译 名：
A PRELIMINARY STUDY ON THE LIBERATION OF THE HYMENOPTEROUS EGG PARASITES OF THE RICE BORER(SCHOENOBIUS INCERTELLUS WALKER)IN AUTUMN RICE-FIELDS IN KWANGTUNG
作 者：
CHENG HON-YIP Central China Agricultural College
摘 要：
The paddy borer (Schoenobius incertellus Walker) is one of the major ricepests in Kwangtung and many other provinces in China. After the Liberation of ourcountry, various methods have been employed to prevent damages caused by this pest,but it is still a serious destructive insect. According to the report made at theConference for the Control of Paddy Borer held in Hangchow, 1952, in the year of1951, more than 2,500,000,000 catties of rice were damaged by the rice borer in nineprovinces in China. During the last two years, our government has tried to helpthe farmers to control it, directing them to kill the moths and pick the batches of eggs in the seed-beds in spring and autumn, and the results were quite satisfactory.In so doing, when the eggs of the borer were killed, the hymenopterous parasites(those usually found are Trichogramma japonicum, Phanurus beneficiens, Tetrastichusschoenobii, etc.) living inside these eggs were also destroyed. It would be much betterto liberate these parasites harboured within those eggs of the borer plucked, so thatthe number of the parasites in the field can be increased and damage caused by the borerdecreased. Three preliminary experiments were carried out in the summer of 1951in nursery field in Loting and in the summer and fall of 1952 in Canton (one innursery field and one in general rice field). Results of these experiments weresummarized as follows:1. The closer the egg masses batches to the liberation point, the higher is the percentage of parasitism.2. The average percentage of parasitism of the hymenopterous parasites in the egg masses of rice borer is higher within the area 7-10 meters from the liberation point than those beyond this limit (averaging 10% higher in the seed-beds and 38.21% in the paddy field).3. Those egg masses collected from field and used for liberation were placed inside a protecting device. In the summer, they are effective only within 7 days after they have been picked, while in the fall the effective period is doubled. After the effective period, the egg masses must be changed, because nearly all the hymenopterous parasites have emerged.4. Three is no corelation between the percentage of parasitism and the density of the egg masses collected in the seed-beds.5. In the third generation of the paddy borer, more Trichogramma were found inside the egg batches than Phanurus, but in the fourth generation the reverse is true, i. e. the number of Phanurus and Tetrastichus is greater than that of Tricho- gramma.
