• Journal of Sericultural and Entomological Science
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• v.20 no.2
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• pp.10-14
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• 1978

There are relatively many reports have been issued on he active movement of cuticle of larva. which tend to protect their body, however, only a few reports have been disclosed on the cuticle of pupal body except the small portion of rectangle which shown tortoise-shell shape. In this connection, many portion of the external structure of pupal cuticle has been studied and the following. results were found: 1) No. spot of rectangle which is sculptured in the surface of cuticle that born by branching. out of the development of cell in imaginal bud of antenna and head were found. However, in the compound eye of net shaped sculpture was found in the (equation omitted) shaped parts which holding. the diameter of about 8u and the surrounding area has the small bump and the one is dark brown coloured comparing with shape. 2) The sculpture shape of thorax is a little different than in the head. However, (equation omitted) portion is varies from the segment to segment. In general, it is not very clear than the compound eye in the head, the dark brown bump shape is slowly fade a from the prothorax, mesothorax to metathorax. 3) The surface of intersegment membrane is colourless or slightly yellow, and the entire surface has stripped marking with thine lines. 4) In the abdominal segment, there are many and small sculptures in net shape around the (equation omitted) shape portions. 5) The size of sculpture in (equation omitted) portion of abdomen is smaller than one in thorax, and in the same segment, the dorsal is smaller than abdomen and the rear portion of the segment is larger than the front of segment. 6) After the 7th abdominal segment, no intersegmental membrane is found and the cuticle of the external structure is the same as external structure of the segment. 7) The seta is not found in head, compound eye, antenna and wing which portions were subdivided by development of imagined bud of the cell, no seta is found in cuticle of the segment in the general cell of the larva stage and also in the dorsal and intersegmental membrane.

• Journal of Sericultural and Entomological Science
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• v.9
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• pp.67-87
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• 1969

1. Objectives and Importance. Many silkworms have been damaged by nuclear polyhedrosis virus diseases thoughout the country every year causing a decease in cocoon production by approximately ten per cent per year. The damage caused by the infections virus has occured in spite of complete disinfection. In this respect, it is well known it is impossible, at the present time, to protect the silkworm from these virus infections through chemical and physical control methods. Therefore, this author has attempted to solve this urgent problem from the view point of heredity and breeding, discovering the different resistances and heritabilities among 120 stains collected from throughout the country, and selecting the ones with highest resistance for the basic materials in the silkworm breeding. 2. Results of work 1) The strains with strong resistance to the nuclear polyhedrosis virus diseases are N$_4$, N$\sub$15/, N$\sub$48/, C$\sub$55/ and Em. the log ED$\sub$50/ values of them vary between 0.799 and 1.611. The susceptible strains are N$\sub$20/, C$\sub$62/, N$\sub$76/, N$\sub$79/ and C$\sub$108/, the log ED$\sub$50/ values of them vary between 5.159 and 7.258. (Reference Table 4) The Japanese strain with a log ED$\sub$50/, value of 3.770 is the strongest, followed by the Chinese strain with a log ED$\sub$50/ value of 3.564. The weakest is the European strain with a log ED$\sub$50/ value of 3.3381. The direction coefficient of the regression equation of the susceptibility varies between 0.1 and 0.6, the uniformness of the resistance of the preserved strains of this country is comparatively low. The hereditary henomena of the resistance of each strain and the conerete method of its application for silkworm breeding main the subjects for later studies. 2) The content of water and ash in silkworm has not been correlated with the capability for resistance to the virus diseases(Reference. Table 8). but it is very significantly correlated with mortality rate (in common reaning). In the case of the silkworms which have just completed the fourth moulting the content of water and ash is not related to the mortality rate. In the case of the silkworms which have just completed the third moulting, however, the water( +0.326) and ash (+0.362) registered a high significance. The ash content in the first ($\div$0.520) and second ($\div$0.386) moults is highly significant but water content in both cases is not significant (Reference Table 7). 3) The No. 205 strain proved to be the best in character among the various F$_1$ hybrids. No. 204 was very good in strength but a little lower in cocoon character than the control. No. 212 was a little low in coccon character and mortality was average, but the cocoon harvest was the best among all the varieties offered for (Reference Table 9). 4), In short, the above mentioned strains which are known to have strong resistance to the virus disease are expected to provide basic data for breeding strong varieties. It is proposed that continued research should be conducted on the characteristics of various strains for a satisfactory preservation of various characteristics.research should be conducted on the characteristics of various strains for a satisfactory preservation of various characteristics.

• Journal of Sericultural and Entomological Science
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• v.27 no.2
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• pp.7-19
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• 1985

The genetic variances and combinding ability of some useful characters were analyzd on sixty four combinations in the 8$\times$8 diallel cross using the four Japanese races(Jam 107, Jam 113, Jam 117 and Jam 119) and the four Chinese races(Jam 108, Jam 114, Jam 118 and Jam 120). The eight quantitative characters were the total larval stage period(TP), the fifth larval instar period(FP), the female cocoon total weight(FW), the male cocoon total weight(MW), the female cocoon layer weight(FL), the male cocoon layer weight(ML), the female cocoon layer ratio(FR), and the male cocoon layer ratio(MR). The results were as follows: The analysis of the genetic variance and the combining ability in the TP and the FP. In TP and FP, h2N was less than h2B. The GCA, SCA and RCA were at a high significant level. Hl/D and (Hl/D)1/2 ere large. The heterosis were small minus. E and D were large. The r was in the positive direction, because the recessive genes were mainly expressed as a short rearing periods. The regressions of the characters were passed below 0 point, because the characters in the TP and the FP were appeared overdominant. The order of the dominance in the TP of the parents were in the order of Jam 119>Jam 113>Jam 117>Jam 108>Jam 120>Jam 114>Jam 107>Jam 118, and that in the FP of the parents were followed in the orders of Jam 117>Jam 113>Jam 108>Jam 114>Jam 119>Jam 107>Jam 120>Jam 118. The analysis of the genetic variance and the combining ability of the FW and the MW. In the FW and the Mw, h2N was less the h2B. The GCA and SCA were large but RCA was little. Hl/D and (Hl/D)1/2 in the parents were large. Heterosis was large. E was appeared large in the FW, and small in the MW. D was small. The r was of the minus direction, because the dominance genes were less expressed. The regression of the these characters were padded below 0 point, because the characters in FW and MW were appeared overdominant. The orders of the dominance in the FW of the parents were as the order of Jam 107>Jam 108>Jam 119>Jam 113>Jam 114>Jam 120>Jam 117>Jam 118, and in the MW of them in the order of Jam 114>Jam 120>Jam 108>Jam 113>Jam 107>Jam 119>Jam 117>Jam 118. The analysis of the genetic variance and the combining ability of the FL and ML. In the FL and the ML, h2N was less than h2B. GCA and SCA were large. RCA was little. Hl/D and (Hl/D)1/2 ere large. Heterosis was large. The r was in the negative direction, because the dominance genes were less expressed. The regression of the characters of FL and ML were appeared overdominant. The dominance in the FL of parents ere in the order of Jam 120>Jam 114>Jam 119>Jam 119>Jam 118>Jam 107>Jam 117>Jam 113, and the ML of them in the order of Jam 114>Jam 108>Jam 120>Jam 117>Jam 118>Jam 107>Jam 119>Jam 113. The analysis of the genetic variance and combining ability of the FR and the MR. In the FR and the Mr, h2N was less than h2B. GCA was large. The SCA and RCA were little. In the FW, Hl/D was large but (Hl/D)1/2 was a little. In MR, Hl/D and (Hl/D)1/2 both were a littel. Heterosis was a little. E in the FR was in the negative direction, because the dominance genes were less expressed but that in the MR was the positive direction because the recessive genes were mainly expressed. The order of the dominance in the FR of the parents were in the order of Jam 117>Jam 114>Jam 108>Jam 120>Jam 118>Jam 119>Jam 107>Jam 113 and that in the MR these were in the order of Jam 114>Jam 117>Jam 108>Jam 118>Jam 107>Jam 119>Jam 120.