Kj. Siegert, CARBOHYDRATE-METABOLISM DURING THE PUPAL MOLT OF THE TOBACCO HORNWORM, MANDUCA-SEXTA, Archives of insect biochemistry and physiology, 28(1), 1995, pp. 63-78
During the pupal molt of the tobacco hornworm, Manduca sexta, the perc
entage of active fat body glycogen phosphorylase increased from 5-10 t
o 20%, but only for a period of 5 h prior to the moll. From the time o
f the appearance of two sclerotized dorsal bars to the time of the mol
t, the concentration of total hemolymph carbohydrates doubled to 100 m
M trehalose. Initially, the glucose level was high (16 mM) when compar
ed with feeding larvae (approximately 1 mM) but decreased to zero just
prior to the molt. The amount of cuticular chitosan decreased from ap
proximately 100 mg to 10 mg al pupation; the exuvia contained approxim
ately 7 mg. While the levels of total lipids in hemolymph were not aff
ected, the lipid content of the fat body decreased significantly prior
to the molt but increased sharply thereafter. Fat body glycogen phosp
horylase in pharate pupae and pupae of M. sexta was substantially acti
vated by the Manduca adipokinetic peptide hormone, which in pharate pu
pae, produced the same response al 2 and 20 pmol per insect as in liga
ted larval abdomens. In pupae the response was clearly reduced. Using
chilling to stimulate glycogen phosphorylase, it was found that the en
zyme in pharate pupae and pupae responded both in vivo and in vitro as
in ligated abdomens of larvae. Thus, a transition to the adult respon
se seems to occur during the pupal and pharate adult development. (C)
1995 Wiley-Liss, Inc.