author(s)
Ram K Wargantiwar and BK Kang

abstract
Different populations of H. armigera, were collected from major tomato growing districts (Amritsar, ASR; Kapurthala, KPT; Patiala, PTA) of Punjab were treated in the laboratory by leaf dip method with fenvalerate alone and in combination with different ratios of synergists like Piperonyl butoxide (PBO), Tri phenyl phosphate (TPP) and Diethyl maleate (DEM) at ratios of 1:2, 1:3 and 1:5. The biochemical estimations were done with resistant populations collected from Amritsar (ASR) along with the susceptible population procured from National Bureau of Agricultural Insect Resources, Bengaluru (NBAIR) and fenvalerate selected strain (ASR-Sel strain) developed in the laboratory by giving selection pressure with fenvalerate up to 10 generations. The result obtained in the present study revealed that PBO at 1:5 had highest synergistic effect on the selected resistant ASR-Sel (9.13-fold) and resistant ASR (7.06-fold) strains as compared to the susceptible population (2.50-fold). However, TPP and DEM showed slight synergism with the combination of fenvalerate in all the tested ratios. A strong positive correlation (r= 0.99) between monooxygenases and pyrethroid resistance in H. armigera with MFO activity 4.02 and 2.05 fold in ASR-Sel and ASR population was observed as compared to susceptible one. The present studies were conducted to investigate the various biochemical mechanisms involved in imparting resistance in tomato fruit borer, H. armigera during 2014-15 at Toxicology Laboratory, Department of Entomology and Department of Biochemistry at Punjab Agricultural University, Ludhiana.