Endocrinological aspects of silk production

Effects of ultralow doses of fenoxycarb on juvenile hormone-regulated physiological parameters in the silkworm,Bombyx mori L.

“…Inhibition of silk gland growth is one of the well-known JH effects (Kurata, 1981;Garel, 1983). Generally, this effect is induced by topical application of JH or JHA at the beginning of the fifth instar and results in a transient inhibition which rapidly abates and is followed by a greater growth rate than in the control larvae (Kurata and Daillie, 1978;Daillie, 1979).…”

“…During this period, JH induces a total inhibition of prothoracic gland activity (Sakurai, 1984;Okuda et al, 1985;Sakurai et al, 1989). From the fourth day, when JH becomes undetectable in the hemolymph (Plantevin et al, 1987), the prothoracic glands (PGs) recover their activity (Okuda et al, 1985), silk gland growth is accelerated (Garel, 1983), and major hemolymph protein synthesis is enhanced (Izumi et al, 1984;Tomino, 1985;Plantevin et al, 1987). Akai and Kobayashi (1971) were the first to show that JH treatment of early last instar larvae prolongs the instar or produces permanent larvae, depending on the doses applied.…”

Effects of starvation and hormones on DNA synthesis in silk gland cells of the silkworm, Bombyx mori

“…The application of JH during the final instar increased larval body weights, in addition to cocoon and silk production rates. A presumed mechanism is that the application of JH prolongs larval feeding during the final instar, leading to an increase in size (Daillie, ; Garel, ), and thereby indirectly increases silk production.…”