Metarhizium anisopliae

Introduction

Metarhizium anisopliae is an insect-pathogenic fungus used to control a wide variety of insect pests in agricultural ecosystems. Especially valuable in managing soil-dwelling larvae, grubs, and foliar pests like grasshoppers and locusts, it is a vital tool in eco-friendly pest management strategies. Its broad insect host range and safety to non-target organisms make it ideal for sustainable and organic farming.

Scientific Description

Metarhizium anisopliae belongs to the Clavicipitaceae family and is classified as an entomopathogenic ascomycete. Its lifecycle begins when spores (conidia) land on an insect host. These germinate, penetrate the exoskeleton, and grow throughout the insect’s internal tissues, ultimately killing the host. It then sporulates externally, allowing secondary infection of nearby insects.

Mechanisms of action:

• Adhesion and Penetration: Conidia adhere to the insect cuticle and secrete enzymes to breach it.
• Internal Colonization: Fungal hyphae invade the insect hemocoel and multiply, disrupting physiological function.
• Toxin Secretion: Produces destruxins and other mycotoxins that suppress the insect’s immune response and hasten death.
• Reproduction: Spores emerge from cadavers and spread in the environment under suitable humidity.

Benefits

• Broad-Spectrum Insect Control: Effective against grasshoppers, termites, beetles, root grubs, locusts, white grubs, and weevils.
• Safe for Non-Target Species: Minimal risk to beneficial insects, vertebrates, and pollinators.
• Soil Persistence: Survives in soil and re-infects pest populations over time.
• Ideal for IPM: Reduces reliance on chemical pesticides and fits well into Integrated Pest Management systems.
• No Residues or Resistance Issues: Leaves no harmful residues and pests do not develop resistance.

Uses

• Target Pests: Grasshoppers, locusts, termites, beetles, white grubs, root weevils, sugarcane borers.
• Crops: Sugarcane, cotton, maize, rice, groundnut, vegetables, coconut, turfgrass.
• Application Methods:
  • Soil application: 2–5 kg/acre of talc-based formulation with compost/FYM
  • Foliar spray: 5–10 g/L water (with sticking agent) for foliar insects
  • Seed treatment: 4 g/kg seed for soil-borne pests
• Best Conditions: 25–30°C, high humidity (>65%) for successful infection
• Reapplication Interval: 10–14 days during pest pressure cycles

Trivia

• One of the earliest fungi used in classical biocontrol — studied since the 1800s.
• Once called Entomophthora anisopliae, it was reclassified based on molecular phylogenetics.
• Used in locust control programs across Africa and South Asia.
• Forms long-lived resting spores in soil, offering season-long protection.