936-941In silkworm, prothoracicotropic hormone
(PTTH), directly or indirectly controls silk production and spinning activity along
with juvenile hormone (JH). An effort was made to exploit the potential of PTTH
by indirectly activating silk gland for increasing silk productivity using short
chain synthetic analogues of PTTH. The analogy in action was also established using
PTTH extracted from the silkmoth. Different doses of 42 synthetic PTTH analogues,
viz., 2.5, 5, 10 and 20 ppm and 3.3 mg/ml of PTTH extracted from silk moth
heads were administered orally to V instar silkworm larvae (Race: KA×NB4D2
and PM× NB4D2) at 0-144 hr at an interval of 24 hr. The
analysed data showed an improvement of about 14-23% in KA × NB4D2
and about 10-14% in PM×NB4D2 in respect of cocoon shell
weight on administration of some of the synthetic PTTH analogues. The PTTH extracted
from the adult brain also showed similar effect. The structural analogy of
synthetic PTTHs (which improved the shell weight) with original PTTH and its
probable mode of action in silkworm are discussed