Neural and Hormonal Control of Pupation in Galleria mellonella (Lepidoptera: Galleriidae)1

Neural and hormonal regulation of development from the last larval ecdysis to pupation was studied in the greater wax moth, Galleria mellonella (L.). An obligatory prepupation feeding period of about 24 hr followed the larval ecdysis. Endocrine competence of the brain fell to a low level at this time, and its subsequent increase depended on the functioning of the suboesophageal ganglion during the 2 or 3 days immediately following ecdysis. The maintenance of brain endocrine activity–presumably prothoracotropic hormone (PTH) production–was required during most of the stadium. During this period, the endocrine activity of the brain could be suppressed by: (1) brief exposure of the larvae to low temperatures; (2) severance of the ventral nerve cord in the 1st abdominal segment; (3) extirpation of the terminal terminal ventral ganglion; and (4) ligation of the abdomen at segment 6. Using H. Piepho's system of developmental staging based on degree of eye pigment retraction, it was found that dependency on terminal ganglion function ended early in eye pigment stage 3 (31); proctodone dependency ended late in that stage (32); dependence on PTH ceased at a point intermediate between stages 3 and 4; and dependency on ecdysone continued until early in stage 4. Pupation could also be inhibited by enforced distortion of body form, up to eye pigment stage 4. Distortion inhibited pupation by the suppression of ecdysone production; the administration of crystalline ecdysone promoted continued development among distorted larvae.