Wednesday, May 28, 2014

Wasp uses zinc-tip drill to lay eggs

Footage captured by scientists has revealed the power of a parasitic wasp, which has evolved a zinc-tipped drill to bore into fruit.

The wasps penetrate the fruit in order to lay their eggs inside.

A team from the Indian Institute of Science in Bangalore found that wasps' fruit-drilling and egg-laying tool - which is thinner than a human hair - has teeth enriched with zinc.

The researchers' study is published in the Journal of Experimental Biology.

The researchers think the fig wasp's egg-laying technique could inspire the design of new tools for microsurgical techniques.

Microscopic drill

The female parasitic fig wasp bores its way through a tough, unripe fig to find the larvae of other pollinating insects already developing inside. Its own offspring will then feed on these larvae as they develop within the safety of the fig.

Lead researcher Dr Namrata Gundiah said: 'She uses her ovipositor... pushing this needle inside [the fruit] at the location, where she has decided to lay her eggs.

'She has to test the chemical environment inside the fruit as she's doing this, and she wants to complete this process fast, because as you see in [our] video, there are predators nearby waiting for her.'

'Start Quote

It's the fun of seeing how nature works, rather than finding a utilitarian value for it'

End Quote Dr Namrata Gundiah Indian Institute of Science

To work out how the wasp managed the arduous task, the team captured images with an electron microscope of the insect's egg-laying appendage, or ovipositor, revealing that its end resembled a drill bit, complete with sharp-edged tooth structures that enabled it to bore through the unripe fruit.

Taking measurements from this tiny drill bit, Dr Gundiah said, revealed the presence of zinc, and that it 'was only at these teeth-like structures.

'So we think the zinc is there to harden the tips.'

Metallic creatures

  • Scientists first discovered zinc and manganese in the ovipositors and mandibles (jaws) of hymenopterous insects - the order that includes wasps, bees and ants - back in 1998

  • In 2002, researchers in the US found that zinc helped harden the jaws of a group of marine worms known collectively as Nereis

Dr Namrata said that the technique could be applied to cut through rock and other hard materials.

'In inhospitable places, this could [provide] a clever way to get samples back for us,' she told BBC News.

'In the end though, it's the fun of seeing how nature works, rather than finding a utilitarian value for it.

'I'm sure if we look at it long enough, there will be lots of applications that will emerge just knowing how things work in nature.'