• International Journal of Industrial Entomology and Biomaterials
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• 제5권1호
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• pp.23-32
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• 2002

The introduction of hybrid and exploitation of heterosis has played a vital role in Indian sericulture industry, which clearly depicts a quantum jump in silk production during the last four decades. Since, the introduction of heterosis, progress in silkworm breeding has depended on success or failure in identifying better combiners. Systematic procedures developed have enabled the breeders to identify the best combiners by combining ability test, line ${\TIMES}$ tester analysis or $D^2$ analysis for maximum expression of heterosis. The level of heterosis expressed in the crossbreed population is determined by the interaction between genotype and prevailing environmental factors. Except some of the pre and post cocoon parameters, heterosis is invariably higher in single crosses compared to three-way and double crosses. However, during hot and humid season, when rearing of F1 bivoltine hybrid is unsuccessful at field level and indigenous races results in very low and poor quality yield, three-way and double crosses can play an important role as an intermediary technology. The objective of this article is to review briefly the concept and causes of heterosis, utilization of different forms of heterosis in silk production and its significance in silkworm, Bombyx mori breeding.

• International Journal of Industrial Entomology and Biomaterials
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• 제16권1호
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• pp.1-5
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• 2008

The present study was carried out with the aim to evaluate the viability of layings (delivery of fertilized and unfertilized eggs) with egg laying duration of elite bivoltine races. The temporal aspect of mating in terms of egg layings duration may also have impact on the number of eggs laid, pattern of egg laying and their viability. After different interval of egg laying duration, moth of Bombyx mori are removed from oviposition site after they have completed egg laying. Present investigation confirmed that there are no significant difference in relation to the occurrence of viable (fertilized) and non viable (unfertilized) eggs and duration of oviposition. Percentage of unfertilized eggs varied from 2.41 to 3.42% in case of CSR-3, 2.59 to 3.62% in case of CSR-6, 2.82 to 3.66% in case of CSR-16 and 2.58 to 3.40% in case of CSR-17 in different treatments. The occurrence of unfertilized eggs are also not significant in the different treatments specially in those eggs which were laid 24 hours after oviposition and kept for 4 months hibernation schedule.

• 한국응용곤충학회지
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• 제26권2호
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• pp.49-62
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• 1987

Matsucoccus속(屬)은 세계(世界)의 소나무림(林)에 걸쳐 분포(分布)하고 있으며 이중 우리나라 전남지방(全南地方)에서 해송림(海松林)에 피해(被害)를 주는 솔껍질깍지벌레가 신종(新種)으로 밝혀져 M. thunbergianae로 명명(命名)하였다. 신종(新種)의 충태별(蟲態別) 형태(形態) 및 생활사(生活史)가 근연종(近緣種)과 비교(比較)되었는데 이는 M. matsumurae (Kuwana) 및 M. resinosae Bean & Godwin과 가장 형태(形態)가 비슷하였다. 본종(本種)은 1년(年) 1세대(世代) 발생(發生)하며 2영충(齡蟲)으로 월동(越冬)하는 반면(反面) M. matsumurae와 M. resinosae는 1년(年) 2세대(世代) 발생(發生)하며 1영충(齡蟲)으로 월동(越冬)한다. 1년(年) 2세대(世代) 이상(以上) 발생(發生)하는 종(種)들에 있어서 세대간(世代間)의 형태적(形態的) 차이(差異)도 언급되었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제3권2호
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• pp.113-116
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• 2001

Fifth instar larvae of the new bivoltine hybrid (CSR2 ${\times}$ CSR5) were reared under different temperature and humidity viz., $20^{\circ}C$ and 85 ${pm}$ 5% R.H (T1), $25^{\circ}C$ and 70 ${pm}$ 5% R.H (T2-Optimum), $30^{\circ}C$ and 80% ${pm}$ 5 R.H (T3) and $35^{\circ}C$and 50 ${pm}$ 5% R.H (T4). The cocoon yield, cocoon characters and disease incidence were studied in normal (non infectious source, i.e control) rearing as well as in 1% infectious source of rearing. The results indicated that V instar larval duration was prolonged and cocoon weight was improved in T1. ERR and shell ratio were significantly improved and disease incidence was minimised in T2. Further significant difference was observed among the treatments with regard to spread of diseases.

• International Journal of Industrial Entomology and Biomaterials
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• 제12권2호
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• pp.75-80
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• 2006

Changes in the levels of protein and free amino acids in the haemolymph of three selected races of the silkworm, Bombyx mori viz., PM, $NB_4D_2$ and $CSR_2$, were investigated during 4th moult, 5th instar and pupal period. The levels of total protein in the haemolymph, increased from first day of 5th instar till sixth day. From seventh day till spinning, the protein levels decreased in all the three races. A sustained decrease in the haemolymph proteins was observed during the pupal development in all the three races. The levels of free amino acids, which were high during 4th moult, declined through the 5th age of larval development till spinning. PM showed a relatively higher free amino acid level (3.192 mg/ml) in haemolymph followed by $NB_4D_2$ (2.601 mg/ml) and $CSR_2$ (2.35 mg/ml). The free amino acid levels decreased gradually from prepupal stage but increased again at the end of pupal period. Racial differences in the changes in the levels of protein and free amino acids in the haemolymph were observed in the larvae and pupae when subjected to two high temperature regimes of $30^{\circ}C$ and $35^{\circ}C$. The results showed that high temperature induces specific changes in the metabolism (reversible thermal stress) that have different adaptive value in different races of the silkworm. Relatively higher increase in the free amino acid levels in the haemolymph of Pure Mysore presumably provides protective cover to tissues against high temperature by an increase in osmolarity and reduction in evaporative water loss. The absence of such a mechanism may be responsible for temperature susceptibility of the bivoltine races like $NB_4D_2$ and $CSR_2$.

• International Journal of Industrial Entomology and Biomaterials
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• 제5권2호
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• pp.175-182
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• 2002

A new high yielding mulberry genotype, Victory-1 (V-1) was recommended to the field for irrigated areas by Central Sericultural Research and Training Institute (CSRTI), Mysore during 1996-1997. As K-2 and S-36 mulberry genotypes are already in the field, a study on the comparative performance of V-1, 5-36 and K-2 varieties, in terms of leaf yield, yield attributes, leaf moisture and moisture retaining capacity and their impact on silkworm rearing was carried out under Telangana conditions of Andhra Pradesh during 1999-2001. Among the three genotypes the leaf yield was found to be significantly (P < 0.01) higher in V-1 (64,130 kg/ha/yr) followed by S-36 (44,064 kg/ha/yr) and K-2 (23,990 kg/ha/yr). The maximum leaf moisture was also observed in V-1 (71.84%) compared to S-36 (66.86%) and K-2 (64%). The moisture retaining ability was more in V-1 (70.17%) followed by S-36 (66.20%) and K-2 (60.08%). The yield attributes were found to be significantly (P < 0.01) enhanced in V-1 over S-36 and K-2. Silkworm rearing results (bioassay) indicated a significant (P < 0.01) reduction in larval duration and improvement in larval weight, effective rate of rearing by number and weight, single cocoon and shell weights and shell ratio in the silkworm lots fed on V-1 variety followed by S-36 and K-2. Hence, in this study, V-1 was found to be superior among the three varieties studied.

• International Journal of Industrial Entomology and Biomaterials
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• 제8권1호
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• pp.27-32
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• 2004

With an objective of evolving quantitatively and qualitatively superior bivolitine silkworm hybrid of Bombyxmori L. for tropics with shorter larval duration without compromising on productivity traits, a breeding programme was initiated at this institute during 1997 by utilizing breeding resource material from the institutes Germplasm collection. The breed SD7 is characterized with plain larvae spinning white oval cocoons and SD12 is characterized by sex-limited larval markings spinning white dumb-bell cocoons. After fixation, these breeds along with other newly evolved breeds were subjected for hybrid evaluation in the laboratory. Based on the hybrid studies, the hybrid SD7${\times}$SD12 was selected and evaluated for one year comprising three major sea- sons (6 trials) of tropics viz., Pre-monsoon (characterized by high temperature, low humidity and without any rain fall), Monsoon (characterized by moderate temperature, heavy rain fall with high humidity) and post-monsoon season (characterized by low temperature and low humidity with frequent rain fall) to know the fluctuations in the larval duration. The evaluation studies indicated that the hybrid is having shorter larval duration with productive merits. The hybrid SD7${\times}$SD12 recorded survival percent of 92.74, shell weight of 46.7 cg, shell ratio % of 24.0 and filament length of 1,200 meters with a shorter larval duration of 24 hrs; when compared to productive hybrid CSR2${\times}$CSR5(control). The breeding methodologies and hybrids usefulness for tropics were discussed.

• International Journal of Industrial Entomology and Biomaterials
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• 제9권1호
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• pp.47-51
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• 2004

To evolve silkworm hybrids with higher survival and productivity and easy and effective seed cocoon production, three new evolved bivoltine hybrids of silkworm (Bombyx mori L.), created with participation of sex-limited lines at eggs and larva stage were evaluated with control Super$_1$${\times}$Hessa$_2$ hybrid at Plovdiv Agrarian University during 2000 - 2002. ANOVA analysis was employed and the performance of hybrids was observed in respect of main quantitative traits. The results obtained show significant superiority of new hybrids T$_{15}$ 4/${\times}$TBV$_{2}$24/, XT$_{215}$38/${\times}$TV$_{3}$2/, XT$_{215}$38/${\times}$B$_{2}$6/ and their reciprocal crosses over the control. They were characterized with 99% hatchability of eggs, 93-95% silkworm survival, 2.32- 2.42 g cocoon weight, 53.5-55.7 cg shell weight, 22.9-23.1% shell ratio, 1,307-1,326 m filament length, 3.08-3.17 denier, 95-96% reelability, 44.4-45.1% silk ratio, 569-593 number of normal eggs per lying and 347-364 mg weight of normal eggs per lying. Newly evolved hybrids were manifested high productivity, 41.0-43.6 kg cocoon yield and 7.33-7.78 kg raw silk yield per one box (20,000$\pm$200 viable eggs), which significant surpass the control Super$_1$${\times}$Hessa$_2$ hybrid with 7.6-14.4% and 10.8-17.6%, respectively. T$_{15}$ 4/${\times}$TBV$_{2}$24/ and XT$_{215}$38/${\times}$TV$_{3}$2/ were considered as highly productive hybrids to local conditions and found suitable to rear in spring season.n.

• International Journal of Industrial Entomology and Biomaterials
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• 제13권1호
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• pp.7-14
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• 2006

A breeding programme was initiated during 2001 to introduce sex-limited larval markings to a productive multivoltine breed - BL67 from an inbred sex-limited line, MY1 (SL) maintained at Central Sericultural Research and Training Institute, Mysore. Introgressive hybridization, recurrent backcrossing for six generations followed by sib-mating resulted in synthesis of a new multivoltine silkworm breed BL67 (SL) with sex-limited larval markings. The new breed was studied for combining ability by crossing with eight bivoltine breeds viz., $NB_4D_2,\;CSR_2,\;CSR_2 (SL),\;CSR_2,\;CSR_4,\;CSR_8,\;CSR_{18}\;and\;CSR_{19}$. General combining ability effects of the new breed showed its superiority over the popular Pure Mysore by expressing significant GCA effects for six out of twelve characters whereas the results are on par with the original multivoltine breed. The hybrid $BL67(SL){\times}CSR2(SL)$ excelled in several quantitative characters such as pupation rate (90.2%), cocoon weight (1.97 g), cocoon shell weight (40 cg), cocoon shell ratio (20.3%), filament length (918 m), denier (2.96), raw silk percentage (14.96%) and neatness (90 p). Studies on cocoon size variability revealed that the cocoons of $BL67(SL){\times}CSR2(SL)$ were found comparatively uniform showing less standard deviation of 6.55 and co-efficient of variation of 3.91 %. The suitability of newly developed breed for easy grain age operation and commercial exploitation with promising hybrid have been discussed.

• International Journal of Industrial Entomology and Biomaterials
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• 제24권1호
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• pp.17-21
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• 2012

The effect of cultivation season on the cocoon filament quality of authorized silkworm variety, GoldenSilk was examined with cocoon filament character, reeling character, and fiber character during 3 years. In cocoon filament character, filament length of spring and autumn cocoon was 979 and 879 m, respectively. Cocoon filament weight of spring and autumn cocoon was 33.1 and 26.5 cg, which is lower than that of general bivoltine strain, BaeGokJam. Raw silk percentage of spring and autumn cocoon was 15.65 and 13.77%, respectively. In reeling character, reelability showed similar trend regardless of cultivation season and strain. However, the length and weight of non-broken filament of spring season were slightly higher than those of autumn cocoon. Cultivation season did not affect on the fiber characteristics such as clearness and neatness, lousiness, and degumming loss. In cocoon character, filament length, size, and weight, spring cocoon filament showed higher value than autumn cocoon, but lower than authorized general silkworm varieties. In reeling characteristics, non-broken length and weight showed the similar trends with the cocoon filament character. However, the reelability of GoldenSilk cocoon was not affected by cultivation season. The reelability of GoldenSilk cocoon was also similar with that of authorized general one. Fiber character including clearness and neatness, lousiness, and degumming loss was also similar regardless of the rearing season and different strain.