Synthesis of analogues of two compounds with known insecticidal activity, both of which contain a 3,3-dichloro-2-propenyloxy group, produced 2-(trifluoromethyl)-4-phenoxyphenyl 3,3-dichloro-2-propenyl ether, which had weak activity against lepidopterous larvae. Structural modifications around this lead compound led to the development of pyridalyl [Pleo, S-1812; 2,6-dichloro-4-(3,3-dichloroallyloxy)phenyl 3-[5-(trifluoromethyl)-2-pyridyloxy]propyl ether], which belongs to a new class of insecticides. Pyridalyl gives very good control of various lepidopterous and thysanopterous pests on cotton and vegetables, without phytotoxicity. It controls populations of Heliothis virescens F and Plutella xylostella (L) which are resistant to various currently used insecticides. It also produces unique insecticidal symptoms, so it may have a different mode of action from other existing insecticides. Pyridalyl is also less harmful than existing insecticides to various beneficial arthropods, so it should provide an important tool in IPM and insecticidal management programmes for the control of lepidopterous and thysanopterous pests. The first market introduction is expected in Japan and some Asian countries in the years between 2004 and 2005.

No abstract

To create a novel insecticide for lepidopterous pest control, we started modi cations of known compounds having a dichloropropenyl moiety that were reported to be active against lepidopterous larvae. Although the lead compound showed only weak activity, some breakthroughs in modi cations brought us dramatic improvements in insecticidal activity and lead to the discovery of pyridalyl. Pyridalyl is highly active against various lepidopterous larvae, thrips and dipterous leafminers. In contrast, it is less toxic to a wide range of bene cial organisms. Unique symptoms in insects exposed to pyridalyl suggest that it has a distinctive insecticidal mode of action. Pyridalyl is expected to be useful in IPM and IRM programs in crop productions.