Prevention of diapause in silkworm eggs by hyperoxia method

Objective  To compare the differences between the effects of high oxygen concentration treating mehod (hyperoxia method) and traditional HCl treating method (HCl method) on prevention of diapause in silkworm (Bombyx mori) eggs, and investigate the application of hyperoxia method in transgenic technology system of silkworm.

Method  The bivoltine silkworm‘Dazao’ were treated by hyperoxia method and HCl method on the 20th hour after spawning. The hatching rate and incubation period were compared, and the best condition of hyperoxia method was investigated. The univoltine silkworm‘Tuerqi’ and transgenic bivoltine silkworm‘Dazao’were treated by hyperoxia method. The effects of hyperoxia method and microinjection on blocking univoltine silkworm diapause were investigated.

Result  Hyperoxia method had similar dispause prevention effects with HCl method considering hatching rate and incubation duration. The best condition was treating 40 hours by 70% (φ) O₂ after spawning for 20 hours. Hyperoxia method could successfully prevent diapause in univoltine silkworm eggs. The hatching rate was (71±20)%. The hatching rate of micro-injected transgenic silkworm eggs treated by hyperoxia method approached (49±9)%, while that of control group was 0.

Conclusion  Hyperoxia method is a feasible new method for replacing HCl method in the future production, enables safe and environmental friendly prevention of diapause in silkworm eggs, solves key problems of diapause prevention in transgenic silkworm eggs, and improves breeding progress of transgenic silkworms.