Through the parent race of balanced lethal system ping30 during the different nutritional conditions, different kinds of temperature of cocoon period protection, the frequency of male moths to mate every day, the protection temperature of the male moths and the silkworm egg production farm survey, that the relative hunger in addition to the quality of the cocoon of the parent race impact, the moths mating performance of male moths not affected.The cocoon period protection with higher temperature has an adverse effect to the quality of the eggs, but the mating performance of male moths had no effect.Male moths to mate two times a day have a higher utilization rate than one mating a day.The protection temperature of the male moth is higher than 10℃,the utilization rate of male moths is decline.In normal circumstances, the male moths utilization of ping30 up to 500% or more, the male within the five cross-moth is safe and effective.It is proposed that the male and female ants of the amount of parent race not more than 1:3 ratio is appropriate in male hybrid eggs production.

Four commercial silkworm varieties, Fengyi, Xinhang, Baiyun and 54A, were rejuvenated and their F1 hybrids were compared with that of the present commercial lines. Results showed that there were same in the performance of fifth instar duration and larval duration, and similar in survival rate. However,most of the productivity traits were improved. Therefore, the rejuvenated lines were improved not only in its pure lines, but also in their F1 hybrid, and suggested to be used for commercial production.

Four commercial silkworm races,Fengyi,Xinhang,Baiyun and 54A,were rejuvenated and compared with the present commercial lines.Results showed that almost all the productivity traits were improved.Larval duration was a little longer in the rejuvenated lines of Xinhang and Baiyun.While the survival rate of the rejuvenated Xinhang was decreased significantly,the rejuvenated line of 54A was higher compared with the commercial line and there was no significant difference shown in Fengyi.The cocoon weight and cocoon shell weight of the rejuvenated lines were all improved in this breeding plan.The number of good eggs of rejuvenated lines was also improved except Xinhang.This research showed that the productivity traits of the rejuvenated lines were better than the commercial line and suggested to be used for commercial production.