Extra-ovariolar egg resorption in a dung beetle, Euoniticellus intermedius

Most oösorption in the dung beetle Euoniticellus intermedius takes place in the haemocoele, oöcytes being extruded from the ovariole before the deposition of the chorion. Oösorption can be induced in the laboratory both by prevention of oviposition and by starvation. For up to two days after the onset of starvation the terminal oöcyte appears normal. After three days the prechorionic oöcyte may move through the ovariole wall; the yolk spheres are then disrupted. On the fourth day little yolk remains in the extruded oöcyte, and most of the extruded cells are degenerating. We suggest that extra-ovariolar egg resorption may be a mechanism for ensuring that the single ovariole is not occluded when conditions are suitable for oviposition.