Newly Isolated Paecilomyces lilacinus and Paecilomyces javanicus as Novel Biocontrol Agents for Plutella xylostella and Spodoptera litura

Abstract

Biocontrol offers an attractive alternative to the use of chemical pesticides in agricultural pest management. The development of high levels of resistance to chemical pesticides have forced researchers to find more alternative biological control agents. The aims of this study were to isolate Paecilomyces spp. with high virulence against diamondback moth (Plutella xylostella) and Oriental leafworm moth (Spodoptera litura), and to investigate suitable agro-industrial residues as a substrate used for solid state fermentation for sporulation of isolates. In this study, Paecilomyces spp. were isolated from soil and insects and identified by morphological and sequencing analyses. The pathogenicity of these isolates was evaluated on Pl. xylostella and S. litura to identify strains with the highest virulence. In addition, agro-industrial residues were used as a cheap substrate for investigating a suitable medium for sporulation on an industrial scale. Six strains of Paecilomyces spp. were isolated including one strain of P. lilacinus and five strain of P. javanicus. P. lilacinus PL01 showed the highest virulence against both Pl. xylostella and S. litura with respective LT₅₀ values of 2.51 and 7.09 days. The five isolated P. javanicus strains also strongly infected Pl. xylostella with LT₅₀ values of 2.52~6.59 days. For sporulation, brown rice alone or brown rice mixed with rice husks and wheat bran or rice bran was suitable for cultivating these isolates. Two newly isolated species of Paecilomyces, P. lilacinus and P. javanicus, can be used as biological control agents for controlling Pl. xylostella and S. litura.