Investigations On Small Green Leafhopper, Empoasca Vitis (G(?)the), And Its Egg Parasitoids In Fujian Tea Plantations

Investigations on the small green leafhopper, Empoasca vitis (Gothe), and its egg parasitoids in six tea varieties (Fuyun no.6, Rougui, Maoxie, Huangdan, Tieguanyin and Fudingdabaicha) were conducted at tea plantations of Fujian Agriculture and Forestry University (FAFU), Anxi, Wuyishan and Fuan from June, 2004 to September, 2005. By dissecting of the leafhopper's eggs from the tea shoots under microscope and rearing the parasitized eggs in the laboratory, the egg dynamics of the leafhopper and its egg parasitoids from the six tea varieties were studied. The correlations between the eggs population dynamics of small green leafhopper and biochemical contents in the leaves of six tea varieties were analyzed by using Duncan's program to reveal their potential resistant mechanisms. The main results are as follows:1. The eggs population dynamics tendencies of the leafhopper among five tea varieties coincided generally and with significant seasonal responses. That is, during the periods of May to June and September to November, the eggs population density of the small green leafhopper reached a peak each, while during other periods, both in the cold and hot seasons, of the study, the eggs population dynamics were lower.2. The different egg densities of the small green leafhopper from the five tea varieties investigated revealed different egg laying preferences among the five tea varieties, which indicated the potential resistance within different tea varieties. The egg densities on five tea varieties ranked as follows: Fuyun no.6>Maoxie > Huangdan >Rougui >Tieguanyin, respectively. This result showed that Fuyun no.6 was the most preferential tea variety for small green leafhopper to lay its eggs and Tieguanyin was the unfavourable tea variety for the leafhopper oviposition.3. From the correlation analysis between the eggs of small green leafhopper on tea plants and some main biochemicals in six different tea varieties, it showed that the leafhopper eggs on tea plants were significantly negative correlated with the content of caffeine and GC(r=-0.8536,r=-0.9703 ) and negatively correlated with contents of polyphenols, catechin and GCG( r=-0.8040,-0.7710,-0.8347). This result revealed that the contents of caffeine, GC, GCG, polyphenols and catechin in tea variety maybe as the potential resistant factors to against the small green leafhopper.4. By dissecting of the leafhopper's eggs from tea shoots and rearing the parasitized eggs in the laboratory, 2 species (Stethynium sp. and Schizophragma sp.) in 2 genera of Mymaridae had been found and recorded for the first time. Among the 2 parasitoids collected in Fujian, Stethynium sp. is the dominant species, which occupied 63.89%, and was significantly more than Schizophragma sp.(36.11 %).