Abstract: Objective The bioactivity of twelve novel pyridine ring derivatives of podophyllotoxin were tested against 3rd instar larvae of Culex pipiens pallens. Methods Using WHO bioassay method. Results From twelve novel pyridine ring derivatives of podophyllotoxin, three compounds 4.4、4.5 and 4.6 have more higher toxicities than others, and the LC₅₀ were 1.66, 3.96 and 1.54 mg/L respectively. Conclusion Based on the data obtained in this investigation, it is possible that the dissimilarity in the structure of the analogues leads to their different bioactivity.

Key words: Pyridine ring derivatives of podophyllotoxin, Culex pipiens pallensl, Botanical insecticide