Keywords: Bombyx mori eggs, hydrochloric acid treatment, economic hatchability

An experiment was conducted in randomized complete block design- split (RCBD - split) to evaluate the efficacy of common acid treatment on diapause termination and hatchability of bi-voltine silkworm eggs of a popular silkworm variety (J₁₂ x C₁₂) at Sericulture Development Section, Khopasi during September-October 2002. A total of 100 eggs/ experimental unit were treated in the HCl solution of 1.0642 specific gravity at 46 ⁰C (15-25 hours after oviposition and 4-7 minutes dipping duration), washed with clean water, dried in shadow and transferred to incubation room. The incubation result showed that the highest economic hatchability (97.59%) was obtained indicating significant result (24.64% higher hatchability compared to the lowest hatchability (72.95%) among various combinations (p<0.05), when the eggs were treated 20:00 hours after oviposition (HAO) for 5 minutes dipping. Similarly, the second and the third highest economic hatchabilities (96.24% and 95.84%, respectively) were obtained as per the eggs treated in the HCl solution 22:30 HAO for a dipping duration of 5 and 4 minutes, respectively. Reversibly, the economic hatchability of eggs decreased significantly as the time of treatment after oviposition lengthened and duration of dipping shortened, i.e. when the eggs were treated in HCl 25:00 HAO for a dipping duration of 4 minutes. Thus, the result showed a strong relationship between treatment after egg laying (main factor) and dipping duration (sub factor) interaction to obtain economic hatchability of bi-voltine silkworm eggs.