The effect of dietary nickel on the immune responses of Spodoptera litura Fabricius larvae

► Lower concentrations and/or shorter durations of Ni exposure stimulate PO activity and encapsulation response. ► Higher concentrations and/or longer durations of Ni exposure inhibited PO activity and encapsulation response. ► Tpye and extent of effects on immune responses of Spodoptera litura varied with Ni concentrations and exposure periods.