motionless ladybirds

laurencehobson · #1 (**permalink**) 13-10-2009, 01:48 PM

Hello all. This is my first post.
At the start of September (in Cambridge) I saw a 7-spot motionless but alive sat on some kind of reddish-brown, fine-weave cocoon(?). I saw this a few years back so kept an eye on this one. It is still there (October 13) and still alive. Does anyone know what's going on?

Thanks

Laurence

jaguarondi · #2 (**permalink**) 13-10-2009, 01:56 PM

Hello Laurence

Welcome to WAB

It's been parasitised. This page shows a similarly unfortunate individual -
Sick ladybird on Flickr - Photo Sharing!

ChrisR · #3 (**permalink**) 13-10-2009, 02:08 PM

We had another, similar report of this the other week. It is the remains of a rather ingenious and grisly parasitic wasp that has eaten the insides of the ladybird (the non-vital organs of course) and then burst out in a rather 'Alien'-style way and woven its cocoon under the still living ladybird host. The parasitic wasp grub gnaws through the motor neurons that control leg movement and then weaves silk around its legs so that the ladybird can't move - but the warning colours and defensive bleeding the ladybirds use to protect themselves will protect the parasitoid too.

Paul mabbott · #4 (**permalink**) 13-10-2009, 02:27 PM

Yes, the wasp is most likely Dinocampus coccinellae which commonly predates Coccinella septempunctata but seldom the smaller ladybirds. One would think that it might be a parasitoid of Harmonia axyridis, the 'harlequin ladybird' but there have been very few observations of this to date. Worth keeping an eye out for this and letting us know if it's seen!

charlieb · #5 (**permalink**) 13-10-2009, 03:01 PM

Out of 60 of the 7-spots I counted today (in half an hour), 5 of them were parasitized.

Paul mabbott · #6 (**permalink**) 13-10-2009, 03:23 PM

Quote:

Originally Posted by charlieb

Out of 60 of the 7-spots I counted today (in half an hour), 5 of them were parasitized.

It's very variable both annually and geographically. A few years back a survey in Scotland found 40% or more of 7-spots were affected.

laurencehobson · #7 (**permalink**) 13-10-2009, 04:57 PM

Thanks for your replies, though I'm a bit sorry I asked now.

ChrisR · #8 (**permalink**) 13-10-2009, 05:06 PM

Quote:

Originally Posted by laurencehobson

Thanks for your replies, though I'm a bit sorry I asked now.

Well when you get down and study insects in some detail it doesn't take long to find some amazing stories like this ... granted, it's a bit gruesome but then again not everything is fluffy and cute

Just think of the evolutionary processes that these parasitoids had to go though to reach this level of complexity ... and this is just one example - there are many thousands of other, equally incredible stories too