Bioefficacy of Azadirachtin, Turmeric Oil and their Mixture against Bihar Hairy Caterpillar, (Spilosoma obliqua Walk)

Azadirachtin and turmeric oil, the major constituents of Azadirachta Indica (neem), and Curcuma longa (turmeric) exhibited significant insect growth inhibition and antifeedant activity against Spilosoma obliqua larvae. The activity of azadirachtin was considerably enhanced following incorporation of different concentrations of turmeric oil in the mixtures. Among the three different proportions (1:1, 2:1, 3:1), azadirachtin-turmeric oil (1:1) mixture recorded pronounced IGR activity (EC₅₀, 1.26 x 10⁻²/2.16 x 10⁻² %) and considerable antifeedant activity (EC₅₀ 2.90 x 10⁻²/1.0 x 10⁻² %) against third/fifth instar larvae. The apparent enhancement in activity of azadirachtin-turmeric oil mixture was attributed to the possible additive, synergistic and/or stabilizing effect of turmeric oil.