Nanosilver is an environment-friendly, harmless alternative of traditional disinfectants which can be potentially applied in the sericulture industry. However, the effects of nanosilver on the intestinal bacterial community of the silkworms (Bombyx mori L.) are unclear. In this study, Illumina MiSeq high-throughput sequencing technology was used to assess the intestinal bacterial community in both male and female silkworms while treated with different concentrations of nanosilver. We found that nanosilver significantly influenced the composition of silkworm intestinal bacterial community on the different taxonomic levels. Most conspicuously, the abundance of Firmicutes was increased by the treatment of 20 mg L−1 nanosilver but decreased by that of 100 mg L−1 nanosilver at the phylum level. The same trend was observed in Bacilli at the class level and in Enterococcus at the genus level. In some extreme cases, application of nanosilver eliminated the bacterium, e.g., Brevibacillus, but increased the population of several other bacteria in the host intestine, such as Blautia, Terrisporobacter, Faecalibacterium, and some bacteria could only be found in nanosilver treatment groups, e.g., Dialister. In addition, although nanosilver generally showed negative effects on the cocooning rate in a dose-dependent manner, we found that 20 mg L−1 nanosilver treatment significantly increased the body weight of silkworms and did not show negative effects on the survival rate. These results indicated that the intestinal bacteria community of silkworm larvae was significantly changed after nanosilver treatment which might consequently influence host growth and development.

The E2F transcription factor family is distributed widely in eukaryotes and has been well studied among mammals. In the present study, the E2F transcription factor 4 (E2F4) gene was isolated from fat bodies of Antheraea pernyi and sequenced. E2F4 comprised a 795 bp open reading frame encoding a deduced amino acid sequence of 264 amino acid residues. The recombinant protein was expressed in Escherichia coli (Transetta DE3), and anti-E2F4 antibodies were prepared. The deduced amino acid sequence displayed significant homology to an E2F4-like protein from Bombyx mori L. Quantitative real-time polymerase chain reaction analysis revealed that E2F4 expression was highest in the integument, followed by the fat body, silk glands, and haemocytes. The expression of E2F4 was upregulated in larvae challenged by bacterial (Escherichia coli, Micrococcus luteus), viral (nuclear polyhedrosis virus), and fungal (Beauveria bassiana) pathogens. These observations indicated that E2F4 is an inducible protein in the immune response of A. pernyi and probably in other insects.

Protein is the main limiting factor and the second most expensive feed component of poultry ration after energy. In many developing countries, poultry feed prices are consistently increasing because of the dependency on imported soybean meal. In order to decrease the dependency of the poultry feed sector on soybean meal it is necessary to find sustainable alternative protein sources. This review summarises recent findings on the nutritive value of maggot meal, earth worm meal, meal worms and silkworm meal and discusses their potential as an alternative protein source for poultry feed sector.

Pebrine caused by Nosema bombycis in the silkworm Bombyx mori L. causes severe economic loss to the sericulture industry. Several species of microsporidia and strains of N. bombycis have been isolated from infected silkworms. The study of the developmental stages of any parasite is important, as it leads to the identification of stages that may be susceptible to control measures. For this study, five microsporidian isolates from B. mori were collected from five different locations in West Bengal, India and a study of the developmental stages from mid-gut smears and histological techniques was undertaken. The observations of mid-gut smears and histological specimens revealed differences in the morphometry and duration of different developmental stages of the parasites.

In this study, silkworm moth (Bombyx mori L.) larvae were regarded as an animal protein source for astronauts in the bioregenerative life support system during long-term deep space exploration in the future. They were fed with mulberry and stem lettuce leaves during the first three instars and the last two instars, respectively. In addition, this kind of environmental approach, which utilised inedible biomass of plants to produce animal protein of high quality, can likewise be applied terrestrially to provide food for people living in extreme environments and/or impoverished agro-ecosystems, such as in polar regions, isolated military bases, ships, submarines, etc.

Respiration characteristics of the larvae during development under two main physiological conditions, namely eating and not-eating of leaves, were studied. Nutrient compositions of silkworm powder (SP), ground and freeze-dried silkworms on the 3rd day of the 5th instar larvae, including protein, fat, vitamins, minerals and fatty acids, were measured using international standard methods.

Silkworms’ respiration rates, measured when larvae were eating mulberry leaves, were higher than those of similar larvae that hadn't eaten such leaves. There was a significant difference between silkworms fed on mulberry leaves and those fed on stem lettuce in the 4th and 5th instars (P<0.01). Amounts of CO2 exhaled by the silkworms under the two physiological regimes differed from each other (P<0.01). There was also a significant difference between the amount of O2 inhaled when the insects were under the two physiological statuses (P<0.01). Moreover, silkworms’ respiration quotient under the eating regime was larger than when under the not-eating regime. The SP was found to be rich in protein and amino acids in total; 12 essential vitamins, nine minerals and twelve fatty acids were detected. Moreover, 359 kcal could be generated per 100 gram of SP (dry weight).

Diapause hormone (DH) and pheromone biosynthesis-activating neuropeptide (PBAN) code for the diapause gene (DH-PBAN) of Bombyx mori Linnaeus. The DH-PBAN gene sequence from the BLAST database was searched against B. mori genomic gene sequences for similarity. Results showed maximum homology with a genomic contig (accession no. D16230). Primers were designed for the intron, exon and promoter regions of the DH-PBAN gene sequence. The corresponding regions were amplified using genomic DNA as template and products of diapause and non-diapause silkworm races were compared. There was no variation in the 425 bp intron and 254 bp exon regions. However, 1.3% nucleotide sequence variation was observed in selected silkworm races. The promoter region showed 4.2% single nucleotide variation in the diapause and non-diapause silkworm races. The promoter region of the diapause gene showed variations in the sequence of the POU (Pit 1, Oct 1 and Unc-86)-binding site of non-diapause and diapause races of B. mori. In phylogenetic analysis, B. mori formed a cluster with other silkworms of the Bombycidae family, whereas the Noctuidae family formed a separate cluster, indicating that the diapause gene is conserved across the insect taxa.

Rearing temperature has an important influence on the efficiency of food utilization by larvae of the silkworm Bombyx mori L. To assess food intake and utilization efficiency in B. mori reared at different temperature combinations, larvae of Pure Mysore race were fed ad libitum on M5 mulberry leaves and reared at four different constant temperatures, viz. 26, 28, 30 and 32°C during instars I to III and combinations of these temperatures during later instars (IV and V). The larvae reared at 28°C (T2) when young and combinations of temperatures 26–26, 28–26, 30–26 and 32–26°C later were taken as controls. The amount of dry food consumed was significantly higher, but a significant decrease in conversion efficiencies (K1 and K2) was noticed in silkworms reared young at 28°C than at the other temperatures. However, the dry food consumed, food converted, assimilation rate and assimilation efficiency increased with the increasing temperature, and larval duration and conversion efficiency decreased significantly with the rise in temperature during both young- and late-instar rearing. Comparisons between these two ages with regard to food utilization parameters were carried out and the factors responsible for these changes are discussed.

The hormetic influence on silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) of the juvenile hormone mimic ω-formyl longifolene oxime propargyl ether (NL13) was assayed. Emulsions containing 2.5, 5.0 and 10.0 ppm of the compound were administered topically as a single dose, to two popular commercial silkworm hybrids, viz. KA × NB4D2 and PM × NB4D2, at 24,48, 72 and 96 h into the 5th instar, and economic characters of the larvae and resultant cocoons measured. A medium and absolute control were maintained in parallel. It was found that administration of 5 ppm of NL13 to 48-h-old 5th instars resulted in the maximum improvement in commercial traits. The possible role of exogenous JH-like compounds in eliciting this response in silkworm is discussed.

In laboratory experiments, pupae of the uzi fly, Exorista sorbillans Wiedemann (Diptera: Tachinidae), an endoparasitoid of the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) were subjected to UV-irradiation for different durations. Upon adult emergence, irradiated and control flies were crossed in all possible combinations and allowed to parasitise healthy silkworms. Adult emergence, fecundity and longevity of the resulting progeny were recorded. Progeny of irradiated E. sorbillans showed significantly reduced adult emergence, oviposicion period and hatchability. The reduction in fecundity was negatively correlated with the duration of exposure to UV radiation. The longevity of uzi flies of both the sexes was also significantly reduced.

The agar gel double diffusion test was evaluated for detection of nuclear polyhedrosis virus infecting the silkworm, Bombyx mori L. (BmNPV). The test was successful using alkali-dissolved BmNPV as antigen. The antiserum raised against dissolved BmNPV gave positive results with a wider range of antigenic concentrations compared to antiserum raised against undissolved BmNPV. Gel plates prepared using phosphate buffered-saline as dissolving medium for agarose gave sharper and clearer precipitation bands compared to those made with sodium carbonate-saline as diluent. Sharp bands were obtained when the experiment was carried out at 25°C, whereas at higher temperature (35°C), the bands were diffused. The test was able to detect antigen concentration as low as 2 × 106 OBs/ml (18.9 μg/ml of antigen protein).

The quantitative and qualitative changes of bacterial flora associated with the silkworm (Bombyx mori) at different stages of its life cycle were studied. Larvae reared on mulberry leaves were dissected and their bacterial populations counted after a 3-day incubation period at 28 ± 2°C. The results showed a higher heterotrophic bacterial population in the fourth and the fifth instars, which coincide with the active feeding stage of the larvae. The similarity of the genera observed in the digestive tract and that observed on the leaves fed to the larvae suggests colonisation of food microflora in the gut following ingestion. The bacteria inhabiting the gut of silkworm were found to be elaborating amylase, caseinase, gelatinase, lipase and urease. The highest percentage of isolates were protease producers followed by lipid and polysaccharide splitters. The results indicate that the bacterial flora play an important role in the digestion of ingested food material.

Heterobeltiosis (relative to better parental variety) and standard heterosis (relative to standard variety) for 10 larval and cocoon quantitative traits among the hybrids between five multivotine and three bivoltine strains of silkworm, Bombyx mori L., were estimated. The results indicated that the hybrids between multivoltine females and bivoltine males gave higher heterosis than their reciprocals. Variance due to general and specific combining ability and the genetic components were also estimated. The role of gene actions governing the different traits studied is discussed.

Grainage parameters, viz. pupal weight, rate of moth emergence, fecundity and hatching were studied among four bivoltine pure races and their five single and four double cross hybrids of silkworm Bombyx mori L. The significant increase in double cross hybrids over pure races was 11.72, 7.43, 19.45 and 12.26% for pupal weight, rate of moth emergence, fecundity and hatching, respectively. The fecundity in double cross hybrids improved significantly over single cross hybrids to the extent of 16.03% whereas pupal weight, rate of moth emergence and hatching increased to the extent of 4.38, 5.90 and 5.76%, respectively.

The extent of standard heterosis and heterobeltiosis was maximum in double cross hybrids and the heterosis was more pronounced for fecundity.

Qualitative assessment of nine promising mulberry varieties with two check cultivars was evaluated with silkworm, Bombyx mori (L.). The feeding experiment revealed that ACC-143 and ACC-203 (S-135) varieties were superior to other varieties and check cultivars in all the economic characters of cocoon. The variety x season interaction was highly significant. ACC-143 and ACC-203 showed significantly better results over other varieties.

The number of instars in the silkworm Anaphe venata was determined using three methods namely: (1) direct observation of cast exuviae by larvae reared through the entire larval stage, (2) use of frequency distributions of head capsule lengths and widths taken from larvae representative of the entire larval stage of the species and (3) morphological observations and examinations of larval segments and anal plates. Seven instars were observed for A. venata. The most reliable method was the direct observation of cast exuviae by larvae reared through the entire larval stage. It is further suggested that either the method of histograms of head capsules or examination of larval segments and anal plates be used to supplement this method for better reliability.

Larva of fifth instar silkworm, Bombyx mori L. (Lepidoptera: Bombycidae), parasitized by uji-fly, Exorista sorbillans (Weidemann) (Diptera: Tachinidae), consumed less food and egested less faecal matter than unparasitized one in the instar period. Uji-fly infested worm showed increased digestibility in the last 2 days while the unparasitized larva ingested excessive amounts of food than needed during these days. A reduction of 18.1% in the mean weight of parasitized worm at pupation was recorded. Further, parasitization resulted in 50.7% reduction in the mean cocoon weight and 51.12% reduction in the mean shell weight. Parasitized worms started spinning a day earlier than the healthy ones and the cocoon spun by the former was abnormal.