A STUDY ON THE QUANTITATIVE RELATIONSHIP OF HORNED GALL APHID AND ITS HOSTS TO THE YIELD OF THE GALLNUT

Chinese gallnut caused by gall aphids is an important industrial raw material.Horned gall aphid,Schlechtendalia chinensis (Bell),is widely distributed over the south part of China.About eighty percent of the gallnuts is formed by the aphid.Unfortunately,the aphid has almost been uncultivated.It is well known that the aphid,its overwintering hosts,some species of mosses,and its summer host tree must exist side by side in the Chinese gallnut woodland.If anyone of them is absent in the woodland,the gallnut would not be developed.But how much of them are suitable to high yield of the gallnut? A first study has been made on the relationship of the gallnut yield to the aphid population and the density of the overwintering host,Plagiamnium maximoviczii (Lindb.) T.Kop.,i.e.Mnium maximoviczii Lindb.,and the summer host,Rhus chinenses Mill.It has been suggested that the gallnut woodland with 375-450m2 of the moss,3 750 of the host tree and 25-35 millon of the autumn migrant of the aphid inoculated on the moss in the last autumn per ha are able to get a high yeild of the gallnut in the natural conditions.