Increase in the weight of silkgland and body during larval development of the hybrid between the domestic silkworm, Bombyx mori, and the Chinese wild silkworm, Theophila mandarina
1993
Dai, P. (Utsunomiya Univ. (Japan). Coll. of Agriculture) | Iwashita, Y.
We determined the silkgland weitht and body weight of the hybrid between the domestic silkworm, Bombyx mori (Bm) and the Chinese wild silkworm, Theophila mandarine (Tm). The growth rate expressed the maximum body weight/the body weight of newly hatched larvae was estimated. The growth rate of Tm was much lower than that of Bm and the growth or their hybrids was intermediate between that of the parents, Bm and Tm. There was a difference in body weight between Bm x Tm and Tm x Bm and Tm x Bm showed clear heterosis. The rate of increase at the silkgland weight of matured Tm larvae compared to newly hatched larvae was lower than that of Bm for the measurements of both wet weight and dry weight, the hybrids showed intermediate values between those of the parents. The growth rate was not different between the hybrids with the reciprocal crossing Bm x Tm and Tm x Bm. In Bm, Tm and their hybrid, the regression of the silkgland weight (y) on the body weight (x) during larval growth in the 5th instar corresponded to the allometry equation and the regression (a) was about 2.0 at 5% level of significance regardless of the silkworm race, cross combination and sex. The growth rate of the silkglands of the hybrids, Bm x Tm or Tm x Bm was larger than that of the body weight and showed a positive allometry. Besides, in our experiment, the relative growth rate of the silkgland the body weight in the hybrid Tm x Bm or Bm x Tm was lower than that of J-1 and C-124, but it was obviously larger in Tm x Bm than in Bm x Tm
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