Abstract
The objective in this preliminary study was to find the appropriate dose of Juvenile Hormone Analogue namely Pyriproxyfen to improve economic characters of Thai hybrid silkworm (Bombyx mori L.), Nanglai x J108 strain. Six doses of Pyriproxyfen (0.01, 0.05, 0.1, 0.5, 1 and 5 ppm) were applied by using the topical method on the dorsal part of the third day of the fifth instar silkworm larvae. The result showed that 0.05 ppm
of pyriproxyfen was most effective on growth and economic characters and the length of larval feeding period extended 2-4 days. Consequently, cocoon weight, cocoon shell weight and pupal weight of the female increased 32.55 %, 16.58 % and 29.55 %, respectively, while those of the male increased 26.93 %, 9.03 % and 34.66 %, respectively. Cocoon weight and length of silk filament increased 3.86 and 12.86 %. However, cocoon shell ratio of both sexes decreased which indicated that pupal weight increased. The data from this experiment can be used for further studies for improving cocoon production.
