Abstract: Fungal microbial pesticides are characterized by high safety, low possibility of resistance and slow action. The chemical pesticides are of quick action and high possibility of resistance. Field trails for control of fall armyworm were conducted with combination of oil suspension Metarhizium anisopliae and reduced dosages of thiamiethonxam and chlorantraniliprole. Metarhizium anisopliae showed slower action against fall armyworm than the chemical pesticides, but showed higher sustainable control than the chemical pesticides. In field trails with combined application of M. anisopliae and the two chemical pesticides under a reduced dosage of 50%, the control was maintained or even better at 5 day post application (dpa) and 15 dpa. The control was 82.6% and 77.2%, respectively, at 25 dpa for combination of M. anisopliae with thiamiethonxam and chlorantraniliprole, which was higher than 67.4% obtained with M. anisopliae alone. Reduced dosage of chemicals in the combination can reduce resistance development and improve persistence. Application of M. anisopliae oil suspension at the base of winter corn can improve the infection rate of fall armyworm mature larvae, thus contributing to reduce overwintering population size and the green management of fall armyworm.

Key words: Metarhizium anisopliae, continuous control, Spodoptera frugiperda