2019年2月6日 - 微生物


初稿作者:Josh Gabbatiss

The popular image of dung beetles involves them rolling balls of poo
across an African landscape. This is true, but it is not the whole


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Reputation: Dung beetles roll across the African savannah with big balls
of, well, dung. The ancient Egyptians were really into them, for some


Reality: From South America to South Africa, the UK to the USA, they
will be there. Not only are dung beetles a diverse and multifaceted
group of insects, they keep our farmland fertile and our pests and
parasites at bay, and even play a part in reducing greenhouse gas
emissions. They do not all eat dung, either.

微生物,本质:從北美洲到南非(South Africa)洲,從英國到美國,都可以看来牠們的身影。牠們品種繁多,能幫我們保持農地的活力和控制害蟲,甚至為下落溫室氣體排放出了一分力。牠們也並非全体食糞為生。

The dung beetle was an icon in ancient Egypt, adorning temples, jewelry
and texts. It was the symbol of a god who rolled the Sun up over the
horizon each day, just like an enormous ball of dung. To this day, this
is the stereotypical dung beetle, the one made famous by natural history
films – a stocky black insect, trundling along with its smelly ball.

蜣螂在古阿拉伯埃及共和国(The Arab Republic of Egypt)是偶像,古埃及(Egypt)人用牠們的形象裝飾神廟、珠寶和書籍。古埃及(Egypt)的一個神每日從地平線推起太陽,蜣螂推著巨大糞球的形象刚好與之吻合。現在,蜣螂廣為人知的至死不渝形象來自科普電影
—— 一隻矮壯的昆蟲推著發臭的糞球渐渐爬行。

“I get that a lot,” says insect ecologist Tomas Roslin at the Swedish
University of Agricultural Sciences, “and then hurry to point out that
there are as many different species of beetles living in dung as there
are, for example, bird species globally”.


The sacred scarab of Egypt is a real animal, but it is just the tip of
the dung heap. Dung beetles can be big or small, adorned with beautiful
colors or horns to fight opponents, and inhabit chilly grasslands or
tropical rainforests. Of the thousands of dung beetle species, only a
fraction actually roll their dung into balls, and many do not eat dung
at all.

阿拉伯埃及共和国(The Arab Republic of Egypt)聖甲蟲是真實存在的,但只是蜣螂大家庭的里边一員而已。蜣螂有大有小,有的顏色鮮豔、有的長著角來打鬥、有的棲息在寒冷的草野、有的棲息在熱帶雨林。在數千種蜣螂中,只有部分會把牠們的糞便滾成球,有广大有史以来不吃糞便。

“With so many different species that exist globally, the differences in
life history are almost endless,” says Trond Larsen, a tropical
ecologist and Director of Conservation International’s Rapid Assessment
Program. “Among the most fascinating dung beetle species are those which
have developed unusual specializations.”


Most dung beetles work hard to live up to their name. In their quest for
dung, some species engage in epic kung fu battles on the savannah.
Others take up residence by monkeys’ anuses, so they can hop onto the
dung as it leaves its owner: a perfect example of “ first come, first


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But according to Larsen, it is common to find over 150 distinct dung
beetle species at a single site in the tropics. With this level of
competition for limited quantities of dung, it is hardly surprising that
some have evolved non dung-based diets.


These diets would still not be to everyone’s taste. Whether it is
carrion, rotting fruit and fungi, or dead invertebrates, dung beetles
seem happy to serve as nature’s bin men, hovering up unpleasant detritus
and waste. One species lives on the backs of giant land snails, sucking
up their mucus while enjoying a free ride.


Perhaps the most fascinating specialists are the dung beetles that have
made the switch from dung to hunting prey.


Predatory dung beetles have long been alluded to in the scientific
literature. One species from Brazil was recorded decapitating large
ants, before leaving their heads behind and rolling the fat abdomens
into an underground lair – as if they were balls of dung.


Most of all, though, some dung beetles really seem to have it in for


Aware of reports that certain beetles attack live millipedes, Larsen
decided to go in search of the killer. After identifying a likely
Peruvian species called Deltochilum valgum, he captured some specimens
to observe their behaviour. “I was amazed to unravel the highly detailed
attack strategies employed by the beetles,” he enthuses. Once again,
decapitation is their favored mode of attack.


However, thanks to their family history of eating dung, these beetles
lack the sharp mouthparts commonly found in carnivorous animals.
Instead, they have to improvise.


“Successful decapitation of millipedes depends on a suite of
morphological adaptations, such as the shape of the hind legs, the
prying ‘teeth’ on the front of the head, and the narrow width of the
head for fitting inside the millipede’s body segments,” says Larsen.
Essentially, the dung beetles slowly prise their unfortunate prey’s body


Millipedes are commonplace and slow, making them the perfect prey for
these makeshift predators. Larsen reckons the evolutionary leap from
feeding on carrion and dead invertebrates to living millipedes is not
huge, and predicts that other dung beetles will also make the switch.


Clarke Scholtz, a veteran entomologist at the University of Pretoria in
South Africa, knows a thing or two about dung beetles. He says that
millipede-eaters are also present across the Atlantic, and agrees that
this lifestyle change is actually rather straightforward.

Scholtz是一位對蜣螂頗有研讨的南非(South Africa)比勒陀尼亞大學資深昆蟲學家。他說印度洋對岸也有出現捕食千足蟲的蜣螂,並贊同這種生活習性的改變其實很简单發生。

“Adult dung beetles are not dung feeders in the strictest sense of the
word,” says Scholtz. “They feed on tiny particles of gut epithelium from
whatever it was that produced the dung, bacteria, fungi and tiny
fractions of dung.”


Meanwhile, carrion-feeding dung beetles, and those feeding on
invertebrates, are slurping on smoothies of juices and insides,
filtering out the nutritious particles just as they would with dung.


Despite their forays into other foodstuffs, the primary business of the
dung beetle family is still, well, “business”. Whether they roll it
around, bury it or live inside it, these beetles know their way around a
pile of poop, and have done since the time of the dinosaurs.


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What’s more, while they are not pushing the Sun across the sky, dung
beetles are doing important work.


“Dung beetles are an essential part of the ecosystem,” says Bryony Sands
of the University of Bristol, UK. “In my opinion, they are as important
as bees, but because of their unglamorous lifestyle their value is
definitely overlooked.”

“蜣螂是生態系統中要求的一部份。” 英國马普托爾大學的Bryony

Faeces are a fact of life, and without an efficient waste disposal
system the world would quickly descend into a swamp of unprocessed
sewage. Dung beetles are that system. “The beetles process the dung by
tunnelling, burying, and fragmenting it,” says Sands. They lay their
eggs in it, their larvae eat it, worms bury it further, and the circle
of dung continues.


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Schultz puts the situation into perspective. “We have 15 million cattle
in South Africa, and each produces about 12 cow pats per day,” he says.
“That equates to about 5,500 tonnes of dung every day. We would all be
knee deep – or shoulder deep – in it if it wasn’t for dung beetles.” And
that is before we even consider the elephant dung.

Schultz舉例:“南非共和国(The Republic of South Africa)有一千五百萬頭牛,每頭牛每天大约排泄12塊牛糞。”他說。“那相當於每日5500噸糞便,假诺沒有蜣螂,糞便將會浸沒我們的膝蓋甚至肩膀。”而這還未算上大象的糞便。

“This whole process not only quickly and efficiently removes dung from
the surface, it brings all those important nutrients back down into the
soil, making the soil fertile and our pastures productive,” says

“這個過程不單快捷高效地將糞便清理出地表,更把糞便中任重(英文名:rèn zhòng)而道远的營養帶回土壤中,恢復土壤肥力使我們的牧場保持高產。”Sands說。

In the UK, which is home to a mere 60 species of dung beetle compared to
South Africa’s 800, the ecosystem services provided by dung beetles
could be saving the cattle industry £367 million each year. Comparable
savings have been estimated in the USA. Not only are dung beetles
boosting pasture fertility, they also disperse seeds, improve soil
structure, and reduce the prevalence of pests and parasites that affect
both humans and livestock.

相較南非(South Africa)的800種蜣螂,英國唯有60種蜣螂,而蜣螂對生態系統的貢獻能够每年為畜牧業節省3億6千7百萬英鎊。美國也有類似的臆想數字。蜣螂不止有助增強牧場肥力,也传扬種子、改进土壤結構,更能抑制那一个危害人畜的害蟲和寄生蟲。

In a 2016 study, Sands showed that dung beetles reduce the spread of
intestinal worms in cattle. Unfortunately, the anti-worm drugs farmers
give to their cattle come out in their dung, and that is bad news for
the beetles. “This is a bit of a catch-22,” says Sands. “The very
chemicals that farmers are using to treat the gut worms are actually
killing the dung beetles, which would be naturally reducing worm
transmission on pasture, making the problem worse in the long run.”


Indeed, the tremendous value of dung beetles has not gone unnoticed.
Some pioneering scientists have used them to orchestrate major
ecological changes.


The most dramatic instance of dung beetle intervention began in
Australia in the 1960s, when the country was facing a dung disaster.
Native dung beetles were used to the dry, hard dung of marsupials, not
the sloppy pats left by introduced cattle. This led to farmlands covered
with cow dung and bush fly swarms of biblical proportions.


In a bold move, the Commonwealth Scientific and Industrial Research
Organization (CSIRO) established the Australian Dung Beetle Project.
Over two decades, a team introduced 53 species of dung beetles from
around the world. The foreign beetles were able to beat back the tide of
manure, leading to a drop of about 90% in bush fly numbers. As a side
note, it has been argued that the decline in flies has also saved the
country’s outdoor cafés from extinction.


Such was the success of the project that it has been repeated both in
Australia and in neighboring New Zealand, and this is not the final word
on dung beetle interventions. “CSIRO and other Australian and New
Zealand researchers have not concluded their efforts in the dung beetle
space,” says Patrick Gleeson, a research technician at CSIRO. He
mentions a recent application to develop a new, national dung beetle

這個計劃已經在澳大利亚联邦(Commonwealth of Australia)和紐西蘭相繼成功,而蜣螂的引入並未畫上句號。“CSIRO和任何澳大利亚與紐西蘭的探讨者在蜣螂領域的繼續努力沒有甘休。”CSIRO的研讨員PatrickGleeson說。他提到一個以来將會實施的,新的全國性蜣螂計劃。

To add to a growing list of dung beetle powers, work by Roslin and his
colleagues has also found evidence that dung beetles can reduce
greenhouse gas emissions.


“We are talking fairly big effects, like a reduction of 40% of total
methane emissions from any single dung pat inhabited by beetles,” Roslin
says. “Dung beetle tunnels will serve as ventilation shafts, bringing
oxygen into the pat. That will shift the balance between different
microbes. Methane-producing microbes don’t like oxygen.”


When you consider the emissions from an entire food supply chain, Roslin
says, the impact of beetles is relatively small. Nevertheless, this
addition to dung beetles’s CV is yet another reminder of their


In Finland, where Roslin conducted his studies, the tiny beetles are a
far cry from the ostentatious, mouse-sized creatures found in Africa.
But they are still playing their role, epitomizing the biologist E.O.
Wilson’s reference to “the little things that run the world”.


“Remember, dung beetles are not just something you see struggling with
balls of elephant dung on African savannas,” says Sands. “They are right
here at home on your doorstep, and they need to be looked after!”


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