Chemical basis of resistance in soya bean to cabbage looper, Trichoplusia ni

Thin layer chromatography resolved nine major compounds from the 60%‐methanol extractables from PI 227687 soya bean (Glycine max (L) Merrill) leaves. The flavonoids, daidzein, an unidentified flavonoid X2 (Rf 0·19), glyceollins, sojagol and coumestrol exhibited antifeedant and/or antibiotic effects against the larvae of cabbage looper, Trichoplusia ni Hb. The results indicate that several compounds in PI 227687 soya beans contribute to its antifeedant and/or antibiotic effects against T ni. The role of these compounds in plant resistance to insects is discussed.