Decapitation or starvation raise haemolymph ecdysteroid titres in the ovoviviparous female cockroach, Blaberus craniifer burm

Abstract

1. 1. Decapitating newly emerged Blaberus craniifer females near the prothorax severs connections between the suboesophageal and prothoracie ganglia, thus depriving them of the neuroendocrine cephalic complex (including brain and suboesophageal ganglion) and the anterior end of prothoracie glands (PGs). 2. 2. As demonstrated by enzyme immunoassay (EIA), headless females have higher levels of ecdysteroids (ECDs) in haemolymph than starved or fed females, indicating that the neuroendocrine cephalic complex influences circulating ECD levels. 3. 3. The time course of hormonal peaks in decapitated females resembles that in starved females during the first post-ecdysial week, suggesting that some as yet unknown regulating mechanism of ECD production lies outside the head. 4. 4. It is suggested that: (a) The PGs are sites for ECDs production in the early post-imaginal period, (b) the prothoracie and suboesophageal ganglia (linked by nerves to PGs) regulate PGs activity, possibly via neural inputs.