Potential of entomopathogenic fungal culture filtrate Nomuraea rileyi (Farlow) Samson (Hypocreales: Clavicipitaceae) in Bengkulu, Indonesia against corn pest Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae).
Fall Armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) is an important maize crop pest that can cause farmers severe losses if not controlled. Biopesticide of entomopathogenic fungi are an environmentally friendly alternative control measure that can reduce farmers' dependence on chemical insecticides. Although there are several entomopathogenic fungi based insecticides such as entomopathogenic fungi conidia, they have been found to have some weaknesses. They are more stable in nature compared to synthetic insecticides and therefore require a longer time to cause pest mortality, there is a need to formulate other alternatives with the use of entomopathogenic fungi biopesticide culture filtrate. Therefore, this study aimed to evaluate the potential of Bengkulu entomopathogenic fungus Nomuraea rileyi culture filtrate isolate as a control agent against corn pest S. frugiperda. The bioactivity testing was carried out by spraying the second instar larvae of S. frugiperda with N. rileyi culture filtrate at concentrations (%): 1.0, 0.5, 0.75, 0.25, 0.125, 0.625, 0.05, 0.005 and control (sterile water). Results showed that the N. rileyi culture filtrate was able to cause mortality of second instar S. frugiperda larvae, with the mortality rate increasing with increasing culture filtrate concentration (i.e. 0.625% - 1.0%). The highest mortality was recorded at a concentration of 1% reaching 100% on day 3, while at concentration of 0.05 and 0.005%, the mortality of S. frugiperda larvae was under 10%. The culture filtrate of N. rileyi also caused mortality above 50% at concentrations of 0.50% and 0.75%. As such we suggest that the biological insecticide developed from entomopathogenic fungi N. rileyi culture filtrate had the potential to be used as an effective biological control agent (biolarvicide) against S. frugiferda.