›› 2013, Vol. 56 ›› Issue (6): 708-714.

• SHORT COMMUNICATIONS • Previous Articles    

Synergistic effects of optical brighteners on the insecticidal activities of Iranian nucleopolyhedrovirus isolates against Helicoverpa armigera (Lepidoptera: Noctuidae) larvae


  1. (Department of Plant Protection, Faculty of Agriculture,University of Maragheh5518183111, Maragheh, Iran)
  • Online:2013-06-20 Published:2013-06-20

Abstract: In order to improve the biological activities (LC50 and LT50 values) of two geographic isolates of Helicoverpa armigera nucleopolyhedrovirus (EAZ-I and EAZ-II), collected from East-Azarbaijan, Iran, some optical brighteners have been combined with the isolates under laboratory conditions to test their activity against early 2nd instar larvae of H. armigera. The results demonstrated that the EAZ-I isolate had better insecticidal activity than EAZ-II due to its lower LC50 and LT50 values of 1.98×103 OB/mL and 122.7 h, respectively. All the optical brighteners used in this study could efficiently enhance virus biological activities, especially Tinopal F-3543 in combination with EAZ-I showing the lowest LC50 at 0.2% level (5.16×102 OB/mL), with 3.84 times higher activity than that of the virus alone. The relative speed of kill demonstrates that all the optical brighteners improved LT50 of the isolates, of which Tinopal F-3543 was identified as the most effective one. These findings suggest that the optical brighteners which target PM permeability can be considered as important alternatives to combine with HearNPV formulations in IPM programs.

Key words: Helicoverpa armigera, nucleopolyhedrovirus, geographic isolates, optical brighteners, insecticidal activity, synergistic effects, LT50, LC50