| Fraxinellone(FR), a plant secondary metabolite, was tested its ovicidal activity against Mythimna Separata, by using poisoned symptoms and histopathology. Meanwhile, its vitellin was also purified. The main results were as follows:1. FR exhibited strongly ovicidal activity against the eggs of M. Separata, and its LC50 value was 5.574 mg/mL.2. At the first day of embryonic development, the germ band of the control was up to the maximum length; to the group treated with 20 mg/mL of FR, part of embryonic germ band was not formed, and a large number of egg yolks and vitellophages were visible. At the second day, to the control, the embryonic inversion was complete and its back was stuck in the eggshell because of the elongation of embryo; to the treated group, their appendages were outward and close to the eggshell. Compared with the control, many egg yolks and vitellophages were around the embryo. At the third day, to the control, the embryo continued to develop, the midgut was visible, and the shape of eggshell was regular; but to the treated, the thin-walled cells existed within its guts.3. At the first day of embryonic development, to the treated group, 20-E was not detected; the concentration of JH-III was 28.03 μg/g(the control: 12.44 μg/g); At the second day, to the control, the ones of 20-E and JH-III were 2.66 and 3.46μg/g, respectively; while to the treated, they were 0.6 and 0.44 μg/g, respectively; At the third day, 20-E of two groups was all not detected; JH-III in the treated group was 0.58 μg/g(the control: 3.54 μg/g). Obviously, FR exhibited its influence on the 20-E and JH-III of eggs of M. separata mainly on first two days.4. The yolk proteins from eggs of M. Separata were purified by using native-PAGE and SDS-PAGE. It was a glycolipoprotein and the molecular weight was 480 kDa. The molecular weights of the two large and two small subunits of vitellin were 196 and 45 kDa, respectively. |
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