Study on Population Dynamic of Hyperparasitoids of Myzus persicae (Sulzer)

Species, amounts and population dynamic of hyperparasitoids of Myzus persicae (Sulzer) were investigated systematically in tobacco fields and breeding greenhouse. The results showed that there were three hyperparasitoids of Myzus persicae, including Pachyneuron aphidis (Bouche), Asaphes suspensus (Nees), and Dendrocerus carpenteri Curtis. The occurrence of the hyperparasitoids was 25 days behind those of Aphidius gifuensis, but the peak occurrence had only 5 day difference, which is one of the major factors restricting the quantity of Myzus persicae population in tobacco field. At breeding greenhouse all year round the highest hyperparasitic rate was 65.0%, but the emergence rate of Aphidius gifuensis was less than 1.0%. In field during production cycle the highest hyperparasitic rate did not exceed 10%. At the process of breeding greenhouse, the highest emergence rate of Aphidius gifuensis was 7 and 21 days after releasing Aphidius gifuensis, but the hyperparasitic rate was at lowest during 7 and 14 days after releasing Aphidius gifuensis. So it was suggested that the best time of producing Aphidius gifuensis was 7 and 14 days after releasing Aphidius gifuensis in field during a production cycle.