Synergistic Effect of neem and Pongamia Oils on the bioefficacy of deltamethrin against diamondback moth, Plutella xylostella (L.) (Lepidoptera: yponomeutidae) on cabbage

Laboratory and field studies were conducted to assess the synergistic effect of two plant oils viz., neem and Pongamia on the bioefficacy of deltamethrin 2.5 EC against diamondback moth, Plutella xylostella (L.) on cabbage during 2007–2009 at Indian Institute of Horticultural Research, Bangalore. Under laboratory conditions, the combination of deltamethrin @ 0.5 mL/L and pongamia oil (0.2%) resulted in highest efficacy (86.67%) followed by deltamethrin (0.5 mL/L) and Pongamia oil (0.1%). Under field conditions also, Pongamia oil (0.2%) with deltamethrin (1mL/L) showed good synergism both in terms of reducing P. xylostella and in realizing higher marketable yield of cabbage. The findings indicate the potential of plant oils as synergists of synthetic pyrethroids.