Silkworm Cloud In Summer 1 �� Yun Xia Breeding

Despite the different seasons Spring, Summer, Autumn in one year, the silkworm race for spring rearing is the main race reared in Yunnan province, it has not strictly distinguished the race for spring rearing from the race for summer-autumn rearing. The specialists (inside and outside of Yunnan province) in the field of silkworm studying have pointed out although the weather of most area in Yunnan is mildness, and it has been called "The four seasons are all like Spring", but there has exist difference in the three seasons, the Spring, the Summer and the Autumn, so it has great discrepancy in the mulberry-leaves quality in different season. The government of Yunnan province has always thought high much of the sericulture production, and it was planned as a mainstay industry, so in recent years, the sericulture production has developed in some cities in the south of Yunnan lying in semitropical area. The climate of those areas is high temperature and humidity, to select the fine silkworm variety fit to breed in such weather is an important task. According to the criteria set down by China Crop Race Examination Council, the quality criteria listed as following: the main criteria are the neatness standard is 90 points, the reelability percentage is 70% or the length of non-broken cocoon filament is 700 metres; the secondary criterion is the ratio of cocoon shell is 21%. If there has a severe climate in the year, the reelability percentage will reduced than normal condition, and the criterions is the reelability percentage will reach at 95% of the control race.In early 1990's, we found plain silkworm individuals in the original strain of authorized race 792, a preserved race of our institute, which is a kind of marking pattern silkworm. We separated the plain silkworm and bred it, according to its external morphology specificity and economic character, we confirmed it was the offspring 792. Then we maintained it as a new race, bred it in different kinds of severe entironment which has high temperature and humidity, high temperature and dryness or high temperature and sultriness. We selected the brood which has high survival rate of larvae and low rate of dead worm cocoon, in those brood, we further select the individual which has normal cocoon shape, equality size, higher ratio of cocoon shell, thin wrinkle of cocoon. After selection of many generations, the new race 792 plain which has stable character was successfully bred. The excellent properties of the race are results from genes and environment. Following this principle, we select the individual which has short 5th instar larval duration and brood duration from the preserved race GC3. During the breeding, we selected the individual which has high larva-pupa survival rate and survival rate of larvae, low rate of dead worm cocoon to subculture. During the pupal stage, the selective standards are normal cocoon shape, equality size, thin wrinkle of cocoon; in the egg stage, the standards are more amount of laid eggs and balance brood; in incubation stage, select the bluish together, high one-day hatchability brood to rear.We bred the race in high temperature of summer and autumn to enhance its vitality every one year, after many generations selecting, we get a new race "963" which has the same quality as "furong"."furong x xianghui" are the main race for summer-autumn rearing bred by Hunan sericultural institute, which have fine economic character and stable inheritance, and suit for rearing in the field of Changjiang river. It has been used in Zhejiang, Sichuan, Guangdong, Fujian province for 7 years. Our institute introduce it in 1992, after several generations rearing the two stocks have been tamed, and they were further cross detected in laboratory, we chosen the best combination "yunxia 1 X yunxia 2" which also named "962fuX 792bai粁iang" .During the choosing process of "yunxia 1 X yunxia 2", the economic character of 4 parents is the chiefly conditions, it has more merits and less disadvantages, and their characters could be complemented each other. The method we...