Effect of neem oil on the toxicity of different synthetic pyrethroids in mixed formulation against the adults of Bagrada cruciferarum Kirk.

The efficacy of cypermethrin, fenvalerate, fenpropathrin and deltamethrin alone and in combination with neem oil in two ratios (1:1, 1:4)was evaluated against the adult painted bug, Bugrada crucfirarum Kirk. On the basis of LC₅₀ values, deltamethrin, fenpropathrin and cypermethrin were respectively 3.99, 2.60 and 2.05 times more toxic than fenvalerate. However, amongst the combinations tested, fenvalerate in combination with neem oil showed synergistic effect with both the ratios (1:1 and 1:4). Other synthetic pyrethroids in combination exhibited antagonism with both these ratios.