Another case of a parasitized spider?

jsloan

Arachnoangel
Old Timer
Joined
Jun 22, 2004
Messages
972
Here's the background on this one:

Within the past week I caught an adult female Trochosa terricola (Lycosidae) in one of my pitfall traps. She was carrying a large egg sac (about 4mm diameter) - so large she tended to lift her abdomen, and it, into the air.

I decided to keep her alive and see how many babies hatched out. So, I put her in a completely clean container (I cleaned it before installing her in it), with a tight lid. After a couple of days I put a large drop of water in one corner of the container and she took a long drink. Then she dropped her egg sac and wandered around the container for a while without it. About an hour later I noticed she'd picked it up again, in her jaws this time and soon after that she started eating it. So much for counting the babies! She eventually ate the whole thing.

The spider herself is a healthy specimen, so last night I took the lid off the container and took a few photographs of her. Later, when I looked at the photos I noticed something near the spider I'd never noticed before: tiny larvae of some kind! I found 10 of them in the container, 7 alive and 3 apparently dead.

I think it's very possible those larvae came from within the egg sac. I hadn't fed her or introduced any other insect or food items into the container since putting her and her egg sac in there. Yet, there they were. I'm wondering if she sensed them in her egg sac and that's why she ate her eggs? Also, apparently she didn't eat these larvae (some kind of defense mechanism on their part?).

I examined the spider and couldn't find any sign of external parasites on her, which is another reason I think these may have come from within the egg sac.

So, now I have some more larvae to keep an eye on! I don't know if these will pupate or not, since they have no food supply. I'll just wait and see. They are certainly alive. Under magnification I can see them moving around, and a couple of them even climbed up the sides of the container!

Unfortunately, adult T. terricola females with egg sacs are very rare in my pitfall traps (this is the only one in the past month) and I haven't found them wandering around. If I find any more I intend to open the sacs and look for more of these larvae. I'll let you know if I find any.

(There are some silk threads visible in the closeup pictures of the larvae. At this point I believe these may just be dragline threads put down by the spider as she wandered around the container.)

Unfortunately, I didn't take any pictures of the spider with its intact egg sac (aaaggghhhh!).

Habitus picture of female. Notice the two larvae next to her (which I didn't see until I later looked at the picture):



Ventral view of larva. BL=2mm. Head region on the right:



Dorsal view. BL=2mm Head region at top:



Another ventral view, showing some tiny legs along one side (upper part of the picture). Head is on the left:

 

ZergFront

Arachnoprince
Old Timer
Joined
May 2, 2009
Messages
1,956
Hmmm...

Maybe find another egg sac of a spider that is very common in your yard you wouldn't mind culling and put the larvae on it. Might be larvae of a mantis fly AKA mantid lacewing..
 

jsloan

Arachnoangel
Old Timer
Joined
Jun 22, 2004
Messages
972
Zergfront might be right, could be some Mantispidae pupae... keep us updated ;)
Whatever it was died. I guess in eating the eggs sac the spider deprived them of food. None of them pupated.

However, I found a live Neriene radiata the other day with a larva attached to its abdomen. I have it alive in a jar where it has a web and is eating. I'll keep it until the larva has gone through its cycle, if possible (see new thread), and see what the larva becomes after pupation.
 

Bastian Drolshagen

Arachnobaron
Old Timer
Joined
Apr 14, 2005
Messages
488
hi,
I only found 1 parasitized spider ever.. a Alopecosa female.
Normally those larvae parasitizing on the opisthosoma are from some kind of wasp.
 

ZergFront

Arachnoprince
Old Timer
Joined
May 2, 2009
Messages
1,956
Top