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

Hoang Chinh Nguyen,Ngoc Thanh Tam Nguyen,Kuan-Hung Lin,Chia-Hung Su,Minh Khiem Nguyen,Quoc Linh Nguyen,Nhu Nhut Nguyen,Thi Van Anh Tran

doi:10.15835/nbha45110726

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.

Highlights

The diamondback moth (Plutella xylostella) and Oriental leafworm moth (Spodoptera litura) are major pests of cabbage, canola, broccoli, and other crucifers
The objectives of this study were to isolate and identify Paecilomyces spp. as biocontrol agents against diamondback moth (Plutella xylostella) and Oriental leafworm moth (Spodoptera litura) under laboratory conditions, and to investigate suitable agro-industrial residues as a substrate used for solid state fermentation for sporulation of isolates
Six strains of Paecilomyces isolates, designed P. lilacinus (PL) 01, P. javanicus (PJ) 01, PJ02, PJ03, PJ04, and PJ05 were isolated from the original infected insects

Summary

Introduction

The diamondback moth (Plutella xylostella) and Oriental leafworm moth (Spodoptera litura) are major pests of cabbage, canola, broccoli, and other crucifers. To control these pests, farmers all over the world spend more than $1 billion on chemical insecticides each year (Talekar and Shelton, 1993). Biocontrol offers an attractive alternative or supplement to the use of chemical pesticides in agricultural pest management to protect crops (Lopez et al, 2014; Kepenekci et al, 2015). The use of fungal agents for biological control of pests is an important strategy to minimize synthetic chemical pesticides which often have adverse effects on humans, animals, and the environment (Mar et al, 2012). Production processes for fungal biopesticides must be low-cost, and yield high concentrations of viable, virulent, persistent spores that can be stabilized to provide a product shelf-life of 12~18 months (Cliquet and Jackson, 2005)

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