Fusarium, an Entomopathogen-A Myth or Reality?
Lav Sharma1, Guilhermina Marques2
1CITAB-Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes and Alto Douro (UTAD), 5000⁻801 Vila Real, Portugal. lsharma@utad.pt.
Abstract:
The Fusarium species has diverse ecological functions ranging from saprophytes, endophytes, and animal and plant pathogens. Occasionally, they are isolated from dead and alive insects. However, research on fusaria-insect associations is very limited as fusaria are generalized as opportunistic insect-pathogens. Additionally, their phytopathogenicity raises concerns in their use as commercial biopesticides. Insect biocontrol potential of Fusarium is favored by their excellent soil survivability as saprophytes, and sometimes, insect-pathogenic strains do not exhibit phytopathogenicity. In addition, a small group of fusaria, those belonging to the Fusarium solani species complex, act as insect mutualists assisting in host growth and fecundity. In this review, we summarize mutualism and pathogenicity among fusaria and insects. Furthermore, we assert on Fusarium entomopathogenicity by analyzing previous studies clearly demonstrating their natural insect-pathogenicity in fields, and their presence in soils. We also review the presence and/or production of a well-known insecticidal metabolite beauvericin by different Fusarium species. Lastly, some proof-of-concept studies are also summarized, which demonstrate the histological as well as immunological changes that a larva undergoes during Fusarium oxysporum pathogenesis. These reports highlight the insecticidal properties of some Fusarium spp., and emphasize the need of robust techniques, which can distinguish phytopathogenic, mutualistic and entomopathogenic fusaria.
Insights
Fusarium fungi exhibit diverse interactions with insects, acting as pathogens, mutualists, or opportunists. Understanding these roles is crucial for developing effective insect biocontrol strategies.
Area of Science:
- Mycology
- Entomology
- Plant Pathology
Background:
- Fusarium species have varied ecological roles, including pathogenicity to plants and insects, and symbiotic relationships.
- Research on Fusarium-insect interactions is limited, often categorizing them as opportunistic pathogens, despite their potential for biocontrol.
- Phytopathogenicity of some Fusarium strains complicates their use as biopesticides, necessitating careful strain selection.
Purpose of the Study:
- To review and summarize the mutualistic and pathogenic interactions between Fusarium species and insects.
- To assert Fusarium entomopathogenicity by analyzing field studies and soil presence.
- To explore the production of insecticidal metabolites like beauvericin by Fusarium species.
Main Methods:
- Literature review of studies on Fusarium-insect associations, focusing on pathogenicity and mutualism.
- Analysis of field data and soil isolation studies to confirm natural insect-pathogenicity.
- Review of research on beauvericin production and its insecticidal effects.
- Summarization of proof-of-concept studies detailing host responses to Fusarium infection.
Main Results:
- Fusarium species display a spectrum of interactions with insects, from mutualism to pathogenicity.
- Certain Fusarium strains, particularly within the Fusarium solani species complex, can be insect mutualists.
- Beauvericin, an insecticidal metabolite, is produced by various Fusarium species.
- Fusarium oxysporum pathogenesis induces histological and immunological changes in insect larvae.
Conclusions:
- Fusarium species possess significant insecticidal properties, with potential for biocontrol applications.
- Distinguishing between phytopathogenic, mutualistic, and entomopathogenic Fusarium strains is essential.
- Further research is needed to develop robust techniques for classifying Fusarium-insect interactions.
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