Toxicology study of fraxinellone as ovicidal agents against Mythimna separata Walker and Bombyx mori Linaeus

Fraxinellone is a naturally occurring degraded limonoid isolated from many species of plants in Meliaceae and Rutaceae. Besides structural modification of the lead compounds, the toxicology study of the lead compounds is also a very important procedure to develop insecticidal agents. Herein the toxicology study of fraxinellone was carried out as the ovicidal agent against the eggs of two lepidopteran insects Mythimna separata Walker and Bombyx mori Linaeus. Fraxinellone selectively exhibited an ovicidal activity against the eggs of M. separata. After treatment with fraxinellone, the eggshells of M. separata were shrinked, whereas those of B. mori had no obvious change. The dynamic process of M. separata embryo development demonstrated that the distinct difference between the treated eggs and the control ones was obvious at the second day after treatment, especially, the control embryo finished blastokinesis, whereas the treated ones were still laid at pre-reversion status and a lot of yolk can be seen around the embryo. It ultimately resulted in the eggshell withered and the egg hatching inhibited.

Metabolism of aged seeds. Changes in rye embryo polyribosomes during seed aging

Germination, total dehydrogenase activity, ribosomal proteins and ribonucleic acids of embryos obtained from winter rye harvested in different years and of distinctly differing viability were studied. Diminishing viability was accompanied by declines in the amount of ribosome-bound mRNA and a drop in the intensity of its synthesis during germination. Electrophoretic analysis of control embryo (fully viable) ribosome proteins revealed 55 different bands: 10 acidic and 45 basic. The embryos of aged seeds had 43 different bands of which 8 were acidic, 35 basic and almost all of which had an altered electrophoretic mobility as compared with the control sample. As aging progressed, the percentages of lysine, histidine and arginine increased while those of tyrosine, methionine, proline and serine decreased.