Abstract: The antifeedant activities of four different kinds of rosin nitrogen derivatives against Agrotis ypsilon 4 instars were investigated by using the method of leaf disc. The results showed that dehydroabietylamine p-chlorine salicylaldehyde Schiff base(2i) and dihydroabietic isopropanol acyl thiourea(4b) could almost completely inhibit A. ypsilon 4 instars feeding, and the antifeedant rates of 2i and 4b were 86.12% and 85.13% at 1 g/L after 24 hours, respectively. In addition, dehydroabietylamine p-methoxy benzaldehyde Schiff base(2b), dihydroabietic 2-hydroxymethyl-1,3-propanediol acyl thiourea(4c) and dihydroabietic furna acyl thiourea(4g) showed strong antifeedant activities against A. ypsilon 4 instars and their antifeedant rates were 52.04%, 66.70% and 50.48%, respectively. The 50% antifeedant concentration(AFC₅₀) for 2i was 0.04 g/L, which was quite low. The values of AFC₅₀ for 2b, 4b, 4c and 4g were 0.66,0.25,1.47 and 0.69 g/L, respectively. Dehydroabietylamine benzaldehyde Schiff base and dihydroabietic acyl thiourea showed strong antifeedant activities against A. ypsilon 4 instars. Methoxy, chlorine atom and hydroxyl could efficiently increase the antifeedant activities of dehydroabietylamine benzaldehyde Schiff base. The position and number of hydroxyl groups in dihydroabietic acyl thiourea had obvious impact on its antifeedant activities. The changes in the structure of dehydroabietamide and dehydroabietic acyl thiourea had little influence on the antifeedant activities against A. ypsilon 4 instars.

Key words: rosin derivative, Agrotis ypsilon, antifeedant activities, AFC₅₀, structure activity relationship