ID Chacicoidea wasp

Fritillary · #1 (**permalink**) 15-09-2009, 02:30 PM

Hello
I would like to know what are these bugs.
They were with bees' eggs (Osmia spp and Megachile spp). They measure about 2 mm long. I found in "Field of Insect of Britain" book, p 265, that probably they are from the superfamily Chalcicoidea, family Pteromalidae but who knows??

I wonder if these are bees parasitoids?
I dont know how to download photos here so I put them in picasa if you want to see
Picasa Web Albums - Flora - Parasitoids

Any idea??

Jason Green · #2 (**permalink**) 15-09-2009, 02:43 PM

Afternoon Frit!

Beauties, aren't they! I agree, Pteromalidae. Your specimen looks to be male to me too, the girls have notable ovipositors.

As a note of caution, there may be similar families, such as Torymidae - as I initally suspected.

Always good to see someone with an interest in these tiny wasps!

Take care,

Jason

Fritillary · #3 (**permalink**) 17-09-2009, 04:35 PM

Many thanks Jason
Since I am amateur and these insects are too small, it is easy to confuse them.
I read that small insects are a vast field to study because people arent too interested.

Regards

Maria

Jason Green · #4 (**permalink**) 17-09-2009, 05:57 PM

Vast indeed! I'm quite into barkflies... an interesting area of study because, as you say, they're under-studied. This means that even beginners in Psocoptera could discover new/rare species!

Torymus · #5 (**permalink**) 17-09-2009, 09:02 PM

Chalcidoidea - all probably Pteromalidae. Several males and females - the males possibly of two species. Very tough indeed to ID these from specimens let alone photographs. However reference to the Universal Chalcidoidea Database hosted by the Natural History Museum would suggest Epistenia coeruleata (formerly E. osmiae) but really not sure.

Fritillary · #6 (**permalink**) 18-09-2009, 01:52 PM

Yes, probably I will visit the Natural History Museum.
By the way I found an interesting description of chalcid parasyte cycle of life although another species, the ones I found must have a very similar way of living.

"CHALCID PARASITE LIFE-CYCLE
Pteromalus is an obligate parasite, which means that it is obliged to parasitize other species in order to reproduce. Adult parasites will feed on sugar water in laboratory experiments, so they probably feed upon nectar in the field. The adult parasites do not feed on either bee prepupae or adult bees. Adult female Pteromalus search for completed cells containing bee prepupae which have finished feeding and have spun their cocoons. The female parasite pierces the leaf and cocoon layers of the bee cell with her ovipositor, a sting-like apparatus modified for laying eggs, and stings the prepupa, thus paralysing it. She then lays eggs upon the surface of the paralysed prepupa. The parasite eggs hatch within 24 - 48 hours, and the young larvae begin to feed upon the paralysed bee prepupa, eventually consuming it almost completely.
If some of the parasite larvae are not finished feeding, they may then turn on their siblings and consume them as well. The parasite larvae then either pupate and develop into adults, or enter a diapause stage which requires cold period, similar to their leafcutting bee host. Once temperatures rise sufficiently, development resumes, and the parasites pupate and emerge as adults through a small hole chewed through the alfalfa leafcutting bee cell. In the incubator, chalcid parasites usually emerge from day 8 through 13 of incubation at 30oC, although they may emerge earlier. "
http://www.saspa.com/PDF/Chalcid%20p...s.nov.2005.pdf