Mortality and maize leaf consumption of Chilo partellus (Lepidoptera: Pyralidae) larvae treated with Beauveria bassiana and Metarhizium anisopliae

Abstract

Second and third instar Chilo partellus larvae were treated with Beauveria bassiana and Metarhizium anisopliae and measurements made of mortality and daily consumption of maize leaf. At the concentration of 1 × 108 conidia/ml, 100% mortality of second and third instar larvae was observed 6 and 15 days after treatment, respectively. Infection by the fungi was associated with a reduction in mean daily food consumption. Four concentrations of the fungi, 1 × 108, 1 × 107, 1 × 106 and 1 × 105 conidia/ml, were tested against second instar larvae. The higher concentrations, 1 × 108 and 1 × 107 conidia/ml, resulted in greater reduction in food consumption as compared to the lower concentrations (1 × 106 and 1 × 105 conidia/ml). Reduction in food consumption of C. partellus larvae treated with B. bassiana and M. anisopliae may offset the slow speed of kill of the fungi. In a glasshouse trial, spraying a conidial suspension (2 × 108 conidia/ml) of the fungi resulted in significant reduction in leaf damage caused by second instar larvae.