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The organophosphorus pesticide poisoning of the silkworm Bombyx mori is one of the major events causing serious damage to sericulture. Added low-dose rare earths are demonstrated to increase resistance in animals. However, very little is known about whether or not added CeCl can increase resistance of silkworm to phoxim poisoning. The present findings suggested that added CeCl to mulberry leaves markedly increased contents of protein, glucose and pyruvate, and carbohydrate metabolism-related enzyme activities, including lactate dehydrogenase, succinate dehydrogenase and malate dehydrogenase, and attenuated free amino acids, urea, uric acid and lactate levels and inhibited the protein metabolism-related enzymes activities, such as protease, alanine aminotransferase and aspartate aminotransferase in the haemolymph of B. mori, under phoxim toxicity. These findings suggest that added CeCl may improve protein and carbohydrate metabolisms, thus leading to increases of growth and survival rate of B. mori under phoxim stress. [ABSTRACT FROM AUTHOR]

Bombyx mori nucleopolyhedrovirus (BmNPV) causes infection in the silkworm that is often lethal. The infection is hard to prevent, partly because of the nature of the virus particles and partly because of the different strains of B. mori. Titanium dioxide nanoparticles (TiO NPs) have been demonstrated to have antimicrobial properties. The present study investigated whether TiO NPs added to an artificial diet can increase the resistance of B. mori larvae to BmNPV and examined the molecular mechanism behind any resistance shown. The results indicated that ingested TiO NPs decreased reactive oxygen species and NO accumulation in B. mori larvae under BmNPV infection, which in turn led to a decrease in their growth inhibition and mortality. In addition, the TiO NPs significantly promoted the expression of resistance-related genes, including those encoding superoxide dismutase, catalase, glutathione peroxidase, acetylcholine esterase, carboxylesterase, heat shock protein 21, glutathione S transferase o1, P53, and transferring and of genes encoding cytochrome p302 and nitric oxide synthase. These findings are a useful addition to the understanding of the mechanism of BmNPV resistance of B. mori larvae in response to TiO NPs addition. Such information also provides a theoretical basis for the use of TiO NPs in sericulture. [ABSTRACT FROM AUTHOR]