Pathogenicity aptness of entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae against Saw-toothed Grain Beetle Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae)

Abstract

The saw-toothed grain beetle, Oryzaephilus surinamensis (Coleoptera: Silvanidae) is one of the most destructive pests known to target foods that are stored. Due to cosmopolitan nature, it is practically certain to be present in any stored food. Excessive application of chemicals can interfere with natural pest control systems by developing resistance and requiring the use of stronger or higher concentrations of the chemicals. The present research was carried out to find a safe and environmentally sustainable substitute for synthetic insecticides to manage saw-toothed grain beetle. Entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae for suppressing the saw-toothed grain beetle Oryzaephilus surinamensis was investigated by using varied fungal concentrations viz. 1×10⁴, 1×10⁶, 1×10⁸, 1×10¹⁰ and 1×10¹² spores/ml in stored split chickpea. Findings of this study have shown that fewer F₁ adults appeared in split chickpea when the highest concentration of B. bassiana was applied as compared to M. anisopliae. Less inhibition percentage of saw-toothed grain beetle adults being found when B. bassiana was applied. Weight loss was more in split chickpea when treated with lowest concentration of B. bassiana.  Adult saw-toothed grain beetles were found to be more susceptible towards M. anisopliae as compared to B. bassiana.  The concentration of 1×10¹² spores per ml of B. bassiana and M. anisopliae are suggested for management of O. surinamensis in stored split chickpea.