• International Journal of Industrial Entomology and Biomaterials
• /
• v.9 no.1
• /
• pp.107-109
• /
• 2004

The present investigation reports a phenomenon hitherto unknown in tropical sericulture, wherein dia-pause nature of bivoltine eggs is overcome through a cross with a non-diapausing race of silkworm, Bombyx mori, L. Eggs of bivoltine silkworm Bombyx mori, L. generally do not hatch under tropical conditions. To prevent diapause, they are subjected to acid treatment or low temperature hibernation scheduled. A race developed at KSSRDI is found to prevent the diapause nature of bivoltine eggs when crossed as male parent, without any acid treatment or hibernation schedule. This phenomenon is reported for the first time, being unique, opens up interesting area of research in silkworm genetics of commercial implications in the industry.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.1 no.1
• /
• pp.35-40
• /
• 2000

• International Journal of Industrial Entomology and Biomaterials
• /
• v.10 no.2
• /
• pp.87-94
• /
• 2005

Mating is an essential behavioural social event in the life cycle of silkworm, Bombyx mori (L.) for the perpetuation of population. A number of intrinsic and extrinsic factors and events of significant importance are involved in successful mating and egg deposition by an adult silk moth which besides biochemical, physiological and environmental factors also includes attraction of reproductively competent male and female moth for mating, duration and frequency of mating, age of moth at the time of mating, reuse of male moth in the production of eggs etc. An attempt has been made in this review article to elucidate briefly the behaviour of male towards female moth after eclosion, impact of duration and frequency of mating on egg deposition and oviposition, reuse of mated male moth in the production of quality and quantity eggs etc. in the silk-worm, B. mori and its significance in silkworm seed production.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.5 no.1
• /
• pp.53-57
• /
• 2002

The growth and multiplication of Aspergillus flavus Link and A. tamarii Kita were observed in vitro under variable temperatures of $22-31^{\circ}C$. The matte weight of mycelium and number of conidia/ml were significantly higher (P < 0.01) at the higher temperature than the lower temperature in both the species of Aspergillus. In vivo the mortality in silkworm, Bombyx mori L. with the infection of Aspergillus species was significantly (P < 0.01) different at different temperature and relative humidity conditions.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.5 no.1
• /
• pp.67-71
• /
• 2002

The implications of temperature (25,30 and 35$^{\circ}C$) and relative humidity (60, 70 and 80%) on the pupation patterns were studied in the silkworm, Bombyx mori L. Larvae of two pure silkworm breeds, Pure Mysore (PM) and NB4D2 and their hybrid, PM ${\times}4 NB4D2 were reared under experimental conditions under natural day photoperiodic (LD 12: 12) condition. The three developmental marker events viz., larval ripening, pharate pupal formation and pupal formation occurred at or around the beginning of the photo-phase. The computed of mean vector (equation omitted), based on the circular statistics, also confirmed the above. However, the length of mean vector, r and the mean vector angular variance, s varied according to temperature and humidity conditions imposed; the variations being non-significant. Extreme temperature and humidity conditions, however, resulted in reduction in pupation rate (%) for PM and PM ${\times}4 NB4D2. On the other hand, in NB4D2 pupation percentage reduced below the economic level. The temperature and humidity together seems to exert synergic impact on the pupation rate at least in the silkworm Bombyx mori, L.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.5 no.1
• /
• pp.44-52
• /
• 2002

To understand the relationship among different quantitative traits, correlation studies were performed by utilizing eighty-eight inbred strains of silkworm, Bombyx mori L. on twelve economic characters. Analysis resulted in correlation of 5th instar period with total larval period (r ＝ 0.7882), cocoon weight with shell weight (r ＝ 0.8326), shell weight with shell ratio (r ＝ 0.5067), shell ratio with raw silk ％ (r ＝ 0.7570), raw silk ％ with filament length (r ＝ 0.3490), filament size (denier) with reelability (r ＝ 0.3193) and boil-off loss % (r ＝ 0.2792). Negative correlation was observed among filament length with filament size (r ＝ 0.7582) and reelability with boil-off loss % (r ＝ -0.3236). Correlation of different quantitative characters for quality silk production is discussed.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.9 no.1
• /
• pp.35-40
• /
• 2004

Bombyx mori densonucleosis virus type 1 (BmDNV1)- a non occluded virus causes flacherie disease in the susceptible stocks of the silkworm, Bombyx mori. However, some stocks are non-susceptible. Non-susceptibility to BmDNV1 in B. mori is a unique case where the virus infection is completely inhibited by a single gene of the host. A survey conducted by this institute in some parts of Karnataka state has revealed that, 43.05% of the total incidence of flacherie disease caused by non-occluded viruses, are due to the synergistic infection of B. mori densonucleosis and infectious flacherie virus. Earlier study indicated that rearing of BmDNV1 resistant silkworm stock is effective in protecting silkworm against BmIFV also. In the present study the response of 78 silkworm stocks which include 42 of non-diapausing and 36 of diapausing groups, to BmDNV1 is investigated. Newly ecdysed third instar larvae were inoculated per-os with 10% inoculum of BmDNV1 extracted from the mid-gut of infected silkworm. One non-diapausing and three diapausing silkworm stocks were found to be resistant to BmDNV1. Eleven silkworm stocks were found to possess moderate resistance whereas rest sixty three were found to be susceptible to BmDNV1. Genetic analysis has shown that the resistance to BmDNV1 is autosomally inherited and controlled by a major dominant or a major recessive gene in different silkworm stocks. These resistant stocks can be utilized as the resource material to develop BmDNV1 resistant commercial hybrids. The selection strategies, depending upon the mode of inheritance of resistance in the resource material chosen, are discussed.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.6 no.1
• /
• pp.21-25
• /
• 2003

The implications of temperature $(25, 30 and 35{\times}1^{\circ}C)$ and relative humidity $(60, 70 and 80{\times}2%)$ on the moulting pattern, moulting duration and moulting survival were studied in the silkworm, Bombyx mori L. Larvae of two pure silkworm breeds, Pure Mysore (PM) and NB$_4$D$_2$and their hybrid, $PM{\times}NB_{4} D_{2}$ were reared under experimental conditions under natural day photoperiodic (LD 12:12) condition. Two developmental marker events in the fourth moulting, settling for moult (SM) and completion of moult (CM) occurred at or around the middle of the photophase. The computed mean vector (equation omitted), based on the circular statistics also confirmed the above. Temperature and humidity did not alter the moulting rhythmicity much. However, extreme temperature and humidity conditions reduced moulting survival in PM and $PM {\times}NB_{4} D_{2}$. Further, moulting survival reduced below the economic level in $NB_{4} D_{2}$. The temperature and humidity together seem to exert synergic impact on the moulting survival of the silkworm Bombyx mori, at least in $NB_{4} D_{2}$.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.11 no.2
• /
• pp.135-138
• /
• 2005

Two pairs of DNA primers were designed for the detection of the Zhenjiang (China) strain of Bombyx mori densonucleosis virus (BmDNV-Z). These primers were designed from the nucleotide sequence of major structural protein gene (putative VD1-ORF2). PCR amplification was attempted from different issues (including silk gland, blood, skin and midgut) and feces of the silkworm which infected wit BmDNV-Z were amplified by PCR. Both of the primers gave expected size of in the DNA bands from midgut and feces, but not in the DNA of silk gland, blood and skin. The two bands were sequenced, and their sequence were same as the sequence designed for. BmDNV-Z could be successfully detected in single silkworm after it was infected for 12 hrs, and could not be detected before 9 hrs after infected.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.7 no.1
• /
• pp.87-91
• /
• 2003

BmNPV (Bombyx mori nuclear polyhedrosis virus) causes nuclear polyhedrosis in silkworms. The tolerance of silkworms to BmNPV is controlled by polygenes. This paper reports on the relative tolerance of silkworm breeds among the germplasm maintained at Andhra Pradesh State Sericultural Research ＆ Development Institute (APSSRDI), Hindupur, India. The silkworm larvae out of second moult were per orally inoculated with BmNPV polyhedra $(l{\times}l0^{th}//ml)$ and reared upto spinning. The response to BmNPV had been categorized into apparent tolerance, real tolerance and susceptibility. Among the 145 silkworm breeds screened, 18 bivoltines and 16 polyvoltines were found to have real tolerance to BmNPV.