Abstract:

The pathogenic Metarhizium rileyi were collected from diseased Spodoptera frugiperda for the purpose of enriching the entomopathogenic fungi resource inAnhuifor green prevention and control of S. frugiperda. In this study, the strain Mr006 was identified using morphological characterization and ITS-rDNA sequence analysis, and the pathogenicity of the strain to the larvae, prepupae, and pupae of S. frugiperda and the field application efficiency were evaluated. The strain Mr006 was identified as M. rileyi and showed pathogenicity in the larvae and pupae of S. frugiperda. A spore concentration of 1×10⁷ spores/mL achieved a corrected mortality of 91.16%, 88.38%, 70.71%, 53.03%, 22.73%, and 76.26% in the 1^st to 5^th instar larvae and pupae, respectively. LC₅₀ values to the 1^st to 5^th instar larvae and pupae were 3.55×10⁴, 8.23×10⁴, 3.63×10⁶, 4.16×10⁷, 4.23×10⁸ and 2.57×10⁵ spores/mL, respectively. LT₅₀ values is negatively correlated with spore concentration and positively correlated with larval instar. At a spore concentration of 1×10⁸ spores /mL, LT₅₀ values to the 1^st to 5^th instar larvae and pupae were 3.47, 3.94, 4.90, 6.73, 9.01 and 4.02 d, respectively. In the field at 20 days after application, the strain achieved a control of over 64% and showed a good persistence against S. frugiperda. The current results indicate the strain Mr006 is highly pathogenic to S. frugiperda and of high biological control potential for further development.

Key words:

Metarhizium rileyi, identification; Spodoptera frugiperda, pathogenicity, control effect