Taxonomy of Non-sporulating Bacteria Tested in Biological Control Against Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae)

Abstract

The complete analysis of the 16S rRNA gene of some non-sporulating bacterial isolates from the soil led us to a reliable taxonomic classification, allowing us to explore its entomopathogenic potential against insect-pest Spodoptera frugiperda. Many studies have shown the rapid development of resistance of S. frugiperda in relation to the methods that have been used in recent decades. Therefore, new research exploring the potential of new soil isolates is important. Thus, a comparative study between the complete and partial taxonomic classification based on 16S rRNA gene was realized as the basis for biological studies. Non-sporulating bacterial isolates were used in lethality bioassays against S. frugiperda larvae to compare bioassays efficacy using Bacillus thuringiensis (Berliner) (Bt) strains and the commercial product Dipel®. The results confirmed the strong resistance of this pest-larvae once it developed until the adulthood phase in all bioassays, applying sporulating or non-sporulating bacteria. Furthermore, an accurate phylogenetic position of the non-sporulating bacterial isolates become possible showing basically three species: Brevibacillus nitrificans, Curtobacterium sp. and Arthrobacter echigonensis. Besides the new biotechnological options for those bacterial isolates, according to the results further research should be done with new bacterial isolates in order to discover its potential to control S. frugiperda, thus assisting Bt in pest control.