Earwigs use 'chemical clouds' for protection

Female earwig Forficula auricularia tending her clutch of eggs

Related Stories

Adult earwigs use a chemical cloud to protect themselves from threats, scientists have discovered.

A team in Germany found secretions from the insects have antibacterial, antifungal and nematode killing properties.

Results also revealed a substance not previously known in insects.

The scientists suggest earwig secretions are multifunctional, serving both to deter predators and to stay safe from illness.

The findings are published in the Journal of Insect Physiology.

Earwigs are known to defend themselves from predators using large pincer-like structures on their abdomens called cerci and by emitting a defensive fluid.

Chemical protection

Slow loris

Meet the slow loris - a mammal with a toxic bite

Discover how lethal chemical cocktails protect plants

How do oogpister beetles make formic acid?

However, little is known about the chemical properties of this secretion.

"There have only been two studies [on earwig secretions] since the 1960s: one regarding the chemistry of the secretion and one regarding behaviour," said Tina Gasch, lead author from the Justus Liebig University Giessen, Germany.

"Since then not much has been done even though they are a really interesting insect Order."

There are approximately 2,000 species of earwigs. They are known as subsocial insects because they display maternal care: a behaviour rarely found in insects.

Ms Gasch explained that certain aspects of earwigs' lifestyles put them at high risk of infection from pathogens - microscopic organisms that can cause illness - and parasites.

"Earwigs spend a huge amount of time underground. During this period there's lots of threats with bacteria, nematodes and things like that," she said.

"Also, earwigs like to aggregate and it is known that in aggregations of insects, infectious diseases spread more easily because they are very close together and they sometimes groom each other."

Ms Gasch explained that she thought earwigs would "need protection" against these types of microorganisms.

Start Quote

Earwigs have been neglected for 60 years. They are really abundant and there is much more to learn about their ecology”

End Quote Tina Gasch Justus Liebig University Giessen

To test this theory, she worked with colleagues to investigate the glandular sacs containing the defensive fluid in frozen adult specimens of three different species of earwig: Forficula auricularia, Apterygida media and Chelidurella guentheri.

They then introduced the fluid extracted from these sacs into cultures of common microorganisms found in soil and other areas earwigs are found.

"It was really exciting. We found the secretions were really effective against bacteria, nematodes and fungi," Ms Gasch told BBC Nature.

All three studied species' secretions showed antibacterial and antifungal activity and the secretions from F. auricularia also killed parasitic worms known as nematodes.

The team also analysed the defensive fluids to determine the chemical compounds within them using a technique called gas chromatography-mass spectrometry (GC-MS).

"The species differ in their secretions and we also found a new substance that hasn't been detected before in insects," said Ms Gasch.

But what the PhD student found particularly surprising was the fact that a "fine sort of mist" was continuously present in the air space around the earwigs.

"It's like a cloud surrounding them and protecting them against microorganisms," she said.

According to Ms Gasch, this is the first experiment of its kind looking at the chemical properties of earwig secretions and she believes there remains more to discover.

"Earwigs have been neglected for 60 years. They are really abundant and there is much more to learn about their ecology," she added.

Join BBC Nature on Facebook and Twitter @BBCNature.

More on This Story

Related Stories

More from nature

  • Cardinal fish and ostracodFish filmed spitting 'fireworks'

    Film crew captures ostracods' spectacular defensive lightshow that makes predatory fish spit them out.

  • Arapaima'Locally extinct'

    A giant fish which used to dominate the Amazon river is now absent in many areas


  • DragonflyRapid reactions

    Dragonfly's super quick reactions recorded in slow motion by BBC film-makers


  • Wingless adult male of the midge Belgica antarcticaExtreme survivor

    Antarctic midge's small genome may be an adaptation to its extreme environment


  • Myotis midastactus specimen (previously identified as Myotis simus)Golden discovery

    A bat from Bolivia is described as a new species by scientists


  • Dinosaurs 'shrank' to become birds

    Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, new research shows.

  • Would we starve without bees?

    Honey bees are under threat, and as pollination significantly contributes to the food we eat, what would we do without them?

  • Eggshells may act like 'sunblock'

    Birds' eggs show adaptations in pigment concentration and thickness to allow the right amount of sun for embryos, scientists say.

  • Female shrimps are more aggressive

    Female snapping shrimps are more aggressive than males when defending their territories despite their smaller claw size, a study shows.

BBC iWonder

  • Honey bee close-upInsect intelligence

    Are honey bees as smart as your sat nav?

  • Tyrannosaurus rex skull (c) Mark Williamson / Science Photo LibraryDinosaur dynasty

    One group of dinosaurs survived and their descendants can be seen all around us today


  • Brown rat cluse upRise of the rodent

    Reports of giant, 'super rats' are filling the headlines. But why are we being overrun by rats?


  • Cuckoo portraitHoliday hotspot

    What makes the UK such an attractive destination for visiting wildlife?


Awesome! And there's nothing common about such beauty.

Elaine Bernon on Facebook comments on the trio of common blue butterflies in our Photo of the Day.

Things To Do

RUN BY THE BBC AND PARTNERS

More Nature Activities >

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.