Pathogenicity of endogenous isolate of Paramyrothecium (=Myrothecium) roridum (Tode) L. Lombard & Crous against the squash beetle Epilachna chrysomelina (F.)

Abstract

The squash beetle Epilachna chrysomelina (F.) is an important insect pest which causes severe damage to cucurbit plants in Iraq. The aims of this study were to isolate and characterize an endogenous isolate of Myrothecium-like species from cucurbit plants and from soil in order to evaluate its pathogenicity to squash beetle. Paramyrothecium roridum (Tode) L. Lombard & Crous was isolated, its phenotypic characteristics were identified and ITS rDNA sequence analysis was done. The pathogenicity of P. roridum strain (MT019839) was evaluated at a concentration of 107 conidia ml-1) water against larvae and adults of E. chrysomelina under laboratory conditions. The results revealed the pathogenicity of the isolate to larvae with variations between larvae instar responses. The highest mortality percentage was reported when the adults were placed in treated litter and it differed significantly from adults treated directly with the pathogen. Our results documented for the first time that P. roridum has potential as an insect pathogen.