Tuesday, 22 October 2013

Update to Interference Patterns (1st October)

A couple of weeks ago, I posted about the braconid wasp Apanteles glomeratus, which is parasitic on the Large White butterfly. At that time I mentioned that I had taken a sample batch of the parasite cocoons, and yesterday I noticed that the petri dish was full of minute wasps. I popped one under the microscope:

The braconid wasp Apanteles glomeratus - adult
I appear to have both males and females, although the females are more numerous, as you might expect (female Ichneumonids are usually self-fertile). Both measure 3mm long, excluding antennae. There are 32 in the sample. 

So we have a few interesting numbers resulting from this sample:

  • Pupation period of the wasp is around 21 days.
  • One fully-grown larva of the Large White can support 32 wasp larvae.
  • A few of the wasp cocoons have not (yet) hatched. Perhaps these are parasitised and will emerge later.

I was a bit surprised that they emerged so quickly, since there are very few Large White larvae around at this time of year, so I presume they must overwinter a hibernators, ready to restart the parasitization cycle when the first batch of Large White larvae hatch next year. 

Documentation of these observations seems quite scarce, and I have communicated the sightings to the appropriate people.

1 comment:

Gill said...

Fantastic - and the shot's a cracker too given the size of the beast. I'm sure you're right that outside they would overwinter and emerge just as the new generation of butterflies were laying.