Field Evaluation of Microbial and Chemical Insecticides for Diamondback Moth and Other Lepidopterous Pests Control on Cabbage

Abstract

The newly introduced experimental Bacillus thuringiensis (BT) pro-ducts and one synthetic chemical were screened in field on their efficacies to control the diamondback moth (DBM, Plutella xylostella), Spodoptera litura and Pieris rapae, and the long-used BT products and synthetic pyrethroids served as the comparing control agents. The results of two field experiments indicated that the newly commercialized SAN415-SC and other experimental BT products such as Florbac-FC, Florbac-XLV, TC0918 and CGA237218 provided better control on the DBM than other brands although suitable dosages still need to be determined. All BT products provided fair control for P. rapac. A newly developed thiourea insecticide/acaricde, Polo (diafen thiuron), performed better than any other entries in this field evaluation on both DBM and S. litura. Two tested synthetic pryethroids had not only lost their abi1iy in controlling the DBM, also resulted in higher DBM counts by reducing both competition from other pests and the parasitization of natural enemies.