Biocontrol of the pine processionary moth, Thaumetopoea wilkinsoni (Tams.) (Lepidoptera: Notodontidae) by forest-derived entomopathogenic fungi

Abstract

The pine processionary moth (PPM), Thaumetopoea wilkinsoni Tams. (Lepidoptera: Notodontidae), is an important forest pest in the Mediterranean region. This study demonstrated for the first time the biocontrol potential of entomopathogenic fungi (EPF) isolated from pine forest soils on Thaumetopoea wilkinsoni. The identity of five isolates obtained by the Tenebrio-bait method was established by macroscopic and microscopic features and ITS-rDNA sequencing. Pathogenicity and virulence of novel indigenous isolates on fourth stage larvae of Thaumetopoea wilkinsoni were then determined. PPM1, PPM3, and PPM5 were identified as Beauveria bassiana Vuill. (Hypocreales: Cordycipitaceae); PPM2 and PPM4 were identified as Fusarium oxysporum Schlecht. (Hypocreales: Nectriaceae). All isolates were found to be pathogenic at a concentration of 107 conidia/mL, with virulence varying between 15% and 100%. The pathogenicity of Fusarium oxysporum on Thaumetopoea wilkinsoni was demonstrated for the first time in this study and its virulence was determined to be 76%. In addition, the virulence of Beauveria bassiana PPM1 isolate reached 100% at a concentration of 107 conidia/mL 14 days after treatment. Moreover, the median lethal concentration (LC50) required to kill 50% of the larval population was estimated to be 5.7 x 103 conidia/mL. Our results are important to improve the application of new EPF species as biological control agents in pest management.