Identification and pathogenicity of entomopathogenic fungi for controlling the beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae)

The identification and pathogenicity of fungal entomopathogens aim for controlling the beet armyworm Spodoptera exigua L. Recently, the control of shallot pest S. exigua keeps using chemical insecticides. Chemical insecticides can cause pest insects to become resistant, demise of useful insects and environmental problem by abundant residue. Therefore, a biological control agent which is safe and effective needs to be sought and developed as an alternative for pest control. In this case, an entomopathogenic fungi is one of the alternatives for controlling shallot pest S. exigua. Many entomopathogenic fungi are associated with soil ecosystems. Fungal entomopathogens are obtained from the land planted with crops and fallow land. Entomopathogen fungi appear from the ground to catching the insect pest, usually Tenebrio molitor larvae was used. This research aims to isolate, characterize, and identify entomopathogen fungi, as well as figuring out the pathogenicity for controlling shallot pest S. exigua. The research results showed that entomopathogen which infects T. ,olitor is the entomopathogen fungi, it caused death in shallot pest S. exigua. Three kinds of entomopathogen fungi were successfully sub-cultured on SDAY media (sabouraud dextrose agar + yeast). These three types of fungi were characterized as Metarhizium anisopliae, Beauveria bassiana and Verticillium lecanii. From the three types of entomopathogen fungi, of which spore germination being tested, M. anisopliae has viability over 95% in average. Meanwhile, B. bassiana and V. lecanii have viability below 95% averagely. Average diameter of each fungal entomopathogen colony of M. anisopliae, B. bassiana and V. lecanii is relatively the same, no siginificant differences were observed. Nevertheless, in general the largest diameter of the colony from early observation until the end of the observation (20 day after inoculation) was found on M. Anisopliae, while V. lecanii generated more conidia when cultured on rice substrate and B. bassiana produced more conidia when cultured on wheat substrate. The observation results on the laboratory indicated 2 g/L water concentration of the entomopathogen fungi of B. bassiana and V. lecanii is capable of annihilating S. exigua larvae until 90%, whereas M. anisopliae with the same concentration caused mortality of S. exigua up to 98%. The results of this research showed that the three types of entomopathogen fungi obtained (B. bassiana, M. anisopliae and V. lecanii) cpotentialy to n be considered for development of biological control agents on shallot pest S. exigua.