a more sedate 1–2 km/year.

A species survival success rate of 54% (23/43) is still pretty impressive. Edwards (2007) is proud to claim that at least one species of introduced dung beetle is now firmly established in every grazing meadow in the country, with a maximum (so far) of 13 exotic species at Toowoomba, Queensland, where several tropical and temperate species overlap. But have any of the anticipated benefits been achieved?

Despite nearly 50 years of work, this is still early days in a terraforming project to change the ecology of an entire continent. Things are looking up, though. In field experiments with cow dung, an average of only 2 bush flies emerged from pats populated by the South African Onthophagus binodis, compared to 128 when the beetles were excluded. That’s a tabloid statistic of 98.4% reduction. Seemingly a mere 3 g of dung beetles per pat was enough to reduce the flies’ nuisance. This is a real advance on the paltry 33.3% reduction achieved when only the native Onthophagus ferox were present

Removal of cow pats has certainly speeded up. Ball rollers such as Sisyphus spinipes, working thousands to a pat, destroy it in a day. And even though this species does not bury its balls (it just rolls them away and anchors them to bits of vegetation), dispersal of the single dropping into lots of tiny bits, each then being devoured by a beetle grub, still achieved the desired result.

Nutrient cycling has also improved. Before the exotic beetles appeared, only about 2 kg of the potential 13.5 kg of nitrogen excreted in the dung of one cow during a summer was returned to the soil. After beetle inoculation, 10 kg is now divested to the hungry grass.

The effects of dung beetles on the cows’ intestinal parasites, spread through cysts or eggs in the dung, then reingested as they spread onto next year’s grass, is still in the balance. In at least one field experiment nematode worm larvae were reduced when the heroic Onthophagus gazella was present, but rainfall had a significant effect too. There is still work to be done here.

On the plus side too, fears that these introduced exotics might interfere with fragile native ecosystems seem to have been calmed. There was always the possibility that incoming dung beetles might outcompete the endemic species. We cannot quite be sure yet, but it seems that the original Australian dung beetles, mostly living on marsupial pellets in the forested areas, continue to mosey along in what is, in effect, a parallel rather than an overlapping ecosystem.

This was always going to be a long-term project. If it took 200 years of European-style farming to create the problem, it might yet take a few more decades to clear things up. It’s just possible that a similar tectonic ecological shift occurred on Madagascar 1,000 years ago. This was when cattle first arrived to an island that for the previous many millions of years was dominated by lemurs and their relatives. Cow dung is not so much of a nuisance as in Australia, but there is still evidence that domestic animal dung (7 million cows, 1.5 million goats and sheep) is used by only a small number of the Malagasy endemics which are still rather adapted to the small droppings of the native forest-dwelling primates.

The last 50 years have been spent concentrating on Australia’s excess cattle dung, but sheep droppings, being harder and drier (but not up to marsupial standards), require different species, and this still needs to be addressed. Throughout the rest of the world individual grasslands and savannahs can have a dung beetle diversity of over 100 different species. Additional new species were released in 2014, but Australia’s meadows are still some way off this figure, so there is certainly room for more introductions in the future. Most Australian dung-beetlers already have their wish-lists ready.2

AN IMPENDING ECOLOGICAL DISASTER OF OUR OWN MAKING

Dung beetles and dung flies (as long as they don’t reach pest proportions) are the unsung heroes of the environment. Without them, as was shown in Australia, we would be wallowing in our own or our farm animals’ ordure. Unfortunately the world has changed since the beetles were worshipped and celebrated by the ancient Egyptians, and now we take them for granted. Indeed, we care so little of them that we are happy to poison them. This is the unfortunate side-effect of our demand for cheap meat brought to our supermarket shelves by intensive farming.

One of the problems with free-range cows is that they tend to eat whatever is growing out of the ground. Mostly this is fresh green grass, but occasionally they swallow an egg or a cyst of some internal parasite such as nematode worms or flukes. These then live inside the cow’s warm, comfortable, protective and highly nutritious body. Along with horse bot fly larvae living inside horse intestines (see page 142), warble fly maggots puncturing and burrowing under the skin of cows and leaving suppurating wounds, larvae of the sheep bot eating the poor animal’s nasal passages, and a whole host of other pests, farmers struggle to keep their animals healthy and profitable. It is no surprise that they give them medicines to counter these noisome attacks.

Ivermectin is a broad-spectrum antiparasite formulation, an ‘endectocide’, an internal pesticide drug. It has a complex multicyclic molecular structure (for the chemically minded it’s a macrocyclic lactone 22,23-dihydroavermectin-B1a), and was originally derived from a bacterium Streptomyces avermitilis by Satoshi Omura of Kitasato University in Tokyo and William Campbell of the Merck Institute for Therapeutic Research in 1981. It is the number one treatment for river blindness in humans, which is caused by a microscopic blood worm. It is very effective. It is also given to all manner of farm animals to counter the parasites that would otherwise blight them.

Ivermectin is delivered to the stock animals in various ways: injection into the skin, as an oral gel bolus, mixed into feed, or as a drench over the skin. However administered, it gets absorbed into the body tissues of the animal. It also gets passed out with the dung, barely changed. After a pour-on formulation was used on young beef calves (0.5 mg/kg body weight) the first day’s dung contained the drug at a concentration of about 22 mg/kg dry weight (about 0.1 g/kg wet weight). That might not seem like a high concentration, but ivermectin is a poison. If it were available in an aerosol spray to attack house flies or bed bugs (which it also kills), it would probably be at a similar dosage. In other words, ivermectin creates poisonous dung. The chemical is still detectable in cow dung 6 weeks after this has been dropped (Sutton et al. 2013). It seems pretty obvious what this will mean for dung-feeding insects.

It wasn’t long before entomologists started to worry about the field impact of ivermectin on dung insects. French entomologist Jean-Paul Lumaret (1986) is generally regarded as being the whistle-blower. Thirty years later and there are some startling statistics. Somewhere in the region of 62–98% of the treatment passes unaltered into the faeces, where it remains for weeks. Cows treated with 0.2 mg/kg subcutaneous injection produced dung which was toxic to that saviour of the western Australian meadowlands, Onthophagus gazella, for 7 days after administration. Poor thing. Excretion of only 1 μg (that’s one-millionth of a gram) per kilogram of dung was toxic to the larvae of the yellow dung fly, Scathophaga stercoraria. No more participating in undergraduate field measurements of mate guarding for them. Fly larvae are particularly susceptible to pesticides. The bush fly and some of its relatives might have given dung-breeding flies a bad name, but many of the smaller, more discrete species are an integral part of the nutrient recycling community of the dung, and part of the huge cohort of important pollinators, presently under the political spotlight. Dosing up sheep has a similar effect (Beynon 2012); timings and concentrations may vary, but the final output still contains the toxins.3

In field experiments, adult dung beetles were not immediately killed, but they suffered what are euphemistically called ‘sublethal effects’; their behaviour and that of their larvae is significantly altered. Egg laying may stop, even though ovary and testes size are normal. Development of the larval stage is delayed; whether this is a slowing down of feeding or a slowing of the metabolism to do with nutrition and growth is not yet clear. Whatever, longer larval periods expose them to extended danger from predators and disease. Sometimes the larvae just stop; effectively this brings slow lingering deaths for the maggots.

In the wild, poisons do not just kill straight away. OK, if an animal dies it is 100% dead, but if it gets a lower dose its physiology can still be damaged; it can become disoriented, it can be less effective at finding food, or a mate, or moving to avoiding a predator. In the complex nesting behaviour seen in dung beetles, it doesn’t take much chemical to interfere with the business of tunnelling, rolling, brood ball construction, guarding or tending. Ironically, the death of the dung beetles and their maggots might actually be exacerbating the parasite situation, since removing the dung, fluke eggs and all, into the soil removes them from the infection cycle (Nichols and Gómez 2014).

Some people might baulk at the idea of me suggesting an ivermectin-affected beetle can be 25% or 50% even 95% dead, but in medicine this is the concept of morbidity. A patient doesn’t need to be either alive or dead for the doctor to act accordingly. If they are feeling a bit poorly, or are at death’s door, they are on opposing ends of this scale. Translating notions of human well-being into the life of a beetle is technically and philosophically challenging, I agree, but another way of looking at it is to think of the affected beetle (or any organism for that matter) as physically, immunologically or behaviourally damaged, or weakened. And if we know anything about natural selection it is that the weak ones are the first to go. They don’t stand a chance.

Sublethal does not mean the same as ‘alive’, it just means ‘not dead yet’. It is the sublethal effects of neonicotinoid insecticides on bees and other insects that have got conservation organisations in Britain and Europe into a lather. Just because the organism in question does not drop down dead out of the air immediately, does not mean it is safe. Indeed, it is probably doomed, but conveniently we don’t have to watch it die. There are farm animal welfare organisations actively quoting sublethal effects as evidence that populations of dung beetles and flies are hardly affected by the use of endectocides. Any specific effects (e.g. on insect larvae) are claimed to be limited and the total effect on the rest of the population is negligible. They continue to promote and reinforce the message that endectocides remain a valuable choice of product for controlling both ecto-and endoparasites of domestic animals. I put this to Darren Mann of the Oxford University Museum of Natural History, Britain’s top professional dung-beetler, I’ll warrant. His ripe response: ‘Anyone who states that endectocides have no effect on the dung fauna and flora is talking shit.’ How apposite, I couldn’t have put it better myself, Darren.

One of the more insidious aspects of ivermectin is that, in some cases, dung from treated animals is more attractive to dung beetles than droppings coming from untreated control heifers. This means that the poisonous nature of the chemical is all the more dangerous, because the likelihood of insects being exposed to it is higher. There are also fears that dung beetle fortitude in the face of chemical assault means that some species, or individuals, may be more resistant to it, more likely to survive feeding on it, so more likely to be eaten by predators. This could have very real consequences higher up the food chain, as the drug becomes accumulated in non-target organisms. It was, after all, this exact same effect which concentrated DDT in top bird predators, leading to population crashes of eagles, falcons, kites and all those other raptors still struggling to recuperate decades after the insecticide was phased out. As yet we still do not know enough about how ivermectins move through the food web.

Fears have been expressed, dung-beetlers are off doing research, but conservation organisations struggle to make headway in protecting the environment in general and the dung fauna in particular. Many nature reserves, in Britain at least, are managed for plants, or butterflies or birds, by using traditional, but possibly unprofitable, grazing regimes to maintain flowery downlands, water meadows or ancient pasture woodlands. Can you imagine the kerfuffle if it became known that at the same time as protecting Duke of Burgundy fritillaries or sand lizards they were also poisoning Emus and Copris?

A correspondent, who will remain nameless, understood the dilemma intimately:

A long while back I did some work for English Nature looking at land use and livestock grazing regimes at sites in England in relation to Asilus crabroniformis [the hornet robber fly]. I spoke to quite a few conservation land owners who essentially said: ‘We don’t use ivermectins etc. on the cattle we graze our sites with.’ Speaking to the graziers, their take on the matter was: ‘We know [so-and-so organization] don’t allow ivermectins to be used on the cattle when they are on their land, so we just give them a dose before we take them to site.’

Urgh.

Harking back to Australia for a moment, it is not difficult to imagine what disruption to the nutrient cycling and dung removal process might look like. Retardation of dung decomposition has long been reported (Wall and Strong 1987). If chemicals are killing, weakening or disrupting coprophage communities, this is likely to exacerbate the situation. It’s easy to picture a future where dung pats just sit in the fields, inert, desolate, lifeless. We’ve been here before.

Ivermectins are not alone in being injurious to dung-breeding organisms. Other veterinary chemicals routinely given to farm animals have similar effects. There is a long list, including dichlorvos, pyrethroids and possibly antibiotics – although some chemicals that decay very quickly, or are more readily expelled in the urine, don’t seem to have such a long-lasting environmental effect.

Unfortunately ‘good husbandry’ is almost a legal prerequisite for animal ownership in Britain. This implies keeping stock animals pest free and healthy. During an email appeal to other coleopterists, Malcolm Story offered me this nugget.

I’ve heard it said that use of ivermectins was ‘good husbandry’ and animal welfare legislation required all owners to practice ‘good husbandry’, so ivermectin use was effectively mandated by law. Having surfed a few websites, I can’t find that statement, but they take every opportunity to insert the phrase ‘good husbandry’ in descriptions of product use.

One of the problems for entomologists is that the beetles do their work for free, and if something is free it is easy to think of it as worthless. I’m not sure how they calculated it, but in an effort to give some commercial weight to dung beetle effort, DUMP (Dung Beetle UK Mapping Project) recently announced that the environmental services provided by even our meagre fauna amounted to £367 million a year.

Even the most ardent dung-beetler must accept that farmers need to raise healthy animals for human consumption, and they need to do this without going bankrupt. But it is the routine, unthinking, robotic, prophylactic administration of these pharmaceuticals that is causing the problem. There must be a balance between chemical pest control and chemical-free dung communities. It’s just that we haven’t got there yet.

MEGAFAUNA AND MICROFAUNA EXTINCTIONS

It’s a sad fact of history that whenever humans arrived at a new land, they managed to hunt the large charismatic megafauna to extinction. In Australia 50,000 years ago they eradicated Diprodon (a marsupial the size of a hippo), Procoptodon (a horse-sized kangaroo) and the marsupial lion Thylacoleo. After the last ice age, 15,000–10,000 years ago, humans spreading north into Europe extinguished the mammoth Mammuthus and the sabre-toothed tiger Smilodon and all the dwarf elephants from the Mediterranean islands of Crete, Cyprus, Malta, Sardinia and Sicily. At the same time they crossed the Bering Strait, from Chukotka into North America, to erase Gliptodon (a giant armadillo-type thing), mastodon (Mammut, slightly smaller than a mammoth) and Megalonyx (a ground sloth weighing a tonne). The extinctions continued throughout the New World as hungry hunter humans finally made their way down to Tierra del Fuego. We know this from the bones still being found. We can only guess at the dung beetles, which the droppings of these animals once supported, that are now gone too.

In Argentina palaeontologists are still unearthing fossilised dung balls as big as, or bigger than those rolled round Africa today. We don’t really know for sure what laid the dung, or what shaped them. There are no suitable large roller beetles left in South America today. The extinction of one set of animals created a cascade that eradicated others too. Just as depletion of prey items will starve the predators, the hunting of the large mammals left nothing for the despondent dung beetles.

There’s nothing we can do about what might have been beautiful glossy mastodon mega-roller beetles, or bizarre diprodon dung tunnellers disporting debonair horns. Extinction is forever. But we might have a go at preventing the same thing happening again. There is another megafauna extinction going on today. Elephants, rhinos, gorillas, tigers and pandas are just some of the large mammals now in precipitous decline around the world. Whether they are being hunted for meat and trophies, or being backed into a corner through climate change, habitat destruction and human encroachment, they are at the edge of the abyss. And so too are the dung beetles they feed with their droppings. Already, African dung beetles are feared to be on the decline (Nichols et al. 2009), joining the similar misfortunes piling on to the hunched shoulders of European scarabaeids in Italy (Carpaneto et al. 2007), Iberia (Lobo 2001), France (Dortel et al. 2013) and Britain (Dung Beetle UK Mapping Project). In Australia, too, dung beetles may also be declining, not through competition with all the exotics brought in, but because of a continuing extinction of native mammals (Coggan 2012). Today, world-wide, 12% of all dung beetle species are reckoned to be ‘endangered’ (on the brink of extinction) or ‘vulnerable’ (fast heading towards that brink). There are dark times ahead for dung beetles.

This is not just an observation of detached, dispassionate, scientific curiosity. There are real ramifications to human destruction of the ecosystem. The complex ecology of the world, very well exemplified by Australia’s dung-based tribulations, is easily upset. It is quite likely that had things gone slightly differently back in Australia’s prehistory, if the hunting had not been quite so thorough, that the whole cow dung debacle could have been avoided. Imagine a world where giant diprodons and marsupial tigers still patrolled the open savannahs, leaving their droppings as they went. The large rollers and hearty tunnellers evolved to take advantage of this copious manna would, perhaps, have been better equipped to deal with the heavy cow pats when they started to drop in 1788.

I’ve admitted from the very start that I’m biased about beetles. Beetles are very important, not just for their handsome lustrous bodies and perky athletic forms, but because of their huge worldwide diversity and their amenability to scientific study. We can’t look at everything, everywhere, all the time, but just looking at beetles gives us a window into the workings and the failings of the ecosystem of which we, humans, are a part. They are our barometer of environmental health, our measure of ecological resilience, our early warning system of impending disaster in the biosphere. We need to pay more attention to beetles, and dung beetles in particular are well worth a closer look.

When Anderson and Coe famously reported 16,000 beetles dispersing an elephant dropping in under 2 hours, or Heinrich and Bartholomew raged enthusiastically about a cupful of dung attracting 3,800 beetles in just 15 minutes, they were trying to express in numbers just how powerful and awe-inspiring these diminutive creatures could be. The same power and awe was felt by a ten-year-old boy when first a dumbledor pushed its way out through clenched fingers and flew off into that chalk downland evening long ago. It would be a terrible and heavy shame on us all if these tales became the stuff of mere legend.


1 Scarabaeidae 437 species, Aphodiidae 127 species, Hybosoridae 40 species, Geotrupidae 1 coprophage species (Ridsdill-Smith and Edwards 2011). This does not include the very many other beetle species that occur in dung, but as has been reiterated enough times already, it is these groups in the superfamily Scarabaeoidea that do the lion’s share of the dung removal and burial.

2 We must, however, not imagine for a moment that there can be quick fix to nuisance dung of all types. In 2008 entomologist Maria Fremlin was intrigued to receive a request from a Toronto university student who had the idea of trying to market a biodegradable doggy poop-scoop bag with dung beetle eggs already inside, to feed on the dung cleared up by owners from Canadian pavements. Well intentioned as it may have been, once she pointed out the intricacies of dung beetle ecology nothing more was heard of this ill-conceived notion.

3 Extrapolating to other animals is fraught with difficulty. Ivermectin-treated reindeer produced dung which was exactly comparable to non-treated controls, in that no beetles or flies were found. This was because the hard dry winter-browse droppings are unattractive, tough nodules. Only the moist summer dung, from eating lush vegetation, contained a significant insect fauna, but this was not part of the experimental cohort (Nilssen et al. 1999).