Silkworm strain that cocoons are reeled without using the boiling water may provide not only cost cut but also new material. It was clear that the water reeling strain which was bred in our laboratory was affected on the environment during the spining stage same as a general varieties, and it’s main factor was impossible to grope for fiber ends. We examined effect of humidity which affect the reelability on grouping end efficiency in the water reeling strains. N43 (from J 02, water reeling strain), N17 (from Daizo) and their Hybrid, N17×N43 were used in the experiment, 4 humidity conditions (low, midA, midB, high) were provided. The hybrid of N17×N43 was able to make cocoon at the experiment. On the other hands, 80% of N43 could not make cocoons and died without pupation at high humidity condition (99% RH). N17 which was another parent of hybrid was investigated in next raring season. Consequently, any larvae did not make a cocoon and some naked pupae appeared in N17. It may be suggested that hybrid larvae of N17×N43 made cocoons by heterosis at high humidity condition (99%RH).
This method is reported for the cryopreservation of ovaries and spermatozoa of the transgenic silkworm (Bombyx mori). At first, female moths were artificially inseminated with frozen-thawed semen of transgenic silkworm strains. The fertility varied from 0% to 92.0% depending on the strain. Addition of frozen-thawed semen from triploid moths, which are infertile but include intact apyrene sperm, improved fecundity of cryopreserved semen. The second experiment was ovary transplantation. Ovaries were removed from 5th instar larvae and cryopreserved in liquid nitrogen. The frozen-thawed ovaries were transplanted to 4th instar female larvae which had been surgically castrated. The emerged female moths were mated with nontreated male moths and deposited eggs. The eggs were genetically identical to the donor transgenic silkworm strains. Eggs were surgically removed from ovarian tubules of moths following transplantation of frozen-thawed ovaries and subjected to parthenogenetic activation and artificial hatching. All resulting moths were female and artificially inseminated with frozen-thawed semen. The used semen was collected from the same transgenic silkworm strains. Then the female moths yielded sound offspring of the transgenic silkworm strain at high rates. The third experiment was method of connecting the thread bodies of the donor with those of ovaries of the recipients. The results of connecting the thread bodies of ovaries were relatively high percentage. The emerged female moths artificially inseminated with frozen-thawed semen yielded well-conditioned offspring of the transgenic silkworm strains.