The silkworm Bombyx mori feeds exclusively on mulberry leaves and is highly sensitive to pesticides in general. Although mulberry plantations are free of agrochemicals, pesticide drift can occur. Chlorantraniliprole, a novel insecticide of the anthranilic diamides class, has been used to control pests in field crops. In this study, we investigated the biological effects of different concentrations of chlorantraniliprole on B. mori silkworm commercial Brazilian hybrids. To evaluate the toxicity of chlorantraniliprole, bio-assays were carried out and data on the lethal concentrations, symptomatology, morphology and variables of silk production were collected. Results indicated that B. mori is extremely sensitive to chlorantraniliprole, even in low concentrations. The highest silkworm mortality rates were observed in the two highest chlorantraniliprole concentrations, 0.2 and 0.1 ppm. Although lower chlorantraniliprole concentrations did not cause death of all the silkworm larvae, various symptoms of toxicity were observed: feeding cessation, regurgitation, late development and incomplete ecdysis. Such symptoms reflect the morphological changes we observed in the midgut epithelium, which affected nutrient uptake and metabolism, and even the production of cocoons. Exposed larvae also produced thin-shelled cocoons, which constitutes a serious economic problem because this type of cocoon is not useful for the silk industry. The results provided herein confirm the toxicity of chlorantraniliprole in silkworm larvae. Therefore, we strongly suggest that, competent authorities of the National Health Surveillance Agency, in pesticide management should take measures to reduce or eliminate the use of chlorantraniliprole in areas nearest to silkworm cultivation.

This study reports the molecular detection of Bombyx mori nucleopolyhedrovirus (BmNPV) in silkworm strains of the Universidade Estadual de Maringá Brazilian Germplasm Bank (UBGB). DNA extraction was carried out by using six Bombyx mori female moths of each strain, followed by PCR amplification. A pair of primers was designed based on a specific sequence of the baculovirus genome related to the BmNPV ORF 14. Another pair of primers was used to amplify the silkworm Actin A3 gene segment, which was used as positive control. Twenty gene pools were analyzed, and fifteen revealed a fragment of 443 base pairs (bp), which indicated the presence of the BmNPV. The frequency of contaminated moths was as following: 100% for silkworm strains M18-2, M12-2 and J1; 83% for C25, C75 and C24 strains; 66% for KR01; 50% for M11-A; 33% for AS3, B106, M8 and M11 and 16% for C211, E8 and Hindu strains. These are promising results for the identification of contaminated B. mori moths by BmNPV, which may prevent virus proliferation in subsequent generations. We also analyzed DNA samples extracted from B. mori eggs, but the results were not conclusive regarding the detection of the fragments of the expected size (443 bp). The difficulty in detecting BmNPV contamination in B. mori eggs may be due to the low concentration of virus in samples.C. R. das Neves Saez et al.

Beyond the production of silk thread, there are several studies showing that the silk is a great biomaterial for surgical sutures and grafts. This paper shows a new technique to produce silk thread changing the natural cycle of silk production, which is the production of cocoons. This new method has the purpose of producing a silk fabric free of impurities, through flat surfaces. Six different surfaces were tested: Glass, Formica Surface, Steel and Zinc Sheets, Cotton tissue and Burlap Bag. The first five surfaces had not presented enough larvae alive for statistical analysis, because there were several damages in silkworms larvae that resulted in mortality and low silk production. On the other hand, the burlap bag surface presented good results for web construction by biospinning and its use was indicated for silk industry focused on biomaterials. The present study suggested the potential of naturally biospun web, using Bombyx mori, to develop a new technique to produce silk thread matrices that will have several applications at the industry and production of biomedical materials.

Nucleotide sequences have been used to distinguish species and specimens for many years. More recently, the use of a partial sequence of 650 bp of the cytochrome c oxidase I, COI mitochondrial gene, has been proposed for species identification, known as DNA barcodes. In this work, a short sequence of the DNA barcode is described-approximately 250 bp, named as "DNA mini-barcode"-to molecularly identify different silkworm strains maintained at the unique public Germplasm Bank of Bombyx mori, at the Universidade Estadual de Maringá, UEM, Brazil. Analysis revealed no significant differences among the silkworm strains. The phylogenetic tree obtained by the neighbor-joining method and K2P distance, in which specimens of B. mandarina were used as outgroup, clustered all the specimens of B. mori in a unique clade. Genetic variability detect within B. mori was low or nonexistent. In conclusion, the partial region of 250 bp of the mitochondrial gene COI herein analyzed may not be efficient to discriminate silkworm strains from the UEM Germplasm Bank of Bombyx mori.