Abstract
In 2004 to 2006, organophosphorus, synthetic pyrethroid insecticides, and insect growth regulators (lufenuron and flufenoxuron: IGRs), were sprayed on sugar beets against first-generation larvae of cabbage armyworms in late June to early July, which resulted in equally successful control effects. In September, however, with no additional insecticide application, damage by second-generation larvae varied depending on the insecticide applied in the previous generation. The sugar beets sprayed with IGRs suffered little damage, in contrast to those sprayed with organophosphorus and synthetic pyrethroid insecticides, which suffered severe damage. From these results, we conclude that these differences are a result of the long-term effect of IGR insecticides on cabbage armyworms, rather than of the retention of natural enemies by the selective effects of the IGRs.
