Abstract:The third instar larvae of cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), were topically treated with two pyrethroid insecticides deltamethrin and fenvalerate, at dosages causing 30% mortality (LD30) to determine their effects on chemical communication system of the adult survivors. The results showed that pyrethroids had no effect on the calling behaviors of the survivors, and 73%-82% calling behavior appeared at 8-8.5 h after the initiation of darkness at the third scotophase on the treated and untreated females as well. No difference appeared between the titer and percentage of the sex pheromone components in control females and female survived from larvae treated with fenvalerate. However, the titers of major component, Z11-16 ∶ Ald, and the minor components, Z9-16 ∶ Ald and Z7-16 ∶ Ald, as well as the total titers of the sex pheromone blend in the survived female moths treated with deltamethrin were significantly higher than that of the untreated female moths. The ratio of two active components, Z11-16 ∶ Ald to Z9-16 ∶ Ald in the female moths treated with deltamethrin differed significantly from untreated female moths.