[Influence of corpora allata on the pigmentation of carausius morosus Br]

Abstract

Indian stick insects were deprived of their Corpora allata during the 4th larval instar and kept together with untreated control animals in 18° or 28° C. The amounts of Carotenoids, Biliverdine and Xanthommatine of the body -excluding eyes, gut and ovary - have been determined. 1. Neither in operated animals nor in normal controls there were marked temperaturedependent differences in Biliverdine and in absolute Carotenoid content. 2. The relative Carotenoid content with respect to body weight increased in operated animals temporarily. Afterwards it decreased beneath that of control animals. This may be an effect of the deposition of Carotenoids into the ova, as the allatectomized animals undergo premature metamorphosis. 3. The Biliverdine content decreases after operation due to blood loss. Later on it increases again, showing that Biliverdine-synthesis is not dependent on the presence of Corpora allata. 4. Higher temperature increases the Xanthommatine content in normal animals but not in animals deprived of their Corpora allata. This may also be an effect of premature metamorphosis, as ommochrome synthesis is reduced in adult animals. 5. Black covering of the ventral halves of the eyes increases the ommochrome content even in the animals without Corpora allata. This indicates, that the morphological colour adaption is not dependent on the presence of Corpora allata.