Serendipity in the wrestle between Trichoderma and Metarhizium

Area of Science:

• Agricultural Science
• Mycology
• Plant Pathology

Background:

• Trichoderma species antagonize plant pathogens and nematodes.
• Metarhizium species are insect-pathogens used for pest control.
• Understanding inter-fungal interactions is crucial for biological control strategies.

Purpose of the Study:

• To investigate the impact of Trichoderma atroviride antagonism on Metarhizium robertsii conidia stress biology.
• To assess how varying levels of biotic stress affect the tolerance and germination of M. robertsii conidia.

Main Methods:

• Metarhizium robertsii was cultured alone or in dual culture with Trichoderma atroviride under different inoculation timings.
• Conidia from these cultures were subjected to osmotic, oxidative, UV-B, and thermal stress.
• Germination rates and tolerance under stress conditions were evaluated for each treatment.

Main Results:

• Conidia produced under minimal medium (MM) showed the highest tolerance to all stresses.
• Conidia exposed to early or simultaneous Trichoderma inoculation (A0, A2) were non-viable.
• Moderate antagonism (A4, A6) or low-nutrient conditions enhanced conidia tolerance to osmotic, oxidative, UV-B, and thermal stress compared to control (PDA).
• Germination speed was highest for MM conidia, followed by A4 and A6, then control; A0 and A2 conidia did not germinate.

Conclusions:

• Biotic stress from fungal competitors or nutrient limitation can significantly enhance the stress tolerance and germination capabilities of Metarhizium robertsii conidia.
• The timing and intensity of inter-fungal interactions play a critical role in modulating the stress response of entomopathogenic fungi.
• These findings have implications for optimizing the use of Metarhizium in biological control programs by considering environmental and microbial interactions.