| The silkworm is an important economic insect, and possesses the very important position in our country national economy. The silkworm race modification always is the pillar of silk industry development. To increase output and improve the economic characters and raise the quality of silkworm cocoon, cultivating and popularizing the new silkworm race is taking the important effect. With the silk cloth product on the international market 's diversify ,top-grade trend development as well as our country silk fabric production and the great change of product structure , we urgently need provide the special use silkworm race of one batch of new-type raw material silk and with the inherent character to raise the quality of raw material cocoon to promote our country silk fabric product structure to adjust and fully satisfies the requirement in the market and strengthen the competition ability on the international market of our country silk cloth .Therefore, it will be the focal point for breeding research to cultivate the special silkworm race from now on, such as disease-resistant, rearing male silkworm , sex-limited race , coarse size race , fine size race, low- cost artificial diet. Along with the swift and violent development of molecular biology, the application of technology, for instance, molecular-aiding breeding will quicken the breeding course of silkworm race.This research chiefly displayed three parts: (1) the breeding of yellow blood inhibition pure-line; (2) hybrid combination of yellow blood inhibition race and sex-limited yellow cocoon line;(3) RAPD's molecular marker of yellow blood inhibition race.The major results were as follows:1. the breeding of pure line with yellow blood inhibitor geneThrough screening yellow blood inhibitor gene from European strain and transfer it into sex-limited marking practical race , namely 871, and selecting gene with good character, except poor character and fixing purely, the pure line of yellow blood inhibition race was obtained with sex-limited marking andfavorable comprehensive economic characters, namely "white silver * ( ??IIw+pz, 3 IIzz ) . In the cocoon shape, the one side is inclined to Chinese strain selection, the other to European strain , thus white silver A system and the white silver B system were established , respectively. Reciprocal cross with sex-limited yellow cocoon strain( ?iiwYZ, & iizz ), Fl were completely white cocoon .which has provided a new way for the yellow cocoon practicably.White silver characters : the white silver race was bred throughhybridization , the female parent of which was Chinese strain "871", the male parentwas European strain "Bageda" , bioltine, tetramoulting, dominant white cocoon.The race was good in aspect of eggs laying and more weight of produced eggs, the number of laid eggs per moth is about 550 . The colour of silkworm egg was gray purple while its egg shell was milky. The duration of incubation was 10 days, the course of hatch was uniform, the newly-hatched silkworm was red black, its action was active; the young silkworm is big , and the caudal abdominal region takes red , sleeping nature quick but uniform ;strong silkworm body color is blue or greenish white , and the silkworm body is long and sturdy with the character of sex-limited marking , female for the general spot, male for the white silkworm, eating mulberry vigorous in the 4th instar but slow in the 5U instar , treading on the leaves and the action is active .The action of mature silkworm is gentle and quiet, but the cocooning is slower . Silver A's cocoon is elliptic in shape ,white silver B' cocoon was long-elliptic and peanut shape. The color of cocoon was pure white, medium- wrinkle; the duration of the 5th instar was 6. 5 - 7.5 days, duration of feeding period was 22 - 24 days; duration of pupal period was 17 -18 days, the mating performed satisfactorily, eggs laying is quick, the poor egg rate is low , and the male moth is able to bear or endure refrigeration . This race physique is strong , its cocoon weight,... |
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