Laboratory evaluation of Beauveria bassiana (Balsamo) Vuillemin against Indarbela quadrinotata Walker (Lepidoptera: Metarbelidae) - a key pest of Casuarina equisetifolia L. in Tamil Nadu

The bark eating caterpillar, Indarbela quadrinotata Walker is a serious pest of Casuarina equisetifolia in Tamil Nadu State. Survey conducted in plantations located in different parts of the State resulted in detection of a potential strain of the biocontrol agent, Beauveria bassiana. Laboratory evaluation of B. bassiana against l. quadrinotata revealed that the fungal suspension at concentrations of 2 x 10⁶, 2 x 10⁷ and 2 x 10⁸ spores/ml was able to kill 66.67 per cent larvae. The fungus at a concentration of 4 x 10⁸ spores/ml gave 100 per cent mortality of the test larvae. The LC₅₀ at 240 hours was 1.6 x 10⁶ spores/ml and the LT₅₀ for the most effective concentration was 82.86 hours.