Aspergillus flavus impairs antioxidative enzymes of Sternochetus mangiferae during mycosis
Kamala P D Jayanthi1, Arthikirubha Ayyasamy1, Vivek Kempraj1
1Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessarghatta Lake Post, Bangalore 560089, India.
Abstract:
Insects depend upon cuticular, humoral and cellular defenses to resist mycosis. However, entomopathogenic fungi through co-evolution have developed mechanisms to counter such defenses. Although a plethora of mechanisms of mycosis by entomopathogenic fungi are well-established, studies on the impairment of insects' antioxidative enzymes during mycosis remain elusive. Here, we used the interaction of Sternochetus mangiferae and its associated entomopathogenic fungus, Aspergillus flavus, as a model to validate our hypothesis. Uninfected insects were exposed to fungal spores for infection to occur. We observed symptoms of mycosis within 48 h of incubation period. Biochemical studies on antioxidative enzymes namely catalase, peroxidase and phenoloxidase, in infected and uninfected insects revealed decreased activity of these enzymes. It appears that A. flavus disables the host's antioxidative enzyme system that plays a crucial role in elimination of oxidative toxins produced during mycosis.
Insights
Entomopathogenic fungi like Aspergillus flavus impair insect defenses by reducing antioxidative enzyme activity. This study reveals how Aspergillus flavus disables crucial enzymes in Sternochetus mangiferae during mycosis.
Area of Science:
- Insect pathology
- Mycology
- Biochemistry
Background:
- Insects possess immune defenses (cuticular, humoral, cellular) against fungal infections (mycosis).
- Entomopathogenic fungi have evolved mechanisms to overcome insect immune responses.
- The impact of mycosis on insect antioxidative enzymes is not well understood.
Purpose of the Study:
- To investigate the effect of Aspergillus flavus infection on the activity of key antioxidative enzymes in Sternochetus mangiferae.
- To validate the hypothesis that entomopathogenic fungi impair insect antioxidative enzyme systems.
Main Methods:
- Sternochetus mangiferae insects were exposed to Aspergillus flavus spores to induce mycosis.
- Biochemical assays were performed on infected and uninfected insects.
- Activity levels of catalase, peroxidase, and phenoloxidase were measured.
Main Results:
- Symptoms of mycosis were observed within 48 hours of fungal spore exposure.
- Infected insects showed significantly decreased activity of catalase, peroxidase, and phenoloxidase compared to uninfected controls.
- Aspergillus flavus appears to inhibit the host's antioxidative enzyme system.
Conclusions:
- Aspergillus flavus actively suppresses the antioxidative enzyme system of Sternochetus mangiferae during mycosis.
- This suppression likely contributes to the fungus's ability to overcome host defenses and establish infection.
- Understanding these mechanisms is crucial for developing novel strategies against insect fungal pathogens.
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