The propodeum is the first abdominal segment in Apocrita Hymenoptera (wasps, bees and ants). It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans their distinctive shape. .....
That part of thorax just above insertion of abdomen, really the first abdominal segment
The I st abdominal segment in the hymenopteran group known as the Apocrita: it is completely fused with the thorax.
First abdominal segment of hymenopterans, fused to the thorax.