Development of potential microbial agents with two new entomopathogenic fungal strains to control the red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

Abstract

Abstract Background Entomopathogenic fungi, representing a class of microbial agent, have been widely used in the field of pest management. The objective of this work was to isolate different species of fungi and to evaluate their virulence against the destructive and invasive red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae). Results Two new entomopathogenic fungal strains isolated from dead diseased RPWs were identified as Metarhizium anisopliae ZZ-A1 and Fusarium oxysporum ZZ-L1 using growth characteristics, morphology, and rDNA-ITS sequence amplification. Bioassays showed that M. anisopliae ZZ-A1 strain exhibited significantly higher corrected mortality than F. oxysporum ZZ-L1 strain (90.92 vs. 77.28%) in fourth instar RPW larvae 12 days after treatment with a concentration of 1.0 × 10 10 conidia/ml, as well as low median lethal concentration (LC 50 ) and median lethal time (LT 50 ) values. Conclusions The results suggest that both fungal isolates can potentially be developed as effective and persistent a microbial agent against this widespread pest, RPW. However, M. anisopliae ZZ-A1 showed relatively higher insecticidal activity than F. oxysporum ZZ-L1.