Abstract:Nematicidal activity of aloperine,cytisine,N—methylcytisine and matrine Wilts bioas· Sayed by the agar medium method and the cotton.Ball method.The corresponding results by the tw.o methods showed that the nematicidal activity of aloperine was the strongest· Its log(1/ID50)(mol/eotton ban)=8.67 was also the strongest in comparison with Re。 Maticidal activity of seven other quinolizidine alkaloids bioassayed by the same method in lit· erature.A hypotheSis that nematicidal activity of quinolizidine alkaloids is mainly determined by types of functional group pair and types of functional group in their molecular structur~ waS prop06ed.BaSed 0n the hypothesis,the structures of alkaloids with strong nematicidal activity were predicted.