Wasp parasitising hoverfly larva

[Bruce Williams]

Stockgrove Country Park, Beds.

I though some of you might be interested to see this pic of a small wasp parasitising a hoverfly larva. The wasp took quite some time over the process and appeared to insert more than one egg. This species has a very short ovipositor and (as you can see from the pic) it inserts it with some considerable force. I posted a pic/thread of the same species at the end of October where it was tentatively identified by ChrisR as Callaspidia defonscolombei.





Bruce

[JRsbugs]

Nice shots Bruce, but poor syrphid larva!

I looked the wasp up and I think Chris has got it right, this one does parasitise syrphid larva but I guess you have looked that up. I found pics on micropics too and it matches well.

Janet

[Wild-Woman]

Good shots. It's just as well we have these little wasps keeping certain insect levels under control. Biological control nature's way.

[Ukwildlifeo]

Excellent photo of some interesting behaviour. I found some hoverfly larva the other day but they were inactive and tucked under logs

[Jason Green]

Morning Jules,

Originally Posted by Wild-Woman

Good shots. It's just as well we have these little wasps keeping certain insect levels under control. Biological control nature's way.

Hoverfly larvae are great biological control agents themselves, with the way they go for aphids. There is another wasp that targets syrphid larvae, and is then actually considered a pest itself for doing so!

Take care,

Jason

[ChrisR]

Great action-shot there Bruce - a superb demonstration of what Callaspidia defonscolombei does I've never actually seen them hunting for hosts - only floating about in Malaise trap alcohol!

The cynipid wing venation is nice and clear on the first photo too - showing that it isn't a chalcid or proctotrupid, as many people would guess.

[Bruce Williams]

Thanks for your comments everyone.

Chris - I contacted John Noyes at the NHM as you suggested. He kindly passed my email on to colleges of his (also NHM) and the identity was confirmed as Callaspidia defonscolombei by David Notton (Senior Curator (Hymenoptera)). So your original identification was was spot-on as was Janet's confirmation.

Bruce

[Bruce Williams]

A question from Ian Gray prompted me to do a little research on the web. Ian asked "Does the hoverfly larva survive this attack until the wasp larvae have no further use for it?". I though my findings might be of interest to other WAB members:

Based on an extract from the Ecological Entomology Journal: It appears that the female C. defonscolombei firstly locates aphid colonies from their odour. The species of hoverfly larva in this image is predatory on aphids (I have pics of that too). So by locating the aphids she also locates the hoverfly larva that are feeding on them. Apparently C. defonscolombei has a preference for larger larvae, attacking only 2nd and 3rd instar larvae. She first of all injects a temporary paralysing venom and then injects the egg.

From other sources.....It seems that the egg is oviposited into the brain of the host thus avoiding exposure to the hosts immune defence reaction. The parasitoid larva waited until the host larva spins its cocoon and then kills it (by consuming it I presume?) and pupates itself. Finally it emerges from the host pupa as an adult.

Bruce

[Rossco]

Brilliant action shots, Bruce, worthy of a text book.

Ross

[Bruce Williams]

Thanks for your encouraging comments Ross - very much appreciated.

Bruce