Friday, 8 December 2017

Another update!

On 14th September 2014, I posted about a Stigmella perpygmaeella leaf mine on Hawthorn with a hymenopteran parasite in the mine. I couldn't get any further with the identification at the time, so left the wasp identification abstract.

I have now got a little further with the wasp identification, so here's a little update, with an updated version of the image.

The original micromoth larva is shown at point A, and is quite clearly chewed and dead. At point B we have the 'visitor', which has a distinctive dark gut. I have now discovered that the intruder is a Eulophid wasp, which is an ectoparasitoid of the micromoth larva.

So the sequence of events is as follows:

  1. Female micromoth lays her egg on the leaf.
  2. Egg hatches and the larva tunnels through the leaf, getting larger as it feeds, until reaching point A.
  3. Female Eulophid detects the moth larva inside the leaf and deposits her egg on or near the moth larva.
  4. Eulophid egg hatches and the wasp larva consumes the moth larva, leaving just the head capsule and other debris.
  5. Eulophid larva moves off back through the mine where it will pupate at point B.

I wonder if the wasp larva makes its little journey back down the mine in order to avoid being detected by a potential hyperparasitoid.

Anyway, here's the picture:

Eulophid larva (B) having consumed Stigmella perpygmaeella larva (A)

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