[The ecdysial rate of the greater wax moth, galleria mellonella l. (Lepidoptera, Pyralidae), after X-irradiation, wounding, and combined injury in the pupal instar]

Abstract

1. Pupae of the greater wax moth,Galleria mellonella L., were exposed to x-rays with different doses, to a certain wounding, or to both treatments in different combinations. The extent of damage was measured as the decrease of the frequency of ecdysis. 2. The factors of damage after the different treatments were analyzed by partial irradiation and histological methods. The results of the histological investigation were compared with normal development of important organs of theGalleria pupa, particularly of the ecdysial glands and the corpora allata. 3. The resistance to x-rays of theGalleria pupa increases about twentyfold during the seven days of the pupal instar. In a given pupal age and after a given dose the radiation damage depends on a direct effect on differentiable tissues and the radiation-induced inability of the hormonal system to repair such a damage. 4. Wounding evokes a systemic response of the pupa. First this results - as indicated by histological examination of the hormonal glands - from an increased amount of juvenile hormone in relation to ecdyson. Secondly the wound possibly causes an excessive release of neurosecretion in the sense of a stress reaction. The response to wounding becomes maximal on the third and sixth day of the pupal instar. The first maximum of sensitivity on the third pupal day is thought to be correlated-with a critical event on the fourth pupal day, namely the withdrawing of the epidermis from the pupal cuticle. The second maximum of sensitivity on the sixth pupal day coincides with the second maximum of activity of the corpora allata at the end of the fifth pupal day. 5. A combination damage is always followed by a relatively large decrease of the ecdysial frequency, independent of the effects of the single injuries. The intervals between and the sequence of the treatments have no influence. The combination damage is particularly an amplification of the effect of wounding caused by radiation. 6. The activity of the corpora allata on the first two days of the pupal instar simultaneously with the ecdysial glands leads to renewed discussion of the "classical scheme", in which the relation of ecdyson and juvenile hormone determines the following moulting to a larval, pupal, or imaginal moult.