Metarhizium Anisopliae fungi

What is Metarhizium anisopliae?

Metarhizium anisopliae is an entomopathogenic fungus – a naturally occurring, soil-dwelling fungus that specifically infects and kills insect pests such as porina caterpillars. Its spores attach to the pest insect’s exoskeleton, germinate, and penetrate the cuticle. Once inside, the fungus grows rapidly, causing the insect to die. Other susceptible pests that come in contact with infected individuals can also become infected, making it an effective biological control agent for targeted insect species – without harming earthworms, bees, or wider soil biology.

In New Zealand, Metarhizium anisopliae is being used as a sustainable alternative to chemical pesticides, particularly for porina caterpillars, and some possible control against grass grubs and root weevils.

How It Works (mode of Action)

  1. Spore Contact – Fungus spores land on the insect’s body.

2. Penetration – Spores germinate and break through the exoskeleton.

3. Colonisation – The fungus multiplies inside the insect, consuming its internal tissues.

4. Death & Spread – The insect dies, and new spores form on its body surface, ready to infect others.

This cycle makes Metarhizium anisopliae a natural, self-sustaining insect control method.

Target Pests in New Zealand

Metarhizium anisopliae is effective against a wide range of soil-dwelling and pasture pests, including:

  • Porina caterpillars (a major pest in New Zealand pastures)

  • Some control against Grass grubs & white grubs (also see Beauveria Bassiana for Grass Grub Control HERE)

By targeting these pests, Metarhizium helps protect pastures, crops, and horticultural systems while reducing reliance on synthetic insecticides.

Benefits of Using Metarhizium anisopliae

✅ Environmentally friendly – reduces chemical pesticide use

✅ Broad-spectrum pest control – effective against multiple insect species

✅ Plant health benefits – research shows it can induce systemic resistance in plants, improving resilience against diseases

✅ Naturally occurring in New Zealand soils – with local strains adapted to native conditions

✅ Compatible with regenerative farming systems

Applications in Pasture & Crop Farming

Metarhizium anisopliae can be applied as a biological insecticide in:

  • Dairy and sheep pastures (for porina control)

  • Regenerative and organic farming systems

Its use supports sustainable agriculture in New Zealand by lowering pest pressure without harming beneficial soil life.

Why Choose Metarhizium anisopliae?

If you are looking for:

  • A biological alternative to chemical sprays

  • Improved pasture persistence and feed quality

  • Support for soil health and biodiversity

  • Long-term, self-replicating pest control

… then Metarhizium anisopliae is a proven tool for integrated pest management.

Safety for Beneficial Insects, Worms & Soil Biology

One of the key advantages of using Metarhizium anisopliae is its selectivity. Unlike broad-spectrum chemical insecticides, it specifically targets certain insect pests and has minimal impact on non-target organisms.

  • Beneficial insects: Research shows that Metarhizium anisopliae mainly infects soil-dwelling pests such as porina, grass grub and root weevils. It does not generally attack beneficial pollinators (like bees) or natural predator insects.

  • Earthworms: Trials have shown that earthworms are not harmed by Metarhizium anisopliae applications, making it safe to use in pasture and cropping systems where worm activity is important for soil health.

  • Soil microbes: Because Metarhizium is a naturally occurring fungus already present in New Zealand soils, applying it does not disrupt the wider soil microbial community. In fact, when used with stimulants like Fish Hydrolysate, it can complement soil biology by adding functional diversity.

  • Environmental safety: Being a naturally existing organism, Metarhizium anisopliae breaks down in the soil over time and does not leave chemical residues.

👉 This makes Metarhizium anisopliae a strong fit for regenerative, sustainable, and organic farming systems, where protecting beneficial species is just as important as pest control.

Application & Best Practice

Recommended Dosage

  • 100ml per hectare

  • For best results, apply with Fish Hydrolysate HERE or another organic food source. This provides nutrients to help keep the fungi alive and active in the soil.

Best Time to Apply

  • Soil conditions: Metarhizium performs best when soils are moist but not waterlogged, allowing spores to spread and infect insect hosts.

  • Temperature: Optimum fungal activity is generally during mild to warm soil temperatures, avoiding extremes of hot, dry conditions.

  • Avoid applying during heavy rain events, which may wash spores away before they establish.

👉 A follow-up application may be beneficial if pest pressure remains high.

Get in touch if this is something of interest to you HERE.