1974 Volume 43 Issue 3 Pages 211-216
Effects of photoperiods on the voltinism (diapause or non-diapause induction) of silkworms, Bombyx mori L., reared on the artificial diet were studied. Silkworm larvae were reared at 28°C throughout under the two photoperiodic conditions. These conditions were short day (8L·16D; 9 a. m.-5 p. m., light, 5 p. m.-9 a. m., dark) and long day (16L·8D; 5 p. m.-9 a. m., light, 9 a. m.-5 p.m., dark). The artificial diet consisted of mulberry leaf powder, agar, potato starch, sucrose, soybean meal, cellulose powder, L-ascorbic acid, citric acid and B-vitamins. The race of the silkworm, Hosho (a bivoltine Chinese race), was used throughout.
1. Being the silkworm larvae reared on the artificial diet, the photoperiodic conditions during the incubation period and the pupal stage did not effect to the voltinism of silkworm.
2. However, in larval stages reared on the artificial diet, a short day illumination (8L·16D) was more effective than a long day (16L·8D) to the change in diapause character of eggs laid by the moths which developed under different photoperiodic conditions. As a result, a short day for 8 hours gave a higher rate of diapause egg producers of moths of the bivoltine race.
3. The changes in diapause character of eggs by moths which developed under different daylengths during larval stages were recognized regardless of every larval stage treated by illumination, though there were some variations. And, the diapause character gradually rose as the silkworm grew, passed through a maximum at the 4th instar and finally fell off.
