Intraspecies variation of Metarhizium brunneum against the green peach aphid, Myzus persicae, provides insight into the complexity of disease progression

Victoria Reingold, Chandrasekhar Kottakota, Nitsan Birnbaum, Malka Goldenberg, Galina Lebedev, Murad Ghanim, Dana Ment

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

BACKGROUND: Intensive application of chemical insecticides is required for aphid pest control. Among the biorational alternatives, entomopathogenic fungi are the most sustainable biocontrol agents; those of the order Hypocreales attack and cause fungal disease in arthropod hosts, with variations in host susceptibility attributed to both fungal and host characteristics. We evaluated inter- and intraspecies variations in Metarhizium spp. virulence and differences in fungal disease progression on adult and nymph stages of the green peach aphid, Myzus persicae (Sulzer), a parthenogenetically reproducing insect species. RESULTS: Minor interspecies diversity was detected between the generalist Metarhizium species examined. Interestingly, significant intraspecies diversity was observed between Metarhizium brunneum isolates Mb7 and MbK. Infected adult aphids demonstrated similar disease progression for both isolates, mortality rates of more than 80% and fivefold reduction in fecundity. However, nymph mortality was detected only following MbK infection, with 50% mortality and significant reduction in molting rates. Confocal laser scanning microscopy demonstrated the variation in the disease stages of conidial adhesion and hemocoel colonization on each examined day post inoculation for each isolate. Significantly faster disease progression was observed in MbK-infected versus Mb7-infected nymphs, the latter demonstrating a higher percentage of uninfected nymphs accompanied with aphid molting. CONCLUSIONS: The observed intraspecies variation suggests that altered conidial adhesion to the nymph cuticle is a major factor affecting virulence. We prove the role of nymph ecdysis as a defense mechanism disrupting fungal infection. Because significant differences were observed between closely related isolates, this study emphasizes the importance of appropriate isolate selection for biological control.

Original languageEnglish
Pages (from-to)2557-2567
Number of pages11
JournalPest Management Science
Volume77
Issue number5
DOIs
StatePublished - 1 May 2021
Externally publishedYes

Keywords

  • Metarhizium
  • Myzus persicae
  • biocontrol
  • entomopathogenic fungus

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Insect Science

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