Abstract: Some characteristics of the humoral defence substance of diapausing pupae of Antheraea pernyi were investigated. The results showed that: (1) After 6 hours of induction with Escherichia coli k-12 antibacterial substance appeared in the haemolymph of the pupae. The antibacterial activity rose to the peak on the 7th day, and disappeared after 15 days. The antibacterial activity induced by injection of salt solution was weaker than that by E.coli, and maintained only about 10 days. (2) In addition to E.coB, Bacillusthuringiensis, Bacillus subtilis as well as Staphlococcus aureus were also susceptible to haemolymph treated with E. coll. The bactericidal effect of the treated haemolymph wasstronger in the first 5 minutes than in the later 15 minutes and was stronger in that induced with E. coli than that with salt solution. (3) B. thuringiensis had the same effect ofinducing antibacterial activity as E. coli, but the diapausing pupae treated with B.Thuringiensis could not devolop and all died after 3 days, while those treated with E. coliedosed normally. (4) Different dosages within a certain range of E. coli produced the sameeffect on induction of antibacterial activity.

Key words: Antheraea pernyi pupa, validity period, antibacterial activity, induction source, induction quantity