Abstract
The author investigated the relation between the time of oviposition and the overwintering of eggs, in order to make clear the conditions of the overwintering in the brown planthopper eggs.
The eggs were reared in the weighing bottles in which relative humidity was kept 100 percent under the condition of natural temperature. The results obtained are as follows:
1) The number of hibernated eggs closely related with the time of oviposition at the end of autumn, thereupon the later the eggs were oviposited at this time, the more the hibernated eggs increased.
2) The stage of embryonic development of the hibernating eggs were subjected to the influence of which the time of the oviposition was early or late in autumn.
The later the eggs were oviposited in autumn, the more the hibernated eggs at the yellow spot stage increased.
As the results mentioned above, it was thought that the stage of embryonic development of the hibernated eggs was the yellow spot stage.
3) According to the results of observations on the fluctuation of the percentages of the survival eggs and the eggs having hatching-ability, the percentage of the survival eggs did not decrease remarkably during the overwinter period from the end of January to the beginning of April but the percentage of the eggs having hatching-ability decreased with the time passed from the end of January onwared gradually, and it showed the tendency to decrease rapidly after the growth of hibernated eggs with the rising of the temperature in spring.
