• Journal of Sericultural and Entomological Science
• /
• v.17 no.2
• /
• pp.119-124
• /
• 1975

By means of in vitro studies, in which isolated suboesophageal of the Bombyx silkworm were cultured, it was shown that at least two Kinds of substances are biosynthesized and exert independent effects on determination of diapause or non-diapause in silkworm eggs. They are referred to as the diapause and non-diapause substance, respectively. Whether diapause or non-diapause eggs are laid may depend upon the different quality of these substances.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.11 no.2
• /
• pp.107-111
• /
• 2005

Impact of microsporidian infection and season on reproductive potential of Bombyx mori L. was investigated in the laboratory. Microsporidian infection significantly (P<0.01) reduced fecundity and hatching and increased sterility and mortality of eggs. Among the microsporidia, Nosema sp. 2 infected silkworm produced eggs with least fecundity and hatching percent as well as highest dead and sterile eggs followed by Nosema sp. 1 and N. bombycis. Microsporidia, in general, significantly reduced fecundity and hatching percent of eggs and increased number of dead and sterile eggs in all the three seasons except N. bombycis in July - August (S3) and Nosema sp. 2 in January February (S1). Since, seed production is the anchor sheet of mulberry sericulture, coefficient of egg lying is considered as an important aspect and the industry quite often facing shortage of disease free layings. The present study indicates that B. mori is more susceptible to microsporidia during S2 followed by S3 and S1 and Nosema sp2. is most virulent followed by Nosema spl. and N. bombycis.

• Journal of Sericultural and Entomological Science
• /
• v.5
• /
• pp.39-42
• /
• 1965

The newly hatched silkworm can not come out with the head ahead, but on the contray, it comes out with the tail ahead when it comes out of the chorion, in case the loose-formed eggs are vibrated artificially, at the end of the incubation. So the newly hatched silkworm can not throw off the chorion alone which covers his head. This kind of eggs occurs about 30% when they are vibrated. In case they were raised, they could not grow well and some of them died. The result was quite bad. In conclusion, it would be better to distribute earlier the loose-formed eggs farmers and the loose-formed eggs must not be vibrated at the end of the incubation.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.9 no.1
• /
• pp.59-63
• /
• 2004

By using PAGE, a study was made on the nonspecific esterase spectra of female genital organs and eggs in Bombyx mori L. The expression of 11 esterase bands was detected during ontogenesis of races and inter-races hybrids kept in Bulgaria. The gene activity of 9 esterase loci was assumed. Esterases specific for the spectrum of diapausing eggs were observed. In two esterase zones, intra- and inter-breed polymorphism was found. Based on the same breed specific expression, the existence of correspondence between esterase bands from spectra of different silkworm tissues and organs was suggested. Stage-specific expression of esterases in female genital glands, indicative of differentiated gene activity during ontogenesis, was established.

• Journal of Sericultural and Entomological Science
• /
• no.11
• /
• pp.55-57
• /
• 1970

There are many reports concerning to the restoring times, and the range of times are very wide. Author restored the artificial hatching silkworm eggs 1 ice pit (5$^{\circ}C$) two different method; one restored in directly after protected following different times 24 hours, 48 hours and 72 hours of room temperature (24$^{\circ}C$), another protected above suggested times and room temperature then indirectly keeping medium temperature (1$0^{\circ}C$)6 hours. It was incubated in $25^{\circ}C$ temperature after about 20 days of restoring. Pure line and hybrid silk warm eggs are no difference hatching ratio in 72 hours blocks by restoring. Especially good hatching ratio obtained by the medium temperature treatment rather than directly restoring.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.9 no.1
• /
• pp.117-121
• /
• 2004

The patterns of diapause-associated proteins of silkworm eggs were analyzed by two-dimensional (2-D) gel electrophoresis. Among the hundreds of spots on the 2-D gels, at least two proteins were considered to be associated with diapause. A protein, spot 4, with an approximate molecular weight of 38 kDa and pI 6.1 was observed in the HCI-treated, cold-treated, and diapause eggs, respectively. Spot 4 was undetectable in unfertilized eggs and non-diapause eggs at two days after oviposition, suggesting that this protein may be associated with the entrance to diapause. A protein, spot 11, with an approximate molecular weight of 21 kDa and pI of 61 was detected in the unfertilized, HCl-treated, and cold-treated eggs, respectively, after oviposition by normal moths. In diapausing eggs, a protein corresponding to spot 11 was observed in 3-, 5-, and 30-day-old eggs, while the protein was not detected one-day-old eggs. The protein corresponding to spot 11 was not detected in unfertilized and non-diapause eggs obtained from subesophabeal ganglion (SG)-extirpated moths either. Spot 11 was also considered to be a diapause specific protein, which occurred at only early embryonic stage under the control of diapause-downregulated gene.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.5 no.2
• /
• pp.205-211
• /
• 2002

Previously, genetic relationships among 321 silkworm races preserved in the Department of Sericulture and Entomology, NIAST, RDA were studied using six isozymes comprising 20 loci. As a part of additional studies, three additional isozymes with 7 loci [phos-phoglucomutase (PGM), glucose phosphate isomerase (GPI), malete dehydrogenase (MDH)] from hemolymphs, midgets, and eggs were employed to reevaluate the previous dendrogram (UPGMA method). Although the current study supported the recognition of the previously identified major groups, some minor changes were apparent among the selected 47 forms. The current study showed that the polymorphic loci of GPI from eggs and MDH from hemolymph appear to be responsible characters for generating a new major group in the genetic relationship. Interpreting the data with current additive isozymes may represent more robust genetic relatioships among 321 silkworm races preserved in Korea, until further evidence is available.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.9 no.1
• /
• pp.73-78
• /
• 2004

The impact of low concentration fluoride on toxification was studied by treating $3^rd$ instar silkworm larvae of Qiufeng${\times}$Baiyu (Fluoride resistant strain) and Jinshong${\times}$Haoyue (Fluoride sensitive strain). The $5^th$ instar silkworm larvae of Zhenong-l, Shu-12, Qiufeng ${\times}$ Baiyu, Chunhua ${\times}$ Qhiushi, Jinshong and Haoyue were fed mulberry leaves treated with sodium fluoride at different concentrations to determine its effect on fecundity. Harmful effects of low concentration fluoride at early instars on growth, development and economic characters of Bombyx mori are related to its resistance. Harmful effect on resistant strain Qiufeng${\times}$Baiyu manifested on prolongation of instar duration of 15 and 6% in 70 ppm, where as the sensitive breed Jinshong${\times}$Haoyue manifested with 100% mortality in 50 ppm. The impact of low concentration fluoride on fecundity resulted in considerable increase in formed eggs (9%) and laid eggs (9%) in Zhenong-l and Shu-12 among treated population over control. The present observations emphasis that fluoride apart from exhibiting harmful effects on silkworm growth and development, however, its low concentration do playa vital role in inducing some positive effect on fecundity and cocoon traits.

• Journal of Sericultural and Entomological Science
• /
• v.14 no.2
• /
• pp.113-123
• /
• 1972

The authors studied on the effect of silkworm eggs collected from the whole silkworm egg producers in Korea to know the cocoon crops, and the results are as follows. There was no remarkable correlation on the effect of silkworm eggs quality for the cocoon crops but can be concluded as follows. 1) There was a weak correlation between the hatching ratio and economical hatching ratio but no correlation between economical hatching ratio and cocoon crops. In other word, hatching ratio couldn't be influenced for the silkworm health. 5) Non-hybrid ratio (miss-crossing ratio) influenced to the amount of reelable cocoons and pupation ratio but on this experiment, there was a little influence for the cocoon crops. The authors found that there is no difference between origin and its F$_1$crops under the more suitable conditions. Non-hybrid ratio can be determined the silkworm eggs quality, but notice that the ratio decrease only when used pure origin. 3) There is some correlation between harvesting amounts of reelable cocoon and pupation ratio. In general, the eggs which harvest small amounts of reelable cocoon are lower on the pupation ratio. 4) The influence of cocoon layer ratio is based on the variety absolutely but cocoon crops also has a little influence on the cocoon layer ratio.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.43 no.2
• /
• pp.37-44
• /
• 2021

Mulberry silkworm is classified into uni, bi and multivoltine based on the frequency of diapause incidence. The variation in the incidence of diapause in bivoltine silkworm provides a unique opportunity to study the process of evolution of adaptive plasticity towards seasonal variations. The diapause expression in bivoltine silkworm is highly variable and is determined by environmental factors experienced by the maternal generation. Diapause in natural populations is functionally associated with the overwintering mechanism that facilitates survival in harsh winter conditions. In contrast, under standard commercial rearing conditions, the domesticated bivoltine silkworm is known to enter diapause in every generation. This paper presents a short review of the literature dealing with the role of temperature, photoperiod, diapause hormone and its receptor in diapause induction. Also, we briefly review the incidence of non-diapause eggs in bivoltine silkworm under controlled conditions.