Morphological and molecular identification of the local entomopathogenic fungus Purpureocillium lilacinum and its pathogenicity against the larvae of superworm Zophobas morio (Coleoptera: Tenebrionidae)

Abstract

Entomopathogenic fungi (EPF) are used as a sustainable substitute for chemical insecticides and have been recognized as effective biocontrol agents for mitigating insect pest populations. In this study, a naturally-occurring beneficial EPF, Purpureocillium lilacinum CBBS3.12 (Hypocreales: Ophiocordycipitaceae) from a cabbage farm was isolated and identified by combining morphological and molecular (ITS rDNA region) diagnostic characters. Fungal morphological key characters were consistent with the established species description and were subsequently validated through their ITS rDNA sequences, showing high sequence similarities to P. lilacinum isolates from diverse geographical locations, such as Mexico, the USA, Austria, Israel, China, and India. Additionally, the pathogenicity of P. lilacinum CBBS3.12 against the last instar larvae of Zophobas morio (Coleoptera: Tenebrionidae) was investigated, revealing significant variations in insect mortality based on different fungal concentrations. The highest mortality was recorded at a concentration of 6.0 x 108 spores mL−1, 6 and 12 days post-inoculation. This investigation underscores the promising capabilities of P. lilacinum CBBS3.12 as a biocontrol organism targeting Z. morio. The present study warrants a more comprehensive evaluation of its virulence against diverse agricultural pests and the identification of its active metabolites and compounds to enhance our understanding of its potential application in pest management programs.