The butterfly, the ant, and other natural mimics

A A A

It sounds like one of Aesop's fables but the story of the blue butterfly and the red ant is probably not one you would like to send your children off to sleep with. The caterpillar of the blue butterfly is "adopted" by the red ant which takes the butterfly larva back to its nest where it treats it like one of its own brood feeding it until it is old enough to turn into an adult butterfly.

The caterpillar, however, repays the ant's generous hospitality by greedily eating as much food as it can and gobbling up the ant's offspring as a tasty side dish.

All five species of large blue butterflies in Europe engage in this form of parasitism on red ants and now scientists have worked out the trick that allows them to do it the caterpillars cover themselves in a chemical that makes them smell like orphaned baby ants.

Researchers have found that the organic molecules secreted on the skin of the blue caterpillars closely match those on the skin of the red ant larvae. What is more, the closer the chemical cocktail is, the stronger the attraction of the ant to the caterpillar.

The findings should help conservationists in their attempts at reintroducing large blue butterflies which are endangered by making sure the chemistry of the caterpillars and the ants match each other as closely as possible.

David Nash of the University of Copenhagen, who led the study published in the journal Science, said the results were a vivid demonstration of the evolutionary "arms race" that can escalate between parasites and their hosts.

"Parasites are always trying to better adapt to their hosts to parasitise them whereas their hosts are experiencing selection pressures to avoid being parasitised," Dr Nash said.

"It means there can be an ongoing evolutionary arms race between the parasite and its host. There have been some previous studies on microscopic organisms showing this can occur in the laboratory but what we have here I think is one of the first cases where we have clear evidence that this has been happening out in the field."

The scientists studied dozens of red ant colonies on an island off the Danish coast and, in each nest they examined, they counted the number of caterpillars of the Alcon large blue butterfly that they found living there

Alcon blue butterflies lay their eggs on the marsh gentian plant and its caterpillars grow in the usual way by feeding on the plant's leaves. But, at the fourth stage of growth, the caterpillars gently lower themselves to the ground on silken threads.

"The caterpillars first start developing on a food plant but once they reach a certain stage they leave the food plant and wait on the ground to be discovered by one of these ants," Dr Nash said.

Often in nature, ants would make a meal of a caterpillar but in the case of the large blues, the passing ants pick them up gently and take them lovingly back to their nest the question was why?

"The butterfly gets into the ant nest by mimicking the surface hydrocarbons, the surface chemicals that the ants have on their own brood," Dr Nash said.

"They are producing this signal that says 'I'm an ant brood'. We've been able to show that the closer that mimicry is, the faster they are picked by the ants and taken back into the ant nest and put amongst the brood.

"Once they are there among the brood they become highly virulent parasites. They eat some of the brood and they also get fed by some of the worker ants, and they get fed in preference to the ants' own brood," he said.

Two species of Myrmica red ants were found to be routinely parasitised by the Alcon blue butterfly but the scientists also discovered that one of these species is far more heavily exploited by the blue's caterpillars than the other species of ant.

"We know that almost any ant within this Myrmica group of ants will pick up a caterpillar and take it back to the nest, but it is only within these two species that it will survive," Dr Nash said.

"We have one species where the ant is exploited at a relatively constant rate and we have another species where, when it is common, it is exploited even more than you'd expect but, when it is rare, it is hardly exploited at all," he said.

The difference in the exploitation rates between the two species of red ant helps the blue butterflies survive because if it relied on just one species there would be a danger of it overexploiting its only host. The second host species means there is a back-up in times of ant scarcity, Dr Nash said.

Parasite peril

Blue butterfly

The large blue butterfly has a complex, parasitic relationship with red ants which involves its caterpillars being taken into the ant's nest and fed. The caterpillars manage this by mimicking the smell of the ants' own larvae

Cuckoo

One of the most famous con tricks in nature is the story of the cuckoo. It lays an egg in the nest ofanother species of bird for it to unwittingly raise the chick as is own. The cuckoo's eggs often mimic the colours and patterns of the eggs of the host species to minimise the risk of rejection

Orchid

The flowers of some species of orchid, such as the Australian hammer orchid, resemble female bees or wasps. This attracts male insects, which become dusted with pollen

Hoverfly

This harmless flying insect lookssuperficially like a wasp. The yellow and black stripes are designed to mimic the warning coloration of stinging insects to help it avoid being attacked and eaten by birds, which have learnt from experience to avoid the striped colours of stinging insects

News
peopleIt seems you can't silence Katie Hopkins, even on Christmas Day...
Arts and Entertainment
Left to right: Stanley Tucci, Sophie Grabol and Christopher Eccleston in ‘Fortitude’
tvSo Sky Atlantic arrived in Iceland to film their new and supposedly snow-bound series 'Fortitude'...
Life and Style
fashion
Arts and Entertainment
tv
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Account Manager

£20000 - £35000 per annum: Recruitment Genius: This full service social media ...

Recruitment Genius: Data Analyst - Online Marketing

£24000 - £35000 per annum: Recruitment Genius: We are 'Changemakers in retail'...

Austen Lloyd: Senior Residential Conveyancer

Very Competitive: Austen Lloyd: Senior Conveyancer - South West We are see...

Austen Lloyd: Residential / Commercial Property Solicitor

Excellent Salary: Austen Lloyd: DORSET MARKET TOWN - SENIOR PROPERTY SOLICITOR...

Day In a Page

Isis in Iraq: Yazidi girls killing themselves to escape rape and imprisonment by militants

'Jilan killed herself in the bathroom. She cut her wrists and hanged herself'

Yazidi girls killing themselves to escape rape and imprisonment
Ed Balls interview: 'If I think about the deficit when I'm playing the piano, it all goes wrong'

Ed Balls interview

'If I think about the deficit when I'm playing the piano, it all goes wrong'
He's behind you, dude!

US stars in UK panto

From David Hasselhoff to Jerry Hall
Grace Dent's Christmas Quiz: What are you – a festive curmudgeon or top of the tree?

Grace Dent's Christmas Quiz

What are you – a festive curmudgeon or top of the tree?
Nasa planning to build cloud cities in airships above Venus

Nasa planning to build cloud cities in airships above Venus

Planet’s surface is inhospitable to humans but 30 miles above it is almost perfect
Surrounded by high-rise flats is a little house filled with Lebanon’s history - clocks, rifles, frogmen’s uniforms and colonial helmets

Clocks, rifles, swords, frogmen’s uniforms

Surrounded by high-rise flats is a little house filled with Lebanon’s history
Return to Gaza: Four months on, the wounds left by Israel's bombardment have not yet healed

Four months after the bombardment, Gaza’s wounds are yet to heal

Kim Sengupta is reunited with a man whose plight mirrors the suffering of the Palestinian people
Gastric surgery: Is it really the answer to the UK's obesity epidemic?

Is gastric surgery really the answer to the UK's obesity epidemic?

Critics argue that it’s crazy to operate on healthy people just to stop them eating
Homeless Veterans appeal: Christmas charity auction Part 2 - now LIVE

Homeless Veterans appeal: Christmas charity auction

Bid on original art, or trips of a lifetime to Africa or the 'Corrie' set, and help Homeless Veterans
Pantomime rings the changes to welcome autistic theatre-goers

Autism-friendly theatre

Pantomime leads the pack in quest to welcome all
The week Hollywood got scared and had to grow up a bit

The week Hollywood got scared and had to grow up a bit

Sony suffered a chorus of disapproval after it withdrew 'The Interview', but it's not too late for it to take a stand, says Joan Smith
From Widow Twankey to Mother Goose, how do the men who play panto dames get themselves ready for the performance of a lifetime?

Panto dames: before and after

From Widow Twankey to Mother Goose, how do the men who play panto dames get themselves ready for the performance of a lifetime?
Thirties murder mystery novel is surprise runaway Christmas hit

Thirties murder mystery novel is surprise runaway Christmas hit

Booksellers say readers are turning away from dark modern thrillers and back to the golden age of crime writing
Anne-Marie Huby: 'Charities deserve the best,' says founder of JustGiving

Anne-Marie Huby: 'Charities deserve the best'

Ten million of us have used the JustGiving website to donate to good causes. Its co-founder says that being dynamic is as important as being kind
The botanist who hunts for giant trees at Kew Gardens

The man who hunts giants

A Kew Gardens botanist has found 25 new large tree species - and he's sure there are more out there