Resistance to Nucleopolyhedrosis Virus of Breeding stocks in Japanese Tusser, Antheraca Yamamai, GUERIN-MENEVILLE

通过尝试培育抗病种群和对核型多角体病毒感染的流行病方法来研究作物生产力的提高，核型多角体病毒使作物产量下降。为了比较交配所产生的经济性状，我们将31只日本河豚与49只中国河豚交配，并比较其经济性状。与日本钳蝎的杂交。(1)尽管母亲的受精率较低，但幼虫发育良好，对NPV感染具有较高的抵抗力。茧层重量和茧层百分含量也较高。利用&lt；F_1&gt；杂交组合，获得了&lt；F_1&gt；X、日本Tusser X&lt；F_1&gt；和&lt；F_1&gt；X&lt；F_1&gt；(2)第2代及以后代杂种在性状上没有表现出与&lt；F_1&gt；杂种的显著差异。3龄幼虫发育异常，第2~4节外侧有黑点。这一繁育阶段对应的是含有染色体异倍体的精巢细胞分裂活动的时间。比较了抗病株(SR)和体色突变株(MT)的幼虫生物学品质和茧丝品质。(1)试验组和试验组的孵化率和产茧量均显著高于对照组。(2)SR雌蜂产丝量较大。雄性和雌性MT产生的纤维强度和伸长性都较好。从田间发生核型多角体病的病原菌出发，探讨了作物歉收的原因。(1)从麻栎叶和茎中分离和回收了大量引起核型多角体病的病原菌。(2)在文献(1)的基础上，推测了病原菌的寄生繁殖方式。

Improvement of the crop productivity was studied by attempting breeding of disease-resistant stocks and by epizootiological approach to nucleopolyhedrosis virus infection which deteriorates the yield of crops .1 . Female Japanese tussers (n=31) and male Chinese tussers,Antheraea pernyi, GUERIN-MENEVILLE (n=49) were mated to compare the economical character of resultant! hybrids with those of Japanese tussers. (1) Despite poor fertilization ratios in mothers, larvae developed well and had high resistance to NPV-infction. Both the weight and percentage of cocoon shells were also higher. Using the <F_1> hybrids, 3 offspring combinations were obtained ; <F_1> X Japanese tusser, Japanese tusser X <F_1> and <F_1> X <F_1> . (2) Hybrids in the 2nd and later generations demonstrated no such remarkable differences in traits as the <F_1> hybrids. However, abnormality was found in the larvae of the 3rd instar which developed blackish dots on the lateral aspect of the 2nd to 4th segments. This breeding stage corresponds to the time of testicular mytotic activity which contained chromosomal heteroploidy.2 . The biological quality of larvae and quality of cocoon filament in the disease-resistant stock (SR) and body-color mutant stock (MT) were compared with controls. (1) The hatchability and cocoon productivity were higher in both SR and MT than controls. (2) SR females produced a larger weight of cocoon filament. Male and female MT produced filament that excelled in strength and stretchability.3 . The cause of poor crop was investigated in relation to pathogens of nucleopolyhedrosis occurring in field rearing. (1) A large amount of pathogens were isolated and recovered from the leaves and stems of oak, Quercus acutissima which caused a prevalance of nucleopolyhedrosis. (2) On the basis of (1), a pattern of pathogen propagation by inhabiting insets was postulated.