Beauveria bassiana and Metarhizium are both entomopathogenic fungi, meaning they are specialized to infect and kill insects. They achieve this through a similar mode of action, which involves a multi-step process:
Attachment and Penetration: These fungi have specialized structures, such as spores or hyphal bodies, which allow them to adhere to the cuticle (outer covering) of insects. Once attached, they produce enzymes that break down the insect’s cuticle, enabling them to penetrate and enter the insect’s body.
Invasion and Colonization: Once inside the insect, the fungi start to grow and multiply, spreading through the insect’s body. They release enzymes and toxins that help break down the insect’s internal tissues, ultimately leading to the insect’s death.
Nutrient Absorption: As the fungi continue to grow, they extract nutrients from the insect’s body, using it as a food source to support their own growth and reproduction.
Disruption of Insect Physiology: The fungi can disrupt the insect’s physiological processes, including its immune system and hormonal regulation, further weakening the insect’s ability to defend against the infection.
Spore Formation and Dispersal: Once the fungi have consumed enough nutrients and grown sufficiently, they start producing new spores or conidia. These spores are the reproductive structures of the fungi and are formed in large numbers. When the insect’s body is fully consumed, the spores are released into the environment, where they can infect other susceptible insects.
Overall, Beauveria bassiana and Metarhizium use a combination of physical attachment, enzymatic breakdown, and nutrient absorption to kill insects and reproduce. This natural biological control method is utilized in various forms for pest management in agriculture and forestry.