Study on Predatory Function of Arma chinensis on Spodoptera litura（Fabricius）

Predatory function of Arma chinensis on Spodoptera litura (Fabricius) was determined in laboratory and field conditions. The results indicated that adults of Arma chinensis had the strongest predatory function on the 1^st-2^nd instar larvaes of Spodoptera litura. The predatory ability of A. chinensis was declined with the growth of S. iturallarvae . The predation amount of the 3^rd instar nymphs was significantly lower than that of the 5^th instar nymphs and adult. When the ratio of releasing A. chinensis to S. litura larvae was 1:15, the predation amount and rate were the highest. The predation amount tended to be stable with the increase of density. The field experiment results indicated that the number of S. litura was controlled effectively after the release of A. chinensis. As the processing time extended, the insect reduction rate increased gradually. The insect reduction rate tended to be stable after 15 days.