Abstract
The purpose of this study was to induce trimolters in four Thai Polyvoltine silkworm, Bombyx mori L; Nang Lai, Nang Tui, Hua Fai and Sumrong strains, at 48 hr of the fourth instar larvae by treatment with KK-42
(1-benzyl-5-[(E)-2, 6-dimethyl-1, 5- heptadienyl] imidazole with the doses of 25 and 30 ppm/larva. The result showed that the induced trimolters was the hightest as 84.2 ± 3.5 % in Nang Tui strain and the lowest as 30 ± 2.4 % in Sumrong strain. The cocoon weight, cocoon shell weight and percentage of cocoon shell in the treated groups were lower than the control groups. The cocoon filament in the treated groups was shorter than the control groups; however, the size of filament in the treated groups was thinner (0.6 ± 0.0 to 07 ± 0.3 d.) than the control group (1.5 ± 0.1 to 1.7 ± 0.2 d.). These results clearly showed that treatment of KK-42 to four polyvoltine silkworm strains at 48 hr of the fourth instar larvae remarkably induced trimolters and the thinner filament than untreated tetramolters.
