Studies On Chemical And Color Communication Mechanisms Among Tea And Tea Green Leafhopper And Mymarid

Tea green leafhopper (Empoasca Vitis Gothe), one of major tea pests in China, has caused severe damage on quality and output of tea. At present, chemical control is the main means, which is easy to cause the problems such as pesticide residues overweight. As a result, people pay more and more attention to biological control. Mymarids are egg parasitoids of leafhoppers and have a good application prospects in biological control of leafhoppers.In this study, we measured the behavioral responses of tea green leafhoppers or mymarids to quest the chemical and color communication mechanism among tea, tea green leafhopper and mymarid. The main results are as follows:1. In order to evaluate the trapping effect of the tea green leafhopper pheromone, sticky bud green plates with the leafhopper pheromone were field tested in the tea garden. The results showed that: the leafhopper pheromone is attractive to leafhoppers.2. Behavioral responses of mymarids to tea volatiles were measured in a Y-tube olfactometer. The odor sources include twigs damaged by leafhoppers, leaves damaged by leafhoppers, healthy leaves from damaged plants, Linalool, E-2-Hexenal, Z-3-Hexen-1-ol, Benzaldehyde, Methyl salicylate, Geraniol, Indole, Z-3-Hexenyl acetate, Methyl Jas-monate, E-2-Pentenal, Z-2-Penten-1-ol, Allyl isothiocyanate, Nerol, Ocimene, Acetophenone, Pentanol, Hexanol, 1-penten-3-ol, Z-Jasmone,β-Ionone,α-Terpinene, Phenethyl alcohol,α-Terpineol, (+)-Cedrol, (+)-3-Caren,α-Humulene and Benzyl alcohol. The following odor sources have showed significant attracting effect on mymarids: 3g twigs damaged by tea green leafhoppers, 4g leaves damaged by leafhoppers, 2g or 3g healthy leaves from damaged plants, 10-4g/ml Linalool, 10-4g/ml 1-penten-3-ol, 10-4g/m or 10-2g/ml Z-Jasmone. 3. Pure white, stone yellow, apple green, ink green, sea blue, peach red, orange, sky blue, bud green and Jasmine yellow, these 10 types of sticky colored plates were field tested in the tea garden. The results showed that: Both the leafhoppers and the mymarids preferred jasmine yellow. The numbers of species and individuals trapped on the different sticky colored plates were significant different. Jasmine yellow and bud green plates trapped the highest numbers of species and individuals. The most of the trapped insects were pest.4. The tea green leafhopper's egg parasitism were observed by regularly picking 30 tea shoots from the fixing tea gardens, dissecting the tea green leafhoppers'eggs from the shoots and rearing the eggs in the petri dishes. The results showed that: The mymarids follow the tea green leafhoppers population obviously according to the investigation. The amount of eggs in the stems were different within different shoot positions. The number between the base of 2nd leaf below bud and the base of 4th leaf below bud is largest. It is also detected that there were some differences of egg parasitic percentages among ten typical tea gardens.5. The egg parasitoids were identified as two species of mymarids: Stethynium empoascae Subba Rao and Schizophragma parvula Ogloblin. Stethynium empoascae is the dominant species.