PTTH - A potential growth activator in silkwonm, <i>Bombyx mori L. </i>for enhancing silk production

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